Pilot Handbook

Preface

The Pilot’s Handbook of Aeronautical Knowledge provides basic knowledge that is essential for pilots. This handbook introduces pilots to the broad spectrum of knowledge that will be needed as they progress in their pilot training. Except for the Code of Federal Regulations pertinent to civil aviation, most of the knowledge areas applicable to pilot certification are presented. This handbook is useful to beginning pilots, as well as those pursuing more advanced pilot certificates.

Occasionally the word “must” or similar language is used where the desired action is deemed critical. The use of such language is not intended to add to, interpret, or relieve a duty imposed by Title 14 of the Code of Federal Regulations (14 CFR).

It is essential for persons using this handbook to become familiar with and apply the pertinent parts of 14 CFR and the Aeronautical Information Manual (AIM). The AIM is available online at www.faa.gov. The current Flight Standards Service airman training and testing material and learning statements for all airman certificates and ratings can be obtained from www.faa.gov.

This handbook supersedes FAA-H-8083-25A, Pilot’s Handbook of Aeronautical Knowledge, dated 2008.

This handbook is available for download, in PDF format, from www.faa.gov.

This handbook is published by the United States Department of Transportation, Federal Aviation Administration, Airman Testing Standards Branch, AFS-630, P.O. Box 25082, Oklahoma City, OK 73125.

Comments regarding this publication should be sent, in email form, to the following address: AFS630comments@faa.gov John S. Duncan Director, Flight Standards Service iii iv

Acknowledgments

The Pilot’s Handbook of Aeronautical Knowledge was produced by the Federal Aviation Administration (FAA) with the assistance of Safety Research Corporation of America. The FAA wishes to acknowledge the following contributors: Mrs. Nancy A. Wright for providing imagery of a de Haviland DH-4 inaugural air mail flight (Chapter 1) The Raab Collection, Philadelphia, Pennsylvania, for images of the first pilot license (Chapter 1) Sandy Kenyon and Rod Magner (magicair.com) for photo of 1929 TravelAir 4000 (Chapter 1) Dr. Pat Veillette for information used on decision-making (Chapter 2) Adventure Seaplanes for photos of a ski and float training plane (Chapter 3) Jack Davis, Stearman Restorers Asociation, for photo of a 1941 PT-17 Army Air Corps trainer (Chapter 3) Michael J. Hoke, Abaris Training Resources, Inc., for images and information about composite aircraft (Chapter 3) Colin Cutler, Boldmethod, for images and content on the topic of ground effect (Chapter 5) Mark R. Korin, Alpha Systems, for images of AOA disaplys (Chapter 5) M. van Leeuwen (www.zap16.com) for image of Piaggio P-180 (Chapter 6) Greg Richter, Blue Mountain Avionics, for autopilot information and imagery (Chapter 6) Mountain High E&S Company for various images provided regarding oxygen systems (Chapter 7) Jeff Callahan, Aerox, for image of MSK-AS Silicone Mask without Microphone (Chapter 7) Nonin Medical, Inc. for image of Onyx pulse oximeter (Chapter 7) Pilotfriend.com for photo of a TKS Weeping Wing (Chapter 7) Chelton Flight Systems for image of FlightLogic (Chapter 8) Avidyne Corporation for image of the Entegra (Chapter 8) Teledyne Controls for image of an air data computer (Chapter 8) Watson Industries, Inc. (www.watson-gyro.com) for image of Attitude and Heading Reference system (Chapter 8) Engineering Arresting Systems Corporation (www.esco.zodiacaerospace.com) for EMAS imagery and EMASMAX technical digrams (Chapter 14) Caasey Rose and Jose Roggeveen (burningholesinthesky.wordpress.com) for flight checklist image (Chapter 14) Tim Murnahan for images of EMAS at Yeager Airport, Charleston, West Virginia, and EMAS arrested aircraft (Chapter 14) Cessna Aircraft Company, Columbia Aircraft Manufacturing Corporation, Eclipse Aviation Corporation, Garmin Ltd., The Boeing Company for images provided and used throughout the Handbook.

Additional appreciation is extended to the Aircraft Owners and Pilots Association (AOPA), the AOPA Air Safety Foundation, the General Aviation Manufacturers Association (GAMA), and the National Business Aviation Association (NBAA) for their technical support and input.

Disclaimer: Information in Chapter 14 pertaining to Runway Incursion Avoidance was created using FAA orders, documents, and Advisory Circulars that were current at the date of publication. Users should not assume that all references are current and should check often for reference updates.

v vi

Table of Contents

Preface .................................................................... iii Limitations: ........................................................... 1-17 Private Pilot .............................................................. 1-17 Acknowledgments .................................................. v Commercial Pilot ...................................................... 1-18 Airline Transport Pilot .............................................. 1-18 Table of Contents ................................................. vii Selecting a Flight School ............................................ 1-18 How To Find a Reputable Flight Program ............... 1-19 Chapter 1 How To Choose a Certificated Flight Introduction To Flying ......................................... 1-1 Instructor (CFI) ......................................................... 1-19 Introduction .................................................................... 1-1 The Student Pilot ......................................................... 1-20 History of Flight ............................................................. 1-2 Basic Requirements .................................................. 1-20 History of the Federal Aviation Administration (FAA) 1-3 Medical Certification Requirements ..................... 1-20 Transcontinental Air Mail Route ................................ 1-4 Becoming a Pilot .......................................................... 1-21 Federal Certification of Pilots and Mechanics ........... 1-4 Knowledge and Skill Tests .......................................... 1-21 The Federal Aviation Act of 1958 .............................. 1-6 Knowledge Tests ...................................................... 1-21 Department of Transportation (DOT) ........................ 1-6 When To Take the Knowledge Test ..................... 1-22 ATC Automation ........................................................ 1-6 Practical Test ............................................................ 1-22 The Professional Air Traffic Controllers When To Take the Practical Test .......................... 1-23 Organization (PATCO) Strike .................................... 1-6 Who Administers the FAA Practical Tests? ......... 1-23 The Airline Deregulation Act of 1978 ....................... 1-7 Role of the Certificated Flight Instructor ................. 1-23 The Role of the FAA ...................................................... 1-7 Role of the Designated Pilot Examiner ................... 1-24 The Code of Federal Regulations (CFR) .................... 1-7 Chapter Summary ....................................................... 1-24 Primary Locations of the FAA ................................... 1-8 Field Offices ........................................................... 1-8 Chapter 2 Aviation Safety Inspector (ASI) ................................ 1-9 Aeronautical Decision-Making ........................... 2-1 FAA Safety Team (FAASTeam) ................................ 1-9 Introduction .................................................................... 2-1 Obtaining Assistance from the FAA .......................... 1-9 History of ADM ............................................................. 2-2 Aeronautical Information Manual (AIM) ............... 1-9 Risk Management .......................................................... 2-3 Handbooks ............................................................ 1-10 Crew Resource Management (CRM) and Single- Advisory Circulars (ACs) ..................................... 1-10 Pilot Resource Management .......................................... 2-4 Flight Publications ................................................ 1-11 Hazard and Risk ............................................................. 2-4 Hazardous Attitudes and Antidotes ............................ 2-5 Pilot and Aeronautical Information ......................... 1-12 Risk ............................................................................. 2-6 Notices to Airmen (NOTAMs) ............................ 1-12 Assessing Risk ........................................................ 2-6 Safety Program Airmen Notification System (SPANS) ............................................................... 1-14 Mitigating Risk ....................................................... 2-8 Aircraft Classifications and Ultralight Vehicles .......... 1-14 The PAVE Checklist ................................................. 2-8 Pilot Certifications ....................................................... 1-16 P = Pilot in Command (PIC) .................................. 2-8 Privileges: ............................................................. 1-16 A = Aircraft ............................................................ 2-8 Limitations: ........................................................... 1-17 V = EnVironment ................................................... 2-9 Recreational Pilot ..................................................... 1-17 E = External Pressures ............................................ 2-9 Privileges: ............................................................. 1-17 Human Factors ............................................................. 2-10 vii Human Behavior .......................................................... 2-11 Chapter 3 The Decision-Making Process ..................................... 2-12 Aircraft Construction .......................................... 3-1 Single-Pilot Resource Management (SRM) ........... 2-13 Introduction .................................................................... 3-1 The 5 Ps Check ........................................................ 2-13 Aircraft Design, Certification, and Airworthiness ......... 3-2 The Plan ............................................................... 2-14 A Note About Light Sport Aircraft ............................ 3-2 Lift and Basic Aerodynamics ......................................... 3-2 The Plane ............................................................. 2-14 Major Components ......................................................... 3-3 The Pilot ............................................................... 2-14 Fuselage ...................................................................... 3-3 The Passengers ..................................................... 2-14 Wings ......................................................................... 3-3 The Programming ................................................ 2-15 Empennage ................................................................. 3-6 Perceive, Process, Perform (3P) Model .................... 2-15 Landing Gear .............................................................. 3-7 PAVE Checklist: Identify Hazards and The Powerplant ........................................................... 3-7 Personal Minimums .............................................. 2-15 Subcomponents .............................................................. 3-8 CARE Checklist: Review Hazards and Types of Aircraft Construction ...................................... 3-8 Evaluate Risks ...................................................... 2-16 Truss Structure ........................................................... 3-8 TEAM Checklist: Choose and Implement Semimonocoque ......................................................... 3-9 Risk Controls ........................................................ 2-16 Composite Construction ............................................. 3-9 The DECIDE Model ............................................. 2-18 History .................................................................... 3-9 Detect (the Problem) ............................................. 2-20 Advantages of Composites ................................... 3-10 Estimate (the Need To React) ............................... 2-20 Disadvantages of Composites ............................... 3-10 Choose (a Course of Action) ................................ 2-20 Fluid Spills on Composites ................................... 3-11 Identify (Solutions) ............................................... 2-20 Lightning Strike Protection ................................... 3-11 Do (the Necessary Actions) .................................. 2-20 The Future of Composites .................................... 3-12 Evaluate (the Effect of the Action) ...................... 2-20 Instrumentation: Moving into the Future .................... 3-12 Decision-Making in a Dynamic Environment ............ 2-21 Control Instruments ................................................. 3-13 Automatic Decision-Making ................................... 2-21 Navigation Instruments ........................................... 3-13 Operational Pitfalls ............................................... 2-21 Global Positioning System (GPS) ................................ 3-13 Stress Management ................................................... 2-21 Chapter Summary ........................................................ 3-13 Use of Resources ...................................................... 2-21 Internal Resources ................................................ 2-23 Chapter 4 External Resources ............................................... 2-23 Principles of Flight .............................................. 4-1 Situational Awareness .................................................. 2-24 Introduction .................................................................... 4-1 Obstacles to Maintaining Situational Awareness ..... 2-24 Structure of the Atmosphere .......................................... 4-1 Workload Management ........................................ 2-24 Air is a Fluid .............................................................. 4-2 Managing Risks .................................................... 2-25 Viscosity ................................................................. 4-2 Automation .................................................................. 2-25 Friction .................................................................... 4-2 Results of the Study .................................................. 2-27 Pressure ................................................................... 4-3 Equipment Use ......................................................... 2-27 Atmospheric Pressure ................................................. 4-3 Autopilot Systems ................................................. 2-27 Pressure Altitude ........................................................ 4-4 Familiarity ............................................................. 2-27 Density Altitude ......................................................... 4-4 Respect for Onboard Systems ............................... 2-29 Effect of Pressure on Density ................................. 4-4 Getting Beyond Rote Workmanship ..................... 2-29 Effect of Temperature on Density .......................... 4-4 Understand the Platform ...................................... 2-29 Effect of Humidity (Moisture) on Density ............. 4-5 Managing Aircraft Automation ............................... 2-29 Theories in the Production of Lift .................................. 4-5 Information Management ..................................... 2-30 Newton’s Basic Laws of Motion ................................ 4-5 Enhanced Situational Awareness ............................. 2-30 Bernoulli’s Principle of Differential Pressure ............ 4-6 Automation Management ......................................... 2-31 Airfoil Design ................................................................ 4-6 Risk Management ..................................................... 2-31 Low Pressure Above .................................................. 4-7 Chapter Summary ....................................................... 2-32 High Pressure Below .................................................. 4-8 viii Pressure Distribution .................................................. 4-8 Weight and Balance ..................................................... 5-40 Airfoil Behavior ......................................................... 4-8 Effect of Weight on Flight Performance .................. 5-42 A Third Dimension ........................................................ 4-9 Effect of Weight on Aircraft Structure ..................... 5-42 Chapter Summary .......................................................... 4-9 Effect of Weight on Stability and Controllability .... 5-42 Effect of Load Distribution ...................................... 5-43 Chapter 5 High Speed Flight ........................................................ 5-44 Aerodynamics of Flight ....................................... 5-1 Subsonic Versus Supersonic Flow ........................... 5-44 Forces Acting on the Aircraft ........................................ 5-1 Speed Ranges ........................................................... 5-44 Thrust ......................................................................... 5-2 Mach Number Versus Airspeed ............................... 5-45 Lift .............................................................................. 5-3 Boundary Layer ........................................................ 5-46 Lift/Drag Ratio ........................................................ 5-5 Laminar Boundary Layer Flow ............................ 5-46 Drag ............................................................................ 5-6 Turbulent Boundary Layer Flow .......................... 5-46 Parasite Drag ........................................................... 5-6 Boundary Layer Separation .................................. 5-46 Induced Drag .......................................................... 5-7 Shock Waves ............................................................ 5-46 Weight ........................................................................ 5-8 Sweepback ................................................................ 5-48 Wingtip Vortices ............................................................ 5-8 Mach Buffet Boundaries .......................................... 5-49 Formation of Vortices ................................................ 5-8 High Speed Flight Controls ...................................... 5-49 Avoiding Wake Turbulence ....................................... 5-9 Chapter Summary ........................................................ 5-51 Ground Effect ............................................................... 5-11 Axes of an Aircraft ....................................................... 5-12 Chapter 6 Moment and Moment Arm .......................................... 5-13 Flight Controls ..................................................... 6-1 Aircraft Design Characteristics ................................... 5-14 Introduction .................................................................... 6-1 Stability .................................................................... 5-14 Flight Control Systems ................................................. 6-2 Static Stability ....................................................... 5-14 Flight Controls ............................................................ 6-2 Primary Flight Controls .............................................. 6-2 Dynamic Stability ................................................. 5-14 Elevator ................................................................... 6-5 Longitudinal Stability (Pitching) .......................... 5-15 T-Tail ...................................................................... 6-6 Lateral Stability (Rolling) ..................................... 5-17 Stabilator ................................................................. 6-7 Directional Stability (Yawing) ............................. 5-19 Canard ..................................................................... 6-7 Free Directional Oscillations (Dutch Roll) .............. 5-20 Rudder ..................................................................... 6-8 Spiral Instability ....................................................... 5-20 Effect of Wing Planform ............................................. 5-20 V-Tail ...................................................................... 6-8 Aerodynamic Forces in Flight Maneuvers ................... 5-22 Secondary Flight Controls .......................................... 6-8 Forces in Turns ......................................................... 5-22 Flaps ........................................................................ 6-8 Forces in Climbs ....................................................... 5-23 Leading Edge Devices ............................................ 6-9 Forces in Descents .................................................... 5-24 Spoilers ................................................................. 6-10 Stalls ............................................................................ 5-25 Trim Tabs .............................................................. 6-10 Angle of Attack Indicators ........................................... 5-26 Balance Tabs ......................................................... 6-11 Basic Propeller Principles ............................................ 5-28 Servo Tabs ............................................................ 6-11 Torque and P-Factor ................................................. 5-30 Antiservo Tabs ...................................................... 6-11 Torque Reaction ....................................................... 5-31 Ground Adjustable Tabs ....................................... 6-11 Corkscrew Effect ...................................................... 5-31 Adjustable Stabilizer ............................................. 6-12 Gyroscopic Action .................................................... 5-31 Autopilot ...................................................................... 6-12 Asymmetric Loading (P-Factor) .............................. 5-32 Chapter Summary ........................................................ 6-12 Load Factors ................................................................. 5-33 Load Factors in Aircraft Design ............................... 5-33 Chapter 7 Load Factors in Steep Turns ..................................... 5-34 Aircraft Systems .................................................. 7-1 Load Factors and Stalling Speeds ............................ 5-34 Introduction .................................................................... 7-1 Load Factors and Flight Maneuvers ......................... 5-36 Powerplant ..................................................................... 7-1 Vg Diagram .............................................................. 5-37 Reciprocating Engines ................................................ 7-2 Rate of Turn .............................................................. 5-38 Propeller ..................................................................... 7-4 Radius of Turn .......................................................... 5-39 ix Fixed-Pitch Propeller .............................................. 7-5 Fuel Gauges .............................................................. 7-26 Fuel Selectors ........................................................... 7-26 Adjustable-Pitch Propeller ...................................... 7-6 Fuel Strainers, Sumps, and Drains ........................... 7-27 Propeller Overspeed in Piston Engine Aircraft ...... 7-7 Fuel Grades ............................................................... 7-27 Induction Systems ...................................................... 7-7 Fuel Contamination .................................................. 7-27 Carburetor Systems .................................................... 7-8 Fuel System Icing ..................................................... 7-28 Mixture Control ...................................................... 7-9 Prevention Procedures .......................................... 7-28 Carburetor Icing ...................................................... 7-9 Refueling Procedures ................................................... 7-29 Carburetor Heat .................................................... 7-10 Heating System ............................................................ 7-29 Carburetor Air Temperature Gauge ...................... 7-11 Fuel Fired Heaters .................................................... 7-29 Outside Air Temperature Gauge .............................. 7-11 Exhaust Heating Systems ......................................... 7-29 Fuel Injection Systems ............................................. 7-11 Combustion Heater Systems .................................... 7-29 Superchargers and Turbosuperchargers ....................... 7-12 Bleed Air Heating Systems ...................................... 7-30 Superchargers ........................................................... 7-12 Electrical System ......................................................... 7-30 Turbosuperchargers .................................................. 7-13 Hydraulic Systems ....................................................... 7-31 System Operation .................................................. 7-14 Landing Gear ............................................................ 7-33 High Altitude Performance ................................... 7-14 Tricycle Landing Gear .......................................... 7-33 Ignition System ............................................................ 7-15 Tailwheel Landing Gear ....................................... 7-33 Oil Systems .................................................................. 7-16 Fixed and Retractable Landing Gear .................... 7-34 Engine Cooling Systems .............................................. 7-17 Brakes ....................................................................... 7-34 Exhaust Systems .......................................................... 7-18 Pressurized Aircraft ..................................................... 7-34 Starting System ............................................................ 7-18 Oxygen Systems ........................................................... 7-37 Combustion .................................................................. 7-18 Oxygen Masks .......................................................... 7-38 Full Authority Digital Engine Control (FADEC) ........ 7-20 Cannula ..................................................................... 7-38 Turbine Engines ........................................................... 7-20 Pressure-Demand Oxygen Systems .......................... 7-38 Types of Turbine Engines ........................................ 7-20 Continuous-Flow Oxygen System ........................... 7-38 Turbojet ................................................................. 7-20 Electrical Pulse-Demand Oxygen System ................ 7-38 Turboprop ............................................................. 7-21 Pulse Oximeters ........................................................ 7-39 Turbofan ............................................................... 7-21 Servicing of Oxygen Systems .................................. 7-39 Turboshaft ............................................................. 7-21 Anti-Ice and Deice Systems ......................................... 7-40 Turbine Engine Instruments ..................................... 7-22 Airfoil Anti-Ice and Deice ....................................... 7-40 Engine Pressure Ratio (EPR) ............................... 7-22 Windscreen Anti-Ice ................................................. 7-41 Exhaust Gas Temperature (EGT) ........................ 7-22 Propeller Anti-Ice ..................................................... 7-41 Torquemeter .......................................................... 7-22 Other Anti-Ice and Deice Systems ........................... 7-41 N Indicator ........................................................... 7-23 Chapter Summary ........................................................ 7-41 N Indicator ........................................................... 7-23 Chapter 8 Turbine Engine Operational Considerations ............ 7-23 Flight Instruments ............................................... 8-1 Engine Temperature Limitations .......................... 7-23 Introduction .................................................................... 8-1 Thrust Variations .................................................. 7-23 Pitot-Static Flight Instruments ....................................... 8-1 Foreign Object Damage (FOD) ............................ 7-23 Impact Pressure Chamber and Lines .......................... 8-2 Turbine Engine Hot/Hung Start ............................ 7-23 Static Pressure Chamber and Lines ............................ 8-2 Compressor Stalls ................................................. 7-23 Altimeter ..................................................................... 8-3 Flameout ............................................................... 7-24 Principle of Operation ............................................. 8-3 Performance Comparison ......................................... 7-24 Effect of Nonstandard Pressure and Temperature .. 8-4 Airframe Systems ........................................................ 7-25 Setting the Altimeter ............................................... 8-5 Fuel Systems ................................................................ 7-25 Altimeter Operation ................................................ 8-6 Gravity-Feed System ............................................... 7-25 Types of Altitude .................................................... 8-6 Fuel-Pump System ................................................... 7-25 Instrument Check .................................................... 8-7 Fuel Primer ............................................................... 7-25 Vertical Speed Indicator (VSI) ................................... 8-7 Fuel Tanks ................................................................ 7-25 x Principle of Operation ............................................. 8-7 Chapter 9 Flight Manuals and Other Documents ............... 9-1 Instrument Check .................................................... 8-8 Introduction .................................................................... 9-1 Airspeed Indicator (ASI) ............................................ 8-8 Preliminary Pages ....................................................... 9-2 Airspeed Indicator Markings .................................. 8-9 General (Section 1) ..................................................... 9-2 Other Airspeed Limitations .................................... 8-9 Limitations (Section 2) ............................................... 9-2 Instrument Check .................................................. 8-10 Airspeed .................................................................. 9-2 Blockage of the Pitot-Static System ......................... 8-10 Powerplant .............................................................. 9-3 Blocked Pitot System ............................................ 8-10 Weight and Loading Distribution ........................... 9-3 Blocked Static System .......................................... 8-11 Flight Limits ........................................................... 9-4 Electronic Flight Display (EFD) .................................. 8-12 Placards ................................................................... 9-4 Airspeed Tape ........................................................... 8-12 Emergency Procedures (Section 3) ............................ 9-4 Attitude Indicator ..................................................... 8-13 Normal Procedures (Section 4) .................................. 9-4 Altimeter ................................................................... 8-13 Performance (Section 5) ............................................. 9-4 Vertical Speed Indicator (VSI) ................................. 8-13 Weight and Balance/Equipment List (Section 6) ....... 9-4 Heading Indicator ..................................................... 8-13 Systems Description (Section 7) ................................ 9-4 Turn Indicator ........................................................... 8-13 Handling, Service, and Maintenance (Section 8) ....... 9-5 Tachometer ............................................................... 8-13 Supplements (Section 9) ............................................. 9-5 Slip/Skid Indicator .................................................... 8-13 Safety Tips (Section 10) ............................................. 9-6 Turn Rate Indicator .................................................. 8-13 Aircraft Documents ........................................................ 9-6 Air Data Computer (ADC) ....................................... 8-14 Certificate of Aircraft Registration ............................. 9-6 Trend Vectors ........................................................... 8-14 Airworthiness Certificate ........................................... 9-7 Gyroscopic Flight Instruments ..................................... 8-15 Aircraft Maintenance .................................................. 9-8 Gyroscopic Principles ............................................... 8-15 Aircraft Inspections ........................................................ 9-8 Rigidity in Space ................................................... 8-15 Annual Inspection ....................................................... 9-8 Precession ............................................................. 8-15 100-Hour Inspection ................................................... 9-8 Sources of Power ...................................................... 8-16 Other Inspection Programs ......................................... 9-9 Turn Indicators ......................................................... 8-16 Altimeter System Inspection .................................. 9-9 Turn-and-Slip Indicator ........................................ 8-16 Transponder Inspection .......................................... 9-9 Turn Coordinator .................................................. 8-17 Emergency Locator Transmitter ............................. 9-9 Inclinometer .............................................................. 8-18 Preflight Inspections ............................................... 9-9 Yaw String ............................................................ 8-18 Minimum Equipment Lists (MEL) and Operations Instrument Check .................................................. 8-18 With Inoperative Equipment ......................................... 9-9 Attitude Indicator ..................................................... 8-18 Preventive Maintenance ............................................... 9-10 Heading Indicator ..................................................... 8-19 Maintenance Entries ............................................. 9-10 Attitude and Heading Reference System (AHRS) ... 8-20 Examples of Preventive Maintenance .................. 9-10 The Flux Gate Compass System .............................. 8-20 Repairs and Alterations ............................................ 9-12 Remote Indicating Compass ..................................... 8-21 Special Flight Permits .............................................. 9-12 Instrument Check .................................................. 8-22 Airworthiness Directives (ADs) .................................. 9-12 Angle of Attack Indicators ........................................... 8-22 Aircraft Owner/Operator Responsibilities ................... 9-13 Compass Systems ......................................................... 8-23 Chapter Summary ........................................................ 9-13 Magnetic Compass ................................................... 8-23 Magnetic Compass Induced Errors ....................... 8-24 Chapter 10 The Vertical Card Magnetic Compass ..................... 8-27 Weight and Balance .......................................... 10-1 Lags or Leads ........................................................ 8-27 Introduction .................................................................. 10-1 Eddy Current Damping ......................................... 8-27 Weight Control ............................................................. 10-1 Outside Air Temperature (OAT) Gauge ...................... 8-28 Effects of Weight ...................................................... 10-2 Chapter Summary ........................................................ 8-28 Weight Changes ....................................................... 10-2 xi Balance, Stability, and Center of Gravity .................... 10-2 Landing Charts ....................................................... 11-26 Effects of Adverse Balance ...................................... 10-3 Stall Speed Performance Charts ............................. 11-27 Stability ................................................................. 10-3 Transport Category Aircraft Performance ................. 11-28 Air Carrier Obstacle Clearance Requirements ........... 11-28 Control .................................................................. 10-3 Chapter Summary ...................................................... 11-28 Management of Weight and Balance Control .......... 10-4 Terms and Definitions .............................................. 10-4 Chapter 12 Principles of Weight and Balance Computations ..... 10-5 Weather Theory ................................................. 12-1 Weight and Balance Restrictions ............................. 10-6 Introduction .................................................................. 12-1 Determining Loaded Weight and CG .......................... 10-7 Atmosphere .................................................................. 12-2 Computational Method ............................................. 10-7 Composition of the Atmosphere ............................... 12-2 Graph Method ........................................................... 10-7 Atmospheric Circulation .......................................... 12-3 Table Method ........................................................... 10-9 Atmospheric Pressure ............................................... 12-3 Computations With a Negative Arm ...................... 10-10 Coriolis Force ............................................................... 12-3 Computations With Zero Fuel Weight ................... 10-10 Measurement of Atmosphere Pressure ........................ 12-4 Shifting, Adding, and Removing Weight ............... 10-10 Altitude and Atmospheric Pressure ............................. 12-5 Weight Shifting ................................................... 10-10 Altitude and Flight ....................................................... 12-6 Weight Addition or Removal .............................. 10-11 Altitude and the Human Body ..................................... 12-6 Chapter Summary ...................................................... 10-11 Wind and Currents ....................................................... 12-7 Wind Patterns ........................................................... 12-7 Chapter 11 Convective Currents ................................................. 12-7 Aircraft Performance ......................................... 11-1 Effect of Obstructions on Wind ................................ 12-8 Introduction .................................................................. 11-1 Low-Level Wind Shear .......................................... 12-11 Importance of Performance Data ................................. 11-1 Wind and Pressure Representation on Surface Structure of the Atmosphere ........................................ 11-2 Weather Maps ......................................................... 12-12 Atmospheric Pressure .................................................. 11-2 Atmospheric Stability ................................................ 12-12 Pressure Altitude .......................................................... 11-3 Inversion ................................................................. 12-13 Density Altitude ........................................................... 11-3 Moisture and Temperature ..................................... 12-13 Effects of Pressure on Density ................................. 11-4 Relative Humidity .................................................. 12-13 Effects of Temperature on Density .......................... 11-5 Temperature/Dew Point Relationship .................... 12-13 Effects of Humidity (Moisture) on Density ............. 11-5 Methods by Which Air Reaches the Saturation Performance ................................................................. 11-5 Point ....................................................................... 12-14 Straight-and-Level Flight ......................................... 11-5 Dew and Frost ........................................................ 12-15 Climb Performance ................................................... 11-6 Fog .......................................................................... 12-15 Angle of Climb (AOC) ......................................... 11-7 Clouds ..................................................................... 12-15 Rate of Climb (ROC) ............................................ 11-7 Ceiling .................................................................... 12-17 Climb Performance Factors .................................. 11-8 Visibility ................................................................. 12-17 Range Performance .................................................. 11-9 Precipitation ............................................................ 12-17 Region of Reversed Command ............................... 11-11 Air Masses ................................................................. 12-17 Takeoff and Landing Performance ......................... 11-12 Fronts ......................................................................... 12-18 Runway Surface and Gradient ................................ 11-12 Warm Front ............................................................ 12-18 Water on the Runway and Dynamic Flight Toward an Approaching Warm Front ...... 12-19 Hydroplaning .......................................................... 11-13 Cold Front .............................................................. 12-20 Takeoff Performance .............................................. 11-14 Fast-Moving Cold Front ..................................... 12-20 Landing Performance ............................................. 11-16 Flight Toward an Approaching Cold Front ........ 12-20 Performance Speeds ................................................... 11-18 Comparison of Cold and Warm Fronts .................. 12-20 Performance Charts .................................................... 11-19 Wind Shifts ............................................................. 12-21 Interpolation ........................................................... 11-20 Stationary Front ...................................................... 12-21 Density Altitude Charts .......................................... 11-20 Occluded Front ....................................................... 12-21 Takeoff Charts ........................................................ 11-20 Thunderstorms ........................................................ 12-22 Climb and Cruise Charts ........................................ 11-21 Hazards .............................................................. 12-23 Crosswind and Headwind Component Chart ......... 11-25 xii Squall Line ......................................................... 12-23 Weather Products Age and Expiration ................... 13-18 What Can Pilots Do? .......................................... 13-19 Tornadoes .......................................................... 12-23 NEXRAD Abnormalities .................................... 13-21 Turbulence ......................................................... 12-24 NEXRAD Limitations ........................................ 13-21 Icing ................................................................... 12-24 AIRMET/SIGMET Display ................................... 13-21 Hail .................................................................... 12-25 Graphical METARs ................................................ 13-21 Ceiling and Visibility ......................................... 12-25 Data Link Weather ................................................. 13-21 Effect on Altimeters ........................................... 12-25 Data Link Weather Products .................................. 13-23 Lightning ............................................................. 12-25 Flight Information Service- Broadcast (FIS-B) .. 13-23 Engine Water Ingestion ..................................... 12-25 Pilot Responsibility .................................................... 13-24 Chapter Summary ...................................................... 12-25 Chapter Summary ...................................................... 13-24 Chapter 13 Chapter 14 Aviation Weather Services ............................... 13-1 Airport Operations ............................................. 14-1 Introduction .................................................................. 13-1 Introduction .................................................................. 14-1 Observations ................................................................ 13-2 Airport Categories ........................................................ 14-1 Surface Aviation Weather Observations .................. 13-2 Types of Airports ...................................................... 14-2 Air Route Traffic Control Center (ARTCC) ........ 13-2 Towered Airport ................................................... 14-2 Upper Air Observations ............................................ 13-2 Nontowered Airport .............................................. 14-2 Radar Observations .................................................. 13-3 Sources for Airport Data .............................................. 14-3 Satellite ..................................................................... 13-4 Aeronautical Charts .................................................. 14-3 Service Outlets ............................................................. 13-4 Chart Supplement U.S. (formerly Airport/Facility Flight Service Station (FSS) ..................................... 13-4 Directory) ................................................................. 14-3 Telephone Information Briefing Service (TIBS) ..... 13-4 Notices to Airmen (NOTAM) .................................. 14-4 Hazardous Inflight Weather Advisory Automated Terminal Information Service (ATIS) ... 14-5 Service (HIWAS) ..................................................... 13-4 Airport Markings and Signs ......................................... 14-5 Transcribed Weather Broadcast (TWEB) Runway Markings and Signs .................................... 14-5 (Alaska Only) .......................................................... 13-4 Relocated Runway Threshold ............................... 14-5 Weather Briefings ........................................................ 13-5 Displaced Threshold ............................................. 14-5 Standard Briefing ..................................................... 13-5 Runway Safety Area ............................................ 14-6 Abbreviated Briefing ................................................ 13-5 Outlook Briefing ...................................................... 13-5 Runway Safety Area Boundary Sign .................... 14-6 Aviation Weather Reports ............................................ 13-5 Runway Holding Position Sign ............................ 14-6 Aviation Routine Weather Report (METAR) .......... 13-6 Runway Holding Position Marking ...................... 14-8 Pilot Weather Reports (PIREPs) .............................. 13-8 Runway Distance Remaining Signs ...................... 14-8 Aviation Forecasts .................................................... 13-9 Runway Designation Marking .............................. 14-8 Terminal Aerodrome Forecasts (TAF) ..................... 13-9 Land and Hold Short Operations (LAHSO) ....... 14-10 Area Forecasts (FA) ............................................... 13-10 Taxiway Markings and Signs ................................. 14-11 Inflight Weather Advisories ................................... 13-11 Enhanced Taxiway Centerline Markings ............ 14-12 AIRMET ............................................................. 13-11 Destination Signs ................................................ 14-12 SIGMET ............................................................. 13-12 Holding Position Signs and Markings for an Convective Significant Meteorological Instrument Landing System (ILS) Critical Area .. 14-12 Information (WST) ............................................. 13-12 Holding Position Markings for Taxiway/Taxiway Winds and Temperature Aloft Forecast (FB) ......... 13-13 Intersections ........................................................ 14-14 Weather Charts ........................................................... 13-13 Marking and Lighting of Permanently Closed Surface Analysis Chart ........................................... 13-13 Runways and Taxiways ...................................... 14-14 Weather Depiction Chart ........................................ 13-15 Temporarily Closed Runways and Taxiways ..... 14-15 Significant Weather Prognostic Charts .................. 13-15 Other Markings ....................................................... 14-15 ATC Radar Weather Displays .................................. 13-16 Airport Signs .......................................................... 14-15 Weather Avoidance Assistance .............................. 13-18 Airport Lighting ......................................................... 14-16 Electronic Flight Displays (EFD) /Multi-Function Airport Beacon ....................................................... 14-16 Display (MFD) Weather ........................................... 13-18 xiii Approach Light Systems ........................................ 14-16 ATC Instructions—Explicit Runway Crossing .... 14-33 Visual Glideslope Indicators .................................. 14-16 ATC Instructions—“Line Up and Wait” Visual Approach Slope Indicator (VASI) ........... 14-16 (LUAW) .............................................................. 14-33 Other Glidepath Systems .................................... 14-16 ATC Instructions— “ Runway Shortened” .......... 14-34 Runway Lighting .................................................... 14-17 Pre-Landing, Landing, and After-Landing ............. 14-34 Runway End Identifier Lights (REIL) ................ 14-17 Engineered Materials Arresting Systems (EMAS) .... 14-35 Incidents ................................................................. 14-35 Runway Edge Lights ........................................... 14-17 EMAS Installations and Information ..................... 14-35 In-Runway Lighting ............................................ 14-18 Pilot Considerations ............................................... 14-36 Control of Airport Lighting .................................... 14-18 Chapter Summary ...................................................... 14-37 Taxiway Lights ....................................................... 14-19 Omnidirectional ................................................. 14-19 Chapter 15 Clearance Bar Lights .......................................... 14-19 Airspace ............................................................. 15-1 Runway Guard Lights ......................................... 14-19 Introduction .................................................................. 15-1 Stop Bar Lights ................................................... 14-19 Controlled Airspace ..................................................... 15-2 Obstruction Lights .................................................. 14-19 Class A Airspace ...................................................... 15-2 New Lighting Technologies ................................... 14-19 Class B Airspace ...................................................... 15-2 Wind Direction Indicators .......................................... 14-20 Class C Airspace ...................................................... 15-2 Traffic Patterns .......................................................... 14-20 Class D Airspace ...................................................... 15-2 Example: Key to Traffic Pattern Operations— Class E Airspace ....................................................... 15-2 Single Runway ....................................................... 14-21 Uncontrolled Airspace ................................................. 15-3 Example: Key to Traffic Pattern Operations— Class G Airspace ...................................................... 15-3 Parallel Runways .................................................... 14-21 Special Use Airspace ................................................... 15-3 Radio Communications .............................................. 14-22 Prohibited Areas ....................................................... 15-3 Radio License ......................................................... 14-22 Restricted Areas ....................................................... 15-3 Radio Equipment .................................................... 14-22 Warning Areas .......................................................... 15-4 Using Proper Radio Procedures ............................ 14-22 Military Operation Areas (MOAs) ........................... 15-4 Lost Communication Procedures ........................... 14-23 Alert Areas ............................................................... 15-4 Air Traffic Control (ATC) Services ........................... 14-24 Controlled Firing Areas (CFAs) ............................... 15-4 Primary Radar ......................................................... 14-24 Other Airspace Areas ................................................... 15-4 ATC Radar Beacon System (ATCRBS) ................ 14-24 Local Airport Advisory (LAA) ................................ 15-6 Transponder ............................................................ 14-25 Military Training Routes (MTRs) ............................ 15-6 Automatic Dependent Surveillance– Temporary Flight Restrictions (TFR) ....................... 15-6 Broadcast (ADS-B) ................................................ 14-26 Published VFR Routes ............................................. 15-6 Radar Traffic Advisories ........................................ 14-26 Terminal Radar Service Areas (TRSAs) .................. 15-7 Wake Turbulence ....................................................... 14-26 National Security Areas (NSAs) .............................. 15-7 Vortex Generation .................................................. 14-26 Air Traffic Control and the National Airspace System .. 15-7 Terminal Area .................................................... 14-27 Coordinating the Use of Airspace ............................ 15-7 En Route ............................................................. 14-27 Operating in the Various Types of Airspace ............ 15-7 Vortex Behavior ..................................................... 14-27 Basic VFR Weather Minimums ............................ 15-7 Vortex Avoidance Procedures ................................ 14-28 Operating Rules and Pilot/Equipment Collision Avoidance ................................................... 14-28 Requirements ........................................................ 15-8 Clearing Procedures ............................................... 14-28 Ultralight Vehicles .............................................. 15-11 Pilot Deviations (PDs) ............................................ 14-30 Unmanned Free Balloons ................................... 15-11 Runway Incursion Avoidance ................................ 14-30 Unmanned Aircraft Systems ............................... 15-11 Causal Factors of Runway Incursions .................... 14-31 Parachute Jumps ................................................. 15-11 Runway Confusion ................................................. 14-31 Chapter Summary ...................................................... 15-11 Causal Factors of Runway Confusion ................ 14-31 ATC Instructions .................................................... 14-32 ATC Instructions— “ Hold Short” ...................... 14-32 xiv Chapter 16 Time and Distance Check From a Station Using a RMI ...................................................................... 16-26 Navigation .......................................................... 16-1 Time a nd Distance Check From a Station Using Introduction .................................................................. 16-1 a CDI ...................................................................... 16-27 Aeronautical Charts ..................................................... 16-2 Course Intercept .................................................... 16-27 Sectional Charts ........................................................ 16-2 Rate of Intercept ................................................. 16-27 VFR Terminal Area Charts ...................................... 16-2 Angle of Intercept .............................................. 16-27 World Aeronautical Charts ....................................... 16-2 Latitude and Longitude (Meridians and Parallels) ....... 16-3 Distance Measuring Equipment (DME) ................. 16-27 Time Zones ............................................................... 16-3 VOR/DME RNAV ................................................. 16-28 Measurement of Direction ........................................ 16-5 Automatic Direction Finder (ADF) ........................ 16-29 Variation ................................................................... 16-6 Global Positioning System ..................................... 16-30 Magnetic Variation ............................................... 16-7 Selective Availability .......................................... 16-31 Magnetic Deviation .............................................. 16-7 VFR Use of GPS ................................................ 16-32 Deviation .................................................................. 16-8 RAIM Capability ................................................ 16-32 Effect of Wind .............................................................. 16-8 Tips for Using GPS for VFR Operations ............... 16-33 Basic Calculations ...................................................... 16-11 VFR Waypoints ..................................................... 16-33 Converting Minutes to Equivalent Hours ............... 16-11 Lost Procedures .......................................................... 16-34 Time T = D/GS ................................................... 16-11 Flight Diversion ......................................................... 16-34 Distance D = GS X T .......................................... 16-11 Chapter Summary ...................................................... 16-35 GS GS = D/T ...................................................... 16-11 Chapter 17 Converting Knots to Miles Per Hour ...................... 16-11 Aeromedical Factors ......................................... 17-1 Fuel Consumption .................................................. 16-11 Introduction .................................................................. 17-1 Flight Computers .................................................... 16-12 Obtaining a Medical Certificate ................................... 17-2 Plotter ..................................................................... 16-12 Health and Physiological Factors Affecting Pilot Pilotage ...................................................................... 16-12 Performance ................................................................. 17-3 Dead Reckoning ......................................................... 16-13 Hypoxia .................................................................... 17-3 Wind Triangle or Vector Analysis ......................... 16-13 Hypoxic Hypoxia .................................................. 17-3 Step 1 .................................................................. 16-14 Hypemic Hypoxia ................................................. 17-3 Step 2 .................................................................. 16-15 Stagnant Hypoxia .................................................. 17-3 Step 3 .................................................................. 16-15 Histotoxic Hypoxia ............................................... 17-4 Step 4 .................................................................. 16-15 Symptoms of Hypoxia .............................................. 17-4 Flight Planning ........................................................... 16-17 Treatment of Hypoxia ........................................... 17-4 Assembling Necessary Material ............................. 16-17 Hyperventilation ....................................................... 17-4 Weather Check ....................................................... 16-17 Middle Ear and Sinus Problems ............................... 17-5 Use of Chart Supplement U.S. (formerly Spatial Disorientation and Illusions ......................... 17-6 Airport/Facility Directory) ..................................... 16-17 Vestibular Illusions ............................................... 17-7 Airplane Flight Manual or Pilot’s Operating Handbook (AFM/POH) .......................................... 16-17 Visual Illusions ..................................................... 17-8 Charting the Course ................................................... 16-18 Postural Considerations ............................................ 17-8 Steps in Charting the Course .................................. 16-18 Demonstration of Spatial Disorientation .................. 17-8 Filing a VFR Flight Plan ............................................ 16-21 Climbing While Accelerating ............................... 17-9 Ground-Based Navigation ......................................... 16-22 Climbing While Turning ....................................... 17-9 Very High Frequency (VHF) Omnidirectional Diving While Turning ........................................... 17-9 Range (VOR) .......................................................... 16-22 Tilting to Right or Left ......................................... 17-9 Using the VOR ................................................... 16-23 Reversal of Motion ............................................... 17-9 Course Deviation Indicator (CDI) .......................... 16-23 Diving or Rolling Beyond the Vertical Plane ....... 17-9 Horizontal Situation Indicator ................................ 16-24 Coping with Spatial Disorientation .......................... 17-9 Radio Magnetic Indicator (RMI) ............................ 16-24 Optical Illusions ..................................................... 17-10 Tracking With VOR ............................................... 16-25 Runway Width Illusion ....................................... 17-10 Tips on Using the VOR .......................................... 16-26 xv Runway and Terrain Slopes Illusion ................... 17-10 Appendix A Performance Data for Cessna Model 172R Featureless Terrain Illusion ................................ 17-10 and Challenger 605 ............................................. A-1 Water Refraction ................................................. 17-10 Haze .................................................................... 17-10 Appendix B Fog ...................................................................... 17-10 Acronyms, Abbreviations, and NOTAM Ground Lighting Illusions ................................... 17-10 Contractions ....................................................... B-1 How To Prevent Landing Errors Due to Optical Illusions ..................................................... 17-10 Appendix C Motion Sickness ..................................................... 17-12 Airport Signs and Markings ............................... C-1 Carbon Monoxide (CO) Poisoning ........................ 17-12 Stress ...................................................................... 17-12 Glossary .............................................................. G-1 Fatigue .................................................................... 17-13 Exposure to Chemicals ........................................... 17-13 Index ...................................................................... I-1 Hydraulic Fluid ................................................... 17-13 Engine Oil ........................................................... 17-14 Fuel ..................................................................... 17-14 Dehydration and Heatstroke ................................... 17-14 Alcohol ................................................................... 17-15 Drugs ...................................................................... 17-16 Altitude-Induced Decompression Sickness (DCS) .. 17-18 DCS After Scuba Diving .................................... 17-18 Vision in Flight .......................................................... 17-19 Vision Types .......................................................... 17-20 Photopic Vision .................................................. 17-20 Mesopic Vision ................................................... 17-21 Scotopic Vision ................................................... 17-21 Central Blind Spot .................................................. 17-21 Empty-Field Myopia .............................................. 17-22 Night Vision ........................................................... 17-22 Night Blind Spot ................................................. 17-22 Dark Adaptation .................................................. 17-23 Scanning Techniques ......................................... 17-23 Night Vision Protection ...................................... 17-23 Self-Imposed Stress ........................................... 17-25 Distance Estimation and Depth Perception ....... 17-25 Binocular Cues .................................................... 17-26 Night Vision Illusions ............................................ 17-26 Autokinesis ......................................................... 17-26 False Horizon ...................................................... 17-26 Reversible Perspective Illusion ........................... 17-26 Size-Distance Illusion ......................................... 17-27 Fascination (Fixation) ......................................... 17-27 Flicker Vertigo .................................................... 17-27 Night Landing Illusions .......................................... 17-27 Enhanced Night Vision Systems ............................ 17-27 Synthetic Vision System ..................................... 17-28 Enhanced Flight Vision System .......................... 17-28 Chapter Summary ...................................................... 17-29 xvi

Chapter 1

Introduction

To Flying

Introduction The Pilot’s Handbook of Aeronautical Knowledge provides basic knowledge for the student pilot learning to fly, as well as pilots seeking advanced pilot certification. For detailed information on a variety of specialized flight topics, see specific Federal Aviation Administration (FAA) handbooks and Advisory Circulars (ACs).

This chapter offers a brief history of flight, introduces the history and role of the FAA in civil aviation, FAA regulations and standards, government references and publications, eligibility for pilot certificates, available routes to flight instruction, the role of the Certificated Flight Instructor (CFI) and Designated Pilot Examiner (DPE) in flight training, Practical Test Standards (PTS), and new, industry-developed Airman Certification Standards (ACS) framework that will eventually replace the PTS.

1-1 billowing heap of cloth capable of no more than a one-way, History of Flight downwind journey.

From prehistoric times, humans have watched the flight of birds, and longed to imitate them, but lacked the power to do Balloons solved the problem of lift, but that was only one of so. Logic dictated that if the small muscles of birds can lift the problems of human flight. The ability to control speed and them into the air and sustain them, then the larger muscles direction eluded balloonists. The solution to that problem lay of humans should be able to duplicate the feat. No one knew in a child’s toy familiar to the East for 2,000 years, but not about the intricate mesh of muscles, sinew, heart, breathing introduced to the West until the 13th century—the kite. The system, and devices not unlike wing flaps, variable-camber kites used by the Chinese for aerial observation, to test winds and spoilers of the modern airplane that enabled a bird to for sailing, as a signaling device, and as a toy, held many of fly. Still, thousands of years and countless lives were lost in the answers to lifting a heavier-than-air device into the air.

attempts to fly like birds.

One of the men who believed the study of kites unlocked The identity of the first “bird-men” who fitted themselves the secrets of winged flight was Sir George Cayley. Born with wings and leapt off of cliffs in an effort to fly are lost in in England 10 years before the Mongolfier balloon flight, time, but each failure gave those who wished to fly questions Cayley spent his 84 years seeking to develop a heavier-than that needed to be answered. Where had the wing flappers air vehicle supported by kite-shaped wings. [Figure 1-2] The gone wrong? Philosophers, scientists, and inventors offered “Father of Aerial Navigation,” Cayley discovered the basic solutions, but no one could add wings to the human body principles on which the modern science of aeronautics is and soar like a bird. During the 1500s, Leonardo da Vinci founded; built what is recognized as the first successful flying filled pages of his notebooks with sketches of proposed model; and tested the first full-size man-carrying airplane.

flying machines, but most of his ideas were flawed because he clung to the idea of birdlike wings. [Figure 1-1 ] By 1655, mathematician, physicist, and inventor Robert Hooke concluded that the human body does not possess the strength to power artificial wings. He believed human flight would require some form of artificial propulsion.

The quest for human flight led some practitioners in another direction. In 1783, the first manned hot air balloon, crafted by Joseph and Etienne Montgolfier, flew for 23 minutes.

Ten days later, Professor Jacques Charles flew the first gas balloon. A madness for balloon flight captivated the public’s imagination and for a time flying enthusiasts turned their expertise to the promise of lighter-than-air flight. But for all its majesty in the air, the balloon was little more than a Figure 1-2. Glider from 1852 by Sir George Cayley, British aviator (1773–1857). Figure 1-1. Leonardo da Vinci’s ornithopter wings.

1-2 For the half-century after Cayley’s death, countless scientists, Petersburg across the waterway to Tampa. Benoist suggested flying enthusiasts, and inventors worked toward building using his “Safety First” airboat and the two men signed an a powered flying machine. Men, such as William Samuel agreement for what would become the first scheduled airline Henson, who designed a huge monoplane that was propelled in the United States. The first aircraft was delivered to St.

by a steam engine housed inside the fuselage, and Otto Petersburg and made the first test flight on December 31, Lilienthal, who proved human flight in aircraft heavier than 1913. [Figure 1-4] air was practical, worked toward the dream of powered flight.

A dream turned into reality by Wilbur and Orville Wright at A public auction decided who would win the honor of Kitty Hawk, North Carolina, on December 17, 1903. becoming the first paying airline customer. The former mayor of St. Petersburg, A. C. Pheil, made the winning bid The bicycle-building Wright brothers of Dayton, Ohio, had of $400.00, which secured his place in history as the first experimented for 4 years with kites, their own homemade paying airline passenger.

wind tunnel, and different engines to power their biplane. One of their great achievements in flight was proving the value of On January 1, 1914, the first scheduled airline flight was the scientific, rather than a build-it-and-see approach. Their conducted. The flight length was 21 miles and lasted 23 biplane, The Flyer, combined inspired design and engineering minutes due to a headwind. The return trip took 20 minutes.

with superior craftsmanship. [Figure 1-3] By the afternoon The line, which was subsidized by Florida businessmen, of December 17th, the Wright brothers had flown a total of continued for 4 months and offered regular passage for $5.00 98 seconds on four flights. The age of flight had arrived. per person or $5.00 per 100 pounds of cargo. Shortly after the opening of the line, Benoist added a new airboat that afforded History of the Federal Aviation more protection from spray during takeoff and landing.

Administration (FAA) The routes were also extended to Manatee, Bradenton, and Sarasota giving further credence to the idea of a profitable During the early years of manned flight, aviation was a commercial airline.

free for all because no government body was in place to establish policies or regulate and enforce safety standards.

The St. Petersburg-Tampa Airboat Line continued throughout Individuals were free to conduct flights and operate aircraft the winter months with flights finally being suspended when with no government oversight. Most of the early flights were the winter tourist industry began to dry up. The airline conducted for sport. Aviation was expensive and became the operated for only 4 months, but 1,205 passengers were playground of the wealthy. Since these early airplanes were carried without injury. This experiment proved commercial small, many people doubted their commercial value. One passenger airline travel was viable.

group of individuals believed otherwise and they became the genesis for modern airline travel.

The advent of World War I offered the airplane a chance to demonstrate its varied capabilities. It began the war as a P. E. Fansler, a Florida businessman living in St. Petersburg, reconnaissance platform, but by 1918, airplanes were being approached Tom Benoist of the Benoist Aircraft Company in St. Louis, Missouri, about starting a flight route from St.

Figure 1-4. Benoist airboat.

Figure 1-3. First flight by the Wright brothers.

1-3 mass produced to serve as fighters, bombers, trainers, as well 11 1 6 Rock Springs New York Iowa City as reconnaissance platforms. 12 2 7 Salt Lake City Bellefonte Omaha 13 3 8 Elko Cleveland North Platte 14 4 9 Reno Bryan Cheyenne Aviation advocates continued to look for ways to use 15 5 10 San Francisco Chicago Rawlins airplanes. Airmail service was a popular idea, but the war prevented the Postal Service from having access to airplanes. The War Department and Postal Service reached an 13 10 5 4 14 9 agreement in 1918. The Army would use the mail service to train its pilots in flying cross-country. The first airmail flight was conducted on May 15, 1918, between New York and Washington, DC. The flight was not considered spectacular; the pilot became lost and landed at the wrong airfield. In August of 1918, the United States Postal Service took control of the airmail routes and brought the existing Army airmail pilots and their planes into the program as postal employees.

Figure 1-6. The transcontinental airmail route ran from New York Transcontinental Air Mail Route to San Francisco.

Airmail routes continued to expand until the Transcontinental Mail Route was inaugurated. [Figure 1-5] This route spanned Department of Commerce made significant advances in from San Francisco to New York for a total distance of 2,612 aviation communications, including the introduction of radio miles with 13 intermediate stops along the way. [Figure 1-6] beacons as an effective means of navigation.

On May 20, 1926, Congress passed the Air Commerce Act, which served as the cornerstone for aviation within the Built at intervals of approximately 10 miles apart, the United States. This legislation was supported by leaders in standard beacon tower was 51 feet high, and was topped the aviation industry who felt that the airplane could not with a powerful rotating light. Below the rotating light, two reach its full potential without assistance from the Federal course lights pointed forward and back along the airway. The Government in improving safety.

course lights flashed a code to identify the beacon’s number.

The tower usually stood in the center of a concrete arrow The Air Commerce Act charged the Secretary of Commerce 70 feet long. A generator shed, where required, stood at the with fostering air commerce, issuing and enforcing air traffic “feather” end of the arrow. [Figure 1-7] rules, licensing pilots, certificating aircraft, establishing airways, and operating and maintaining aids to air navigation. Federal Certification of Pilots and Mechanics The Department of Commerce created a new Aeronautics The Aeronautics Branch of the Department of Commerce Branch whose primary mission was to provide oversight for the began pilot certification with the first license issued on April aviation industry. In addition, the Aeronautics Branch took over 6, 1927. The recipient was the Chief of the Aeronautics the construction and operation of the nation’s system of lighted Branch, William P. MacCracken, Jr. [Figure 1-8] (Orville airways. The Postal Service, as part of the Transcontinental Wright, who was no longer an active flier, had declined the Air Mail Route system, had initiated this system. The honor.) MacCracken’s license was the first issued to a pilot by a civilian agency of the Federal Government. Some 3 months later, the Aeronautics Branch issued the first Federal aircraft mechanic license.

Equally important for safety was the establishment of a system of certification for aircraft. On March 29, 1927, the Aeronautics Branch issued the first airworthiness type certificate to the Buhl Airster CA-3, a three-place open biplane.

In 1934, to recognize the tremendous strides made in aviation and to display the enhanced status within the department, the Aeronautics Branch was renamed the Bureau of Air Commerce. [Figure 1-9] Within this time frame, the Bureau Figure 1-5. The de Haviland DH-4 on the New York to San of Air Commerce brought together a group of airlines Francisco inaugural route in 1921.

1-4

D-KC

Figure 1-9. The third head of the Aeronautics Branch, Eugene L. Vidal, is flanked by President Franklin D. Roosevelt (left) and Secretary of Agriculture Henry A. Wallace (right). The photograph was taken in 1933. During Vidal’s tenure, the Aeronautics Branch was renamed the Bureau of Air Commerce on July 1, 1934. The new name more accurately reflected the status of the organization within the Department of Commerce.

and encouraged them to form the first three Air Traffic Control (ATC) facilities along the established air routes.

Figure 1-7. A standard airway beacon tower.

Figure 1-8. Standard airway beacon installation.

Then in 1936, the Bureau of Air Commerce took over the responsibilities of operating the centers and continued to advance the ATC facilities. ATC has come a long way from the early controllers using maps, chalkboards, and performing mental math calculations in order to separate aircraft along flight routes.

The Civil Aeronautics Act of 1938 In 1938, the Civil Aeronautics Act transferred the civil aviation responsibilities to a newly created, independent body, named the Civil Aeronautics Authority (CAA). This Act empowered the CAA to regulate airfares and establish new routes for the airlines to service.

President Franklin Roosevelt split the CAA into two agencies—the Civil Aeronautics Administration (CAA) and the Civil Aeronautics Board (CAB). Both agencies were still part of the Department of Commerce but the CAB functioned independently of the Secretary of Commerce.

The role of the CAA was to facilitate ATC, certification of airmen and aircraft, rule enforcement, and the development of new airways. The CAB was charged with rule making to enhance safety, accident investigation, and the economic regulation of the airlines. Then in 1946, Congress gave the CAA the responsibility of administering the Federal Aid Figure 1-8. The first pilot license was issued to William P.

MacCracken, Jr.

1-5 Airport Program. This program was designed to promote the future. The DOT began operation on April 1, 1967. At the establishment of civil airports throughout the country. this same time, the Federal Aviation Agency was renamed to the Federal Aviation Administration (FAA).

The Federal Aviation Act of 1958 By mid-century, air traffic had increased and jet aircraft had The role of the CAB was assumed by the newly created National Transportation Safety Board (NTSB), which was been introduced into the civil aviation arena. A series of mid-air collisions underlined the need for more regulation charged with the investigation of all transportation accidents within the United States.

of the aviation industry. Aircraft were not only increasing in numbers, but were now streaking across the skies at much As aviation continued to grow, the FAA took on additional higher speeds. The Federal Aviation Act of 1958 established a new independent body that assumed the roles of the CAA duties and responsibilities. With the highjacking epidemic of the 1960s, the FAA was responsible for increasing the and transferred the rule making authority of the CAB to the newly created Federal Aviation Agency (FAA). In addition, security duties of aviation both on the ground and in the air.

After September 11, 2001, the duties were transferred to the FAA was given complete control of the common civil- military system of air navigation and ATC. The man who a newly created body called the Department of Homeland Security (DHS).

was given the honor of being the first Administrator of the FAA was former Air Force General Elwood Richard “Pete” With numerous aircraft flying in and out of larger cities, the Quesada. He served as the administrator from 1959–1961.

[Figure 1-10] FAA began to concentrate on the environmental aspect of aviation by establishing and regulating the noise standards Department of Transportation (DOT) of aircraft. Additionally, in the 1960s and 1970s, the FAA began to regulate high altitude (over 500 feet) kite and balloon On October 15, 1966, Congress established the Department flying. In 1970, more duties were assumed by the FAA in the of Transportation (DOT), which was given oversight of the addition of a new federal airport aid program and increased transportation industry within the United States. The result responsibility for airport safety.

was a combination of both air and surface transportation. Its mission was and is to serve the United States by ensuring a ATC Automation fast, safe, efficient, accessible, and convenient transportation system meeting vital national interests and enhancing the By the mid-1970s, the FAA had achieved a semi-automated ATC system based on a marriage of radar and computer quality of life of the American people, then, now, and into technology. By automating certain routine tasks, the system allowed controllers to concentrate more efficiently on the vital task of providing aircraft separation. Data appearing directly on the controllers’ scopes provided the identity, altitude, and groundspeed of aircraft carrying radar beacons.

Despite its effectiveness, this system required enhancement to keep pace with the increased air traffic of the late 1970s.

The increase was due in part to the competitive environment created by the Airline Deregulation Act of 1978. This law phased out CAB’s economic regulation of the airlines, and CAB ceased to exist at the end of 1984.

To meet the challenge of traffic growth, the FAA unveiled the National Airspace System (NAS) Plan in January 1982. The new plan called for more advanced systems for en route and terminal ATC, modernized flight service stations, and improvements in ground-to-air surveillance and communication.

The Professional Air Traffic Controllers Organization (PATCO) Strike While preparing the NAS Plan, the FAA faced a strike by key members of its workforce. An earlier period of Figure 1-10. First Administrator of the FAA was General Elwood discord between management and the Professional Air Richard “Pete” Quesada, 1959–1961.

1-6 Traffic Controllers Organization (PATCO) culminated in a Howard Cannon. [Figure 1-11] There was stiff opposition to 1970 “sickout” by 3,000 controllers. Although controllers the bill—from the major airlines who feared free competition, subsequently gained additional wage and retirement from labor unions who feared non-union employees, and benefits, another period of tension led to an illegal strike in from safety advocates who feared that safety would be August 1981. The government dismissed over 11,000 strike sacrificed. Public support was, however, strong enough to participants and decertified PATCO. By the spring of 1984, pass the act. The act appeased the major airlines by offering the FAA ended the last of the special restrictions imposed to generous subsidies and pleased workers by offering high keep the airspace system operating safely during the strike. unemployment benefits if they lost their jobs as a result. The most important effect of the act, whose laws were slowly The Airline Deregulation Act of 1978 phased in, was on the passenger market. For the first time Until 1978, the CAB regulated many areas of commercial in 40 years, airlines could enter the market or (from 1981) expand their routes as they saw fit. Airlines (from 1982) aviation such as fares, routes, and schedules. The Airline Deregulation Act of 1978, however, removed many of also had full freedom to set their fares. In 1984, the CAB was finally abolished since its primary duty of regulating the these controls, thus changing the face of civil aviation in the United States. After deregulation, unfettered free competition airline industry was no longer necessary.

ushered in a new era in passenger air travel.

The Role of the FAA The CAB had three main functions: to award routes to The Code of Federal Regulations (CFR) airlines, to limit the entry of air carriers into new markets, The FAA is empowered by regulations to promote aviation and to regulate fares for passengers. Much of the established safety and establish safety standards for civil aviation. The practices of commercial passenger travel within the United FAA achieves these objectives under the Code of Federal States went back to the policies of Walter Folger Brown, the Regulations (CFR), which is the codification of the general United States Postmaster General during the administration and permanent rules published by the executive departments of President Herbert Hoover. Brown had changed the mail and agencies of the United States Government. The payments system to encourage the manufacture of passenger regulations are divided into 50 different codes, called Titles, aircraft instead of mail-carrying aircraft. His influence that represent broad areas subject to Federal regulation.

was crucial in awarding contracts and helped create four FAA regulations are listed under Title 14, “Aeronautics and major domestic airlines: United, American, Eastern, and Space,” which encompasses all aspects of civil aviation from Transcontinental and Western Air (TWA). Similarly, how to earn a pilot’s certificate to maintenance of an aircraft.

Brown had also helped give Pan American a monopoly on Title 14 CFR Chapter 1, Federal Aviation Administration, international routes.

is broken down into subchapters A through N as illustrated in Figure 1-12.

The push to deregulate, or at least to reform the existing laws governing passenger carriers, was accelerated by President For the pilot, certain parts of 14 CFR are more relevant Jimmy Carter, who appointed economist and former than others. During flight training, it is helpful for the pilot professor Alfred Kahn, a vocal supporter of deregulation, to to become familiar with the parts and subparts that relate head the CAB. A second force to deregulate emerged from abroad. In 1977, Freddie Laker, a British entrepreneur who owned Laker Airways, created the Skytrain service, which offered extraordinarily cheap fares for transatlantic flights.

Laker’s offerings coincided with a boom in low-cost domestic flights as the CAB eased some limitations on charter flights (i.e., flights offered by companies that do not actually own planes but leased them from the major airlines). The big air carriers responded by proposing their own lower fares. For example, American Airlines, the country’s second largest airline, obtained CAB approval for “SuperSaver” tickets.

All of these events proved to be favorable for large-scale deregulation. In November 1977, Congress formally deregulated air cargo. In late 1978, Congress passed the Figure 1-11. President Jimmy Carter signs the Airline Deregulation Airline Deregulation Act of 1978, legislation that had been Act in late 1978.

principally authored by Senators Edward Kennedy and 1-7 Code of Federal Regulations Title Volume Chapter Subchapters Title 14 1 I A Definitions and Abbreviations Aeronautics B Procedural Rules and Space C Aircraft 2 D Airmen E Airspace F Air Traffic and General Rules 3 G Air Carriers and Operators for Compensation or Hire: Certification and Operations H Schools and Other Certified Agencies I Airports J Navigational Facilities K Administrative Regulations L–M Reserved N War Risk Insurance 4 II A Economic Regulations B Procedural Regulations C Reserved D Special Regulations E Organization F Policy Statements III A General B Procedure C Licensing 5 V VI A Office of Management and Budget B Air Transportation Stabilization Board Figure 1-12. Overview of 14 CFR, available online free from the FAA and for purchase through commercial sources.

to flight training and pilot certification. For instance, 14 development of innovative aviation systems and concepts, CFR part 61 pertains to the certification of pilots, flight development of new ATC equipment and software, and instructors, and ground instructors. It also defines the modification of existing systems and procedures.

eligibility, aeronautical knowledge, and flight proficiency, as well as training and testing requirements for each type of Field Offices pilot certificate issued. 14 CFR part 91 provides guidance in Flight Standards Service the areas of general flight rules, visual flight rules (VFR), and Within the FAA, the Flight Standards Service promotes safe instrument flight rules (IFR), while 14 CFR part 43 covers air transportation by setting the standards for certification aircraft maintenance, preventive maintenance, rebuilding, and oversight of airmen, air operators, air agencies, and and alterations.

designees. It also promotes safety of flight of civil aircraft and air commerce by: Primary Locations of the FAA • Accomplishing certification, inspection, surveillance, The FAA headquarters are in Washington, DC, and there are investigation, and enforcement.

nine regional offices strategically located across the United States. The agency’s two largest field facilities are the Mike • Setting regulations and standards.

Monroney Aeronautical Center (MMAC) in Oklahoma • Managing the system for registration of civil aircraft City, Oklahoma, and the William J. Hughes Technical and all airmen records.

Center (WJHTC) in Atlantic City, New Jersey. Home to FAA training and logistics services, the MMAC provides The focus of interaction between Flight Standards Service a number of aviation safety-related and business support and the aviation community/general public is the Flight services. The WJHTC is the premier aviation research and Standards District Office (FSDO).

development and test and evaluation facility in the country.

The center’s programs include testing and evaluation in ATC, communication, navigation, airports, aircraft safety, and security. Furthermore, the WJHTC is active in long-range 1-8 Flight Standards District Office (FSDO) Safety Team (FAASTeam) exemplifies this commitment.

The FAASTeam has replaced the Aviation Safety Program The FAA has approximately 80 FSDOs. [Figure 1-13] These (ASP), whose education of airmen on all types of safety offices provide information and services for the aviation subjects successfully reduced accidents. Its success led to community. FSDO phone numbers are listed in the telephone its demise because the easy-to-fix accident causes have been directory under Government Offices, DOT, FAA. Another addressed. To take aviation safety one step further, Flight convenient method of finding a local office is to use the Standards Service created the FAASTeam, which is devoted FSDO locator available at: www.faa.gov/about/office_org/ to reducing aircraft accidents by using a coordinated effort field_offices/fsdo.

to focus resources on elusive accident causes.

In addition to accident investigation and the enforcement of Each of the FAA’s nine regions has a Regional FAASTeam aviation regulations, the FSDO is also responsible for the Office dedicated to this new safety program and managed by certification and surveillance of air carriers, air operators, the Regional FAASTeam Manager (RFM). The FAASTeam flight schools/training centers, and airmen including pilots is “teaming” up with individuals and the aviation industry and flight instructors. Each FSDO is staffed by Aviation to create a unified effort against accidents and tip the safety Safety Inspectors (ASIs) who play a key role in making the culture in the right direction. To learn more about this effort nation’s aviation system safe.

to improve aviation safety, to take a course at their online learning center, or to join the FAASTeam, visit their website Aviation Safety Inspector (ASI) at www.faasafety.gov .

The ASIs administer and enforce safety regulations and standards for the production, operation, maintenance, and/ Obtaining Assistance from the FAA or modification of aircraft used in civil aviation. They also Information can be obtained from the FAA by phone, specialize in conducting inspections of various aspects of the Internet/e-mail, or mail. To talk to the FAA toll-free 24 aviation system, such as aircraft and parts manufacturing, hours a day, call 1-866-TELL-FAA (1-866-835-5322). To aircraft operation, aircraft airworthiness, and cabin safety.

visit the FAA’s website, go to www.faa.gov. Individuals can ASIs must complete a training program at the FAA Academy also e-mail an FAA representative at a local FSDO office by in Oklahoma City, Oklahoma, which includes airman accessing the staff e-mail address available via the “Contact evaluation and pilot testing techniques and procedures. ASIs FAA” link at the bottom of the FAA home page. Letters can also receive extensive on-the-job training and recurrent be sent to: training on a regular basis. The FAA has approximately 3,700 inspectors located in its FSDO offices. All questions Federal Aviation Administration concerning pilot certification (and/or requests for other 800 Independence Ave, SW aviation information or services) should be directed to the Washington, DC 20591 local FSDO.

FAA Reference Material FAA Safety Team (FAASTeam) The FAA provides a variety of important reference material The FAA is dedicated to improving the safety of United for the student, as well as the advanced civil aviation pilot.

States civilian aviation by conveying safety principles and In addition to the regulations provided online by the FAA, practices through training, outreach, and education. The FAA several other publications are available to the user. Almost all reference material is available online at www.faa.gov in downloadable format. Commercial aviation publishers also provide published and online reference material to further aid the aviation pilot.

Aeronautical Information Manual (AIM) The Aeronautical Information Manual (AIM) is the official guide to basic flight information and ATC procedures for the aviation community flying in the NAS of the United States.

[Figure 1-14] An international version, containing parallel information as well as specific information on international airports, is also available. The AIM also contains information of interest to pilots, such as health and medical facts, flight Figure 1-13. Atlanta Flight Standards District Office (FSDO).

1-9 Aeronautical Information Manual (AIM) The Aeronautical Information Manual is designed to provide the aviation community with basic flight information and ATC procedures for use in the NAS of the United States. It also contains the fundamentals required in order to fly in the United States NAS, including items of interest to pilots concerning health/medical facts, factors affecting flight safety, etc.

Aircraft Flying Handbooks (by category) The Aircraft Flying Handbooks are designed as technical manuals to introduce basic pilot skills and knowledge that are essential for piloting aircraft. They provide information on transition to other aircraft and the operation of various aircraft systems.

Aviation Instructor’s Handbook The Aviation Instructor’s Handbook provides the foundation for beginning instructors to understand and apply the fundamentals of instructing. This handbook also provides aviation instructors with up-to-date information on learning and teaching, and how to relate this information to the task of conveying aeronautical knowledge and skills to students.

Experienced aviation instructors also find the new and Figure 1-14. Aeronautical Information Manual.

updated information useful for improving their effectiveness in training activities.

safety, a pilot/controller glossary of terms used in the Instrument Flying Handbook system, and information on safety, accidents, and reporting The Instrument Flying Handbook is designed for use by of hazards. This manual is offered for sale on a subscription instrument flight instructors and pilots preparing for basis or is available online at: http://bookstore.gpo.gov .

instrument rating tests. Instructors find this handbook a valuable training aid as it includes basic reference material for knowledge testing and instrument flight training.

Order forms are provided at the beginning of the manual or online and should be sent to the Superintendent of Documents, Instrument Procedures Handbook United States Government Printing Office (GPO). The AIM The Instrument Procedures Handbook is designed as a is complemented by other operational publications that are technical reference for professional pilots who operate available via separate subscriptions or online.

under IFR in the NAS and expands on information contained in the Instrument Flying Handbook.

Handbooks Handbooks are developed to provide specific information Figure 1-15. A sample of handbooks available to the public. Most about a particular topic that enhances training or understanding.

can be downloaded free of charge from the FAA website.

The FAA publishes a variety of handbooks that generally fall into three categories: aircraft, aviation, and examiners and of a text book used in a classroom or a one page document.

inspectors. [Figure 1-15] These handbooks can be purchased Some ACs are free while others cost money. They are to from the Superintendent of Documents or downloaded at www. be used for information only and are not regulations. The faa.gov/regulations_policies. Aviation handbooks are also FAA website www.faa.gov/regulations_policies/advisory_ published by various commercial aviation companies. Aircraft circulars/ provides a database that is a searchable repository flight manuals commonly called Pilot Operating Handbooks of all aviation safety ACs. All ACs, current and historical, (POH) are documents developed by the airplane manufacturer, are provided and can be viewed as a portable document approved by the FAA, and are specific to a particular make format (PDF) copy.

and model aircraft by serial number. This subject is covered in greater detail in Chapter 8, “Flight Manuals and Other ACs provide a single, uniform, agency-wide system that the Documents,” of this handbook. [Figure 1-16] FAA uses to deliver advisory material to FAA customers, industry, the aviation community, and the public. An AC may be needed to: Advisory Circulars (ACs) An AC is an informational document that the FAA wants to • Provide an acceptable, clearly understood method for distribute to the aviation community. This can be in the form complying with a regulation 1-10 Figure 1-16. Pilot Operating Handbooks from manufacturers.

• Standardize implementation of a regulation or Flight Publications harmonize implementation for the international The FAA, in concert with other government agencies, aviation community orchestrates the publication and changes to publications that are key to safe flight. Figure 1-18 illustrates some • Resolve a general misunderstanding of a regulation publications a pilot may use.

• Respond to a request from some government entity, such as General Accounting Office, NTSB, or the Office of the Inspector General • Help the industry and FAA effectively implement a regulation • Explain requirements and limits of an FAA grant program • Expand on standards needed to promote aviation safety, including the safe operation of airports There are three parts to an AC number, as in 25-42C. The first part of the number identifies the subject matter area of the AC and corresponds to the appropriate 14 CFR part.

For example, an AC on “Certification: Pilots and Flight and Ground Instructors” is numbered as AC 61-65E. Since ACs are numbered sequentially within each subject area, the second part of the number beginning with the dash identifies this sequence. The third part of the number is a letter assigned by the originating office and shows the revision sequence if an AC is revised. The first version of an AC does not have a revision letter. In Figure 1-17 , this is the fifth revision, as Figure 1-17. Example of an Advisory Circular in its fifth revision.

designated by the “E.” 1-11 NEVADA 245 ALAMO LANDING FLD 2 W UTC 8( 7DT) N37 ° 21.75 (L92) W115 ° 11.67 LAS VEGAS 3719 NOTAM FILE RNO RWY 14–32: 5000X120 (DIRT) RWY 14: Brush. RWY 32: Berm.

RWY 15–33: 2500X70 (DIRT) RWY 15: Berm. RWY 33: Berm.

AIRPORT REMARKS: Unattended. Uncontrolled vehicle access. No line of sight between rwy ends. Rwys 15–33 and Rwy 14–32 livestock in vicinity of rwys.

COMMUNICATIONS: CTAF 122.9 AUSTIN (TMT) 4 SW UTC 8( 7DT) N39 ° 28.08 W117 ° 11.72 LAS VEGAS 5735 B NOTAM FILE RNO H–3C, L–9B RWY 18–36: H6000X75 (ASPH) S–30 MIRL RWY 18: REIL. PAPI(P2L)—GA 3.0 ° TCH 40 . RWY 36: REIL. PAPI(P2L)—GA 3.0 ° TCH 40 . Fence.

AIRPORT REMARKS: Unattended. Military acft opr in vicinity of arpt. ACTIVATE MIRL Rwy 18–36, PAPI Rwys 18 and 36, REIL Rwy 18 and 36—CTAF.

WEATHER DATA SOURCES: AWOS–3PT 132.925 (775) 964–1144.

COMMUNICATIONS: CTAF 122.9 RADIO AIDS TO NAVIGATION: NOTAM FILE RNO.

MINA (H) VORTAC MVA N38 ° 33.92 115.1 Chan 98 W118 ° 01.97 019 ° 66.7 NM to fld. 7860/17E.

HIWAS.

BATTLE MOUNTAIN (BAM) 3 SE UTC 8( 7DT) N40 ° 35.94 W116 ° 52.46 SALT LAKE CITY 4536 B S4 FUEL 100LL, JET A NOTAM FILE RNO H–3C, L–9B, 11B RWY 12–30: H7302X150 (ASPH) S–30, D–104, 2S–132 MIRL IAP RWY 03–21: H7299X150 (ASPH) S–30, D–125, 2S–159 MIRL RWY 03: VASI(V2R)—GA 3.0 ° TCH 26 .

RWY 21: PAPI(P4L)—GA 3.0 ° TCH 45 .

AIRPORT REMARKS: Attended Oct–May 1500–0100Z ‡ , Jun–Sep 1500–0200Z ‡ . After hrs call 775–635–2245. ACTIVATE MIRL Rwy 03–21 and Rwy 12–30, and perimeter lgts H1—CTAF.

WEATHER DATA SOURCES: AWOS–3 119.45 (775) 635–8419.

COMMUNICATIONS: CTAF/UNICOM 122.8 MT LEWIS RCO 122.65 (RENO RADIO) SALT LAKE CENTER APP/DEP CON 132.25 RADIO AIDS TO NAVIGATION: NOTAM FILE RNO.

(H) VORTACW 112.2 BAM Chan 59 N40 ° 34.15 W116 ° 55.34 033 ° 2.8 NM to fld. 4536/18E.

VORTAC unusable: 050 ° –060 ° byd 30 NM blo 12,000 115 ° –165 ° byd 15 NM blo 12,000 255 ° –290 ° byd 15 NM blo 12,000 DME unusable 246 ° –255 ° byd 34 NM blo 14,000 • • • • • • • • • • • • • • • • HELIPAD H1: H60X60 (CONC) HELIPAD H2: H60X60 (CONC) HELIPORT REMARKS: Rwy H1 perimeter lights. ACTIVATE MIRL Rwy 03–21 and Rwy 12–30, and perimeter lgts H1—CTAF.

, Figure 1-18. From left to right, a sectional VFR chart, IFR chart, and chart supplement U.S. (formerly Airport/Facility Directory) with a sample of a page from the supplement.

Pilot and Aeronautical Information • Notification of an operationally significant change in volcanic ash or other dust contamination (an ASHTAM) Notices to Airmen (NOTAMs) Notices to Airmen, or NOTAMs, are time-critical aeronautical • Software code risk announcements with associated information either temporary in nature or not sufficiently patches to reduce specific vulnerabilities known in advance to permit publication on aeronautical charts or in other operational publications. The information NOTAM information is generally classified into four receives immediate dissemination via the National Notice to categories: NOTAM (D) or NOTAMs that receive distant Airmen (NOTAM) System. NOTAMs contain current notices dissemination, distant and Flight Data Center (FDC) to airmen that are considered essential to the safety of flight, NOTAMs, Pointer NOTAMs, and Military NOTAMs as well as supplemental data affecting other operational pertaining to military airports or NAVAIDs that are part of the publications. There are many different reasons that NOTAMs NAS. NOTAMs are available through Flight Service Station are issued. Following are some of those reasons: (FSS), Direct User Access Terminal Service (DUATS), private vendors, and many online websites.

• Hazards, such as air shows, parachute jumps, kite flying, and rocket launches NOTAM (D) Information • Flights by important people such as heads of state NOTAM (D) information is disseminated for all navigational • Closed runways facilities that are part of the NAS, and all public use airports, • Inoperable radio navigational aids seaplane bases, and heliports listed in the Chart Supplement U.S. (formerly Airport/Facility Directory). NOTAM (D) • Military exercises with resulting airspace restrictions information now includes such data as taxiway closures, • Inoperable lights on tall obstructions personnel and equipment near or crossing runways, and airport lighting aids that do not affect instrument approach • Temporary erection of obstacles near airfields criteria, such as visual approach slope indicator (VASI).

• Passage of flocks of birds through airspace (a NOTAM All D NOTAMs are required to have one of the following in this category is known as a BIRDTAM) keywords as the first part of the text: RWY, TWY, RAMP, • Notifications of runway/taxiway/apron status with APRON, AD, OBST, NAV, COM, SVC, AIRSPACE, (U), respect to snow, ice, and standing water (a SNOWTAM) or (O). [Figure 1-19] 1-12 FDC NOTAMs • Flight restrictions in the proximity of the President and other parties FDC NOTAMs are issued by the National Flight Data Center and contain information that is regulatory in nature • 14 CFR part 139 certificated airport condition changes pertaining to flight including, but not limited to, changes • Snow conditions affecting glide slope operation to charts, procedures, and airspace usage. FDC NOTAMs • Air defense emergencies refer to information that is regulatory in nature and includes the following: • Emergency flight rules • Interim IFR flight procedures: • Substitute airway routes 1. Airway structure changes • Special data 2. Instrument approach procedure changes (excludes • U.S. Government charting corrections Departure Procedures (DPs) and Standard • Laser activity Terminal Arrivals (STARs) 3. Airspace changes in general NOTAM Composition 4. Special instrument approach procedure changes NOTAMs contain the elements below from left to right in the following order: • Temporary flight restrictions (discussed in Chapter 15): • An exclamation point (!)

1. Disaster areas • Accountability Location (the identifier of the 2. Special events generating a high degree of interest accountability location) 3. Hijacking Keyword Example Meaning RWY RWY 3/21 CLSD Runways 3 and 21 are closed to aircraft.

TWY TWY F LGTS OTS Taxiway F lights are out of service.

RAMP RAMP TERMINAL EAST SIDE The ramp in front of the east side of the terminal has ongoing CONSTRUCTION construction.

APRON APRON SW TWY C NEAR The apron near the southwest taxiway C in front of the hangars HANGARS CLSD is closed.

AD AD ABN OTS Aerodromes: The airport beacon is out of service.

OBST OBST TOWER 283 (245 AGL) 2.2 Obstruction: The lights are out of service on a tower that is 283 feet S LGTS OTS (ASR 1065881) TIL above mean sea level (MSL) or 245 feet above ground level (AGL) 0707272300 2.2 statute miles south of the field. The FCC antenna structure registration (ASR) number is 1065881. The lights will be returned to service 2300 UTC (Coordinated Universal Time) on July 27, 2007.

NAV NAV VOR OTS Navigation: The VOR located on this airport is out of service.

COM COM ATIS OTS Communications: The Automatic Terminal information Service (ATIS) is out of service.

SVC SVC TWR 1215-0330 Service: The control tower has new operating hours, 1215-0330 MON -FRI/1430-2300 SAT/1600-0100 UTC Monday Thru Friday. 1430-2300 UTC on Saturday and SUN TIL 0707300100 1600-0100 UTC on Sunday until 0100 on July 30, 2007.

SVC FUEL UNAVBL TIL 0707291600 Service: All fuel for this airport is unavailable until July 29, 2007, at 1600 UTC.

SVC CUSTOMS UNAVBL TIL 0708150800 Service: United States Customs service for this airport will not be available until August 15, 2007, at 0800 UTC.

AIRSPACE AIRSPACE AIRSHOW ACFT Airspace. There is an airshow being held at this airport with aircraft 5000/BLW 5 NMR AIRPORT flying 5,000 feet and below within a 5 nautical mile radius.

AVOIDANCE ADZD WEF Avoidance is advised from 2000 UTC on July 15, 2007, until 2200 0707152000-0707152200 on July 15, 2007.

U ORT 6K8 (U) RWY ABANDONED VEHICLE Unverified aeronautical information.

O LOZ LOZ (O) CONTROLLED BURN OF Other aeronautical information received from any authorized source HOUSE 8 NE APCH END RWY 23 WEF that may be beneficial to aircraft operations and does not meet 0710211300-0710211700 defined NOTAM criteria.

Figure 1-19. NOTAM (D) Information.

1-13 • Affected Location (the identifier of the affected facility Flight information publications outlining baseline data: or location) • Notices to Airmen (NTAP)—Published by System • KEYWORD (one of the following: RWY, TWY, Operations Services, System Operations and Safety, RAMP, APRON, AD, COM, NAV, SVC, OBST, Publications, every 28 days) AIRSPACE, (U) and (O)) • Chart Supplement U.S. (formerly Airport/Facility • Surface Identification (optional—this shall be the Directory) runway identification for runway related NOTAMs, • Pacific Chart Supplement the taxiway identification for taxiway-related • Alaska Supplement NOTAMs, or the ramp/apron identification for ramp/ apron-related NOTAMs) • Alaska Terminal • Condition (the condition being reported) • Aeronautical Information Manual (AIM) • Time (identifies the effective time(s) of the NOTAM condition) NOTAMs are available in printed form through subscription from the Superintendent of Documents, from an FSS, or online at PilotWeb ( www.pilotweb.nas.faa.gov ), which Altitude and height are in feet mean sea level (MSL) up to provides access to current NOTAM information. Local 17,999; e.g., 275, 1225 (feet and MSL is not written), and in airport NOTAMs can be obtained online from various flight levels (FL) for 18,000 and above; e.g., FL180, FL550.

websites. Some examples are www.fltplan.com and www.

When MSL is not known, above ground level (AGL) will be aopa.org/whatsnew/notams.html. Most sites require a free written (304 AGL).

registration and acceptance of terms but offer pilots updated NOTAMs and TFRs.

When time is expressed in a NOTAM, the day begins at 0000 and ends at 2359. Times used in the NOTAM system are Safety Program Airmen Notification System (SPANS) universal time coordinated (UTC) and shall be stated in 10 digits (year, month, day, hour, and minute). The following In 2004, the FAA launched the Safety Program Airmen are two examples of how the time would be presented: Notification System (SPANS), an online event notification system that provides timely and easy-to-assess seminar !DCA LDN NAV VOR OTS WEF and event information notification for airmen. The SPANS system is taking the place of the current paper-based mail 0708051600-0708052359 system. This provides better service to airmen while reducing costs for the FAA. Anyone can search the SPANS system !DCA LDN NAV VOR OTS WEF and register for events. To read more about SPANS, visit 0709050000-0709050400 www.faasafety.gov/spans .

NOTAM Dissemination and Availability Aircraft Classifications and Ultralight The system for disseminating aeronautical information is Vehicles made up of two subsystems: the Airmen's Information System The FAA uses various ways to classify or group machines (AIS) and the NOTAM System. The AIS consists of charts and operated or flown in the air. The most general grouping uses publications and is disseminated by the following methods: the term aircraft. This term is in 14 CFR 1.1 and means a device that is used or intended to be used for flight in the air.

Aeronautical charts depicting permanent baseline data: Ultralight vehicle is another general term the FAA uses.

• IFR Charts—Enroute High Altitude ConterminousU.S., This term is defined in 14 CFR 103. As the term implies, Enroute Low Altitude Conterminous U.S., Alaska powered ultralight vehicles must weigh less than 254 pounds Charts, and Pacific Charts empty weight and unpowered ultralight vehicles must • U.S. Terminal Procedures—Departure Procedures weigh less than 155 pounds. Rules for ultralight vehicles (DPs), Standard Terminal Arrivals (STARs) and are significantly different from rules for aircraft; ultralight Standard Instrument Approach Procedures (SIAPs) vehicle certification, registration, and operation rules are also • VFR Charts—Sectional Aeronautical Charts, Terminal contained in 14 CFR 103.

Area Charts (TAC), and World Aeronautical Charts (WAC) 1-14 The FAA differentiates aircraft by their characteristics and center of gravity with respect to the wing. Flight control physical properties. Key groupings defined in 14 CFR 1.1 of the aircraft depends on the wing's ability to flexibly include: deform rather than the use of control surfaces.

• Airplane—an engine-driven fixed-wing aircraft Size and weight are other methods used in 14 CFR 1.1 to heavier than air, that is supported in flight by the group aircraft: dynamic reaction of the air against its wings.

• Large aircraft—an aircraft of more than 12,500 • Glider—a heavier-than-air aircraft, that is supported pounds, maximum certificated takeoff weight.

in flight by the dynamic reaction of the air against its lifting surfaces and whose free flight does not depend • Light-sport aircraft (LSA)—an aircraft, other than principally on an engine. a helicopter or powered-lift that, since its original certification, has continued to meet the definition in • Lighter-than-air aircraft—an aircraft that can rise and 14 CFR 1.1. (LSA can include airplanes, airships, remain suspended by using contained gas weighing balloons, gliders, gyro planes, powered parachutes, less than the air that is displaced by the gas.

and weight-shift-control.)

- Airship—an engine-driven lighter-than-air • Small Aircraft—aircraft of 12,500 pounds or less, aircraft that can be steered.

maximum certificated takeoff weight.

- Balloon—a lighter-than-air aircraft that is not engine driven, and that sustains flight through the We also use broad classifications of aircraft with respect to use of either gas buoyancy or an airborne heater.

the certification of airmen or with respect to the certification of the aircraft themselves. See the next section, Pilot • Powered-lift—a heavier-than-air aircraft capable of Certifications, and Chapter 3, for further discussion of vertical takeoff, vertical landing, and low speed flight certification. These definitions are in 14 CFR 1.1: that depends principally on engine-driven lift devices or engine thrust for lift during these flight regimes and • Category on nonrotating airfoil(s) for lift during horizontal flight.

1. As used with respect to the certification, ratings, • Powered parachute—a powered aircraft comprised of privileges, and limitations of airmen, means a a flexible or semi-rigid wing connected to a fuselage broad classification of aircraft. Examples include: so that the wing is not in position for flight until airplane; rotorcraft; glider; and lighter-than-air; the aircraft is in motion. The fuselage of a powered and parachute contains the aircraft engine, a seat for each 2. As used with respect to the certification of occupant and Is attached to the aircraft's landing gear.

aircraft, means a grouping of aircraft based upon • Rocket—an aircraft propelled by ejected expanding intended use or operating limitations. Examples gases generated in the engine from self-contained include: transport, normal, utility, acrobatic, propellants and not dependent on the intake of outside limited, restricted, and provisional.

substances. It includes any part which becomes • Class separated during the operation.

1. As used with respect to the certification, ratings, • Rotorcraft—a heavier-than-air aircraft that depends privileges, and limitations of airmen, means a principally for its support in flight on the lift generated classification of aircraft within a category having by one or more rotors.

similar operating characteristics. Examples - Gyroplane—a rotorcraft whose rotors are not Include: single engine; multiengine; land; water; engine-driven, except for Initial starting, but gyroplane, helicopter, airship, and free balloon; are made to rotate by action of the air when and the rotorcraft Is moving; and whose means of 2. As used with respect to the certification of propulsion, consisting usually of conventional aircraft, means a broad grouping of aircraft having propellers, is Independent of the rotor system.

similar characteristics of propulsion, flight, or - Helicopter—a rotorcraft that, for its horizontal landing. Examples include: airplane, rotorcraft, motion, depends principally on its engine-driven gilder, balloon, landplane, and seaplane.

rotors.

• Type • Weight-shift-control—a powered aircraft with a framed 1. As used with respect to the certification, ratings, pivoting wing and a fuselage controllable only in pitch privileges, and limitations of airmen, means and roll by the pilot's ability to change the aircraft’s 1-15 a specific make and basic model of aircraft, • Privileges—define where and when the pilot may fly, Including modifications thereto that do not with whom they may fly, the purpose of the flight, and change its handling or flight characteristics. the type of aircraft they are allowed to fly.

Examples include: 737-700, G-IV, and 1900; and • Limitations—the FAA may impose limitations on a 2. As used with respect to the certification of pilot certificate if, during training or the practical test, aircraft, means those aircraft which are similar the pilot does not demonstrate all skills necessary to in design. Examples include: 737-700 and 737 exercise all privileges of a privilege level, category, 700C; G-IV and G-IV-X; and 1900 and 1900C.

class, or type rating.

Endorsements, a form of authorization, are written to establish This system of definitions allows the FAA to group and that the certificate holder has received training in specific skill regulate aircraft to provide for their safe operation.

areas. Endorsements are written and signed by an authorized individual, usually a certificated flight instructor (CFI), and Pilot Certifications are based on aircraft classification. [Figure 1-21] The type of intended flying influences what type of pilot’s certificate is required. Eligibility, training, experience, Sport Pilot and testing requirements differ depending on the type of To become a sport pilot, the student pilot is required to have certificates sought. [Figure 1-20] Each type of pilot’s flown, at a minimum, the following hours depending upon certificate has privileges and limitations that are inherent the aircraft: within the certificate itself. However, other privileges and • Airplane: 20 hours limitations may be applicable based on the aircraft type, • Powered Parachute: 12 hours operation being conducted, and the type of certificate.

For example, a certain certificate may have privileges and • Weight-Shift Control (Trikes): 20 hours limitations under 14 CFR part 61 and part 91.

• Glider: 10 hours • Rotorcraft (gyroplane only): 20 hours • Lighter-Than-Air: 20 hours (airship) or 7 hours (balloon) To earn a Sport Pilot Certificate, one must: • Be at least 16 years old to become a student sport pilot (14 years old for gliders or balloons) • Be at least 17 years old to test for a sport pilot certificate (16 years old for gliders or balloons) • Be able to read, write, and understand the English language • Hold a current and valid driver’s license as evidence of medical eligibility When operating as a sport pilot, some of the following privileges and limitations may apply.

Privileges: • Operate as pilot in command (PIC) of a light-sport aircraft • Carry a passenger and share expenses (fuel, oil, airport expenses, and aircraft rental) • Fly during the daytime using VFR, a minimum of 3 statute miles visibility and visual contact with the Figure 1-20. Front side (top) and back side (bottom) of an airman ground are required certificate issued by the FAA.

1-16 Recreational pilot to conduct solo flights for the purpose of obtaining an additional certificate or rating while under the supervision of an authorized flight instructor: section 61.101(i).

I certify that (First name, MI, Last name) has received the required training of section 61.87 in a (make and model aircraft). I have determined he/she is prepared to conduct a solo flight on (date) under the following conditions: (List all conditions which require endorsement, e.g., flight which requires communication with air traffic control, flight in an aircraft for which the pilot does not hold a category/class rating, etc.).

Figure 1-21. Example endorsement for a recreational pilot to conduct solo flights for the purpose of determining an additional certificate or rating.

Limitations: As a recreational pilot, cross-country flight is limited to a 50 NM range from the departure airport but is permitted with • Prohibited from flying in Class A airspace additional training per 14 CFR part 61, section 61.101(c).

• Prohibited from flying in Class B, C, or D airspace Additionally, recreational pilots are restricted from flying until you receive training and a logbook endorsement at night and flying in airspace where communications with from an instructor ATC are required.

• No flights outside the United States without prior The minimum aeronautical experience requirements for a permission from the foreign aviation authority recreational pilot license involve: • May not tow any object • 30 hours of flight time including at least: • No flights while carrying a passenger or property for • 15 hours of dual instruction compensation or hire • 2 hours of en route training • Prohibited from flying in furtherance of a business • 3 hours in preparation for the practical test The sport pilot certificate does not list aircraft category • 3 hours of solo flight and class ratings. After successfully passing the practical test for a sport pilot certificate, regardless of the light-sport When operating as a recreational pilot, some of the following aircraft privileges you seek, the FAA will issue you a sport privileges and limitations may apply.

pilot certificate without any category and class ratings. The Instructor will provide you with the appropriate logbook Privileges: endorsement for the category and class of aircraft in which you are authorized to act as pilot in command.

• Carry no more than one passenger; • Not pay less than the pro rata share of the operating Recreational Pilot expenses of a flight with a passenger, provided the To become a recreational pilot, one must: expenses involve only fuel, oil, airport expenses, or • Be at least 17 years old aircraft rental fees • Be able to read, write, speak, and understand the Limitations: English language • Pass the required knowledge test • A recreational pilot may not act as PIC of an aircraft that is certificated for more than four occupants or has • Meet the aeronautical experience requirements in more than one powerplant.

either a single-engine airplane, a helicopter, or a gyroplane.

Private Pilot • Obtain a logbook endorsement from an instructor A private pilot is one who flies for pleasure or personal • Pass the required practical test business without accepting compensation for flying except in some very limited, specific circumstances. The Private • Obtain a third-class medical certificate issued under Pilot Certificate is the certificate held by the majority of 14 CFR part 67 1-17 active pilots. It allows command of any aircraft (subject to appropriate ratings) for any noncommercial purpose and gives almost unlimited authority to fly under VFR.

Passengers may be carried and flight in furtherance of a business is permitted; however, a private pilot may not be compensated in any way for services as a pilot, although passengers can pay a pro rata share of flight expenses, such as fuel or rental costs. If training under 14 CFR part 61, experience requirements include at least 40 hours of piloting time, including 20 hours of flight with an instructor and 10 hours of solo flight. [Figure 1-22] Figure 1-23. A complex aircraft.

Commercial Pilot and understand the English language, and be “of good moral A commercial pilot may be compensated for flying. Training standing.” A pilot may obtain an ATP certificate with restricted for the certificate focuses on a better understanding of privileges enabling him/her to serve as an SIC in scheduled aircraft systems and a higher standard of airmanship. The airline operations. The minimum pilot experience is reduced Commercial Pilot Certificate itself does not allow a pilot based upon specific academic and flight training experience.

to fly in instrument meteorological conditions (IMC), and The minimum age to be eligible is 21 years. [Figure 1-24] commercial pilots without an instrument rating are restricted to daytime flight within 50 NM when flying for hire.

Selecting a Flight School A commercial airplane pilot must be able to operate Selecting a flight school is an important consideration in a complex airplane, as a specific number of hours of the flight training process. FAA-approved training centers, complex (or turbine-powered) aircraft time are among FAA-approved pilot schools, noncertificated flying schools, the prerequisites, and at least a portion of the practical and independent flight instructors conduct flight training in examination is performed in a complex aircraft. A complex the United States. All flight training is conducted under the aircraft must have retractable landing gear, movable flaps, auspices of the FAA following the regulations outlined in and a controllable-pitch propeller. See 14 CFR part 61, 14 CFR parts 142, 141, or 61. Training centers, also referred section 61.31(e) for additional information. [Figure 1-23] to as flight academies, operate under 14 CFR part 142 and are certificated by the FAA. Application for certification Airline Transport Pilot is voluntary and the training center must meet stringent The airline transport pilot (ATP) is tested to the highest level requirements for personnel, equipment, maintenance, of piloting ability. The ATP certificate is a prerequisite for facilities, and must teach a curriculum approved by the serving as a PIC and second in command (SIC) of scheduled FAA. Training centers typically utilize a number of flight airline operations. It is also a prerequisite for serving as a PIC simulation training devices as part of its curricula. Flight in select charter and fractional operations. The minimum pilot training conducted at a training center is primarily done experience is 1,500 hours of flight time. In addition, the pilot under contract to airlines and other commercial operators must be at least 23 years of age, be able to read, write, speak, in transport or turbine aircraft, however many also provide Figure 1-22. A typical aircraft a private pilot might fly. Figure 1-24. Type of aircraft flown by an airline transport pilot.

1-18 flight training for the private pilot certificate, commercial How To Find a Reputable Flight Program pilot certificate, instrument rating, and ATP certificate.

To obtain information about pilot training, contact the local FSDO, which maintains a current file on all schools within its Flight schools operating under 14 CFR part 141 are district. The choice of a flight school depends on what type of certificated by the FAA. Application for certification is certificate is sought, and whether an individual wishes to fly voluntary and the school must meet stringent requirements as a sport pilot or wishes to pursue a career as a professional for personnel, equipment, maintenance, facilities, and must pilot. Another consideration is the amount of time that can teach an established curriculum, which includes a training be devoted to training. Ground and flight training should course outline (TCO) approved by the FAA. The certificated be obtained as regularly and frequently as possible because schools may qualify for a ground school rating and a flight this assures maximum retention of instruction and the school rating. In addition, the school may be authorized achievement of requisite proficiency.

to give its graduates practical (flight) tests and knowledge (computer administered written) tests. The FAA Pilot School Do not make the determination based on financial concerns Search database located at http://av-info.faa.gov/PilotSchool.

alone, because the quality of training is very important.

asp, lists certificated ground and flight schools and the pilot Prior to making a final decision, visit the schools under training courses each school offers.

consideration and talk with management, instructors, and students. Request a personal tour of the flight school facility.

Enrollment in a 14 CFR part 141 flight school ensures quality, continuity, and offers a structured approach to flight Be inquisitive and proactive when searching for a flight training because these facilities must document the training school, do some homework, and develop a checklist of curriculum and have their flight courses approved by the questions by talking to pilots and reading articles in flight FAA. These strictures allow 14 CFR part 141 schools to magazines. The checklist should include questions about complete certificates and ratings in fewer flight hours, which aircraft reliability and maintenance practices, and questions can mean a savings on the cost of flight training for the for current students such as whether or not there is a safe, student pilot. For example, the minimum requirement for a clean aircraft available when they are scheduled to fly.

Private Pilot Certificate is 35 hours in a part 141-certificated school and 40 hours in a part 61-certificated school. (This Questions for the training facility should be aimed at difference may be insignificant for a Private Pilot Certificate determining if the instruction fits available personal time.

because the national average indicates most pilots require 60 What are the school’s operating hours? Does the facility have to 75 hours of flight training.)

dedicated classrooms available for ground training required by the FAA? Is there an area available for preflight briefings, Many excellent flight schools find it impractical to qualify postflight debriefings, and critiques? Are these rooms private for the FAA part 141 certificates and are referred to as part in nature in order to provide a nonthreatening environment 61 schools. 14 CFR part 61 outlines certificate and rating in which the instructor can explain the content and outcome requirements for pilot certification through noncertificated of the flight without making the student feel self-conscious?

schools and individual flight instructors. It also states what knowledge-based training must be covered and how much Examine the facility before committing to any flight training.

flight experience is required for each certificate and rating.

Evaluate the answers on the checklist, and then take time to Flight schools and flight instructors who train must adhere think things over before making a decision. This proactive to the statutory requirements and train pilots to the standards approach to choosing a flight school will ensure a student found in 14 CFR part 61.

pilot contracts with a flight school or flight instructor best suited to their individual needs.

One advantage of flight training under 14 CFR part 61 is its flexibility. Flight lessons can be tailored to the individual How To Choose a Certificated Flight Instructor (CFI) student, because 14 CFR part 61 dictates the required Whether an individual chooses to train under 14 CFR part minimum flight experience and knowledge-based training 141 or part 61, the key to an effective flight program is the necessary to gain a specific pilot’s license, but it does not quality of the ground and flight training received from the stipulate how the training is to be organized. This flexibility CFI. The flight instructor assumes total responsibility for can also be a disadvantage because a flight instructor who training an individual to meet the standards required for fails to organize the flight training can cost a student pilot certification within an ever-changing operating environment.

time and expense through repetitious training. One way for A CFI should possess an understanding of the learning a student pilot to avoid this problem is to ensure the flight process, knowledge of the fundamentals of teaching, and instructor has a well-documented training syllabus.

1-19 the ability to communicate effectively with the student pilot. Airman Certification and Rating Application (IACRA). If During the certification process, a flight instructor applicant the application is completed on paper, it must be sent to is tested on the practical application of these skills in specific the local Flight Standards District Office (FSDO), who will teaching situations. The flight instructor is crucial to the forward it to AFS-760. Once the application is processed, the scenario-based training program endorsed by the FAA. He applicant will receive the Student Pilot Certificate by mail at or she is trained to function in the learning environment as an the address provided on the application.

advisor and guide for the learner. The duties, responsibilities, and authority of the CFI include the following: The aforementioned process will become effective on April 1, 2016. The new certificate will be printed on a plastic card, • Orient the student to the scenario-based training which will replace the paper certificate that was issued in the system past. The plastic card certificate will not have an expiration • Help the student become a confident planner and date. Paper certificates issued prior to the new process will inflight manager of each flight and a critical evaluator still expire according to the date on the certificate; however, of their own performance under the new process, paper certificates cannot be renewed.

Once the paper certificate expires, the Student Pilot must • Help the student understand the knowledge submit a new application under the new process. Another requirements present in real world applications significant change in the new process is that flight instructors • Diagnose learning difficulties and help the student will now make endorsements for solo privileges in the overcome them Student Pilot’s logbook, instead of endorsing the Student • Evaluate student progress and maintain appropriate Pilot Certificate.

records To be eligible for a Student Pilot Certificate, the applicant • Provide continuous review of student learning must: Should a student pilot find the selected CFI is not training in • Be at least 16 years of age (14 years of age to pilot a a manner conducive for learning, or the student and CFI do glider or balloon).

not have compatible schedules, the student pilot should find • Be able to read, speak, write, and understand the another CFI. Choosing the right CFI is important because the English language.

quality of instruction and the knowledge and skills acquired from their flight instructor affect a student pilot’s entire Medical Certification Requirements flying career.

The second step in becoming a pilot is to obtain a medical certificate (if the choice of aircraft is an airplane, helicopter, The Student Pilot gyroplane, or an airship). (The FAA suggests the individual The first step in becoming a pilot is to select a type of aircraft.

get a medical certificate before beginning flight training to FAA rules for obtaining a pilot’s certificate differ depending avoid the expense of flight training that cannot be continued on the type of aircraft flown. Individuals can choose among due to a medical condition.) Balloon or glider pilots do not airplanes, gyroplanes, weight-shift, helicopters, powered need a medical certificate, but do need to write a statement parachutes, gliders, balloons, or airships. A pilot does not certifying that no medical defect exists that would prevent need a certificate to fly ultralight vehicles.

them from piloting a balloon or glider. The new sport pilot category does not require a medical examination; a driver’s Basic Requirements license can be used as proof of medical competence.

A student pilot is one who is being trained by an instructor Applicants who fail to meet certain requirements or who pilot for his or her first full certificate, and is permitted have physical disabilities which might limit, but not to fly alone (solo) under specific, limited circumstances.

prevent, their acting as pilots, should contact the nearest Before a student pilot may be endorsed to fly solo, that FAA office. Anyone requesting an FAA Medical Clearance, student must have a Student Pilot Certificate. There are Medical Certificate, or Student Pilot Medical Certificate can multiple ways that an aspiring pilot can obtain their Student electronically complete an application through the FAA’s Pilot Certificate. The application may be processed by an MedXPress system available at https://medxpress.faa.gov /.

FAA inspector or technician, an FAA-Designated Pilot Examiner, a Certified Flight Instructor (CFI), or an Airman A medical certificate is obtained by passing a physical Certification Representative (ACR). If the application is examination administered by a doctor who is an FAA- completed electronically, the authorized person will submit authorized AME. There are approximately 6,000 the application to the FAA’s Airman Certification Branch FAA-authorized AMEs in the nation. To find an AME near (AFS-760) in Oklahoma City, OK, via the Integrated 1-20 you, go to the FAA’s AME locator at www.faa.gov/pilots/ of training and testing materials which are available in print amelocator/. Medical certificates are designated as first class, form from the Superintendent of Documents, GPO, and second class, or third class. Generally, first class is designed online at the Regulatory Support Division: www.faa.gov / for the airline transport pilot; second class for the commercial about/office_org/headquarters_offices/avs/offices/afs/afs600.

pilot; and third class for the student, recreational, and private pilot. A Student Pilot Certificate can be processed by an FAA The CFI may also use commercial publications as a source inspector or technician, an FAA Designated pilot examiner of study materials, especially for aircraft categories where (DPE), an Airman Certification Representative (ACR), or a government materials are limited. A student pilot should Certified Flight Instructor (CFI). This certificate allows an follow the flight instructor’s advice on what and when to individual who is being trained by a flight instructor to fly study. Planning a definite study program and following it as alone (solo) under specific, limited circumstances and must closely as possible will help in scoring well on the knowledge be carried with the student pilot while exercising solo flight test. Haphazard or disorganized study habits usually result privileges. The Student Pilot Certificate is only required in an unsatisfactory score.

when exercising solo flight privileges. The new plastic student certificate does not have an expiration date. For In addition to learning aeronautical knowledge, such as the airmen who were issued a paper certificate, that certificate principles of flight, a student pilot is also required to gain will remain valid until its expiration date. A paper certificate skill in flight maneuvers. The selected category and class of cannot be renewed. When the paper certificate expires, a new aircraft determines the type of flight skills and number of application must be completed via the IACRA system, and flight hours to be obtained. There are four steps involved in a new plastic certificate will be issued. learning a flight maneuver: • The CFI introduces and demonstrates flight maneuver Student Pilot Solo Requirements to the student.

Once a student has accrued sufficient training and experience, • The CFI talks the student pilot through the maneuver.

a CFI can endorse the student’s logbook to authorize limited solo flight in a specific type (make and model) of aircraft.

• The student pilot practices the maneuver under CFI A student pilot may not carry passengers, fly in furtherance supervision.

of a business, or operate an aircraft outside of the various • The CFI authorizes the student pilot to practice the endorsements provided by the flight instructor. There is no maneuver solo.

minimum aeronautical knowledge or experience requirement for the issuance of a Student Pilot Certificate, however, the Once the student pilot has shown proficiency in the required applicant must be at least 16 years of age (14 years of age for knowledge areas, flight maneuvers, and accrued the required a pilot for glider or balloon), and they must be able to read, amount of flight hours, the CFI endorses the student pilot speak, write and understand the English language. There are, logbook, which allows the student pilot to take the written however, minimum aeronautical knowledge and experience and practical tests for pilot certification.

requirements for student pilots to solo.

Knowledge and Skill Tests Becoming a Pilot Knowledge Tests The course of instruction a student pilot follows depends on The knowledge test is the computer portion of the tests taken the type of certificate sought. It should include the ground and to obtain pilot certification. The test contains questions of flight training necessary to acquire the knowledge and skills the objective, multiple-choice type. This testing method required to safely and efficiently function as a certificated conserves the applicant's time, eliminates any element of pilot in the selected category and class of aircraft. The individual judgment in determining grades, and saves time specific knowledge and skill areas for each category and in scoring.

class of aircraft are outlined in 14 CFR part 61. Eligibility, aeronautical knowledge, proficiency, and aeronautical FAA Airman Knowledge Test Guides for every type of pilot requirements can be found in 14 CFR part 61.

certificate address most questions you may have regarding • Recreational Pilot, see subpart D the knowledge test process. The guides are available on- line (free of charge) at http://www.faa.gov/training_testing/ • Private Pilot, see subpart E testing/test_guides/.

• Sport Pilot, see subpart J The knowledge-based portion of training is obtained through FAA handbooks such as this one, textbooks, and other sources 1-21 When To Take the Knowledge Test knowledge and skill must be demonstrated by the applicant.

Since the FAA requires all practical tests be conducted in The knowledge test is more meaningful to the applicant accordance with the appropriate PTS and the policies set forth and more likely to result in a satisfactory grade if it is taken in the Introduction section of the PTS book. The pilot applicant after beginning the flight portion of the training. Therefore, should become familiar with this book during training.

the FAA recommends the knowledge test be taken after the student pilot has completed a solo cross-country flight. The The PTS book is a testing document and not intended to be operational knowledge gained by this experience can be used a training syllabus. An appropriately-rated flight instructor to the student’s advantage in the knowledge test. The student is responsible for training the pilot applicant to acceptable pilot’s CFI is the best person to determine when the applicant standards in all subject matter areas, procedures, and is ready to take the knowledge test.

maneuvers. Descriptions of tasks and information on how to perform maneuvers and procedures are contained in reference Practical Test and teaching documents such as this handbook. A list of The FAA has developed PTS for FAA pilot certificates reference documents is contained in the Introduction section and associated ratings. [Figure 1-25] In 2015, the FAA of each PTS book. Copies may obtained by: began transitioning to the ACS approach. The ACS is essentially an “enhanced” version of the PTS. It adds task- • Downloading from the FAA website at www.faa.gov specific knowledge and risk management elements to each • Purchasing print copies from the GPO, Pittsburgh, PTS Area of Operation and Task. The result is a holistic, Pennsylvania, or via their official online bookstore integrated presentation of specific knowledge, skills, and at www.access.gpo.gov risk management elements and performance metrics for each Area of Operation and Task The ACS evaluation program The flight proficiency maneuvers listed in 14 CFR part 61 will eventually replace the PTS program for evaluating and are the standard skill requirements for certification. They certifying pilots.

are outlined in the PTS as “areas of operation.” These are phases of the practical test arranged in a logical sequence The practical tests are administered by FAA ASIs and DPEs.

within the standard. They begin with preflight preparation Title 14 CFR part 61 specifies the areas of operation in which and end with postflight procedures. Each area of operation FAA-S-8081-12C FAA-S-8081-14B FAA-S-8081-8B Figure 1-25. Examples of Practical Test Standards.

1-22 contains “tasks,” which are comprised of knowledge areas, or GPO bookstores. Most airport fixed-base operators and flight flight procedures, and/or flight maneuvers appropriate to the schools carry a variety of government publications and charts, area of operation. The candidate is required to demonstrate as well as commercially published materials.

knowledge and proficiency in all tasks for the original issuance of all pilot certificates. Who Administers the FAA Practical Tests?

Due to the varied responsibilities of the FSDOs, practical tests When To Take the Practical Test are usually given by DPEs. An applicant should schedule the 14 CFR part 61 establishes the ground school and flight practical test by appointment to avoid conflicts and wasted experience requirements for the type of certification and time. A list of examiner names can be obtained from the local aircraft selected. However, the CFI best determines when an FSDO. Since a DPE serves without pay from the government applicant is qualified for the practical test. A practice practical for conducting practical tests and processing the necessary test is an important step in the flight training process. reports, the examiner is allowed to charge a reasonable fee.

There is no charge for the practical test when conducted by The applicant will be asked to present the following an FAA inspector.

documentation: Role of the Certificated Flight Instructor • FAA Form 8710-1 (8710.11 for sport pilot applicants), To become a CFI, a pilot must meet the provisions of 14 CFR Application for an Airman Certificate and/or Rating, part 61. The FAA places full responsibility for student flight with the flight instructor’s recommendation training on the shoulders of the CFI, who is the cornerstone • An Airman Knowledge Test Report with a of aviation safety. It is the job of the flight instructor to train satisfactory grade the student pilot in all the knowledge areas and teach the skills necessary for the student pilot to operate safely and • A medical certificate (not required for glider or balloon), a Student Pilot Certificate, and a pilot competently as a certificated pilot in the NAS. The training includes airmanship skills, pilot judgment and decision- logbook endorsed by a flight instructor for solo, solo cross-country (airplane and rotorcraft), and for the making, and good operating practices.

make and model aircraft to be used for the practical test (driver’s license or medical certificate for sport A pilot training program depends on the quality of the ground and flight instruction the student pilot receives. The pilot applicants) flight instructor must possess a thorough understanding of • The pilot log book records the learning process, knowledge of the fundamentals of • A graduation certificate from an FAA-approved school teaching, and the ability to communicate effectively with the (if applicable) student pilot. Use of a structured training program and formal course syllabus is crucial for effective and comprehensive The applicant must provide an airworthy aircraft with flight training. It should be clear to the student in advance of equipment relevant to the areas of operation required for every lesson what the course of training will involve and the the practical test. He or she will also be asked to produce criteria for successful completion. This should include the and explain the: flight instructor briefing and debriefing the student before and after every lesson. Additionally, scenario-based training has • Aircraft’s registration certificate become the preferred method of flight instruction today. This • Aircraft’s airworthiness certificate involves presenting the student with realistic flight scenarios • Aircraft’s operating limitations or FAA-approved and recommended actions for mitigating risk.

aircraft flight manual (if required) Insistence on correct techniques and procedures from the • Aircraft equipment list beginning of training by the flight instructor ensures that the • Required weight and balance data student pilot develops proper flying habits. Any deficiencies • Maintenance records in the maneuvers or techniques must immediately be emphasized and corrected. A flight instructor serves as a role • Applicable airworthiness directives (ADs) model for the student pilot who observes the flying habits of his or her flight instructor during flight instruction, as well For a detailed explanation of the required pilot maneuvers and as when the instructor conducts other pilot operations. Thus, performance standards, refer to the PTS pertaining to the type the flight instructor becomes a model of flying proficiency of certification and aircraft selected. These standards may be for the student who, consciously or unconsciously, attempts downloaded free of charge from the FAA at www.faa.gov. They to imitate the instructor. For this reason, a flight instructor may also be purchased from the Superintendent of Documents 1-23 should observe recognized safety practices, as well as serve the public, and must adhere to FAA policies and regulations during all flight operations. procedures in certification matters. The FAA expects the DPE to administer practical tests with the same degree of The student pilot who enrolls in a pilot training program professionalism, using the same methods, procedures, and commits considerable time, effort, and expense to achieve a standards as an FAA ASI.

pilot certificate. Students often judge the effectiveness of the Chapter Summary flight instructor and the success of the pilot training program based on their ability to pass the requisite FAA practical The FAA has entered the second century of civil aviation as a test. A competent flight instructor stresses to the student that robust government organization and is taking full advantage of practical tests are a sampling of pilot ability compressed into technology, such as Global Positioning System (GPS) satellite a short period of time. The goal of a flight instructor is to technology to enhance the safety of civil aviation. The Internet train the “total” pilot.

has also become an important tool in promoting aviation safety and providing around-the-clock resources for the aviation Role of the Designated Pilot Examiner community. Handbooks, regulations, standards, references, The Designated Pilot Examiner (DPE) plays an important and online courses are now available at www.faa.gov .

role in the FAA’s mission of promoting aviation safety by administering FAA practical tests for pilot and Flight In keeping with the FAA’s belief that safety is a learned Instructor Certificates and associated ratings. Although behavior, the FAA offers many courses and seminars to administering these tests is a responsibility of the ASI, the enhance air safety. The FAA puts the burden of instilling safe FAA’s highest priority is making air travel safer by inspecting flying habits on the flight instructor, who should follow basic aircraft that fly in the United States. To satisfy the need for flight safety practices and procedures in every flight operation pilot testing and certification services, the FAA delegates he or she undertakes with a student pilot. Operational safety certain responsibilities to private individuals who are not practices include, but are not limited to, collision avoidance FAA employees.

procedures consisting of proper scanning techniques, use of checklists, runway incursion avoidance, positive transfer of Appointed in accordance with 14 CFR part 183, section controls, and workload management. These safety practices 183.23, a DPE is an individual who meets the qualification are discussed more fully within this handbook. Safe flight also requirements of the Pilot Examiner’s Handbook, FAA Order depends on Scenario-Based Training (SBT) that teaches the 8710.3, and who: student pilot how to respond in different flight situations. The FAA has incorporated these techniques along with decision- • Is technically qualified making methods, such as aeronautical decision-making • Holds all pertinent category, class, and type ratings (ADM), risk management, and crew resource management for each aircraft related to their designation (CRM), which are covered more completely in Chapter 2, • Meets requirements of 14 CFR part 61, sections 61.56, Aeronautical Decision-Making.

61.57, and 61.58, as appropriate • Is current and qualified to act as PIC of each aircraft for which he or she is authorized • Maintains at least a Third-Class Medical Certificate, if required • Maintains a current Flight Instructor Certificate, if required Designated to perform specific pilot certification tasks on behalf of the FAA, a DPE may charge a reasonable fee. Generally, a DPE’s authority is limited to accepting applications and conducting practical tests leading to the issuance of specific pilot certificates and/or ratings. The majority of FAA practical tests at the private and commercial pilot levels are administered by DPEs.

DPE candidates must have good industry reputations for professionalism, integrity, a demonstrated willingness to 1-24

Chapter 2

Aeronautical

Decision-Making

Introduction Aeronautical decision-making (ADM) is decision-making in a unique environment—aviation. It is a systematic approach to the mental process used by pilots to consistently determine the best course of action in response to a given set of circumstances. It is what a pilot intends to do based on the latest information he or she has.

2-1 The importance of learning and understanding effective History of ADM ADM skills cannot be overemphasized. While progress is For over 25 years, the importance of good pilot judgment, or continually being made in the advancement of pilot training aeronautical decision-making (ADM), has been recognized methods, aircraft equipment and systems, and services as critical to the safe operation of aircraft, as well as accident for pilots, accidents still occur. Despite all the changes in avoidance. The airline industry, motivated by the need to technology to improve flight safety, one factor remains the reduce accidents caused by human factors, developed the first same: the human factor which leads to errors. It is estimated training programs based on improving ADM. Crew resource that approximately 80 percent of all aviation accidents are management (CRM) training for flight crews is focused on related to human factors and the vast majority of these the effective use of all available resources: human resources, accidents occur during landing (24.1 percent) and takeoff hardware, and information supporting ADM to facilitate crew (23.4 percent). [Figure 2-1] cooperation and improve decision-making. The goal of all flight crews is good ADM and the use of CRM is one way ADM is a systematic approach to risk assessment and stress to make good decisions.

management. To understand ADM is to also understand how personal attitudes can influence decision-making and Research in this area prompted the Federal Aviation how those attitudes can be modified to enhance safety in the Administration (FAA) to produce training directed at flight deck. It is important to understand the factors that cause improving the decision-making of pilots and led to current humans to make decisions and how the decision-making FAA regulations that require that decision-making be taught process not only works, but can be improved.

as part of the pilot training curriculum. ADM research, development, and testing culminated in 1987 with the This chapter focuses on helping the pilot improve his or publication of six manuals oriented to the decision-making her ADM skills with the goal of mitigating the risk factors needs of variously rated pilots. These manuals provided associated with flight. Advisory Circular (AC) 60-22, multifaceted materials designed to reduce the number “Aeronautical Decision-Making,” provides background of decision-related accidents. The effectiveness of these references, definitions, and other pertinent information about materials was validated in independent studies where student ADM training in the general aviation (GA) environment.

pilots received such training in conjunction with the standard [Figure 2-2] flying curriculum. When tested, the pilots who had received ADM-training made fewer in-flight errors than those who had Percentage of General Aviation Accidents Flight Time Flight Time Flight Time 2% 83% 15% 24.1% 23.4% 15.7% 13% 9.7% 4.7% 3.3% 3.5% 2.6% Preflights/ Takeoff/ Climb Cruise Descent Maneuvering Approach Landing Other Taxi Initial Climb Figure 2-1. The percentage of aviation accidents as they relate to the different phases of flight. Note that the greatest percentage of accidents take place during a minor percentage of the total flight.

2-2 Figure 2-2. Advisory Circular (AC) 60-22, “Aeronautical Decision Making,” carries a wealth of information for the pilot to learn.

not received ADM training. The differences were statistically 5. Using all resources significant and ranged from about 10 to 50 percent fewer 6. Evaluating the effectiveness of one’s ADM skills judgment errors. In the operational environment, an operator flying about 400,000 hours annually demonstrated a 54 Risk Management percent reduction in accident rate after using these materials The goal of risk management is to proactively identify for recurrency training.

safety-related hazards and mitigate the associated risks. Risk management is an important component of ADM. When a Contrary to popular opinion, good judgment can be taught.

pilot follows good decision-making practices, the inherent risk Tradition held that good judgment was a natural by-product in a flight is reduced or even eliminated. The ability to make of experience, but as pilots continued to log accident-free good decisions is based upon direct or indirect experience flight hours, a corresponding increase of good judgment and education. The formal risk management decision-making was assumed. Building upon the foundation of conventional process involves six steps as shown in Figure 2-3.

decision-making, ADM enhances the process to decrease the probability of human error and increase the probability of a Consider automotive seat belt use. In just two decades, seat safe flight. ADM provides a structured, systematic approach belt use has become the norm, placing those who do not to analyzing changes that occur during a flight and how these wear seat belts outside the norm, but this group may learn to changes might affect the safe outcome of a flight. The ADM wear a seat belt by either direct or indirect experience. For process addresses all aspects of decision-making in the flight example, a driver learns through direct experience about the deck and identifies the steps involved in good decision-making.

value of wearing a seat belt when he or she is involved in a car accident that leads to a personal injury. An indirect learning Steps for good decision-making are: experience occurs when a loved one is injured during a car 1. Identifying personal attitudes hazardous to safe flight accident because he or she failed to wear a seat belt.

2. Learning behavior modification techniques As you work through the ADM cycle, it is important to 3. Learning how to recognize and cope with stress remember the four fundamental principles of risk management.

4. Developing risk assessment skills 2-3 Crew Resource Management (CRM) and Single-Pilot Resource Management START Identify While CRM focuses on pilots operating in crew environments, Hazards many of the concepts apply to single-pilot operations. Many CRM principles have been successfully applied to single-pilot aircraft and led to the development of Single-Pilot Resource Assess Monitor Management (SRM). SRM is defined as the art and science Risks Results of managing all the resources (both on-board the aircraft and from outside sources) available to a single pilot (prior

RISK

to and during flight) to ensure the successful outcome of the MANAGEMENT flight. SRM includes the concepts of ADM, risk management

PROCESS

(RM), task management (TM), automation management (AM), controlled flight into terrain (CFIT) awareness, and Analyze Use situational awareness (SA). SRM training helps the pilot Controls Controls maintain situational awareness by managing the automation and associated aircraft control and navigation tasks. This Make Control enables the pilot to accurately assess and manage risk and Decisions make accurate and timely decisions.

SRM is all about helping pilots learn how to gather information, analyze it, and make decisions. Although the Figure 2-3. Risk management decision-making process.

flight is coordinated by a single person and not an onboard flight crew, the use of available resources such as auto-pilot 1. Accept no unnecessary risk. Flying is not possible and air traffic control (ATC) replicates the principles of CRM.

without risk, but unnecessary risk comes without a corresponding return. If you are flying a new airplane Hazard and Risk for the first time, you might determine that the risk Two defining elements of ADM are hazard and risk. Hazard of making that flight in low visibility conditions is is a real or perceived condition, event, or circumstance that a unnecessary.

pilot encounters. When faced with a hazard, the pilot makes 2. Make risk decisions at the appropriate level. Risk an assessment of that hazard based upon various factors. The decisions should be made by the person who can pilot assigns a value to the potential impact of the hazard, develop and implement risk controls. Remember which qualifies the pilot’s assessment of the hazard—risk.

that you are pilot-in-command, so never let anyone else—not ATC and not your passengers—make risk Therefore, risk is an assessment of the single or cumulative decisions for you.

hazard facing a pilot; however, different pilots see hazards 3. Accept risk when benefits outweigh dangers (costs).

differently. For example, the pilot arrives to preflight and In any flying activity, it is necessary to accept some discovers a small, blunt type nick in the leading edge at the degree of risk. A day with good weather, for example, middle of the aircraft’s prop. Since the aircraft is parked on is a much better time to fly an unfamiliar airplane for the tarmac, the nick was probably caused by another aircraft’s the first time than a day with low IFR conditions.

prop wash blowing some type of debris into the propeller.

The nick is the hazard (a present condition). The risk is prop 4. Integrate risk management into planning at all levels.

fracture if the engine is operated with damage to a prop blade.

Because risk is an unavoidable part of every flight, safety requires the use of appropriate and effective risk The seasoned pilot may see the nick as a low risk. He management not just in the preflight planning stage, realizes this type of nick diffuses stress over a large area, is but in all stages of the flight.

located in the strongest portion of the propeller, and based on experience; he does not expect it to propagate a crack that While poor decision-making in everyday life does not always can lead to high risk problems. He does not cancel his flight.

lead to tragedy, the margin for error in aviation is thin. Since ADM enhances management of an aeronautical environment, all pilots should become familiar with and employ ADM.

2-4 The inexperienced pilot may see the nick as a high risk factor in the difference between the forecast altitudes, he assigned because he is unsure of the affect the nick will have on the a low risk to the hazard and took a chance. He and the operation of the prop, and he has been told that damage to passengers died from a poor risk assessment of the situation.

a prop could cause a catastrophic failure. This assessment Hazardous Attitudes and Antidotes leads him to cancel his flight.

Being fit to fly depends on more than just a pilot’s physical Therefore, elements or factors affecting individuals are condition and recent experience. For example, attitude different and profoundly impact decision-making. These affects the quality of decisions. Attitude is a motivational are called human factors and can transcend education, predisposition to respond to people, situations, or events in a experience, health, physiological aspects, etc.

given manner. Studies have identified five hazardous attitudes that can interfere with the ability to make sound decisions Another example of risk assessment was the flight of a and exercise authority properly: anti-authority, impulsivity, Beechcraft King Air equipped with deicing and anti-icing. invulnerability, macho, and resignation. [Figure 2-4] The pilot deliberately flew into moderate to severe icing conditions while ducking under cloud cover. A prudent pilot Hazardous attitudes contribute to poor pilot judgment but would assess the risk as high and beyond the capabilities of can be effectively counteracted by redirecting the hazardous the aircraft, yet this pilot did the opposite. Why did the pilot attitude so that correct action can be taken. Recognition of take this action?

hazardous thoughts is the first step toward neutralizing them.

After recognizing a thought as hazardous, the pilot should Past experience prompted the action. The pilot had label it as hazardous, then state the corresponding antidote.

successfully flown into these conditions repeatedly although Antidotes should be memorized for each of the hazardous the icing conditions were previously forecast 2,000 feet above attitudes so they automatically come to mind when needed.

the surface. This time, the conditions were forecast from the surface. Since the pilot was in a hurry and failed to factor The Five Hazardous Attitudes Antidote Anti-authority: “Don’t tell me.” This attitude is found in people who do not like anyone telling them what to do. In a sense, they are saying, “No one can tell me what to do.” They may be resentful of having someone tell them what to do or may regard rules, regulations, and procedures Follow the rules. They are usually right.

as silly or unnecessary. However, it is always your prerogative to question authority if you feel it is in error.

Impulsivity: “Do it quickly.” This is the attitude of people who frequently feel the need to do something, anything, immediately. They do not stop to think about what they are about to do, they do not Not so fast. Think first.

select the best alternative, and they do the first thing that comes to mind.

Invulnerability: “It won’t happen to me.” Many people falsely believe that accidents happen to others, but never to them. They know accidents can happen, and they know that anyone can be affected. However, It could happen to me.

they never really feel or believe that they will be personally involved. Pilots who think this way are more likely to take chances and increase risk.

Macho: “I can do it.” Pilots who are always trying to prove that they are better than anyone else think, “I can do it—I'll show them.” Pilots with this type of attitude will try to prove themselves by Taking chances is foolish.

taking risks in order to impress others. While this pattern is thought to be a male characteristic, women are equally susceptible.

Resignation: “What’s the use?” Pilots who think, “What’s the use?” do not see themselves as being able to make a great deal of difference in what happens to them. When things go well, the pilot is apt to think that it is good luck. When things go badly, the pilot may feel that someone is I’m not helpless. I can make a difference.

out to get them or attribute it to bad luck. The pilot will leave the action to others, for better or worse. Sometimes, such pilots will even go along with unreasonable requests just to be a "nice guy."

Figure 2-4. The five hazardous attitudes identified through past and contemporary study.

2-5 Risk Risk Assessment Matrix During each flight, the single pilot makes many decisions Severity under hazardous conditions. To fly safely, the pilot needs Catastrophic Critical Marginal Negligible Likelihood to assess the degree of risk and determine the best course of Probable Serious High High action to mitigate the risk.

Occasional High Serious Assessing Risk Remote Serious Low Medium For the single pilot, assessing risk is not as simple as it sounds.

Improbable For example, the pilot acts as his or her own quality control in making decisions. If a fatigued pilot who has flown 16 hours is asked if he or she is too tired to continue flying, the Figure 2-5. This risk matrix can be used for almost any operation answer may be “no.” Most pilots are goal oriented and when by assigning likelihood and consequence. In the case presented, asked to accept a flight, there is a tendency to deny personal the pilot assigned a likelihood of occasional and the severity as limitations while adding weight to issues not germane to the catastrophic. As one can see, this falls in the high risk area.

mission. For example, pilots of helicopter emergency services (EMS) have been known (more than other groups) to make cause the pilot to assign “occasional” to determine the flight decisions that add significant weight to the patient’s probability of encountering IMC.

welfare. These pilots add weight to intangible factors (the patient in this case) and fail to appropriately quantify actual The following are guidelines for making assignments.

hazards, such as fatigue or weather, when making flight • Probable—an event will occur several times decisions. The single pilot who has no other crew member for consultation must wrestle with the intangible factors that • Occasional—an event will probably occur sometime draw one into a hazardous position. Therefore, he or she has • Remote—an event is unlikely to occur, but is possible a greater vulnerability than a full crew.

• Improbable—an event is highly unlikely to occur Examining National Transportation Safety Board (NTSB) reports and other accident research can help a pilot learn to Severity of an Event assess risk more effectively. For example, the accident rate The next element is the severity or consequence of a pilot’s during night visual flight rules (VFR) decreases by nearly action(s). It can relate to injury and/or damage. If the 50 percent once a pilot obtains 100 hours and continues to individual in the example above is not an instrument rated decrease until the 1,000 hour level. The data suggest that for pilot, what are the consequences of him or her encountering the first 500 hours, pilots flying VFR at night might want to inadvertent IMC conditions? In this case, because the pilot establish higher personal limitations than are required by the is not IFR rated, the consequences are catastrophic. The regulations and, if applicable, apply instrument flying skills following are guidelines for this assignment.

in this environment.

• Catastrophic—results in fatalities, total loss • Critical—severe injury, major damage Several risk assessment models are available to assist in the process of assessing risk. The models, all taking slightly • Marginal—minor injury, minor damage different approaches, seek a common goal of assessing risk • Negligible—less than minor injury, less than minor in an objective manner. The most basic tool is the risk matrix.

system damage [Figure 2-5] It assesses two items: the likelihood of an event occurring and the consequence of that event.

Simply connecting the two factors as shown in Figure 2-5 indicates the risk is high and the pilot must either not fly or Likelihood of an Event fly only after finding ways to mitigate, eliminate, or control Likelihood is nothing more than taking a situation and the risk.

determining the probability of its occurrence. It is rated as probable, occasional, remote, or improbable. For example, a Although the matrix in Figure 2-5 provides a general viewpoint pilot is flying from point A to point B (50 miles) in marginal of a generic situation, a more comprehensive program can be visual flight rules (MVFR) conditions. The likelihood of made that is tailored to a pilot’s flying. [Figure 2-6] This encountering potential instrument meteorological conditions program includes a wide array of aviation-related activities (IMC) is the first question the pilot needs to answer. The specific to the pilot and assesses health, fatigue, weather, experiences of other pilots, coupled with the forecast, might 2-6 RISK ASSESSMENT Pilot’s Name Flight From To SLEEP HOW IS THE DAY GOING?

1. Did not sleep well or less than 8 hours 1. Seems like one thing after another (late, 2. Slept well making errors, out of step) 0 3 2. Great day HOW DO YOU FEEL?

IS THE FLIGHT 1. Have a cold or ill 4 2. Feel great 0 1. Day?

3. Feel a bit off 2 2. Night?

WEATHER AT TERMINATION PLANNING 1. Greater than 5 miles visibility and 3,000 feet 1. Rush to get off ground ceilings 1 2. No hurry 2. At least 3 miles visibility and 1,000 feet ceilings, 3. Used charts and computer to assist but less than 3,000 feet ceilings and 5 miles 4. Used computer program for all planning Yes visibility 3 No 3. IMC conditions 4 5. Did you verify weight and balance? Yes No Column total 6. Did you evaluate performance? Yes No 7. Do you brief your passangers on the Yes ground and in flight? No Column total TOTAL SCORE Low risk Endangerment Not complex flight Exercise caution Area of concern 0 10 20 30 Figure 2-6. Example of a more comprehensive risk assessment program.

2-7 capabilities, etc. The scores are added and the overall score Once a pilot identifies the risks of a flight, he or she needs falls into various ranges, with the range representative of to decide whether the risk, or combination of risks, can be actions that a pilot imposes upon himself or herself. managed safely and successfully. If not, make the decision to cancel the flight. If the pilot decides to continue with the flight, Mitigating Risk he or she should develop strategies to mitigate the risks. One way a pilot can control the risks is to set personal minimums Risk assessment is only part of the equation. After for items in each risk category. These are limits unique to that determining the level of risk, the pilot needs to mitigate the individual pilot’s current level of experience and proficiency.

risk. For example, the pilot flying from point A to point B (50 miles) in MVFR conditions has several ways to reduce risk: For example, the aircraft may have a maximum crosswind • Wait for the weather to improve to good visual flight component of 15 knots listed in the aircraft flight manual rules (VFR) conditions.

(AFM), and the pilot has experience with 10 knots of direct • Take an instrument-rated pilot.

crosswind. It could be unsafe to exceed a 10 knot crosswind component without additional training. Therefore, the 10 knot • Delay the flight.

crosswind experience level is that pilot’s personal limitation • Cancel the flight.

until additional training with a certificated flight instructor • Drive. (CFI) provides the pilot with additional experience for flying in crosswinds that exceed 10 knots.

One of the best ways single pilots can mitigate risk is to use the IMSAFE checklist to determine physical and mental One of the most important concepts that safe pilots readiness for flying: understand is the difference between what is “legal” in terms of the regulations, and what is “smart” or “safe” in terms of 1. Illness—Am I sick? Illness is an obvious pilot risk.

pilot experience and proficiency.

2. Medication—Am I taking any medicines that might affect my judgment or make me drowsy?

P = Pilot in Command (PIC) 3. Stress—Am I under psychological pressure from the The pilot is one of the risk factors in a flight. The pilot must job? Do I have money, health, or family problems?

ask, “Am I ready for this trip?” in terms of experience, Stress causes concentration and performance problems.

recency, currency, physical, and emotional condition. The While the regulations list medical conditions that IMSAFE checklist provides the answers.

require grounding, stress is not among them. The pilot should consider the effects of stress on performance.

A = Aircraft What limitations will the aircraft impose upon the trip? Ask 4. Alcohol—Have I been drinking within 8 hours?

Within 24 hours? As little as one ounce of liquor, one the following questions: bottle of beer, or four ounces of wine can impair flying • Is this the right aircraft for the flight?

skills. Alcohol also renders a pilot more susceptible • Am I familiar with and current in this aircraft? Aircraft to disorientation and hypoxia.

performance figures and the AFM are based on a brand 5. Fatigue—Am I tired and not adequately rested?

new aircraft flown by a professional test pilot. Keep Fatigue continues to be one of the most insidious that in mind while assessing personal and aircraft hazards to flight safety, as it may not be apparent to performance.

a pilot until serious errors are made.

• Is this aircraft equipped for the flight? Instruments?

6. Emotion—Am I emotionally upset?

Lights? Navigation and communication equipment adequate?

The PAVE Checklist • Can this aircraft use the runways available for the trip Another way to mitigate risk is to perceive hazards. By with an adequate margin of safety under the conditions incorporating the PAVE checklist into preflight planning, to be flown?

the pilot divides the risks of flight into four categories: P ilot in-command (PIC), A ircraft, en V ironment, and E xternal • Can this aircraft carry the planned load?

pressures (PAVE) which form part of a pilot’s decision- • Can this aircraft operate at the altitudes needed for the making process.

trip?

• Does this aircraft have sufficient fuel capacity, with With the PAVE checklist, pilots have a simple way to reserves, for trip legs planned?

remember each category to examine for risk prior to each flight.

2-8 • Does the fuel quantity delivered match the fuel guidance? Is the terminal airport equipped with them?

quantity ordered? Are they working? Will the pilot need to use the radio to activate the airport lights?

V = EnVironment • Check the Notices to Airmen (NOTAM) for closed Weather runways or airports. Look for runway or beacon lights Weather is a major environmental consideration. Earlier it was out, nearby towers, etc.

suggested pilots set their own personal minimums, especially • Choose the flight route wisely. An engine failure gives when it comes to weather. As pilots evaluate the weather for the nearby airports supreme importance.

a particular flight, they should consider the following: • Are there shorter or obstructed fields at the destination • What is the current ceiling and visibility? In and/or alternate airports?

mountainous terrain, consider having higher minimums for ceiling and visibility, particularly if Airspace the terrain is unfamiliar.

• If the trip is over remote areas, is there appropriate • Consider the possibility that the weather may be clothing, water, and survival gear onboard in the event different than forecast. Have alternative plans and of a forced landing?

be ready and willing to divert, should an unexpected • If the trip includes flying over water or unpopulated change occur.

areas with the chance of losing visual reference to the • Consider the winds at the airports being used and the horizon, the pilot must be prepared to fly IFR.

strength of the crosswind component.

• Check the airspace and any temporary flight restriction • If flying in mountainous terrain, consider whether (TFRs) along the route of flight.

there are strong winds aloft. Strong winds in mountainous terrain can cause severe turbulence and Nighttime downdrafts and be very hazardous for aircraft even when there is no other significant weather. Night flying requires special consideration.

• Are there any thunderstorms present or forecast? • If the trip includes flying at night over water or unpopulated areas with the chance of losing visual • If there are clouds, is there any icing, current or reference to the horizon, the pilot must be prepared forecast? What is the temperature/dew point spread to fly IFR.

and the current temperature at altitude? Can descent be made safely all along the route?

• Will the flight conditions allow a safe emergency landing at night?

• If icing conditions are encountered, is the pilot experienced at operating the aircraft’s deicing or • Perform preflight check of all aircraft lights, interior anti-icing equipment? Is this equipment in good and exterior, for a night flight. Carry at least two condition and functional? For what icing conditions flashlights—one for exterior preflight and a smaller is the aircraft rated, if any?

one that can be dimmed and kept nearby.

Terrain E = External Pressures Evaluation of terrain is another important component of External pressures are influences external to the flight that analyzing the flight environment.

create a sense of pressure to complete a flight—often at the expense of safety. Factors that can be external pressures • To avoid terrain and obstacles, especially at night or include the following: in low visibility, determine safe altitudes in advance by using the altitudes shown on VFR and IFR charts • Someone waiting at the airport for the flight’s arrival during preflight planning.

• A passenger the pilot does not want to disappoint • Use maximum elevation figures (MEFs) and other • The desire to demonstrate pilot qualifications easily obtainable data to minimize chances of an • The desire to impress someone (Probably the two most inflight collision with terrain or obstacles.

dangerous words in aviation are “Watch this!”) Airport • The desire to satisfy a specific personal goal (“get home-itis,” “get-there-itis,” and “let’s-go-itis”) • What lights are available at the destination and alternate airports? VASI/PAPI or ILS glideslope • The pilot’s general goal-completion orientation 2-9 • Emotional pressure associated with acknowledging • Advise those who are waiting at the destination that that skill and experience levels may be lower than a the arrival may be delayed. Know how to notify them pilot would like them to be. Pride can be a powerful when delays are encountered.

external factor!

• Manage passengers’ expectations. Make sure passengers know that they might not arrive on a firm Managing External Pressures schedule, and if they must arrive by a certain time, Management of external pressure is the single most important they should make alternative plans.

key to risk management because it is the one risk factor • Eliminate pressure to return home, even on a casual category that can cause a pilot to ignore all the other risk day flight, by carrying a small overnight kit containing factors. External pressures put time-related pressure on the prescriptions, contact lens solutions, toiletries, or other pilot and figure into a majority of accidents.

necessities on every flight.

The use of personal standard operating procedures (SOPs) is The key to managing external pressure is to be ready for one way to manage external pressures. The goal is to supply a and accept delays. Remember that people get delayed when release for the external pressures of a flight. These procedures traveling on airlines, driving a car, or taking a bus. The pilot’s include but are not limited to: goal is to manage risk, not create hazards. [Figure 2-7] • Allow time on a trip for an extra fuel stop or to make an unexpected landing because of weather.

Human Factors • Have alternate plans for a late arrival or make backup Why are human conditions, such as fatigue, complacency airline reservations for must-be-there trips.

and stress, so important in aviation? These conditions, along with many others, are called human factors. Human factors • For really important trips, plan to leave early enough directly cause or contribute to many aviation accidents and so that there would still be time to drive to the destination, if necessary.

Pilot Aircraft A pilot must continually make decisions about competency, A pilot will frequently base decisions on the evaluations of the condition of health, mental and emotional state, level of fatigue, aircraft, such as performance, equipment, or airworthiness.

and many other variables. For example, a pilot may be called early in the morning to make a long flight. If a pilot has had only During a preflight, a pilot noticed a small amount of oil dripping a few hours of sleep and is concerned that the congestion from the bottom of the cowling. Although the quantity of oil being experienced could be the onset of a cold, it would be seemed insignificant at the time, the pilot decided to delay the prudent to consider if the flight could be accomplished safely. takeoff and have a mechanic check the source of the oil.

The pilot’s good judgment was confirmed when the mechanic A pilot had only 4 hours of sleep the night before being asked found that one of the oil cooler hose fittings was loose.

by the boss to fly to a meeting in a city 750 miles away. The reported weather was marginal and not expected to improve.

External pressures After assessing fitness as a pilot, it was decided that it would not be wise to make the flight. The boss was initially unhappy, The interaction between the pilot, airplane, and the environment but later convinced by the pilot that the risks involved were is greatly influenced by the purpose of each flight operation.

unacceptable. The pilot must evaluate the three previous areas to decide on the desirability of undertaking or continuing the flight as planned.

It is worth asking why the flight is being made, how critical is it to Environment maintain the schedule, and is the trip worth the risks?

This encompasses many elements not pilot or airplane related.

It can include such factors as weather, air traffic control, On a ferry flight to deliver an airplane from the factory, in navigational aids (NAVAIDS), terrain, takeoff and landing marginal weather conditions, the pilot calculated the areas, and surrounding obstacles. Weather is one element that groundspeed and determined that the airplane would arrive at can change drastically over time and distance.

the destination with only 10 minutes of fuel remaining. The pilot was determined to keep on schedule by trying to “stretch” the A pilot was landing a small airplane just after a heavy jet had fuel supply instead of landing to refuel. After landing with low departed a parallel runway. The pilot assumed that wake fuel state, the pilot realized that this could have easily resulted turbulence would not be a problem since landings had been in an emergency landing in deteriorating weather conditions.

performed under similar circumstances. Due to a combination This was a chance that was not worth taking to keep the of prevailing winds and wake turbulence from the heavy jet planned schedule.

drifting across the landing runway, the airplane made a hard landing. The pilot made an error when assessing the flight environment.

Figure 2-7. The PAVE checklist.

2-10 have been documented as a primary contributor to more than both its knowledge base and scope. Human factors involves 70 percent of aircraft accidents. gathering research specific to certain situations (i.e., flight, maintenance, stress levels, knowledge) about human abilities, Typically, human factor incidents/accidents are associated limitations, and other characteristics and applying it to tool with flight operations but recently have also become a major design, machines, systems, tasks, jobs, and environments concern in aviation maintenance and air traffic management to produce safe, comfortable, and effective human use. The as well. [Figure 2-8] Over the past several years, the FAA has entire aviation community benefits greatly from human made the study and research of human factors a top priority factors research and development as it helps better understand by working closely with engineers, pilots, mechanics, and how humans can most safely and efficiently perform their ATC to apply the latest knowledge about human factors in jobs and improve the tools and systems in which they interact.

an effort to help operators and maintainers improve safety and efficiency in their daily operations. Human Behavior Studies of human behavior have tried to determine an Human factors science, or human factors technologies, individual’s predisposition to taking risks and the level of is a multidisciplinary field incorporating contributions an individual’s involvement in accidents. In 1951, a study from psychology, engineering, industrial design, statistics, regarding injury-prone children was published by Elizabeth operations research, and anthropometry. It is a term that Mechem Fuller and Helen B. Baune, of the University of covers the science of understanding the properties of Minnesota. The study was comprised of two separate groups human capability, the application of this understanding to of second grade students. Fifty-five students were considered the design, development and deployment of systems and accident repeaters and 48 students had no accidents. Both services, and the art of ensuring successful application of groups were from the same school of 600 and their family human factor principles into all aspects of aviation to include demographics were similar.

pilots, ATC, and aviation maintenance. Human factors is often considered synonymous with CRM or maintenance The accident-free group showed a superior knowledge resource management (MRM) but is really much broader in of safety, was considered industrious and cooperative Figure 2-8. Human factors effects pilots, aviation maintenance technicians (AMTs) and air traffic control (ATC).

2-11 with others, but were not considered physically inclined. deflected position. Both the after takeoff and before landing The accident-repeater group had better gymnastic skills, checklists require the tiller to be placed in the neutral position.

was considered aggressive and impulsive, demonstrated Everyman had overlooked this item.

rebellious behavior when under stress, were poor losers, and liked to be the center of attention. One interpretation of this Now, is Everyman accident prone or just unlucky? Skipping data—an adult predisposition to injury stems from childhood details on a checklist appears to be a common theme in the behavior and environment—leads to the conclusion that preceding accidents. While most pilots have made similar any pilot group should be comprised only of pilots who are mistakes, these errors were probably caught prior to a mishap safety-conscious, industrious, and cooperative. due to extra margin, good warning systems, a sharp copilot, or just good luck. What makes a pilot less prone to accidents?

Clearly, this is not only an inaccurate inference, it is impossible. Pilots are drawn from the general population and The successful pilot possesses the ability to concentrate, exhibit all types of personality traits. Thus, it is important that manage workloads, and monitor and perform several good decision-making skills be taught to all pilots. simultaneous tasks. Some of the latest psychological screenings used in aviation test applicants for their ability Historically, the term “pilot error” has been used to describe to multitask, measuring both accuracy, as well as the an accident in which an action or decision made by the individual’s ability to focus attention on several subjects pilot was the cause or a contributing factor that led to the simultaneously. The FAA oversaw an extensive research accident. This definition also includes the pilot’s failure study on the similarities and dissimilarities of accident-free to make a correct decision or take proper action. From a pilots and those who were not. The project surveyed over broader perspective, the phrase “human factors related” more 4,000 pilots, half of whom had “clean” records while the aptly describes these accidents. A single decision or event other half had been involved in an accident.

does not lead to an accident, but a series of events and the resultant decisions together form a chain of events leading Five traits were discovered in pilots prone to having to an outcome. accidents. These pilots: • Have disdain toward rules In his article “Accident-Prone Pilots,” Dr. Patrick R. Veillette • Have very high correlation between accidents on their uses the history of “Captain Everyman” to demonstrate how flying records and safety violations on their driving aircraft accidents are caused more by a chain of poor choices records rather than one single poor choice. In the case of Captain Everyman, after a gear-up landing accident, he became • Frequently fall into the “thrill and adventure seeking” involved in another accident while taxiing a Beech 58P Baron personality category out of the ramp. Interrupted by a radio call from the dispatcher, • Are impulsive rather than methodical and disciplined, Everyman neglected to complete the fuel cross-feed check both in their information gathering and in the speed before taking off. Everyman, who was flying solo, left the and selection of actions to be taken right-fuel selector in the cross-feed position. Once aloft and • Have a disregard for or tend to under utilize outside cruising, he noticed a right roll tendency and corrected with sources of information, including copilots, flight aileron trim. He did not realize that both engines were feeding attendants, flight service personnel, flight instructors, off the left wing’s tank, making the wing lighter.

and ATC After two hours of flight, the right engine quit when The Decision-Making Process Everyman was flying along a deep canyon gorge. While he was trying to troubleshoot the cause of the right engine’s An understanding of the decision-making process provides failure, the left engine quit. Everyman landed the aircraft on the pilot with a foundation for developing ADM and SRM a river sand bar but it sank into ten feet of water.

skills. While some situations, such as engine failure, require an immediate pilot response using established procedures, there is Several years later Everyman flew a de Havilland Twin usually time during a flight to analyze any changes that occur, Otter to deliver supplies to a remote location. When he gather information, and assess risks before reaching a decision.

returned to home base and landed, the aircraft veered sharply to the left, departed the runway, and ran into a marsh 375 Risk management and risk intervention is much more than the feet from the runway. The airframe and engines sustained simple definitions of the terms might suggest. Risk management considerable damage. Upon inspecting the wreck, accident and risk intervention are decision-making processes designed investigators found the nose wheel steering tiller in the fully to systematically identify hazards, assess the degree of risk, and 2-12 determine the best course of action. These processes involve arises. These decision points include preflight, pretakeoff, the identification of hazards, followed by assessments of the hourly or at the midpoint of the flight, pre-descent, and just risks, analysis of the controls, making control decisions, using prior to the final approach fix or for VFR operations, just the controls, and monitoring the results. prior to entering the traffic pattern.

The steps leading to this decision constitute a decision- The 5 Ps are based on the idea that pilots have essentially making process. Three models of a structured framework five variables that impact his or her environment and forcing for problem-solving and decision-making are the 5P, the 3P him or her to make a single critical decision, or several less using PAVE, CARE and TEAM, and the DECIDE models. critical decisions, that when added together can create a They provide assistance in organizing the decision process. critical outcome. These variables are the Plan, the Plane, the All these models have been identified as helpful to the single Pilot, the Passengers, and the Programming. This concept pilot in organizing critical decisions. stems from the belief that current decision-making models tended to be reactionary in nature. A change has to occur Single-Pilot Resource Management (SRM) and be detected to drive a risk management decision by the pilot. For instance, many pilots complete risk management Single-Pilot Resource Management (SRM) is about how to sheets prior to takeoff. These form a catalog of risks gather information, analyze it, and make decisions. Learning that may be encountered that day. Each of these risks is how to identify problems, analyze the information, and make assigned a numerical value. If the total of these numerical informed and timely decisions is not as straightforward as the values exceeds a predetermined level, the flight is altered or training involved in learning specific maneuvers. Learning cancelled. Informal research shows that while these are useful how to judge a situation and “how to think” in the endless documents for teaching risk factors, they are almost never variety of situations encountered while flying out in the “real used outside of formal training programs. The 5P concept is world” is more difficult.

an attempt to take the information contained in those sheets and in the other available models and use it.

There is no one right answer in ADM, rather each pilot is expected to analyze each situation in light of experience The 5P concept relies on the pilot to adopt a “scheduled” level, personal minimums, and current physical and mental review of the critical variables at points in the flight where readiness level, and make his or her own decision.

decisions are most likely to be effective. For instance, the The 5 Ps Check easiest point to cancel a flight due to bad weather is before the pilot and passengers walk out the door and load the aircraft.

SRM sounds good on paper, but it requires a way for pilots So the first decision point is preflight in the flight planning to understand and use it in their daily flights. One practical room, where all the information is readily available to make application is called the “Five Ps (5 Ps).” [Figure 2-9] The a sound decision, and where communication and Fixed 5 Ps consist of “the Plan, the Plane, the Pilot, the Passengers, Base Operator (FBO) services are readily available to make and the Programming.” Each of these areas consists of a set alternate travel plans.

of challenges and opportunities that every pilot encounters.

Each challenge and opportunity can substantially increase or The second easiest point in the flight to make a critical safety decrease the risk of successfully completing the flight based decision is just prior to takeoff. Few pilots have ever had on the pilot’s ability to make informed and timely decisions.

to make an “emergency takeoff.” While the point of the 5P The 5 Ps are used to evaluate the pilot’s current situation at check is to help the pilot fly, the correct application of the 5 key decision points during the flight or when an emergency P before takeoff is to assist in making a reasoned go/no-go decision based on all the information available. That decision The SRM Five “Ps” Check will usually be to “go,” with certain restrictions and changes, but may also be a “no-go.” The key idea is that these two THE PLAN points in the process of flying are critical go/no-go points on THE PLANE THE PILOT each and every flight.

The third place to review the 5 Ps is at the midpoint of the THE THE PASSENGERS PROGRAMMING flight. Often, pilots may wait until the Automated Terminal information Service (ATIS) is in range to check weather, yet, at this point in the flight, many good options have already passed behind the aircraft and pilot. Additionally, fatigue Figure 2-9. The Five Ps checklist.

2-13 and low-altitude hypoxia serve to rob the pilot of much of the “plane” has expanded to include database currency, his or her energy by the end of a long and tiring flight day. automation status, and emergency backup systems that were This leads to a transition from a decision-making mode to an unknown a few years ago. Much has been written about acceptance mode on the part of the pilot. If the flight is longer single pilot IFR flight, both with and without an autopilot.

than 2 hours, the 5 P check should be conducted hourly. While this is a personal decision, it is just that—a decision.

Low IFR in a non-autopilot equipped aircraft may depend The last two decision points are just prior to descent into the on several of the other Ps to be discussed. Pilot proficiency, terminal area and just prior to the final approach fix, or if currency, and fatigue are among them.

VFR, just prior to entering the traffic pattern as preparations for landing commence. Most pilots execute approaches with The Pilot the expectation that they will land out of the approach every Flying, especially when business transportation is involved, time. A healthier approach requires the pilot to assume that can expose a pilot to risks such as high altitudes, long trips changing conditions (the 5 Ps again) will cause the pilot to requiring significant endurance, and challenging weather.

divert or execute the missed approach on every approach.

Advanced avionics, when installed, can expose a pilot to high This keeps the pilot alert to all manner of conditions that stresses because of the inherent additional capabilities which may increase risk and threaten the safe conduct of the flight.

are available. When dealing with pilot risk, it is always best Diverting from cruise altitude saves fuel, allows unhurried to consult the “IMSAFE” checklist (see page 2-6).

use of the autopilot and is less reactive in nature. Diverting from the final approach fix, while more difficult, still allows The combination of late nights, pilot fatigue, and the effects the pilot to plan and coordinate better, rather than executing of sustained flight above 5,000 feet may cause pilots to a futile missed approach. Let’s look at a detailed discussion become less discerning, less critical of information, less of each of the Five Ps.

decisive, and more compliant and accepting. Just as the most critical portion of the flight approaches (for instance a night The Plan instrument approach, in the weather, after a 4-hour flight), The “Plan” can also be called the mission or the task. It the pilot’s guard is down the most. The 5 P process helps a contains the basic elements of cross-country planning, pilot recognize the physiological challenges that they may weather, route, fuel, publications currency, etc. The “Plan” face towards the end of the flight prior to takeoff and allows should be reviewed and updated several times during the them to update personal conditions as the flight progresses.

course of the flight. A delayed takeoff due to maintenance, Once risks are identified, the pilot is in a better place to fast moving weather, and a short notice TFR may all radically make alternate plans that lessen the effect of these factors alter the plan. The “plan” is not only about the flight plan, and provide a safer solution.

but also all the events that surround the flight and allow the pilot to accomplish the mission. The plan is always being The Passengers updated and modified and is especially responsive to changes One of the key differences between CRM and SRM is the in the other four remaining Ps. If for no other reason, the 5 P way passengers interact with the pilot. The pilot of a highly check reminds the pilot that the day’s flight plan is real life capable single-engine aircraft maintains a much more personal and subject to change at any time.

relationship with the passengers as he/she is positioned within an arm’s reach of them throughout the flight.

Obviously, weather is a huge part of any plan. The addition of datalink weather information gives the advanced avionics The necessity of the passengers to make airline connections pilot a real advantage in inclement weather, but only if the or important business meetings in a timely manner enters pilot is trained to retrieve and evaluate the weather in real into this pilot’s decision-making loop. Consider a flight time without sacrificing situational awareness. And of course, to Dulles Airport in which and the passengers, both close weather information should drive a decision, even if that friends and business partners, need to get to Washington, decision is to continue on the current plan. Pilots of aircraft D.C. for an important meeting. The weather is VFR all the without datalink weather should get updated weather in flight way to southern Virginia, then turns to low IFR as the pilot through an FSS and/or Flight Watch.

approaches Dulles. A pilot employing the 5 P approach might consider reserving a rental car at an airport in northern The Plane North Carolina or southern Virginia to coincide with a Both the “plan” and the “plane” are fairly familiar to most refueling stop. Thus, the passengers have a way to get to pilots. The “plane” consists of the usual array of mechanical Washington, and the pilot has an out to avoid being pressured and cosmetic issues that every aircraft pilot, owner, or into continuing the flight if the conditions do not improve.

operator can identify. With the advent of advanced avionics, 2-14 Passengers can also be pilots. If no one is designated as pilot The SRM process is simple. At least five times before in command (PIC) and unplanned circumstances arise, the and during the flight, the pilot should review and consider decision-making styles of several self-confident pilots may the “Plan, the Plane, the Pilot, the Passengers, and the come into conflict. Programming” and make the appropriate decision required by the current situation. It is often said that failure to make Pilots also need to understand that non-pilots may not a decision is a decision. Under SRM and the 5 Ps, even the understand the level of risk involved in flight. There is an decision to make no changes to the current plan is made element of risk in every flight. That is why SRM calls it risk through a careful consideration of all the risk factors present.

management, not risk elimination. While a pilot may feel comfortable with the risk present in a night IFR flight, the Perceive, Process, Perform (3P) Model passengers may not. A pilot employing SRM should ensure The Perceive, Process, Perform (3P) model for ADM offers the passengers are involved in the decision-making and given a simple, practical, and systematic approach that can be used tasks and duties to keep them busy and involved. If, upon a during all phases of flight. To use it, the pilot will: factual description of the risks present, the passengers decide • Perceive the given set of circumstances for a flight to buy an airline ticket or rent a car, then a good decision has • Process by evaluating their impact on flight safety generally been made. This discussion also allows the pilot to move past what he or she thinks the passengers want to • Perform by implementing the best course of action do and find out what they actually want to do. This removes self-induced pressure from the pilot.

Use the Perceive, Process, Perform, and Evaluate method as a continuous model for every aeronautical decision that you The Programming make. Although human beings will inevitably make mistakes, anything that you can do to recognize and minimize potential The advanced avionics aircraft adds an entirely new threats to your safety will make you a better pilot.

dimension to the way GA aircraft are flown. The electronic instrument displays, GPS, and autopilot reduce pilot Depending upon the nature of the activity and the time workload and increase pilot situational awareness. While available, risk management processing can take place in programming and operation of these devices are fairly any of three timeframes. [Figure 2-10] Most flight training simple and straightforward, unlike the analog instruments activities take place in the “time-critical” timeframe for they replace, they tend to capture the pilot’s attention and risk management. The six steps of risk management can be hold it for long periods of time. To avoid this phenomenon, combined into an easy-to-remember 3P model for practical the pilot should plan in advance when and where the risk management: Perceive, Process, Perform with the PAVE, programming for approaches, route changes, and airport CARE and TEAM checklists. Pilots can help perceive information gathering should be accomplished, as well as hazards by using the PAVE checklist of: Pilot, Aircraft, times it should not. Pilot familiarity with the equipment, the enVironment, and External pressures. They can process route, the local ATC environment, and personal capabilities hazards by using the CARE checklist of: Consequences, vis-à-vis the automation should drive when, where, and how Alternatives, Reality, External factors. Finally, pilots can the automation is programmed and used.

perform risk management by using the TEAM choice list of: Transfer, Eliminate, Accept, or Mitigate.

The pilot should also consider what his or her capabilities are in response to last minute changes of the approach (and PAVE Checklist: Identify Hazards and Personal the reprogramming required) and ability to make large-scale changes (a reroute for instance) while hand flying the aircraft. Minimums Since formats are not standardized, simply moving from one In the first step, the goal is to develop situational awareness manufacturer’s equipment to another should give the pilot by perceiving hazards, which are present events, objects, or pause and require more conservative planning and decisions.

circumstances that could contribute to an undesired future event. In this step, the pilot will systematically identify and Strategic Deliberate Time-Critical Used in a complex operation (e.g., Uses experience and brainstorming to identify “On the fly” mental or verbal review using introduction of new equipment); involves hazards, assess risks, and develop controls the basic risk management process research, use of analysis tools, formal for planning operations, review of standard during the execution phase of an activity.

Purpose testing, or long term tracking of risks. operating or training procedures, etc.

Figure 2-10. Risk management processing can take place in any of three timeframes.

2-15 list hazards associated with all aspects of the flight: P ilot, A lternatives—delay until morning; reschedule A ircraft, en V ironment, and E xternal pressures, which makes meeting; drive up the PAVE checklist. [Figure 2-11] For each element, R eality —dangers and distractions of fatigue could ask “what could hurt me, my passengers, or my aircraft?” lead to an accident All four elements combine and interact to create a unique E xternal pressures—business meeting at destination situation for any flight. Pay special attention to the pilot- might influence me aircraft combination, and consider whether the combined “pilot-aircraft team” is capable of the mission you want to fly.

A good rule of thumb for the processing phase: if you find For example, you may be a very experienced and proficient yourself saying that it will “probably” be okay, it is definitely pilot, but your weather flying ability is still limited if you time for a solid reality check. If you are worried about missing are flying a 1970s-model aircraft with no weather avoidance a meeting, be realistic about how that pressure will affect gear. On the other hand, you may have a new technically not just your initial go/no-go decision, but also your inflight advanced aircraft with moving map GPS, weather datalink, decisions to continue the flight or divert.

and autopilot—but if you do not have much weather flying experience or practice in using this kind of equipment, you TEAM Checklist: Choose and Implement Risk cannot rely on the airplane’s capability to compensate for Controls your own lack of experience.

Once you have perceived a hazard (step one) and processed its impact on flight safety (step two), it is time to move to the CARE Checklist: Review Hazards and Evaluate Risks third step, perform. Perform risk management by using the In the second step, the goal is to process this information to TEAM checklist of: T ransfer, E liminate, A ccept, M itigate determine whether the identified hazards constitute risk, which to deal with each factor. [Figure 2-13] is defined as the future impact of a hazard that is not controlled or eliminated. The degree of risk posed by a given hazard T ransfer—Should this risk decision be transferred to can be measured in terms of exposure (number of people or someone else (e.g., do you need to consult the chief resources affected), severity (extent of possible loss), and flight instructor?)

probability (the likelihood that a hazard will cause a loss). The E liminate—Is there a way to eliminate the hazard?

goal is to evaluate their impact on the safety of your flight, A ccept—Do the benefits of accepting risk outweigh and consider “why must I CARE about these circumstances?” the costs?

For each hazard that you perceived in step one, process by M itigate—What can you do to mitigate the risk?

using the CARE checklist of: C onsequences, A lternatives, R eality, E xternal factors. [Figure 2-12] For example, let's The goal is to perform by taking action to eliminate hazards evaluate a night flight to attend a business meeting: or mitigate risk, and then continuously evaluate the outcome C onsequences—departing after a full workday creates of this action. With the example of low ceilings at destination, fatigue and pressure for instance, the pilot can perform good ADM by selecting a suitable alternate, knowing where to find good weather, Pilots can perceive hazards by using the PAVE checklist: EnVironment Departure and destination airports have long runways.

Weather is the main hazard. Although it is VFR, it is a typical summer day in the Mid-Atlantic region: hot (near 90 °F) hazy Pilot (visibility 7 miles), and humid with a density altitude of 2,500 feet. Weather at the destination airport (located in the Gayle is a healthy and well-rested private pilot with approximately 300 hours total flight time. Hazards include her mountains) is still IMC but forecast to improve to visual meteorological conditions (VMC) prior to her arrival. En route lack of overall and cross-country experience and the fact that she has not flown at all in 2 months. weather is VMC, but there is an AIRMET Sierra for pockets of IMC over mountain ridges along the proposed route of flight.

Aircraft External pressures Although it does not have a panel-mount GPS or weather Gayle is making the trip to spend a weekend with relatives she avoidance gear, the aircraft—a C182 Skylane with long-range fuel tanks—is in good mechanical condition with no inoperative does not see very often. Her family is very excited and has made a number of plans for the visit.

equipment. The instrument panel is a standard “six-pack.” Figure 2-11. A real-world example of how the 3P model guides decisions on a cross-country trip using the PAVE checklist.

2-16 Pilots can perceive hazards by using the CARE checklist: Pilot Aircraft • C onsequences: Gayle’s inexperience and lack of recent • C onsequences: This area presents low risk because the flight time create some risks for an accident, primarily because aircraft is in excellent mechanical condition and Gayle is she plans to travel over mountains on a hazy day and land familiar with its avionics.

at an unfamiliar mountain airport that is still in IMC • A lternatives: Had there been a problem with her aircraft, conditions.

Gayle might have considered renting another plane from her • A lternatives: Gayle might mitigate the pilot-related risk by flight school. Bear in mind, however, that alternatives hiring a CFI to accompany her and provide dual cross- sometimes create new hazards. In this instance, there may country instruction. An added benefit is the opportunity to be hazards associated with flying an unfamiliar aircraft with broaden her flying experience in safe conditions.

different avionics.

• R eality: Accepting the reality that limited experience can • R eality: It is important to recognize the reality of an aircraft’s create additional risks is a key part of sound risk management mechanical condition. If you find a maintenance discrepancy and mitigation.

and then find yourself saying that it is “probably” okay to fly • E xternal Factors: Like many pilots, Gayle must contend with with it anyway, you need to revisit the consequences part of the emotional pressure associated with acknowledging that this checklist.

her skill and experience levels may be lower than she would • E xternal Factors: Pilot decision-making can sometimes be like them to be. Pride can be a powerful external factor!

influenced by the external pressure of needing to return the airplane to the FBO by a certain date and time. Because Gayle owns the airplane, there was no such pressure in this Environment case.

• C onsequences: For a pilot whose experience consists mostly of local flights in good VMC, launching a long cross- External pressures country flight over mountainous terrain in hazy conditions could lead to pilot disorientation and increase the risk of an • C onsequences: Any number of factors can create the risk of accident. emotional pressure from a “get-there” mentality. In Gayle’s • A lternatives: Options include postponing the trip until the case, the consequences of her strong desire to visit family, visibility improves, or modifying the route to avoid extended her family’s expectations, and personal pride could induce periods of time over the mountains. her to accept unnecessary risks.

• R eality: Hazy conditions and mountainous terrain clearly • A lternatives: Gayle clearly needs to develop a mitigating create risks for an inexperienced VFR-only pilot. strategy for each of the external factors associated with this • E xternal Factors: Few pilots are immune to the pressure of trip.

“get-there-itis,” which can sometimes induce a decision to • R eality: Pilots sometimes tend to discount or ignore the launch or continue in less than ideal weather conditions. potential impact of these external factors. Gayle’s open acknowledgement of these factors (e.g., “I might be pressured into pressing on so my mother won’t have to worry about our late arrival.”) is a critical element of effective risk management.

• E xternal Factors: (see above) Figure 2-12. A real-world examples of how the 3P model guides decisions on a cross-country trip using the CARE checklist.

and carrying sufficient fuel to reach it. This course of action • Using personal minimums checklist to make some would mitigate the risk. The pilot also has the option to decisions in advance of the flight. To develop a good eliminate it entirely by waiting for better weather. personal minimums checklist, you need to assess your abilities and capabilities in a non-flying environment, Once the pilot has completed the 3P decision process and when there is no pressure to make a specific trip. Once selected a course of action, the process begins anew because developed, a personal minimums checklist will give now the set of circumstances brought about by the course of you a clear and concise reference point for making action requires analysis. The decision-making process is a your go/no-go or continue/discontinue decisions.

continuous loop of perceiving, processing, and performing.

• In addition to having personal minimums, some pilots With practice and consistent use, running through the 3P also like to use a preflight risk assessment checklist to cycle can become a habit that is as smooth, continuous, and help with the ADM and risk management processes.

automatic as a well-honed instrument scan. This basic set This kind of form assigns numbers to certain risks of practical risk management tools can be used to improve and situations, which can make it easier to see when risk management.

a particular flight involves a higher level of risk • Develop a list of good alternatives during your Your mental willingness to follow through on safe decisions, processing phase. In marginal weather, for instance, especially those that require delay or diversion is critical. You you might mitigate the risk by identifying a reasonable can bulk up your mental muscles by: 2-17 Pilots can perform risk management by using the TEAM checklist: Pilot Aircraft To manage the risk associated with her inexperience and lack To manage risk associated with any doubts about the aircraft’s of recent flight time, Gayle can: mechanical condition, Gayle can: • T ransfer the risk entirely by having another pilot act as PIC.

• T ransfer the risk by using a different airplane.

• E liminate the risk by canceling the trip.

• E liminate the risk by canceling the trip.

• A ccept the risk and fly anyway.

• A ccept the risk.

• M itigate the risk by flying with another pilot.

• M itigate the remaining (residual) risk through review of aircraft performance and careful preflight inspection.

Gayle chooses to mitigate the major risk by hiring a CFI to accompany her and provide dual cross-country instruction.

Since she finds no problems with the aircraft’s mechanical An added benefit is the opportunity to broaden her flying condition, Gayle chooses to mitigate any remaining risk experience.

through careful preflight inspection of the aircraft.

Environment External pressures To manage the risk associated with hazy conditions and To mitigate the risk of emotional pressure from family mountainous terrain, Gayle can: expectations that can drive a “get-there” mentality, Gayle can: • T ransfer the risk of VFR in these conditions by asking an • T ransfer the risk by having her co-pilot act as PIC and make instrument-rated pilot to fly the trip under IFR. the continue/divert decision.

• E liminate the risk by canceling the trip. • E liminate the risk by canceling the trip.

• A ccept the risk. • A ccept the risk.

• M itigate the risk by careful preflight planning, filing a VFR • M itigate the risk by managing family expectations and flight plan, requesting VFR flight following, and using making alternative arrangements in the event of diversion to resources such as Flight Watch. another airport.

Detailed preflight planning must be a vital part of Gayle’s Gayle and her co-pilot choose to address this risk by agreeing weather risk mitigation strategy. The most direct route would that each pilot has a veto on continuing the flight, and that they put her over mountains for most of the trip. Because of the will divert if either becomes uncomfortable with flight conditions.

thick haze and pockets of IMC over mountains, Gayle might Because the destination airport is still IMC at the time of mitigate the risk by modifying the route to fly over valleys. This departure, Gayle establishes a specific point in the trip—an en change will add 30 minutes to her estimated time of arrival route VORTAC located between the destination airport and the (ETA), but the extra time is a small price to pay for avoiding two alternates—as the logical place for her “final” continue/ possible IMC over mountains. Because her destination airport divert decision. Rather than give her family a specific ETA that is IMC at the time of departure, Gayle needs to establish that might make Gayle feel pressured to meet the schedule, she VFR conditions exist at other airports within easy driving manages her family’s expectations by advising them that she distance of her original destination. In addition, Gayle should will call when she arrives.

review basic information (e.g., traffic pattern altitude, runway layout, frequencies) for these alternate airports. To further mitigate risk and practice good cockpit resource management, Gayle should file a VFR flight plan, use VFR flight following, and call Flight Watch to get weather updates en route. Finally, basic functions on her handheld GPS should also be practiced.

Figure 2-13. A real-world example of how the 3P model guides decisions on a cross-country trip using the TEAM checklist.

alternative airport for every 25–30 nautical mile The DECIDE Model segment of your route.

Using the acronym “DECIDE,” the six-step process DECIDE Model is another continuous loop process that provides the • Preflight your passengers by preparing them for the pilot with a logical way of making decisions. [Figure 2-14] possibility of delay and diversion, and involve them DECIDE means to Detect, Estimate, Choose a course of in your evaluation process.

action, Identify solutions, Do the necessary actions, and • Another important tool—overlooked by many pilots— Evaluate the effects of the actions.

is a good post-flight analysis. When you have safely secured the airplane, take the time to review and First, consider a recent accident involving a Piper Apache (PA analyze the flight as objectively as you can. Mistakes 23). The aircraft was substantially damaged during impact and judgment errors are inevitable; the most important with terrain at a local airport in Alabama. The certificated thing is for you to recognize, analyze, and learn from airline transport pilot (ATP) received minor injuries and the them before your next flight.

certificated private pilot was not injured. The private pilot 2-18 was receiving a checkride from the ATP (who was also a engine failure by reducing power on the right engine to zero designated examiner) for a commercial pilot certificate with thrust. This caused the aircraft to yaw right.

a multi-engine rating. After performing airwork at altitude, they returned to the airport and the private pilot performed a The procedure to identify the failed engine is a two-step single-engine approach to a full stop landing. He then taxied process. First, adjust the power to the maximum controllable back for takeoff, performed a short field takeoff, and then level on both engines. Because the left engine is the only joined the traffic pattern to return for another landing. During engine delivering thrust, the yaw increases to the right, which the approach for the second landing, the ATP simulated a right necessitates application of additional left rudder application.

Aeronautical Decision-Making A. Analytical B. Automatic/Naturalistic Situation Pilot Aircraft Enviroment External factors Pilot Aircraft Enviroment External factors Detection Detection Evaluation of event Evaluation of event • Risk or hazard • Potential outcomes • Capabilities of pilot • Aircraft capabilities • Risk to flight • Outside factors • Pilot training • Pilot experience Outcome desired Outcome desired Solutions to get you there Solution 1 Solution 2 Solution 3 Solution 4 Take action What is best action to do Effect of decision Successful Problem remains Done The DECIDE model 1.

2.

3.

5.

6.

Figure 2-14. The DECIDE model has been recognized worldwide. Its application is illustrated in column A while automatic/naturalistic decision-making is shown in column B.

2-19 The failed engine is the side that requires no rudder pressure, detecting the problem. In the previous example, the change in this case the right engine. Second, having identified the that occurred was a yaw.

failed right engine, the procedure is to feather the right engine and adjust power to maintain descent angle to a landing.

Estimate (the Need To React) In the engine-out example, the aircraft yawed right, the pilot However, in this case the pilot feathered the left engine because was on final approach, and the problem warranted a prompt he assumed the engine failure was a left engine failure. During solution. In many cases, overreaction and fixation excludes twin-engine training, the left engine out is emphasized more a safe outcome. For example, what if the cabin door of a than the right engine because the left engine on most light Mooney suddenly opened in flight while the aircraft climbed twins is the critical engine. This is due to multiengine airplanes through 1,500 feet on a clear sunny day? The sudden opening being subject to P-factor, as are single-engine airplanes.

would be alarming, but the perceived hazard the open door The descending propeller blade of each engine will produce presents is quickly and effectively assessed as minor. In greater thrust than the ascending blade when the airplane is fact, the door’s opening would not impact safe flight and operated under power and at positive angles of attack. The can almost be disregarded. Most likely, a pilot would return descending propeller blade of the right engine is also a greater to the airport to secure the door after landing.

distance from the center of gravity, and therefore has a longer moment arm than the descending propeller blade of the left The pilot flying on a clear day faced with this minor problem engine. As a result, failure of the left engine will result in the may rank the open cabin door as a low risk. What about most asymmetrical thrust (adverse yaw) because the right the pilot on an IFR climb out in IMC conditions with light engine will be providing the remaining thrust. Many twins are intermittent turbulence in rain who is receiving an amended designed with a counter-rotating right engine. With this design, clearance from ATC? The open cabin door now becomes the degree of asymmetrical thrust is the same with either engine a higher risk factor. The problem has not changed, but the inoperative. Neither engine is more critical than the other.

perception of risk a pilot assigns it changes because of the multitude of ongoing tasks and the environment. Experience, Since the pilot never executed the first step of identifying discipline, awareness, and knowledge influences how a pilot which engine failed, he feathered the left engine and set the ranks a problem.

right engine at zero thrust. This essentially restricted the aircraft to a controlled glide. Upon realizing that he was Choose (a Course of Action) not going to make the runway, the pilot increased power to After the problem has been identified and its impact both engines causing an enormous yaw to the left (the left estimated, the pilot must determine the desirable outcome propeller was feathered) whereupon the aircraft started to turn and choose a course of action. In the case of the multiengine left. In desperation, the instructor closed both throttles and pilot given the simulated failed engine, the desired objective the aircraft hit the ground and was substantially damaged.

is to safely land the airplane.

This case is interesting because it highlights two particular Identify (Solutions) issues. First, taking action without forethought can be just The pilot formulates a plan that will take him or her to the as dangerous as taking no action at all. In this case, the objective. Sometimes, there may be only one course of action pilot’s actions were incorrect; yet, there was sufficient available. In the case of the engine failure already at 500 time to take the necessary steps to analyze the simulated feet or below, the pilot solves the problem by identifying emergency. The second and more subtle issue is that decisions one or more solutions that lead to a successful outcome. It is made under pressure are sometimes executed based upon important for the pilot not to become fixated on the process limited experience and the actions taken may be incorrect, to the exclusion of making a decision.

incomplete, or insufficient to handle the situation.

Do (the Necessary Actions) Detect (the Problem) Once pathways to resolution are identified, the pilot selects the Problem detection is the first step in the decision-making most suitable one for the situation. The multiengine pilot given process. It begins with recognizing a change occurred or an the simulated failed engine must now safely land the aircraft.

expected change did not occur. A problem is perceived first by the senses and then it is distinguished through insight Evaluate (the Effect of the Action) and experience. These same abilities, as well as an objective Finally, after implementing a solution, evaluate the decision analysis of all available information, are used to determine to see if it was correct. If the action taken does not provide the nature and severity of the problem. One critical error the desired results, the process may have to be repeated.

made during the decision-making process is incorrectly 2-20 pitfalls that come with the development of pilot experience.

Decision-Making in a Dynamic Environment These are classic behavioral traps into which pilots have A solid approach to decision-making is through the use of been known to fall. More experienced pilots, as a rule, try analytical models, such as the 5 Ps, 3P, and DECIDE. Good to complete a flight as planned, please passengers, and meet decisions result when pilots gather all available information, schedules. The desire to meet these goals can have an adverse review it, analyze the options, rate the options, select a course effect on safety and contribute to an unrealistic assessment of action, and evaluate that course of action for correctness.

of piloting skills. All experienced pilots have fallen prey to, or have been tempted by, one or more of these tendencies in In some situations, there is not always time to make decisions their flying careers. These dangerous tendencies or behavior based on analytical decision-making skills. A good example patterns, which must be identified and eliminated, include is a quarterback whose actions are based upon a highly fluid the operational pitfalls shown in Figure 2-15.

and changing situation. He intends to execute a plan, but new circumstances dictate decision-making on the fly. This type Stress Management of decision-making is called automatic decision-making or Everyone is stressed to some degree almost all of the time. A naturalized decision-making. [Figure 2-14B] certain amount of stress is good since it keeps a person alert and prevents complacency. Effects of stress are cumulative Automatic Decision-Making and, if the pilot does not cope with them in an appropriate In an emergency situation, a pilot might not survive if he or way, they can eventually add up to an intolerable burden.

she rigorously applies analytical models to every decision Performance generally increases with the onset of stress, made as there is not enough time to go through all the options.

peaks, and then begins to fall off rapidly as stress levels Under these circumstances he or she should attempt to find exceed a person’s ability to cope. The ability to make the best possible solution to every problem.

effective decisions during flight can be impaired by stress.

There are two categories of stress—acute and chronic. These For the past several decades, research into how people are both explained in Chapter 17, “Aeromedical Factors.” actually make decisions has revealed that when pressed for time, experts faced with a task loaded with uncertainty first Factors referred to as stressors can increase a pilot’s risk of assess whether the situation strikes them as familiar. Rather error in the flight deck. [Figure 2-16] Remember the cabin than comparing the pros and cons of different approaches, door that suddenly opened in flight on the Mooney climbing they quickly imagine how one or a few possible courses of through 1,500 feet on a clear sunny day? It may startle the action in such situations will play out. Experts take the first pilot, but the stress would wane when it became apparent workable option they can find. While it may not be the best of the situation was not a serious hazard. Yet, if the cabin door all possible choices, it often yields remarkably good results.

opened in IMC conditions, the stress level makes significant impact on the pilot’s ability to cope with simple tasks. The The terms “naturalistic” and “automatic decision-making” key to stress management is to stop, think, and analyze before have been coined to describe this type of decision-making.

jumping to a conclusion. There is usually time to think before The ability to make automatic decisions holds true for a drawing unnecessary conclusions.

range of experts from firefighters to chess players. It appears the expert’s ability hinges on the recognition of patterns and There are several techniques to help manage the accumulation consistencies that clarify options in complex situations. Experts of life stresses and prevent stress overload. For example, to appear to make provisional sense of a situation, without help reduce stress levels, set aside time for relaxation each actually reaching a decision, by launching experience-based day or maintain a program of physical fitness. To prevent actions that in turn trigger creative revisions.

stress overload, learn to manage time more effectively to avoid pressures imposed by getting behind schedule and not This is a reflexive type of decision-making anchored in meeting deadlines.

training and experience and is most often used in times of emergencies when there is no time to practice analytical Use of Resources decision-making. Naturalistic or automatic decision-making To make informed decisions during flight operations, a pilot improves with training and experience, and a pilot will find must also become aware of the resources found inside and himself or herself using a combination of decision-making outside the flight deck. Since useful tools and sources of tools that correlate with individual experience and training.

information may not always be readily apparent, learning to recognize these resources is an essential part of ADM Operational Pitfalls training. Resources must not only be identified, but a pilot Although more experienced pilots are likely to make more must also develop the skills to evaluate whether there is automatic decisions, there are tendencies or operational 2-21 Operational pitfalls Operational Pitfalls Peer pressure Poor decision-making may be based upon an emotional response to peers, rather than evaluating a situation objectively.

Mindset A pilot displays mind set through an inability to recognize and cope with changes in a given situation.

Get-there-itis This disposition impairs pilot judgment through a fixation on the original goal or destination, combined with a disregard for any alternative course of action.

Duck-under syndrome A pilot may be tempted to make it into an airport by descending below minimums during an approach. There may be a belief that there is a built-in margin of error in every approach procedure, or a pilot may want to admit that the landing cannot be completed and a missed approach must be initiated.

Scud running This occurs when a pilot tries to maintain visual contact with the terrain at low altitudes while instrument conditions exist.

Continuing visual flight rules (VFR) into instrument conditions Spatial disorientation or collision with ground/obstacles may occur when a pilot continues VFR into instrument conditions. This can be even more dangerous if the pilot is not instrument rated or current.

Getting behind the aircraft This pitfall can be caused by allowing events or the situation to control pilot actions. A constant state of surprise at what happens next may be exhibited when the pilot is getting behind the aircraft.

Loss of positional or situational awareness In extreme cases, when a pilot gets behind the aircraft, a loss of positional or situational awareness may result. The pilot may not know the aircraft’s geographical location or may be unable to recognize deteriorating circumstances.

Operating without adequate fuel reserves Ignoring minimum fuel reserve requirements is generally the result of overconfidence, lack of flight planning, or disregarding applicable regulations.

Descent below the minimum en route altitude The duck-under syndrome, as mentioned above, can also occur during the en route portion of an IFR flight.

Flying outside the envelope The assumed high performance capability of a particular aircraft may cause a mistaken belief that it can meet the demands imposed by a pilot’s overestimated flying skills.

Neglect of flight planning, preflight inspections, and checklists A pilot may rely on short- and long-term memory, regular flying skills, and familiar routes instead of established procedures and published checklists. This can be particularly true of experienced pilots.

Figure 2-15. Typical operational pitfalls requiring pilot awareness.

Stressors Environmental Conditions associated with the environment, such as temperature and humidity extremes, noise, vibration, and lack of oxygen.

Physiological stress Physical conditions, such as fatigue, lack of physical fitness, sleep loss, missed meals (leading to low blood sugar levels), and illness.

Psychological stress Social or emotional factors, such as a death in the family, a divorce, a sick child, or a demotion at work. This type of stress may also be related to mental workload, such as analyzing a problem, navigating an aircraft, or making decisions.

Figure 2-16. System stressors. Environmental, physiological, and psychological stress are factors that affect decision-making skills.

These stressors have a profound impact especially during periods of high workload.

2-22 time to use a particular resource and the impact its use will have upon the safety of flight. For example, the assistance of ATC may be very useful if a pilot becomes lost, but in an emergency situation, there may be no time available to contact ATC.

Internal Resources One of the most underutilized resources may be the person in the right seat, even if the passenger has no flying experience. When appropriate, the PIC can ask passengers to assist with certain tasks, such as watching for traffic or reading checklist items. The following are some other ways Figure 2-17. When possible, have a passenger reconfirm that critical a passenger can assist: tasks are completed.

• Provide information in an irregular situation, especially if familiar with flying. A strange smell or Checklists are essential flight deck internal resources. They sound may alert a passenger to a potential problem.

are used to verify the aircraft instruments and systems are • Confirm after the pilot that the landing gear is down.

checked, set, and operating properly, as well as ensuring the proper procedures are performed if there is a system • Learn to look at the altimeter for a given altitude in a malfunction or in-flight emergency. Students reluctant to descent.

use checklists can be reminded that pilots at all levels of • Listen to logic or lack of logic.

experience refer to checklists, and that the more advanced the aircraft is, the more crucial checklists become. In addition, the Also, the process of a verbal briefing (which can happen pilot’s operating handbook (POH) is required to be carried on whether or not passengers are aboard) can help the PIC in board the aircraft and is essential for accurate flight planning the decision-making process. For example, assume a pilot and resolving in-flight equipment malfunctions. However, provides a lone passenger a briefing of the forecast landing the most valuable resource a pilot has is the ability to manage weather before departure. When the Automatic Terminal workload whether alone or with others.

Information Service (ATIS) is picked up, the weather has significantly changed. The discussion of this forecast External Resources change can lead the pilot to reexamine his or her activities ATC and flight service specialists are the best external and decision-making. [Figure 2-17] Other valuable internal resources during flight. In order to promote the safe, orderly resources include ingenuity, aviation knowledge, and flying flow of air traffic around airports and, along flight routes, the skill. Pilots can increase flight deck resources by improving ATC provides pilots with traffic advisories, radar vectors, these characteristics.

and assistance in emergency situations. Although it is the PIC’s responsibility to make the flight as safe as possible, When flying alone, another internal resource is verbal a pilot with a problem can request assistance from ATC.

communication. It has been established that verbal [Figure 2-18] For example, if a pilot needs to level off, be communication reinforces an activity; touching an object while communicating further enhances the probability an activity has been accomplished. For this reason, many solo pilots read the checklist out loud; when they reach critical items, they touch the switch or control. For example, to ascertain the landing gear is down, the pilot can read the checklist. But, if he or she touches the gear handle during the process, a safe extension of the landing gear is confirmed.

It is necessary for a pilot to have a thorough understanding of all the equipment and systems in the aircraft being flown.

Lack of knowledge, such as knowing if the oil pressure gauge is direct reading or uses a sensor, is the difference between making a wise decision or poor one that leads to a tragic error.

Figure 2-18. Controllers work to make flights as safe as possible.

2-23 given a vector, or decrease speed, ATC assists and becomes but result in accidents as the pilot diverts attention to the integrated as part of the crew. The services provided by ATC perceived problem and neglects proper control of the aircraft.

can not only decrease pilot workload, but also help pilots make informed in-flight decisions.

Workload Management Effective workload management ensures essential operations The Flight Service Stations (FSSs) are air traffic facilities are accomplished by planning, prioritizing, and sequencing that provide pilot briefing, en route communications, VFR tasks to avoid work overload. [Figure 2-19] As experience search and rescue services, assist lost aircraft and aircraft is gained, a pilot learns to recognize future workload in emergency situations, relay ATC clearances, originate requirements and can prepare for high workload periods Notices to Airmen (NOTAM), broadcast aviation weather during times of low workload. Reviewing the appropriate and National Airspace System (NAS) information, receive chart and setting radio frequencies well in advance of when and process IFR flight plans, and monitor navigational aids they are needed helps reduce workload as the flight nears the (NAVAIDs). In addition, at selected locations, FSSs provide airport. In addition, a pilot should listen to ATIS, Automated En Route Flight Advisory Service (Flight Watch), issue Surface Observing System (ASOS), or Automated Weather airport advisories, and advise Customs and Immigration of Observing System (AWOS), if available, and then monitor transborder flights. Selected FSSs in Alaska also provide the tower frequency or Common Traffic Advisory Frequency TWEB recordings and take weather observations.

(CTAF) to get a good idea of what traffic conditions to expect. Checklists should be performed well in advance so Situational Awareness there is time to focus on traffic and ATC instructions. These procedures are especially important prior to entering a high- Situational awareness is the accurate perception and density traffic area, such as Class B airspace.

understanding of all the factors and conditions within the five fundamental risk elements (flight, pilot, aircraft, Recognizing a work overload situation is also an important environment, and type of operation that comprise any given component of managing workload. The first effect of aviation situation) that affect safety before, during, and after high workload is that the pilot may be working harder but the flight. Monitoring radio communications for traffic, accomplishing less. As workload increases, attention cannot weather discussion, and ATC communication can enhance be devoted to several tasks at one time, and the pilot may situational awareness by helping the pilot develop a mental begin to focus on one item. When a pilot becomes task picture of what is happening.

saturated, there is no awareness of input from various sources, so decisions may be made on incomplete information and the Maintaining situational awareness requires an understanding possibility of error increases. [Figure 2-20] of the relative significance of all flight related factors and their future impact on the flight. When a pilot understands what is When a work overload situation exists, a pilot needs to stop, going on and has an overview of the total operation, he or she think, slow down, and prioritize. It is important to understand is not fixated on one perceived significant factor. Not only how to decrease workload. For example, in the case of the is it important for a pilot to know the aircraft’s geographical cabin door that opened in VFR flight, the impact on workload location, it is also important he or she understand what is should be insignificant. If the cabin door opens under happening. For instance, while flying above Richmond, IFR different conditions, its impact on workload changes.

Virginia, toward Dulles Airport or Leesburg, the pilot Therefore, placing a situation in the proper perspective, should know why he or she is being vectored and be able to anticipate spatial location. A pilot who is simply making turns without understanding why has added an additional burden to his or her management in the event of an emergency. To maintain situational awareness, all of the skills involved in ADM are used.

Obstacles to Maintaining Situational Awareness Fatigue, stress, and work overload can cause a pilot to fixate on a single perceived important item and reduce an overall situational awareness of the flight. A contributing factor in many accidents is a distraction that diverts the pilot’s attention from monitoring the instruments or scanning outside the aircraft. Many flight deck distractions begin as a Figure 2-19. Balancing workloads can be a difficult task.

minor problem, such as a gauge that is not reading correctly, 2-24 remaining calm, and thinking rationally are key elements in • In addition to the SAFETY list, discuss with reducing stress and increasing the capacity to fly safely. This passengers whether or not smoking is permitted, flight ability depends upon experience, discipline, and training. route altitudes, time en route, destination, weather during flight, expected weather at the destination, Managing Risks controls and what they do, and the general capabilities and limitations of the aircraft.

The ability to manage risks begins with preparation. Here are some things a pilot can do to manage risks: • Use a sterile flight deck (one that is completely silent with no pilot communication with passengers or by • Assess the flight’s risk based upon experience. Use passengers) from the time of departure to the first some form of risk assessment. For example, if the intermediate altitude and clearance from the local weather is marginal and the pilot has little IMC airspace.

training, it is probably a good idea to cancel the flight.

• Use a sterile flight deck during arrival from the first • Brief passengers using the SAFETY list: radar vector for approach or descent for the approach.

S Seat belts fastened for taxi, takeoff, landing • Keep the passengers informed during times when the Shoulder harness fastened for takeoff, landing workload is low.

Seat position adjusted and locked in place • Consider using the passenger in the right seat for A Air vents (location and operation) simple tasks, such as holding the chart. This relieves the pilot of a task.

All environmental controls (discussed) Action in case of any passenger discomfort Automation F Fire extinguisher (location and operation) In the GA community, an automated aircraft is generally E Exit doors (how to secure; how to open) comprised of an integrated advanced avionics system consisting of a primary flight display (PFD), a multifunction Emergency evacuation plan flight display (MFD) including an instrument-certified global Emergency/survival kit (location and contents) positioning system (GPS) with traffic and terrain graphics, T Traffic (scanning, spotting, notifying pilot) and a fully integrated autopilot. This type of aircraft is commonly known as a technically advanced aircraft (TAA).

Talking, (“sterile flight deck” expectations) In a TAA aircraft, there are typically two display (computer) Y Your questions? (Speak up!)

screens: PFD (left display screen) and MFD.

High Task load Low

Pilot capabilities

Preflight

Time

Takeoff Cruise Approach & landing

Task requirements

Figure 2-20. The pilot has a certain capacity of doing work and handling tasks. However, there is a point where the tasking exceeds the pilot’s capability. When this happens, tasks are either not performed properly or some are not performed at all.

2-25 Automation is the single most important advance in aviation important to remember to check and confirm calculations.

technologies. Electronic flight displays (EFDs) have made Always remember that it is up to the pilot to maintain basic vast improvements in how information is displayed and airmanship skills and use those skills often to maintain what information is available to the pilot. Pilots can access proficiency in all tasks.

electronic databases that contain all of the information traditionally contained in multiple handbooks, reducing Although automation has made flying safer, automated clutter in the flight deck. [Figure 2-21] systems can make some errors more evident and sometimes hide other errors or make them less evident. There are MFDs are capable of displaying moving maps that mirror concerns about the effect of automation on pilots. In a study sectional charts. These detailed displays depict all airspace, published in 1995, the British Airline Pilots Association including Temporary Flight Restrictions (TFRs). MFDs are officially voiced its concern that “Airline pilots increasingly so descriptive that many pilots fall into the trap of relying lack ‘basic flying skills’ as a result of reliance on automation.” solely on the moving maps for navigation. Pilots also draw upon the database to familiarize themselves with departure This reliance on automation translates into a lack of basic flying and destination airport information. skills that may affect the pilot’s ability to cope with an in-flight emergency, such as sudden mechanical failure. The worry that More pilots now rely on electronic databases for flight pilots are becoming too reliant on automated systems and are planning and use automated flight planning tools rather not being encouraged or trained to fly manually has grown than planning the flight by the traditional methods of laying with the increase in the number of MFD flight decks.

out charts, drawing the course, identifying navigation points (assuming a VFR flight), and using the POH to As automated flight decks began entering everyday line figure out the weight and balance and performance charts. operations, instructors and check airmen grew concerned Whichever method a pilot chooses to plan a flight, it is about some of the unanticipated side effects. Despite the promise of reducing human mistakes, the flight managers reported the automation actually created much larger errors at times. In the terminal environment, the workload in an automated flight deck actually seemed higher than in the older analog flight decks. At other times, the automation seemed to lull the flight crews into complacency. Over time, concern surfaced that the manual flying skills of the automated flight crews deteriorated due to over-reliance on computers. The flight crew managers said they worried that pilots would have less “stick-and-rudder” proficiency when those skills were needed to manually resume direct control of the aircraft.

A major study was conducted to evaluate the performance of two groups of pilots. The control group was composed of pilots who flew an older version of a common twin-jet airliner equipped with analog instrumentation and the experimental group was composed of pilots who flew the same aircraft, but newer models equipped with an electronic flight instrument system (EFIS) and a flight management system (FMS). The pilots were evaluated in maintaining aircraft parameters, such as heading, altitude, airspeed, glideslope, and localizer deviations, as well as pilot control inputs. These were recorded during a variety of normal, abnormal, and emergency maneuvers during 4 hours of simulator sessions.

Figure 2-21. Electronic flight instrumentation comes in many systems and provides a myriad of information to the pilot.

2-26 Results of the Study practices” and procedures have remedied some of the earlier problems with automation.

When pilots who had flown EFIS for several years were required to fly various maneuvers manually, the aircraft Pilots must maintain their flight skills and ability to maneuver parameters and flight control inputs clearly showed some aircraft manually within the standards set forth in the PTS. It erosion of flying skills. During normal maneuvers, such as is recommended that pilots of automated aircraft occasionally turns to headings without a flight director, the EFIS group disengage the automation and manually fly the aircraft to exhibited somewhat greater deviations than the analog group.

maintain stick-and-rudder proficiency. It is imperative that Most of the time, the deviations were within the practical test the pilots understand that the EFD adds to the overall quality standards (PTS), but the pilots definitely did not keep on the of the flight experience, but it can also lead to catastrophe if localizer and glideslope as smoothly as the analog group.

not utilized properly. At no time is the moving map meant to substitute for a VFR sectional or low altitude en route chart.

The differences in hand-flying skills between the two groups became more significant during abnormal maneuvers, such as Equipment Use accelerated descent profiles known as “slam-dunks.” When given close crossing restrictions, the analog crews were more Autopilot Systems adept at the mental math and usually maneuvered the aircraft In a single-pilot environment, an autopilot system can greatly in a smoother manner to make the restriction. On the other reduce workload. [Figure 2-23] As a result, the pilot is free hand, the EFIS crews tended to go “heads down” and tried to focus his or her attention on other flight deck duties. This to solve the crossing restriction on the FMS. [Figure 2-22] can improve situational awareness and reduce the possibility of a CFIT accident. While the addition of an autopilot may Another situation used in the simulator experiment reflected certainly be considered a risk control measure, the real real world changes in approach that are common and can challenge comes in determining the impact of an inoperative be assigned on short notice. Once again, the analog crews unit. If the autopilot is known to be inoperative prior to transitioned more easily to the parallel runway’s localizer, departure, this may factor into the evaluation of other risks.

whereas the EFIS crews had a much more difficult time with the pilot going head down for a significant amount of time For example, the pilot may be planning for a VHF trying to program the new approach into the FMS.

omnidirectional range (VOR) approach down to minimums on a dark night into an unfamiliar airport. In such a case, the While a pilot’s lack of familiarity with the EFIS is often pilot may have been relying heavily on a functioning autopilot an issue, the approach would have been made easier by capable of flying a coupled approach. This would free the disengaging the automated system and manually flying the pilot to monitor aircraft performance. A malfunctioning approach. At the time of this study, the general guidelines autopilot could be the single factor that takes this from a in the industry were to let the automated system do as much medium to a serious risk. At this point, an alternative needs of the flying as possible. That view has since changed and to be considered. On the other hand, if the autopilot were to it is recommended that pilots use their best judgment when fail at a critical (high workload) portion of this same flight, choosing which level of automation will most efficiently do the pilot must be prepared to take action. Instead of simply the task considering the workload and situational awareness.

being an inconvenience, this could quickly turn into an emergency if not properly handled. The best way to ensure Emergency maneuvers clearly broadened the difference in a pilot is prepared for such an event is to carefully study the manual flying skills between the two groups. In general, the issue prior to departure and determine well in advance how analog pilots tended to fly raw data, so when they were given an autopilot failure is to be handled.

an emergency, such as an engine failure, and were instructed to fly the maneuver without a flight director, they performed Familiarity it expertly. By contrast, SOP for EFIS operations at the time As previously discussed, pilot familiarity with all equipment was to use the flight director. When EFIS crews had their flight is critical in optimizing both safety and efficiency. If a pilot is directors disabled, their eye scan again began a more erratic unfamiliar with any aircraft systems, this will add to workload searching pattern and their manual flying subsequently suffered.

and may contribute to a loss of situational awareness. This level of proficiency is critical and should be looked upon as Those who reviewed the data saw that the EFIS pilots who a requirement, not unlike carrying an adequate supply of fuel.

better managed the automation also had better flying skills.

As a result, pilots should not look upon unfamiliarity with the While the data did not reveal whether those skills preceded aircraft and its systems as a risk control measure, but instead as or followed automation, it did indicate that automation a hazard with high risk potential. Discipline is key to success.

management needed to be improved. Recommended “best 2-27 N E GS W 24 NAV S 21 OBS N E W S 21 OBS N E W S HDG NAV1 108.00 113.00 134.000 118.000 COM1 WPT ______ DIS __._NM DTK ___° TRK 360° NAV2 108.00 110.60 123.800 118.000 COM2 4 000 4 200 60 1 4 000 000 100 20 9 3 900 90 3 800 ° 4300 70 TAS 106 KT OAT 7° C VOR 1 XPDR 5537 IDNT LCL 10:12:34 ALERTS Figure 2-22. Two similar flight decks equipped with the same information two different ways, analog and digital. What are they indicating?

Chances are that the analog pilot will review the top display before the bottom display. Conversely, the digitally trained pilot will review the instrument panel on the bottom first.

2-28 The following are two simple rules for use of an EFD: • Be able to fly the aircraft to the standards in the PTS.

Although this may seem insignificant, knowing how to fly the aircraft to a standard makes a pilot’s airmanship smoother and allows him or her more time to attend to the system instead of managing multiple tasks.

• Read and understand the installed electronic flight systems manuals to include the use of the autopilot and the other onboard electronic management tools.

Managing Aircraft Automation Figure 2-23. An example of an autopilot system. Before any pilot can master aircraft automation, he or she must first know how to fly the aircraft. Maneuvers training remains an important component of flight training because Respect for Onboard Systems almost 40 percent of all GA accidents take place in the Automation can assist the pilot in many ways, but a thorough understanding of the system(s) in use is essential to gaining the benefits it can offer. Understanding leads to respect, which is achieved through discipline and the mastery of the onboard systems. It is important to fly the aircraft using minimal information from the primary flight display (PFD). This includes turns, climbs, descents, and being able to fly approaches.

Reinforcement of Onboard Suites The use of an EFD may not seem intuitive, but competency becomes better with understanding and practice. Computer- based software and incremental training help the pilot become comfortable with the onboard suites. Then the pilot needs to practice what was learned in order to gain experience.

Reinforcement not only yields dividends in the use of automation, it also reduces workload significantly.

Getting Beyond Rote Workmanship The key to working effectively with automation is getting beyond the sequential process of executing an action. If a pilot has to analyze what key to push next, or always uses the same sequence of keystrokes when others are available, he or she may be trapped in a rote process. This mechanical process indicates a shallow understanding of the system.

Again, the desire is to become competent and know what to do without having to think about, “what keystroke is next.” Operating the system with competency and comprehension benefits a pilot when situations become more diverse and tasks increase.

Understand the Platform Contrary to popular belief, flight in aircraft equipped with different electronic management suites requires the same attention as aircraft equipped with analog instrumentation and a conventional suite of avionics. The pilot should review Figure 2-24. Examples of different platforms. Top to bottom are the and understand the different ways in which EFD are used in Beechcraft Baron G58, Cirrus SR22, and Cirrus Entega.

a particular aircraft. [Figure 2-24] 2-29 landing phase, one realm of flight that still does not involve fixated on the knobs and try to memorize each and every programming a computer to execute. Another 15 percent sequence of button pushes, pulls, and turns. A far better of all GA accidents occurs during takeoff and initial climb. strategy for accessing and managing the information available in advanced avionics computers is to stop, look, and read.

An advanced avionics safety issue identified by the FAA Reading before pushing, pulling, or twisting can often save concerns pilots who apparently develop an unwarranted a pilot some trouble.

over-reliance in their avionics and the aircraft, believing that the equipment will compensate for pilot shortcomings. Once behind the display screens on an advanced avionics Related to the over-reliance is the role of ADM, which is aircraft, the pilot’s goal is to meter, manage, and prioritize probably the most significant factor in the GA accident record the information flow to accomplish specific tasks.

of high performance aircraft used for cross-country flight. Certificated flight instructors (CFIs), as well as pilots The FAA advanced avionics aircraft safety study found that transitioning to advanced avionics, will find it helpful to poor decision-making seems to afflict new advanced avionics corral the information flow. This is possible through such pilots at a rate higher than that of GA as a whole. The review tactics as configuring the aspects of the PFD and MFD of advanced avionics accidents cited in this study shows the screens according to personal preferences. For example, majority are not caused by something directly related to the most systems offer map orientation options that include aircraft, but by the pilot’s lack of experience and a chain of “north up,” “track up,” “DTK” (desired track up), and poor decisions. One consistent theme in many of the fatal “heading up.” Another tactic is to decide, when possible, accidents is continued VFR flight into IMC. how much (or how little) information to display. Pilots can also tailor the information displayed to suit the needs of a Thus, pilot skills for normal and emergency operations hinge specific flight.

not only on mechanical manipulation of the stick and rudder, but also include the mental mastery of the EFD. Three key Information flow can also be managed for a specific flight management skills are needed to fly the advanced operation. The pilot has the ability to prioritize information avionics safely: information, automation, and risk. for a timely display of exactly the information needed for any given flight operation. Examples of managing information Information Management display for a specific operation include: For the newly transitioning pilot, the PFD, MFD, and GPS/ • Program map scale settings for en route versus VHF navigator screens seem to offer too much information terminal area operation.

presented in colorful menus and submenus. In fact, the pilot • Utilize the terrain awareness page on the MFD for a may be drowning in information but unable to find a specific night or IMC flight in or near the mountains.

piece of information. It might be helpful to remember these • Use the nearest airports inset on the PFD at night or systems are similar to computers that store some folders on over inhospitable terrain.

a desktop and some within a hierarchy.

• Program the weather datalink set to show echoes and The first critical information management skill for flying with METAR status flags.

advanced avionics is to understand the system at a conceptual level. Remembering how the system is organized helps the Enhanced Situational Awareness pilot manage the available information. It is important to An advanced avionics aircraft offers increased safety with understanding that learning knob-and-dial procedures is not enhanced situational awareness. Although aircraft flight enough. Learning more about how advanced avionics systems manuals (AFM) explicitly prohibit using the moving map, work leads to better memory for procedures and allows pilots topography, terrain awareness, traffic, and weather datalink to solve problems they have not seen before.

displays as the primary data source, these tools nonetheless give the pilot unprecedented information for enhanced There are also limits to understanding. It is generally impossible situational awareness. Without a well-planned information to understand all of the behaviors of a complex avionics management strategy, these tools also make it easy for an system. Knowing to expect surprises and to continually learn unwary pilot to slide into the complacent role of passenger new things is more effective than attempting to memorize in command.

mechanical manipulation of the knobs. Simulation software and books on the specific system used are of great value.

Consider the pilot whose navigational information management strategy consists solely of following the The second critical information management skill is stop, magenta line on the moving map. He or she can easily fly look, and read. Pilots new to advanced avionics often become into geographic or regulatory disaster, if the straight-line GPS 2-30 course goes through high terrain or prohibited airspace, or if for proper operation, and promptly take appropriate action if the moving map display fails. the system does not perform as expected.

A good strategy for maintaining situational awareness For example, at the most basic level, managing the autopilot information management should include practices that help means knowing at all times which modes are engaged ensure that awareness is enhanced, not diminished, by the use and which modes are armed to engage. The pilot needs to of automation. Two basic procedures are to always double- verify that armed functions (e.g., navigation tracking or check the system and verbal callouts. At a minimum, ensure altitude capture) engage at the appropriate time. Automation the presentation makes sense. Was the correct destination fed management is another good place to practice the callout into the navigation system? Callouts—even for single-pilot technique, especially after arming the system to make a operations—are an excellent way to maintain situational change in course or altitude.

awareness, as well as manage information.

In advanced avionics aircraft, proper automation management Other ways to maintain situational awareness include: also requires a thorough understanding of how the autopilot interacts with the other systems. For example, with some • Perform verification check of all programming. Before autopilots, changing the navigation source on the e-HSI from departure, check all information programmed while GPS to LOC or VOR while the autopilot is engaged in NAV on the ground.

(course tracking mode) causes the autopilot’s NAV mode to • Check the flight routing. Before departure, ensure all disengage. The autopilot’s lateral control will default to ROL routing matches the planned flight route. Enter the (wing level) until the pilot takes action to reengage the NAV planned route and legs, to include headings and leg mode to track the desired navigation source.

length, on a paper log. Use this log to evaluate what has been programmed. If the two do not match, do not Risk Management assume the computer data is correct, double check the Risk management is the last of the three flight management computer entry.

skills needed for mastery of the glass flight deck aircraft. The • Verify waypoints. enhanced situational awareness and automation capabilities offered by a glass flight deck airplane vastly expand its safety • Make use of all onboard navigation equipment. For and utility, especially for personal transportation use. At the example, use VOR to back up GPS and vice versa.

same time, there is some risk that lighter workloads could • Match the use of the automated system with pilot lead to complacency.

proficiency. Stay within personal limitations.

Humans are characteristically poor monitors of automated • Plan a realistic flight route to maintain situational systems. When asked to passively monitor an automated awareness. For example, although the onboard system for faults, abnormalities, or other infrequent events, equipment allows a direct flight from Denver, humans perform poorly. The more reliable the system, the Colorado, to Destin, Florida, the likelihood of poorer the human performance. For example, the pilot only rerouting around Eglin Air Force Base’s airspace is monitors a backup alert system, rather than the situation high.

that the alert system is designed to safeguard. It is a paradox • Be ready to verify computer data entries. For example, of automation that technically advanced avionics can both incorrect keystrokes could lead to loss of situational increase and decrease pilot awareness.

awareness because the pilot may not recognize errors made during a high workload period.

It is important to remember that EFDs do not replace basic flight knowledge and skills. They are a tool for improving Automation Management flight safety. Risk increases when the pilot believes the gadgets Advanced avionics offer multiple levels of automation, from compensate for lack of skill and knowledge. It is especially strictly manual flight to highly automated flight. No one level important to recognize there are limits to what the electronic of automation is appropriate for all flight situations, but in systems in any light GA aircraft can do. Being PIC requires order to avoid potentially dangerous distractions when flying sound ADM, which sometimes means saying “no” to a flight.

with advanced avionics, the pilot must know how to manage the course deviation indicator (CDI), the navigation source, Risk is also increased when the pilot fails to monitor the and the autopilot. It is important for a pilot to know the systems. By failing to monitor the systems and failing to peculiarities of the particular automated system being used.

check the results of the processes, the pilot becomes detached This ensures the pilot knows what to expect, how to monitor 2-31 from the aircraft operation and slides into the complacent role of passenger in command. Complacency led to tragedy in a 1999 aircraft accident.

In Colombia, a multi-engine aircraft crewed with two pilots struck the face of the Andes Mountains. Examination of their FMS revealed they entered a waypoint into the FMS incorrectly by one degree resulting in a flight path taking them to a point 60 NM off their intended course. The pilots were equipped with the proper charts, their route was posted on the charts, and they had a paper navigation log indicating the direction of each leg. They had all the tools to manage and monitor their flight, but instead allowed the automation to fly and manage itself. The system did exactly what it was programmed to do; it flew on a programmed course into a mountain resulting in multiple deaths. The pilots simply failed to manage the system and inherently created their own hazard.

Although this hazard was self-induced, what is notable is the risk the pilots created through their own inattention. By failing to evaluate each turn made at the direction of automation, the pilots maximized risk instead of minimizing it. In this case, a totally avoidable accident become a tragedy through simple pilot error and complacency.

For the GA pilot transitioning to automated systems, it is helpful to note that all human activity involving technical devices entails some element of risk. Knowledge, experience, and mission requirements tilt the odds in favor of safe and successful flights. The advanced avionics aircraft offers many new capabilities and simplifies the basic flying tasks, but only if the pilot is properly trained and all the equipment is working as advertised.

Chapter Summary This chapter focused on helping the pilot improve his or her ADM skills with the goal of mitigating the risk factors associated with flight in both classic and automated aircraft.

In the end, the discussion is not so much about aircraft, but about the people who fly them.

2-32

Chapter 3

Aircraft

Construction

Introduction An aircraft is a device that is used, or intended to be used, for flight according to the current Title 14 of the Code of Federal Regulations (14 CFR) part 1, Definitions and Abbreviations.

Categories of aircraft for certification of airmen include airplane, rotorcraft, glider, lighter-than-air, powered-lift, powered parachute, and weight-shift control aircraft. Title 14 CFR part 1 also defines airplane as an engine-driven, fixed-wing aircraft that is supported in flight by the dynamic reaction of air against its wings. Another term, not yet codified in 14 CFR part 1, is advanced avionics aircraft, which refers to an aircraft that contains a global positioning system (GPS) navigation system with a moving map display, in conjunction with another system, such as an autopilot.

This chapter provides a brief introduction to the structure of aircraft and uses an airplane for most illustrations. Light Sport Aircraft (LSA), such as weight-shift control aircraft, balloon, glider, powered parachute, and gyroplane, have their own handbooks to include detailed information regarding aerodynamics and control.

3-1 process, each part is inspected to ensure that it has been built Aircraft Design, Certification, and exactly according to the approved design. This inspection is Airworthiness called a conformity inspection.

The FAA certifies three types of aviation products: aircraft, aircraft engines, and propellers. Each of these products When the aircraft is complete, with the airframe, engine, and has been designed to a set of airworthiness standards.

propeller, it is inspected and the FAA issues an airworthiness These standards are parts of Title 14 of the Code of certificate for the aircraft. Having an airworthiness Federal Regulations (14 CFR), published by the FAA. The certificate means the complete aircraft meets the design and airworthiness standards were developed to help ensure that manufacturing standards, and is in a condition for safe flight.

aviation products are designed with no unsafe features.

This airworthiness certificate must be carried in the aircraft Different airworthiness standards apply to the different during all flight operations. The airworthiness certificate categories of aviation products as follows: remains valid as long as the required maintenance and • Normal, Utility, Acrobatic, and Commuter Category inspections are kept up to date for the aircraft.

Airplanes- 14 CFR part 23 Airworthiness certificates are classified as either “Standard” • Transport Category Airplanes—14 CFR part 25 or “Special.” Standard airworthiness certificates are white, • Normal Category—14 CFR part 27 and are issued for normal, utility, acrobatic, commuter, or • Transport Category Rotorcraft—14 CFR part 29 transport category aircraft. They are also issued for manned free balloons and aircraft designated as “Special Class.” • Manned Free Balloons—14 CFR part 31 • Aircraft Engines—14 CFR part 33 Special airworthiness certificates are pink, and are issued • Propellers—14 CFR part 35 for primary, restricted, and limited category aircraft, and light sport aircraft. They are also issued as provisional airworthiness certificates, special flight permits (ferry Some aircraft are considered “special classes” of aircraft and permits), and for experimental aircraft.

do not have their own airworthiness standards, such as gliders and powered lift. The airworthiness standards used for these More information on airworthiness certificates can be found aircraft are a combination of requirements in 14 CFR parts in Chapter 9, in 14 CFR parts 175-225, and also on the FAA 23, 25, 27, and 29 that the FAA and the designer have agreed website at www.faa.gov .

are appropriate for the proposed aircraft.

Lift and Basic Aerodynamics The FAA issues a Type Certificate (TC) for the product when they are satisfied it complies with the applicable In order to understand the operation of the major components airworthiness standards. When the TC is issued, a Type and subcomponents of an aircraft, it is important to Certificate Data Sheet (TCDS) is generated that specifies understand basic aerodynamic concepts. This chapter briefly the important design and operational characteristics of the introduces aerodynamics; a more detailed explanation can be aircraft, aircraft engine, or propeller. The TCDS defines the found in Chapter 5, Aerodynamics of Flight.

product and are available to the public from the FAA website at www.faa.gov .

Four forces act upon an aircraft in relation to straight-and level, unaccelerated flight. These forces are thrust, lift, A Note About Light Sport Aircraft weight, and drag. [Figure 3-1] Light sport aircraft are not designed according to FAA airworthiness standards. Instead, they are designed to a Thrust is the forward force produced by the powerplant/ consensus of standards agreed upon in the aviation industry.

propeller. It opposes or overcomes the force of drag. As a The FAA has agreed the consensus of standards is acceptable general rule, it is said to act parallel to the longitudinal axis.

as the design criteria for these aircraft. Light sport aircraft do This is not always the case as explained later.

not necessarily have individually type certificated engines and propellers. Instead, a TC is issued to the aircraft as a Drag is a rearward, retarding force and is caused by disruption whole. It includes the airframe, engine, and propeller.

of airflow by the wing, fuselage, and other protruding objects.

Drag opposes thrust and acts rearward parallel to the relative Aircraft, aircraft engines, and propellers can be manufactured wind.

one at a time from the design drawings, or through an FAA approved manufacturing process, depending on the size and capabilities of the manufacturer. During the manufacturing 3-2 One of the most significant components of aircraft design is Lift CG. It is the specific point where the mass or weight of an aircraft may be said to center; that is, a point around which, if the aircraft could be suspended or balanced, the aircraft would remain relatively level. The position of the CG of an aircraft determines the stability of the aircraft in flight.

Drag As the CG moves rearward (towards the tail), the aircraft Thrust becomes more and more dynamically unstable. In aircraft with fuel tanks situated in front of the CG, it is important that the CG is set with the fuel tank empty. Otherwise, as the Weight fuel is used, the aircraft becomes unstable. [Figure 3-3] The CG is computed during initial design and construction and is further affected by the installation of onboard equipment, aircraft loading, and other factors.

Figure 3-1. The four forces.

Major Components Although airplanes are designed for a variety of purposes, most Weight is the combined load of the aircraft itself, the crew, of them have the same major components. [Figure 3-4] The the fuel, and the cargo or baggage. Weight pulls the aircraft overall characteristics are largely determined by the original downward because of the force of gravity. It opposes lift design objectives. Most airplane structures include a fuselage, and acts vertically downward through the aircraft’s center wings, an empennage, landing gear, and a powerplant.

of gravity (CG).

Fuselage Lift opposes the downward force of weight, is produced by The fuselage is the central body of an airplane and is designed the dynamic effect of the air acting on the wing, and acts to accommodate the crew, passengers, and cargo. It also perpendicular to the flight path through the wing’s center provides the structural connection for the wings and tail of lift (CL).

assembly. Older types of aircraft design utilized an open truss structure constructed of wood, steel, or aluminum tubing.

An aircraft moves in three dimensions and is controlled by [Figure 3-5] The most popular types of fuselage structures moving it about one or more of its axes. The longitudinal, used in today’s aircraft are the monocoque (French for or roll, axis extends through the aircraft from nose to tail, “single shell”) and semimonocoque. These structure types with the line passing through the CG. The lateral or pitch are discussed in more detail under aircraft construction later axis extends across the aircraft on a line through the wing in the chapter.

tips, again passing through the CG. The vertical, or yaw, axis passes through the aircraft vertically, intersecting the CG. All Wings control movements cause the aircraft to move around one or The wings are airfoils attached to each side of the fuselage more of these axes and allows for the control of the aircraft and are the main lifting surfaces that support the airplane in in flight. [Figure 3-2] Yawing Rolling Pitching Lateral axis Longitudinal axis Vertical axis Figure 3-2. Illustrates the pitch, roll, and yaw motion of the aircraft along the lateral, longitudinal, and vertical axes, respectively.

3-3 Longerons Lift CG CL Fixed Variable Struts Nose-down force Nose-up force independent of airspeed dependent upon airspeed Longerons Vertical forces acting on an airplane in flight.

Insufficient elevator nose-down force Lift CL CG Bulkhead Stringers CG too far aft Figure 3-5. Truss-type fuselage structure.

If the CG is too far aft, there might not be enough elevator nose-down force at the low stall airspeed to get the nose down for recovery.

flight. There are numerous wing designs, sizes, and shapes used by the various manufacturers. Each fulfills a certain need with respect to the expected performance for the particular Lift airplane. How the wing produces lift is explained in Chapter 5, Aerodynamics of Flight.

CG CL Wings may be attached at the top, middle, or lower portion of the fuselage. These designs are referred to as high-, mid-, Insufficient elevator and low-wing, respectively. The number of wings can also nose-up force CG too far forward vary. Airplanes with a single set of wings are referred to as monoplanes, while those with two sets are called biplanes.

If the CG is too far forward, there will not be enough elevator nose-up force to flare the airplane for landing.

[Figure 3-6] Figure 3-3. Center of gravity (CG).

Many high-wing airplanes have external braces, or wing struts that transmit the flight and landing loads through the Empennage Wing struts to the main fuselage structure. Since the wing struts are usually attached approximately halfway out on the wing, this type of wing structure is called semi-cantilever. A few high-wing and most low-wing airplanes have a full cantilever wing designed to carry the loads without external struts.

Powerplant Fuselage The principal structural parts of the wing are spars, ribs, and stringers. [Figure 3-7] These are reinforced by trusses, I-beams, tubing, or other devices, including the skin. The wing ribs determine the shape and thickness of the wing (airfoil). In most modern airplanes, the fuel tanks are either Landing gear an integral part of the wing’s structure or consist of flexible containers mounted inside of the wing.

Figure 3-4. Airplane components.

3-4 Figure 3-6. Monoplane (left) and biplane (right).

Attached to the rear, or trailing edges, of the wings are two operation for which an aircraft is intended and is tailored types of control surfaces referred to as ailerons and flaps. to specific types of flying. These design variations are Ailerons extend from about the midpoint of each wing discussed in Chapter 5, Aerodynamics of Flight, which outward toward the tip, and move in opposite directions to provides information on the effect controls have on lifting create aerodynamic forces that cause the airplane to roll. surfaces from traditional wings to wings that use both flexing Flaps extend outward from the fuselage to near the midpoint (due to billowing) and shifting (through the change of the of each wing. The flaps are normally flush with the wing’s aircraft’s CG). For example, the wing of the weight-shift surface during cruising flight. When extended, the flaps move control aircraft is highly swept in an effort to reduce drag simultaneously downward to increase the lifting force of the and allow for the shifting of weight to provide controlled wing for takeoffs and landings. [Figure 3-8] flight. [Figure 3-9] Handbooks specific to most categories of aircraft are available for the interested pilot and can be found on the Federal Aviation Administration (FAA) website Alternate Types of Wings at www.faa.gov .

Alternate types of wings are often found on aircraft. The shape and design of a wing is dependent upon the type of Wing flap Spar Aileron Fuel tank Skin Ribs Wing tip Stringers Figure 3-7. Wing components.

3-5 Basic section Plain flap Figure 3-9. Weight-shift control aircraft use the shifting of weight for control.

Split flap portions of the trailing edge of the control surface. These movable trim tabs, which are controlled from the flight deck, reduce control pressures. Trim tabs may be installed on the ailerons, the rudder, and/or the elevator.

Slotted flap A second type of empennage design does not require an elevator. Instead, it incorporates a one-piece horizontal stabilizer that pivots from a central hinge point. This type of design is called a stabilator and is moved using the control wheel, just as the elevator is moved. For example, when a pilot pulls back on the control wheel, the stabilator pivots so the trailing edge moves up. This increases the aerodynamic Fowler flap tail load and causes the nose of the airplane to move up.

Stabilators have an antiservo tab extending across their trailing edge. [Figure 3-11] The antiservo tab moves in the same direction as the trailing edge of the stabilator and helps make the stabilator less Slotted Fowler flap sensitive. The antiservo tab also functions as a trim tab to relieve control pressures and helps maintain the stabilator in the desired position.

Vertical stabilizer Horizontal stabilizer Figure 3-8. Types of flaps.

Empennage Rudder The empennage includes the entire tail group and consists Trim tabs of fixed surfaces, such as the vertical stabilizer and the horizontal stabilizer. The movable surfaces include the rudder, the elevator, and one or more trim tabs. [Figure 3-10] The rudder is attached to the back of the vertical stabilizer.

During flight, it is used to move the airplane’s nose left Elevator and right. The elevator, which is attached to the back of the horizontal stabilizer, is used to move the nose of the airplane Figure 3-10. Empennage components.

up and down during flight. Trim tabs are small, movable 3-6 Antiservo tab Stabilator pivot point Figure 3-11. Stabilator components.

Landing Gear The landing gear is the principal support of the airplane when parked, taxiing, taking off, or landing. The most common type of landing gear consists of wheels, but airplanes can also be equipped with floats for water operations or skis for landing on snow. [Figure 3-12] Wheeled landing gear consists of three wheels—two main wheels and a third wheel positioned either at the front or rear of the airplane. Landing gear with a rear mounted wheel is called conventional landing gear.

Airplanes with conventional landing gear are sometimes referred to as tailwheel airplanes. When the third wheel is located on the nose, it is called a nosewheel, and the design is referred to as a tricycle gear. A steerable nosewheel or tailwheel permits the airplane to be controlled throughout all operations while on the ground. Most aircraft are steered by moving the rudder pedals, whether nosewheel or tailwheel.

Additionally, some aircraft are steered by differential braking.

The Powerplant Figure 3-12. Types of landing gear: floats (top), skis (middle), and The powerplant usually includes both the engine and the wheels (bottom).

propeller. The primary function of the engine is to provide the power to turn the propeller. It also generates electrical is a rotating airfoil that produces thrust through aerodynamic power, provides a vacuum source for some flight instruments, action. A high-pressure area is formed at the back of the and in most single-engine airplanes, provides a source of propeller’s airfoil, and low pressure is produced at the face of heat for the pilot and passengers. [Figure 3-13] The engine the propeller, similar to the way lift is generated by an airfoil is covered by a cowling, or a nacelle, which are both types used as a lifting surface or wing. This pressure differential of covered housing. The purpose of the cowling or nacelle develops thrust from the propeller, which in turn pulls the is to streamline the flow of air around the engine and to help airplane forward. Engines may be turned around to be pushers cool the engine by ducting air around the cylinders.

with the propeller at the rear.

The propeller, mounted on the front of the engine, translates There are two significant factors involved in the design the rotating force of the engine into thrust, a forward acting of a propeller that impact its effectiveness. The angle of a force that helps move the airplane through the air. A propeller 3-7 operate the flight instruments, essential systems, such as anti-icing, and passenger services, such as cabin lighting.

Engine The flight controls are the devices and systems that govern the attitude of an aircraft and, as a result, the flight path Propeller followed by the aircraft. In the case of many conventional airplanes, the primary flight controls utilize hinged, trailing- edge surfaces called elevators for pitch, ailerons for roll, and the rudder for yaw. These surfaces are operated by the pilot in the flight deck or by an automatic pilot.

In the case of most modern airplanes, airplane brakes consist of multiple pads (called caliper pads) that are hydraulically squeezed toward each other with a rotating disk (called a rotor) between them. The pads place pressure on the rotor Cowling which is turning with the wheels. As a result of the increased friction on the rotor, the wheels inherently slow down and stop turning. The disks and brake pads are made either from steel, like those in a car, or from a carbon material that weighs Figure 3-13. Engine compartment.

less and can absorb more energy. Because airplane brakes are used principally during landings and must absorb enormous propeller blade, as measured against the hub of the propeller, amounts of energy, their life is measured in landings rather keeps the angle of attack (AOA) (See definition in Glossary) than miles.

relatively constant along the span of the propeller blade, reducing or eliminating the possibility of a stall. The amount Types of Aircraft Construction of lift being produced by the propeller is directly related to The construction of aircraft fuselages evolved from the early the AOA, which is the angle at which the relative wind meets wood truss structural arrangements to monocoque shell the blade. The AOA continuously changes during the flight structures to the current semimonocoque shell structures.

depending upon the direction of the aircraft.

Truss Structure The pitch is defined as the distance a propeller would travel in The main drawback of truss structure is its lack of a one revolution if it were turning in a solid. These two factors streamlined shape. In this construction method, lengths of combine to allow a measurement of the propeller’s efficiency.

tubing, called longerons, are welded in place to form a well- Propellers are usually matched to a specific aircraft/ braced framework. Vertical and horizontal struts are welded powerplant combination to achieve the best efficiency at a to the longerons and give the structure a square or rectangular particular power setting, and they pull or push depending on shape when viewed from the end. Additional struts are needed how the engine is mounted.

to resist stress that can come from any direction. Stringers and bulkheads, or formers, are added to shape the fuselage Subcomponents and support the covering.

The subcomponents of an airplane include the airframe, electrical system, flight controls, and brakes.

As technology progressed, aircraft designers began to enclose the truss members to streamline the airplane and improve The airframe is the basic structure of an aircraft and is performance. This was originally accomplished with cloth designed to withstand all aerodynamic forces, as well as the fabric, which eventually gave way to lightweight metals such stresses imposed by the weight of the fuel, crew, and payload.

as aluminum. In some cases, the outside skin can support all or a major portion of the flight loads. Most modern aircraft The primary function of an aircraft electrical system is to use a form of this stressed skin structure known as monocoque generate, regulate, and distribute electrical power throughout or semimonocoque construction. [Figure 3-14] the aircraft. There are several different power sources on aircraft to power the aircraft electrical systems. These Monocoque power sources include: engine-driven alternating current Monocoque construction uses stressed skin to support almost (AC) generators, auxiliary power units (APUs), and external all loads much like an aluminum beverage can. Although power. The aircraft’s electrical power system is used to very strong, monocoque construction is not highly tolerant 3-8 automobile manufacturing where the unibody is considered Monocoque standard in manufacturing.

Bulkhead Semimonocoque Semimonocoque construction, partial or one-half, uses a substructure to which the airplane’s skin is attached. The substructure, which consists of bulkheads and/or formers of various sizes and stringers, reinforces the stressed skin Stressed skin by taking some of the bending stress from the fuselage. The main section of the fuselage also includes wing attachment Formers points and a firewall. On single-engine airplanes, the engine is usually attached to the front of the fuselage. There is a fireproof partition between the rear of the engine and the Semimonocoque flight deck or cabin to protect the pilot and passengers from accidental engine fires. This partition is called a firewall and Stringers Bulkhead is usually made of heat-resistant material such as stainless steel. However, a new emerging process of construction is the integration of composites or aircraft made entirely of composites.

Skin Composite Construction Formers History The use of composites in aircraft construction can be dated to World War II aircraft when soft fiberglass insulation was Figure 3-14. Semimonocoque and monocoque fuselage design.

used in B-29 fuselages. By the late 1950s, European high performance sailplane manufacturers were using fiberglass to deformation of the surface. For example, an aluminum as primary structures. In 1965, the FAA type certified the beverage can supports considerable forces at the ends of first all-fiberglass aircraft in the normal category, a Swiss the can, but if the side of the can is deformed slightly while sailplane called a Diamant HBV. Four years later, the FAA supporting a load, it collapses easily.

certified a four-seat, single-engine Windecker Eagle in the normal category. By 2005, over 35 percent of new aircraft Because most twisting and bending stresses are carried by were constructed of composite materials.

the external skin rather than by an open framework, the need for internal bracing was eliminated or reduced, saving weight Composite is a broad term and can mean materials such as and maximizing space. One of the notable and innovative fiberglass, carbon fiber cloth, Kevlar™ cloth, and mixtures methods for using monocoque construction was employed by of all of the above. Composite construction offers two Jack Northrop. In 1918, he devised a new way to construct advantages: extremely smooth skins and the ability to easily a monocoque fuselage used for the Lockheed S-1 Racer.

form complex curved or streamlined structures. [Figure 3-15] The technique utilized two molded plywood half-shells that were glued together around wooden hoops or stringers. To Composite Materials in Aircraft construct the half shells, rather than gluing many strips of Composite materials are fiber-reinforced matrix systems.

plywood over a form, three large sets of spruce strips were The matrix is the “glue” used to hold the fibers together soaked with glue and laid in a semi-circular concrete mold and, when cured, gives the part its shape, but the fibers carry that looked like a bathtub. Then, under a tightly clamped most of the load. There are many different types of fibers lid, a rubber balloon was inflated in the cavity to press and matrix systems.

the plywood against the mold. Twenty-four hours later, the smooth half-shell was ready to be joined to another to In aircraft, the most common matrix is epoxy resin, which is create the fuselage. The two halves were each less than a a type of thermosetting plastic. Compared to other choices quarter inch thick. Although employed in the early aviation such as polyester resin, epoxy is stronger and has good high- period, monocoque construction would not reemerge for temperature properties. There are many different types of several decades due to the complexities involved. Every epoxies available with a wide range of structural properties, day examples of monocoque construction can be found in cure times and temperatures, and costs.

3-9 and Columbia line of production aircraft, leading to their high performance despite their fixed landing gear. Composites also help mask the radar signature of “stealth” aircraft designs, such as the B-2 and the F-22. Today, composites can be found in aircraft as varied as gliders to most new helicopters.

Lack of corrosion is a third advantage of composites. Boeing is designing the 787, with its all-composite fuselage, to have both a higher pressure differential and higher humidity in the cabin than previous airliners. Engineers are no longer as concerned about corrosion from moisture condensation on the hidden areas of the fuselage skins, such as behind insulation blankets. This should lead to lower long-term maintenance costs for the airlines.

Figure 3-15. Composite aircraft.

Another advantage of composites is their good performance in a flexing environment, such as in helicopter rotor blades.

The most common reinforcing fibers used in aircraft Composites do not suffer from metal fatigue and crack growth construction are fiberglass and carbon fiber. Fiberglass as do metals. While it takes careful engineering, composite has good tensile and compressive strength, good impact rotor blades can have considerably higher design lives than resistance, is easy to work with, and is relatively inexpensive metal blades, and most new large helicopter designs have all and readily available. Its main disadvantage is that it is composite blades, and in many cases, composite rotor hubs.

somewhat heavy, and it is difficult to make a fiberglass load- carrying structure lighter than a well designed equivalent Disadvantages of Composites aluminum structure.

Composite construction comes with its own set of disadvantages, the most important of which is the lack of Carbon fiber is generally stronger in tensile and compressive visual proof of damage. Composites respond differently from strength than fiberglass and has much higher bending other structural materials to impact, and there is often no stiffness. It is also considerably lighter than fiberglass.

obvious sign of damage. For example, if a car backs into an However, it is relatively poor in impact resistance; the fibers aluminum fuselage, it might dent the fuselage. If the fuselage are brittle and tend to shatter under sharp impact. This can is not dented, there is no damage. If the fuselage is dented, be greatly improved with a “toughened” epoxy resin system, the damage is visible and repairs are made.

as used in the Boeing 787 horizontal and vertical stabilizers.

Carbon fiber is more expensive than fiberglass, but the price In a composite structure, a low energy impact, such as a has dropped due to innovations driven by the B-2 program bump or a tool drop, may not leave any visible sign of the in the 1980s and Boeing 777 work in the 1990s. Very well- impact on the surface. Underneath the impact site there may designed carbon fiber structures can be significantly lighter be extensive delaminations, spreading in a cone-shaped area than an equivalent aluminum structure, sometimes by 30 from the impact location. The damage on the backside of percent or so.

the structure can be significant and extensive, but it may be hidden from view. Anytime one has reason to think there Advantages of Composites may have been an impact, even a minor one, it is best to Composite construction offers several advantages over get an inspector familiar with composites to examine the metal, wood, or fabric, with its lighter weight being the most structure to determine underlying damage. The appearance frequently cited. Lighter weight is not always automatic. It of “whitish” areas in a fiberglass structure is a good tip-off must be remembered that building an aircraft structure out of that delaminations of fiber fracture has occurred.

composites does not guarantee it will be lighter; it depends on the structure, as well as the type of composite being used.

A medium energy impact (perhaps the car backing into the structure) results in local crushing of the surface, which A more important advantage is that a very smooth, compound should be visible to the eye. The damaged area is larger than curved, aerodynamic structure made from composites the visible crushed area and will need to be repaired. A high reduces drag. This is the main reason sailplane designers energy impact, such as a bird strike or hail while in flight, switched from metal and wood to composites in the 1960s.

results in a puncture and a severely damaged structure. In In aircraft, the use of composites reduces drag for the Cirrus 3-10 medium and high energy impacts, the damage is visible to the The potential for heat damage to the resin is another eye, but low energy impact is difficult to detect. [Figure 3-16] disadvantage of using composites. While “too hot” depends on the particular resin system chosen, many epoxies begin If an impact results in delaminations, crushing of the surface, to weaken over 150 °F. White paint on composites is often or a puncture, then a repair is mandatory. While waiting used to minimize this issue. For example, the bottom of for the repair, the damaged area should be covered and a wing that is painted black facing a black asphalt ramp protected from rain. Many composite parts are composed on a hot, sunny day can get as hot as 220 °F. The same of thin skins over a honeycomb core, creating a “sandwich” structure, painted white, rarely exceeds 140 °F. As a result, structure. While excellent for structural stiffness reasons, composite aircraft often have specific recommendations such a structure is an easy target for water ingress (entering), on allowable paint colors. If the aircraft is repainted, these leading to further problems later. A piece of “speed tape” recommendations must be followed. Heat damage can also over the puncture is a good way to protect it from water, but occur due to a fire. Even a quickly extinguished small brake it is not a structural repair. The use of a paste filler to cover fire can damage bottom wing skins, composite landing gear up the damage, while acceptable for cosmetic purposes, is legs, or wheel pants.

not a structural repair, either.

Also, chemical paint strippers are very harmful to composites and must not be used on them. If paint needs to be removed 0 0 0 0 from composites, only mechanical methods are allowed, such +45 +45 -45 -45 as gentle grit blasting or sanding. Many expensive composite 0 0 parts have been ruined by the use of paint stripper and such 90 90 90 90 damage is generally not repairable.

0 0 -45 -45 +45 +45 0 0 Fluid Spills on Composites 0 0 Some owners are concerned about fuel, oil, or hydraulic fluid Pyramid pattern matrix crack from impact spills on composite surfaces. These are generally not a problem Low Energy Impact with modern composites using epoxy resin. Usually, if the spill does not attack the paint, it will not hurt the underlying Local fiber/matrix crushing composite. Some aircraft use fiberglass fuel tanks, for example, 0 0 0 0 in which the fuel rides directly against the composite surface +45 +45 -45 -45 with no sealant being used. If the fiberglass structure is made 0 0 90 90 with some of the more inexpensive types of polyester resin, 90 90 there can be a problem when using auto gas with ethanol 0 0 -45 -45 blended into the mixture. The more expensive types of +45 +45 0 0 polyester resin, as well as epoxy resin, can be used with auto 0 0 gas, as well as 100 octane aviation gas (avgas) and jet fuel.

Delaminations Back side fiber fracture Medium Energy Impact Lightning Strike Protection Lightning strike protection is an important consideration in 0 0 0 0 aircraft design. When an aircraft is hit by lightning, a very +45 +45 -45 -45 large amount of energy is delivered to the structure. Whether Through 0 0 90 90 penetration flying a light general aviation (GA) aircraft or a large airliner, 90 90 small damage 0 0 the basic principle of lightning strike protection is the same.

zone -45 -45 +45 +45 For any size aircraft, the energy from the strike must be spread 0 0 over a large surface area to lower the amps per square inch 0 0 Loose to a harmless level.

Delaminations fiber ends High Energy Impact If lightning strikes an aluminum airplane, the electrical energy naturally conducts easily through the aluminum Figure 3-16. Impact energy affects the visibility, as well as the structure. The challenge is to keep the energy out of avionics, severity, of damage in composite structures. High and medium fuel systems, etc., until it can be safely conducted overboard.

energy impacts, while severe, are easy to detect. Low energy impacts The outer skin of the aircraft is the path of least resistance.

can easily cause hidden damage.

3-11 In a composite aircraft, fiberglass is an excellent electrical insulator, while carbon fiber conducts electricity, but not as easily as aluminum. Therefore, additional electrical conductivity needs to be added to the outside layer of composite skin. This is done typically with fine metal meshes bonded to the skin surfaces. Aluminum and copper mesh are the two most common types, with aluminum used on fiberglass and copper on carbon fiber. Any structural repairs on lightning-strike protected areas must also include the mesh as well as the underlying structure.

For composite aircraft with internal radio antennas, there must be “windows” in the lightning strike mesh in the area of the antenna. Internal radio antennas may be found in fiberglass composites because fiberglass is transparent to radio frequencies, where carbon fiber is not.

The Future of Composites In the decades since World War II, composites have earned an important role in aircraft structure design. Their design flexibility and corrosion resistance, as well as the high strength-to-weight ratios possible, will undoubtedly continue to lead to more innovative aircraft designs in the future.

From the Cirrus SR-20 to the Boeing 787, it is obvious that composites have found a home in aircraft construction and are here to stay. [Figure 3-17] Instrumentation: Moving into the Future Until recently, most GA aircraft were equipped with individual instruments utilized collectively to safely operate and maneuver the aircraft. With the release of the electronic flight display (EFD) system, conventional instruments have been replaced by multiple liquid crystal display (LCD) screens. The first screen is installed in front of the pilot position and is referred to as the primary flight display (PFD).

The second screen, positioned approximately in the center of the instrument panel, is referred to as the multi-function display (MFD). These two screens de-clutter instrument Figure 3-17. Composite materials in aircraft, such as Columbia 350 panels while increasing safety. This has been accomplished (top), Boeing 787 (middle), and a Coast Guard HH-65 (bottom).

through the utilization of solid state instruments that have a failure rate far less than those of conventional analog instrumentation. [Figure 3-18] Performance Instruments The performance instruments indicate the aircraft’s actual With today’s improvements in avionics and the introduction performance. Performance is determined by reference to the altimeter, airspeed or vertical speed indicator (VSI), heading of EFDs, pilots at any level of experience need an astute knowledge of the onboard flight control systems, as well as indicator, and turn-and-slip indicator. The performance instruments directly reflect the performance the aircraft an understanding of how automation melds with aeronautical decision-making (ADM). These subjects are covered in detail is achieving. The speed of the aircraft can be referenced on the airspeed indicator. The altitude can be referenced in Chapter 2, Aeronautical Decision-Making.

on the altimeter. The aircraft’s climb performance can be Whether an aircraft has analog or digital (glass) instruments, determined by referencing the VSI. Other performance the instrumentation falls into three different categories: instruments available are the heading indicator, angle of performance, control, and navigation. attack indicator, and the slip-skid indicator. [Figure 3-19] 3-12 selected navigation facility or fix. They also provide pilotage information so the aircraft can be maneuvered to keep it on a predetermined path. The pilotage information can be in either two or three dimensions relative to the ground-based or space-based navigation information. [Figures 3-21 and 3-22] Global Positioning System (GPS) GPS is a satellite-based navigation system composed of a network of satellites placed into orbit by the United States Department of Defense (DOD). GPS was originally intended for military applications, but in the 1980s the government made the system available for civilian use. GPS works in all weather conditions, anywhere in the world, 24 hours a day. A GPS receiver must be locked onto the signal of at least three satellites to calculate a two-dimensional position (latitude and longitude) and track movement. With four or more satellites in view, the receiver can determine the user’s three-dimensional position (latitude, longitude, and altitude).

Other satellites must also be in view to offset signal loss and signal ambiguity. The use of the GPS is discussed in more detail in Chapter 17, Navigation. Additionally, GPS is discussed in the Aeronautical Information Manual (AIM).

Chapter Summary This chapter provides an overview of aircraft structures.

A more in-depth understanding of aircraft structures and controls can be gained through the use of flight simulation Figure 3-18. Analog display (top) and digital display (bottom) from software or interactive programs available online through a Cessna 172.

aviation organizations, such as the Aircraft Owners and Pilots Association (AOPA). Pilots are also encouraged to subscribe Control Instruments to or review the various aviation periodicals that contain The control instruments display immediate attitude and power valuable flying information. As discussed in Chapter 1, the changes and are calibrated to permit adjustments in precise National Aeronautics and Space Administration (NASA) and increments. [Figure 3-20] The instrument for attitude display the FAA also offer free information for pilots.

is the attitude indicator. The control instruments do not indicate aircraft speed or altitude. In order to determine these variables and others, a pilot must reference the performance instruments.

Navigation Instruments The navigation instruments indicate the position of the aircraft in relation to a selected navigation facility or fix.

This group of instruments includes various types of course indicators, range indicators, glideslope indicators, and bearing pointers. Newer aircraft with more technologically advanced instrumentation provide blended information, giving the pilot more accurate positional information.

Navigation instruments are comprised of indicators that display GPS, very high frequency (VHF) omni-directional radio range (VOR), nondirectional beacon (NDB), and instrument landing system (ILS) information. The instruments indicate the position of the aircraft relative to a 3-13 Airspeed indicator Attitude indicator Altimeter indicator Turn coordinator Heading indicator Vertical speed indicator _ _ _ _ _ _ _ _ ._ _ _ _ Slip/Skid indicator WPT DIS NM DTK °T TRK 360°T NAV1 108.00 113.00 134.000 118.000 COM1 NAV2 108.00 110.60 123.800 118.000 COM2 Airspeed tape indicator 4 000 200 Vertical speed and Altimeter and tape indicator altitude trend tape 60 1 4 000 9 20 3 900 Turn rate trend vector 80 ° 2 270

°

TAS 100 KT Heading bug VOR 1 3500 Course arrow Turn rate indicator XPDR 5537 IDNT LCL23:00:34 ALERTS Figure 3-19. Performance instruments.

3-14 Manifold pressure gauge Attitude indicator _ _ _ _ _ _ _ _ ._ _ _ _ WPT DIS NM DTK ° TRK 360° NAV1 108.00 113.00 134.000 118.000 COM1

23.0

NAV2 108.00 110.60 123.800 118.000 COM2 23.0 4 100 60 1 4 000 000 100 20 9 13.7 270° 2 TAS 100 KT Tachometer VOR 1 XPDR 5537 IDNT LCL23:00:34 ALERTS Figure 3-20. Control instruments.

3-15 A The aircraft illustrated is heading N 020°, but the course is to the left.

3 30 TO W 6 ° HDG 360° CRS 340° E 24 S OBS 3 VOR 1 30 I2 I5 2I Present position, inbound on 160° radial.

30 3 ° 3 N 33 6 33 30 N HDG 360° CRS 340° GS W E 24 12 24 NAV 3 30 21 15 S OBS I2 2I TO I5 W 6 E 24 21 12 View is from the pilot’s S OBS perspective, and the movable card is reset after each turn.

° Figure 3-21. A comparison of navigation information as depicted on both analog and digital displays.

4 400 Fly down Fly up 4 300 Glideslope needle indicates “fly up” to intercept glideslope Glideslope needle indicates “fly down” to intercept glideslope 4 200 15 12 15 12 E S E S TO 20 TO 21 2 0 I 0 21 2 0 I 0 4 000 4 000 24 I0 I0 4 400 24 I0 I0 20 20 FR 20 20 N FR W NAV 1 N 3 900 W NAV 1 33 30 OBS 33 30 4 300 OBS 3 800 4 200 4 000 4 000 3 900 Glideslope 3 800 Figure 3-22. Analog and digital indications for glideslope interception.

3-16

Chapter 4

Principles of

Flight

Introduction This chapter examines the fundamental physical laws governing the forces acting on an aircraft in flight, and what effect these natural laws and forces have on the performance characteristics of aircraft. To control an aircraft, be it an airplane, helicopter, glider, or balloon, the pilot must understand the principles involved and learn to use or counteract these natural forces.

Structure of the Atmosphere The atmosphere is an envelope of air that surrounds the Earth and rests upon its surface. It is as much a part of the Earth as the seas or the land, but air differs from land and water as it is a mixture of gases. It has mass, weight, and indefinite shape.

The atmosphere is composed of 78 percent nitrogen, 21 percent oxygen, and 1 percent other gases, such as argon or helium. Some of these elements are heavier than others.

The heavier elements, such as oxygen, settle to the surface of the Earth, while the lighter elements are lifted up to the region of higher altitude. Most of the atmosphere’s oxygen is contained below 35,000 feet altitude.

4-1 Air is a Fluid the viscosity of air. However, since air is a fluid and has viscosity properties, it resists flow around any object to When most people hear the word “fluid,” they usually think some extent.

of liquid. However, gasses, like air, are also fluids. Fluids take on the shape of their containers. Fluids generally do not Friction resist deformation when even the smallest stress is applied, or they resist it only slightly. We call this slight resistance Another factor at work when a fluid flows over or around viscosity. Fluids also have the ability to flow. Just as a liquid an object is called friction. Friction is the resistance that one flows and fills a container, air will expand to fill the available surface or object encounters when moving over another.

volume of its container. Both liquids and gasses display these Friction exists between any two materials that contact each unique fluid properties, even though they differ greatly in other.

density. Understanding the fluid properties of air is essential to understanding the principles of flight.

The effects of friction can be demonstrated using a similar example as before. If identical fluids are poured down two Viscosity identical ramps, they flow in the same manner and at the same speed. If the surface of one ramp is rough, and the other Viscosity is the property of a fluid that causes it to resist smooth, the flow down the two ramps differs significantly.

flowing. The way individual molecules of the fluid tend to The rough surface ramp impedes the flow of the fluid due adhere, or stick, to each other determines how much a fluid to resistance from the surface (friction). It is important to resists flow. High-viscosity fluids are “thick” and resist flow; remember that all surfaces, no matter how smooth they low-viscosity fluids are “thin” and flow easily. Air has a low appear, are not smooth on a microscopic level and impede viscosity and flows easily.

the flow of a fluid.

Using two liquids as an example, similar amounts of oil and The surface of a wing, like any other surface, has a certain water poured down two identical ramps will flow at different roughness at the microscopic level. The surface roughness rates due to their different viscosity. The water seems to flow causes resistance and slows the velocity of the air flowing freely while the oil flows much more slowly.

over the wing. [Figure 4-1] As another example, different types of similar liquids will Molecules of air pass over the surface of the wing and actually display different behaviors because of different viscosities.

adhere (stick, or cling) to the surface because of friction. Air Grease is very viscous. Given time, grease will flow, even molecules near the surface of the wing resist motion and have though the flow rate will be slow. Motor oil is less viscous a relative velocity near zero. The roughness of the surface than grease and flows much more easily, but it is more viscous impedes their motion. The layer of molecules that adhere to and flows more slowly than gasoline.

the wing surface is referred to as the boundary layer.

All fluids are viscous and have a resistance to flow, whether or not we observe this resistance. We cannot easily observe Leading edge of wing under 1,500x magnification Figure 4-1. Microscopic surface of a wing.

4-2 Once the boundary layer of the air adheres to the wing by friction, further resistance to the airflow is caused by the viscosity, the tendency of the air to stick to itself. When Inches of Millibars Standard Standard these two forces act together to resist airflow over a wing, Mercury Sea Level Sea Level 30 1016 it is called drag. Pressure Pressure 29.92 Hg 1013 mb 25 847 Pressure 20 677 Pressure is the force applied in a perpendicular direction to the 15 508 surface of an object. Often, pressure is measured in pounds of 10 339 force exerted per square inch of an object, or PSI. An object completely immersed in a fluid will feel pressure uniformly 5 170 A t m o s p h e r i c P r e s s u r e around the entire surface of the object. If the pressure on one 0 0 surface of the object becomes less than the pressure exerted on the other surfaces, the object will move in the direction of the lower pressure.

Atmospheric Pressure Although there are various kinds of pressure, pilots are mainly concerned with atmospheric pressure. It is one of the basic factors in weather changes, helps to lift an aircraft, and actuates some of the important flight instruments. These Figure 4-2. Standard sea level pressure.

instruments are the altimeter, airspeed indicator, vertical speed indicator, and manifold pressure gauge.

Standard Atmosphere Temperature Air is very light, but it has mass and is affected by the Altitude (ft) Pressure (Hg) (°C) (°F) attraction of gravity. Therefore, like any other substance, 0 29.92 15.0 59.0 it has weight, and because of its weight, it has force. Since 1,000 28.86 13.0 55.4 air is a fluid substance, this force is exerted equally in all 2,000 27.82 11.0 51.9 directions. Its effect on bodies within the air is called pressure.

3,000 26.82 9.1 48.3 Under standard conditions at sea level, the average pressure 4,000 25.84 7.1 44.7 exerted by the weight of the atmosphere is approximately 5,000 24.89 5.1 41.2 14.70 pounds per square inch (psi) of surface, or 1,013.2 6,000 23.98 3.1 37.6 millibars (mb). The thickness of the atmosphere is limited; 7,000 23.09 1.1 34.0 8,000 22.22 -0.9 30.5 therefore, the higher the altitude, the less air there is above.

9,000 21.38 -2.8 26.9 For this reason, the weight of the atmosphere at 18,000 feet 10,000 20.57 -4.8 23.3 is one-half what it is at sea level.

11,000 19.79 -6.8 19.8 12,000 19.02 -8.8 16.2 The pressure of the atmosphere varies with time and location.

13,000 18.29 -10.8 12.6 Due to the changing atmospheric pressure, a standard 14,000 17.57 -12.7 9.1 reference was developed. The standard atmosphere at sea 15,000 16.88 -14.7 5.5 level is a surface temperature of 59 °F or 15 °C and a surface 16,000 16.21 -16.7 1.9 pressure of 29.92 inches of mercury ("Hg) or 1,013.2 mb. 17,000 15.56 -18.7 -1.6 18,000 14.94 -20.7 -5.2 [Figure 4-2] 19,000 14.33 -22.6 -8.8 20,000 13.74 -24.6 -12.3 A standard temperature lapse rate is when the temperature decreases at the rate of approximately 3.5 °F or 2 °C per Figure 4-3. Properties of standard atmosphere.

thousand feet up to 36,000 feet, which is approximately –65 °F or –55 °C. Above this point, the temperature is considered referred to as International Standard Atmosphere (ISA) or constant up to 80,000 feet. A standard pressure lapse rate is ICAO Standard Atmosphere. Any temperature or pressure when pressure decreases at a rate of approximately 1 "Hg that differs from the standard lapse rates is considered per 1,000 feet of altitude gain to 10,000 feet. [Figure 4-3] nonstandard temperature and pressure.

The International Civil Aviation Organization (ICAO) has established this as a worldwide standard, and it is often 4-3 Since aircraft performance is compared and evaluated with The computation of density altitude involves consideration respect to the standard atmosphere, all aircraft instruments are of pressure (pressure altitude) and temperature. Since aircraft calibrated for the standard atmosphere. In order to properly performance data at any level is based upon air density under account for the nonstandard atmosphere, certain related terms standard day conditions, such performance data apply to must be defined. air density levels that may not be identical with altimeter indications. Under conditions higher or lower than standard, Pressure Altitude these levels cannot be determined directly from the altimeter.

Pressure altitude is the height above a standard datum plane (SDP), which is a theoretical level where the weight of the Density altitude is determined by first finding pressure altitude, and then correcting this altitude for nonstandard atmosphere is 29.92 "Hg (1,013.2 mb) as measured by a barometer. An altimeter is essentially a sensitive barometer temperature variations. Since density varies directly with pressure and inversely with temperature, a given pressure calibrated to indicate altitude in the standard atmosphere. If the altimeter is set for 29.92 "Hg SDP, the altitude indicated altitude may exist for a wide range of temperatures by allowing the density to vary. However, a known density is the pressure altitude. As atmospheric pressure changes, the SDP may be below, at, or above sea level. Pressure altitude occurs for any one temperature and pressure altitude. The density of the air has a pronounced effect on aircraft and is important as a basis for determining airplane performance, as well as for assigning flight levels to airplanes operating at engine performance. Regardless of the actual altitude of the aircraft, it will perform as though it were operating at an or above 18,000 feet.

altitude equal to the existing density altitude.

The pressure altitude can be determined by one of the following methods: Air density is affected by changes in altitude, temperature, and humidity. High density altitude refers to thin air, while 1. Setting the barometric scale of the altimeter to 29.92 low density altitude refers to dense air. The conditions that and reading the indicated altitude result in a high density altitude are high elevations, low 2. Applying a correction factor to the indicated altitude atmospheric pressures, high temperatures, high humidity, or according to the reported altimeter setting some combination of these factors. Lower elevations, high atmospheric pressure, low temperatures, and low humidity Density Altitude are more indicative of low density altitude.

SDP is a theoretical pressure altitude, but aircraft operate in a nonstandard atmosphere and the term density altitude is used Effect of Pressure on Density for correlating aerodynamic performance in the nonstandard Since air is a gas, it can be compressed or expanded. When atmosphere. Density altitude is the vertical distance above sea air is compressed, a greater amount of air can occupy a given level in the standard atmosphere at which a given density is volume. Conversely, when pressure on a given volume of air to be found. The density of air has significant effects on the is decreased, the air expands and occupies a greater space.

aircraft’s performance because as air becomes less dense, At a lower pressure, the original column of air contains a it reduces: smaller mass of air. The density is decreased because density • Power because the engine takes in less air is directly proportional to pressure. If the pressure is doubled, the density is doubled; if the pressure is lowered, the density is • Thrust because a propeller is less efficient in thin air lowered. This statement is true only at a constant temperature.

• Lift because the thin air exerts less force on the airfoils Effect of Temperature on Density Density altitude is pressure altitude corrected for nonstandard Increasing the temperature of a substance decreases its temperature. As the density of the air increases (lower density. Conversely, decreasing the temperature increases density altitude), aircraft performance increases; conversely the density. Thus, the density of air varies inversely with as air density decreases (higher density altitude), aircraft temperature. This statement is true only at a constant pressure.

performance decreases. A decrease in air density means a high density altitude; an increase in air density means a In the atmosphere, both temperature and pressure decrease lower density altitude. Density altitude is used in calculating with altitude and have conflicting effects upon density.

aircraft performance because under standard atmospheric However, a fairly rapid drop in pressure as altitude increases conditions, air at each level in the atmosphere not only has usually has a dominating effect. Hence, pilots can expect the a specific density, its pressure altitude and density altitude density to decrease with altitude.

identify the same level.

4-4 Effect of Humidity (Moisture) on Density Theories in the Production of Lift The preceding paragraphs refer to air that is perfectly dry. In In order to achieve flight in a machine that is heavier than air, reality, it is never completely dry. The small amount of water there are several obstacles we must overcome. One of those vapor suspended in the atmosphere may be almost negligible obstacles, discussed previously, is the resistance to movement under certain conditions, but in other conditions humidity called drag. The most challenging obstacle to overcome in may become an important factor in the performance of an aviation, however, is the force of gravity. A wing moving aircraft. Water vapor is lighter than air; consequently, moist through air generates the force called lift, also previously air is lighter than dry air. Therefore, as the water content discussed. Lift from the wing that is greater than the force of of the air increases, the air becomes less dense, increasing gravity, directed opposite to the direction of gravity, enables density altitude and decreasing performance. It is lightest or an aircraft to fly. Generating this force called lift is based on least dense when, in a given set of conditions, it contains the some important principles, Newton's basic laws of motion, maximum amount of water vapor.

and Bernoulli's principle of differential pressure.

Humidity, also called relative humidity, refers to the amount Newton’s Basic Laws of Motion of water vapor contained in the atmosphere and is expressed The formulation of lift has historically been an adaptation as a percentage of the maximum amount of water vapor the over the past few centuries of basic physical laws. These air can hold. This amount varies with temperature. Warm air laws, although seemingly applicable to all aspects of lift, holds more water vapor, while cold air holds less. Perfectly do not explain how lift is formulated. In fact, one must dry air that contains no water vapor has a relative humidity consider the many airfoils that are symmetrical, yet produce of zero percent, while saturated air, which cannot hold any significant lift.

more water vapor, has a relative humidity of 100 percent.

Humidity alone is usually not considered an important factor The fundamental physical laws governing the forces acting in calculating density altitude and aircraft performance, but upon an aircraft in flight were adopted from postulated it is a contributing factor.

theories developed before any human successfully flew an aircraft. The use of these physical laws grew out of the As temperature increases, the air can hold greater amounts Scientific Revolution, which began in Europe in the 1600s.

of water vapor. When comparing two separate air masses, Driven by the belief the universe operated in a predictable the first warm and moist (both qualities tending to lighten manner open to human understanding, many philosophers, the air) and the second cold and dry (both qualities making mathematicians, natural scientists, and inventors spent their it heavier), the first must be less dense than the second.

lives unlocking the secrets of the universe. One of the most Pressure, temperature, and humidity have a great influence well-known was Sir Isaac Newton, who not only formulated on aircraft performance because of their effect upon density.

the law of universal gravitation, but also described the three There are no rules of thumb that can be easily applied, but basic laws of motion.

the affect of humidity can be determined using several online formulas. In the first example, the pressure is needed at the Newton’s First Law: “Every object persists in its state of rest altitude for which density altitude is being sought. Using or uniform motion in a straight line unless it is compelled to Figure 4-2, select the barometric pressure closest to the change that state by forces impressed on it.” associated altitude. As an example, the pressure at 8,000 feet is 22.22 "Hg. Using the National Oceanic and Atmospheric This means that nothing starts or stops moving until some Administration (NOAA) website (www.srh.noaa.gov/ outside force causes it to do so. An aircraft at rest on the ramp epz/?n=wxcalc_densityaltitude) for density altitude, enter remains at rest unless a force strong enough to overcome the 22.22 for 8,000 feet in the station pressure window. Enter its inertia is applied. Once it is moving, its inertia keeps a temperature of 80° and a dew point of 75°. The result is a it moving, subject to the various other forces acting on it.

density altitude of 11,564 feet. With no humidity, the density These forces may add to its motion, slow it down, or change altitude would be almost 500 feet lower.

its direction.

Another website ( www.wahiduddin.net/calc/density _ Newton’s Second Law: “Force is equal to the change in altitude.htm) provides a more straight forward method of momentum per change in time. For a constant mass, force determining the effects of humidity on density altitude equals mass times acceleration.” without using additional interpretive charts. In any case, the effects of humidity on density altitude include a decrease in overall performance in high humidity conditions.

4-5 When a body is acted upon by a constant force, its resulting Since air is recognized as a body, and it is understood that acceleration is inversely proportional to the mass of the body air will follow the above laws, one can begin to see how and is directly proportional to the applied force. This takes and why an airplane wing develops lift. As the wing moves into account the factors involved in overcoming Newton’s through the air, the flow of air across the curved top surface First Law. It covers both changes in direction and speed, increases in velocity creating a low-pressure area.

including starting up from rest (positive acceleration) and coming to a stop (negative acceleration or deceleration). Although Newton, Bernoulli, and hundreds of other early scientists who studied the physical laws of the universe did Newton’s Third Law: “For every action, there is an equal not have the sophisticated laboratories available today, they and opposite reaction.” provided great insight to the contemporary viewpoint of how lift is created.

In an airplane, the propeller moves and pushes back the Airfoil Design air; consequently, the air pushes the propeller (and thus the airplane) in the opposite direction—forward. In a jet airplane, An airfoil is a structure designed to obtain reaction upon its the engine pushes a blast of hot gases backward; the force of surface from the air through which it moves or that moves equal and opposite reaction pushes against the engine and past such a structure. Air acts in various ways when submitted forces the airplane forward.

to different pressures and velocities; but this discussion is confined to the parts of an aircraft that a pilot is most Bernoulli’s Principle of Differential Pressure concerned with in flight—namely, the airfoils designed to A half-century after Newton formulated his laws, Daniel produce lift. By looking at a typical airfoil profile, such as Bernoulli, a Swiss mathematician, explained how the pressure the cross section of a wing, one can see several obvious of a moving fluid (liquid or gas) varies with its speed of characteristics of design. [Figure 4-5] Notice that there is motion. Bernoulli’s Principle states that as the velocity of a a difference in the curvatures (called cambers) of the upper moving fluid (liquid or gas) increases, the pressure within and lower surfaces of the airfoil. The camber of the upper the fluid decreases. This principle explains what happens to surface is more pronounced than that of the lower surface, air passing over the curved top of the airplane wing.

which is usually somewhat flat.

A practical application of Bernoulli’s Principle is the venturi NOTE: The two extremities of the airfoil profile also differ in tube. The venturi tube has an air inlet that narrows to a appearance. The rounded end, which faces forward in flight, throat (constricted point) and an outlet section that increases is called the leading edge; the other end, the trailing edge, is in diameter toward the rear. The diameter of the outlet is quite narrow and tapered.

the same as that of the inlet. The mass of air entering the tube must exactly equal the mass exiting the tube. At the A reference line often used in discussing the airfoil is constriction, the speed must increase to allow the same the chord line, a straight line drawn through the profile amount of air to pass in the same amount of time as in all connecting the extremities of the leading and trailing edges.

other parts of the tube. When the air speeds up, the pressure The distance from this chord line to the upper and lower also decreases. Past the constriction, the airflow slows and surfaces of the wing denotes the magnitude of the upper and the pressure increases. [Figure 4-4] lower camber at any point. Another reference line, drawn 6 6 6 6 6 6 4 4 4 4 4 4 VELOCITY PRESSURE VELOCITY PRESSURE VELOCITY PRESSURE 2 2 2 2 2 2 8 8 8 8 8 8 0 I0 0 I0 0 I0 0 I0 0 I0 0 I0 Figure 4-4. Air pressure decreases in a venturi tube.

4-6 lift and is not suitable for high-speed flight. Advancements in engineering have made it possible for today’s high-speed Mean camber line Trailing edge jets to take advantage of the concave airfoil’s high lift r o f u p b e p e characteristics. Leading edge (Kreuger) flaps and trailing m r s a u C r f a c e edge (Fowler) flaps, when extended from the basic wing structure, literally change the airfoil shape into the classic e a c r f r s u C a l o w e m b e r o f concave form, thereby generating much greater lift during slow flight conditions.

Leading edge Chord line On the other hand, an airfoil that is perfectly streamlined and offers little wind resistance sometimes does not have Figure 4-5. Typical airfoil section.

enough lifting power to take the airplane off the ground.

Thus, modern airplanes have airfoils that strike a medium from the leading edge to the trailing edge, is the mean camber between extremes in design. The shape varies according to line. This mean line is equidistant at all points from the upper the needs of the airplane for which it is designed. Figure 4-6 and lower surfaces.

shows some of the more common airfoil designs.

An airfoil is constructed in such a way that its shape takes Low Pressure Above advantage of the air’s response to certain physical laws. This In a wind tunnel or in flight, an airfoil is simply a streamlined develops two actions from the air mass: a positive pressure object inserted into a moving stream of air. If the airfoil lifting action from the air mass below the wing, and a negative profile were in the shape of a teardrop, the speed and the pressure lifting action from lowered pressure above the wing.

pressure changes of the air passing over the top and bottom would be the same on both sides. But if the teardrop shaped As the air stream strikes the relatively flat lower surface of airfoil were cut in half lengthwise, a form resembling the a wing or rotor blade when inclined at a small angle to its basic airfoil (wing) section would result. If the airfoil were direction of motion, the air is forced to rebound downward, then inclined so the airflow strikes it at an angle, the air causing an upward reaction in positive lift. At the same time, moving over the upper surface would be forced to move the air stream striking the upper curved section of the leading faster than the air moving along the bottom of the airfoil.

edge is deflected upward. An airfoil is shaped to cause an This increased velocity reduces the pressure above the airfoil.

action on the air, and forces air downward, which provides an equal reaction from the air, forcing the airfoil upward. If Applying Bernoulli’s Principle of Pressure, the increase in a wing is constructed in such form that it causes a lift force the speed of the air across the top of an airfoil produces a greater than the weight of the aircraft, the aircraft will fly.

If all the lift required were obtained merely from the Early airfoil deflection of air by the lower surface of the wing, an aircraft would only need a flat wing like a kite. However, the balance of the lift needed to support the aircraft comes from the flow Later airfoil of air above the wing. Herein lies the key to flight.

It is neither accurate nor useful to assign specific values to the Clark 'Y' airfoil percentage of lift generated by the upper surface of an airfoil (Subsonic) versus that generated by the lower surface. These are not constant values. They vary, not only with flight conditions, Laminar flow airfoil but also with different wing designs.

(Subsonic) Different airfoils have different flight characteristics. Many Circular arc airfoil thousands of airfoils have been tested in wind tunnels and in (Supersonic) actual flight, but no one airfoil has been found that satisfies every flight requirement. The weight, speed, and purpose Double wedge airfoil of each aircraft dictate the shape of its airfoil. The most (Supersonic) efficient airfoil for producing the greatest lift is one that has a concave or “scooped out” lower surface. As a fixed design, Figure 4-6. Airfoil designs.

this type of airfoil sacrifices too much speed while producing 4-7 drop in pressure. This lowered pressure is a component of Low angle of attack total lift. The pressure difference between the upper and lower surface of a wing alone does not account for the total lift force produced.

The downward backward flow from the top surface of an CP airfoil creates a downwash. This downwash meets the flow from the bottom of the airfoil at the trailing edge. Applying Newton’s third law, the reaction of this downward backward k e l ° c f a g 8 t flow results in an upward forward force on the airfoil. n - t o a A High Pressure Below A certain amount of lift is generated by pressure conditions underneath the airfoil. Because of the manner in which air flows underneath the airfoil, a positive pressure results, Normal angle of attack particularly at higher angles of attack. However, there is another aspect to this airflow that must be considered. At a point close to the leading edge, the airflow is virtually stopped (stagnation point) and then gradually increases speed. At some point near the trailing edge, it again reaches a velocity CP equal to that on the upper surface. In conformance with Bernoulli’s principle, where the airflow was slowed beneath e the airfoil, a positive upward pressure was created (i.e., as k l c ° f g a 4 t o n t the fluid speed decreases, the pressure must increase). Since + a A the pressure differential between the upper and lower surface of the airfoil increases, total lift increases. Both Bernoulli’s Principle and Newton’s Laws are in operation whenever lift is being generated by an airfoil.

High angle of attack Pressure Distribution From experiments conducted on wind tunnel models and on full size airplanes, it has been determined that as air flows CP along the surface of a wing at different angles of attack (AOA), there are regions along the surface where the pressure is negative, or less than atmospheric, and regions where the f pressure is positive, or greater than atmospheric. This negative o k c e ° l pressure on the upper surface creates a relatively larger force a 0 t g t n a + on the wing than is caused by the positive pressure resulting A from the air striking the lower wing surface. Figure 4-7 shows the pressure distribution along an airfoil at three different angles of attack. The average of the pressure variation for any given AOA is referred to as the center of pressure (CP).

Aerodynamic force acts through this CP. At high angles of Figure 2-8. Pressure distribution on an airfoil & CP changes Figure 4-7. Pressure distribution on an airfoil and CP changes with an angle of attack.

attack, the CP moves forward, while at low angles of attack with AOA.

the CP moves aft. In the design of wing structures, this CP travel is very important, since it affects the position of the lift is a complex subject. The production of lift is much more air loads imposed on the wing structure in both low and high complex than a simple differential pressure between upper AOA conditions. An airplane’s aerodynamic balance and and lower airfoil surfaces. In fact, many lifting airfoils do controllability are governed by changes in the CP.

not have an upper surface longer than the bottom, as in the case of symmetrical airfoils. These are seen in high-speed Airfoil Behavior aircraft having symmetrical wings, or on symmetrical rotor Although specific examples can be cited in which each of blades for many helicopters whose upper and lower surfaces the principles predict and contribute to the formation of lift, 4-8 are identical. In both examples, the only difference is the relationship of the airfoil with the oncoming airstream (angle). A paper airplane, which is simply a flat plate, has a bottom and top exactly the same shape and length. Yet, these airfoils do produce lift, and “flow turning” is partly (or fully) responsible for creating lift.

As an airfoil moves through air, the airfoil is inclined Tip against the airflow, producing a different flow caused by the v o airfoil’s relationship to the oncoming air. Think of a hand r t e x being placed outside the car window at a high speed. If the hand is inclined in one direction or another, the hand will move upward or downward. This is caused by deflection, which in turn causes the air to turn about the object within the air stream. As a result of this change, the velocity about the object changes in both magnitude and direction, in turn Figure 4-8. Tip vortex.

resulting in a measurable velocity force and direction.

Chapter Summary A Third Dimension Modern general aviation aircraft have what may be considered To this point, the discussion has centered on the flow across high performance characteristics. Therefore, it is increasingly the upper and lower surfaces of an airfoil. While most of the necessary that pilots appreciate and understand the principles lift is produced by these two dimensions, a third dimension, upon which the art of flying is based. For additional the tip of the airfoil also has an aerodynamic effect. The high- information on the principles discussed in this chapter, visit pressure area on the bottom of an airfoil pushes around the tip the National Aeronautics and Space Administration (NASA) to the low-pressure area on the top. [Figure 4-8] This action Beginner’s Guide to Aerodynamics at www.grc.nasa.gov/ creates a rotating flow called a tip vortex. The vortex flows www/k-12/airplane/bga.html.

behind the airfoil creating a downwash that extends back to the trailing edge of the airfoil. This downwash results in an overall reduction in lift for the affected portion of the airfoil.

Manufacturers have developed different methods to counteract this action. Winglets can be added to the tip of an airfoil to reduce this flow. The winglets act as a dam preventing the vortex from forming. Winglets can be on the top or bottom of the airfoil. Another method of countering the flow is to taper the airfoil tip, reducing the pressure differential and smoothing the airflow around the tip.

4-9 4-10

Chapter 5

Aerodynamics

of Flight

Forces Acting on the Aircraft Thrust, drag, lift, and weight are forces that act upon all aircraft in flight. Understanding how these forces work and knowing how to control them with the use of power and flight controls are essential to flight. This chapter discusses the aerodynamics of flight—how design, weight, load factors, and gravity affect an aircraft during flight maneuvers.

The four forces acting on an aircraft in straight-and-level, unaccelerated flight are thrust, drag, lift, and weight. They are defined as follows: • Thrust—the forward force produced by the powerplant/ propeller or rotor. It opposes or overcomes the force of drag. As a general rule, it acts parallel to the longitudinal axis. However, this is not always the case, as explained later.

• Drag—a rearward, retarding force caused by disruption of airflow by the wing, rotor, fuselage, and other protruding objects. As a general rule, drag opposes thrust and acts rearward parallel to the relative wind.

• Lift—is a force that is produced by the dynamic effect of the air acting on the airfoil, and acts perpendicular to the flight path through the center of lift (CL) and perpendicular to the lateral axis. In level flight, lift opposes the downward force of weight.

5-1 • Weight—the combined load of the aircraft itself, the thrust has an upward component. But because the aircraft is in crew, the fuel, and the cargo or baggage. Weight is level flight, weight does not contribute to drag. [Figure 5-2] a force that pulls the aircraft downward because of the force of gravity. It opposes lift and acts vertically In glides, a portion of the weight vector is directed along downward through the aircraft’s center of gravity (CG). the forward flight path and, therefore, acts as thrust. In other words, any time the flight path of the aircraft is not horizontal, In steady flight, the sum of these opposing forces is always lift, weight, thrust, and drag vectors must each be broken down zero. There can be no unbalanced forces in steady, straight into two components.

flight based upon Newton’s Third Law, which states that for every action or force there is an equal, but opposite, reaction Another important concept to understand is angle of attack or force. This is true whether flying level or when climbing (AOA). Since the early days of flight, AOA is fundamental to or descending. understanding many aspects of airplane performance, stability, and control. The AOA is defined as the acute angle between the It does not mean the four forces are equal. It means the chord line of the airfoil and the direction of the relative wind.

opposing forces are equal to, and thereby cancel, the effects of each other. In Figure 5-1, the force vectors of thrust, drag, lift, Discussions of the preceding concepts are frequently omitted and weight appear to be equal in value. The usual explanation in aeronautical texts/handbooks/manuals. The reason is states (without stipulating that thrust and drag do not equal not that they are inconsequential, but because the main weight and lift) that thrust equals drag and lift equals weight. ideas with respect to the aerodynamic forces acting upon Although true, this statement can be misleading. It should be an aircraft in flight can be presented in their most essential understood that in straight, level, unaccelerated flight, it is elements without being involved in the technicalities of the true that the opposing lift/weight forces are equal. They are aerodynamicist. In point of fact, considering only level flight, also greater than the opposing forces of thrust/drag that are and normal climbs and glides in a steady state, it is still true equal only to each other. Therefore, in steady flight: that lift provided by the wing or rotor is the primary upward force, and weight is the primary downward force.

• The sum of all upward components of forces (not just lift) equals the sum of all downward components of By using the aerodynamic forces of thrust, drag, lift, and forces (not just weight) weight, pilots can fly a controlled, safe flight. A more detailed • The sum of all forward components of forces (not just discussion of these forces follows.

thrust) equals the sum of all backward components of forces (not just drag) Thrust For an aircraft to start moving, thrust must be exerted and be This refinement of the old “thrust equals drag; lift equals greater than drag. The aircraft continues to move and gain weight” formula explains that a portion of thrust is directed speed until thrust and drag are equal. In order to maintain a upward in climbs and slow flight and acts as if it were lift while a portion of weight is directed backward opposite to the Flight path direction of flight and acts as if it were drag. In slow flight, Relative wind Lift CL Thrust Lift CG Drag Drag Thrust Component of weight opposed to lift Weight Rearward component of weight Figure 5-1. Relationship of forces acting on an aircraft.

Figure 5-2. Force vectors during a stabilized climb.

5-2 constant airspeed, thrust and drag must remain equal, just as In level flight, when thrust is increased, the aircraft speeds lift and weight must be equal to maintain a constant altitude. up and the lift increases. The aircraft will start to climb If in level flight, the engine power is reduced, the thrust is unless the AOA is decreased just enough to maintain the lessened, and the aircraft slows down. As long as the thrust relationship between lift and weight. The timing of this is less than the drag, the aircraft continues to decelerate. To decrease in AOA needs to be coordinated with the increase a point, as the aircraft slows down, the drag force will also in thrust and airspeed. Otherwise, if the AOA is decreased too decrease. The aircraft will continue to slow down until thrust fast, the aircraft will descend, and if the AOA is decreased again equals drag at which point the airspeed will stabilize. too slowly, the aircraft will climb.

Likewise, if the engine power is increased, thrust becomes As the airspeed varies due to thrust, the AOA must also vary greater than drag and the airspeed increases. As long as to maintain level flight. At very high speeds and level flight, the thrust continues to be greater than the drag, the aircraft it is even possible to have a slightly negative AOA. As thrust continues to accelerate. When drag equals thrust, the aircraft is reduced and airspeed decreases, the AOA must increase flies at a constant airspeed. in order to maintain altitude. If speed decreases enough, the required AOA will increase to the critical AOA. Any further Straight-and-level flight may be sustained at a wide range increase in the AOA will result in the wing stalling. Therefore, of speeds. The pilot coordinates AOA and thrust in all extra vigilance is required at reduced thrust settings and low speed regimes if the aircraft is to be held in level flight. An speeds so as not to exceed the critical angle of attack. If the important fact related to the principal of lift (for a given airplane is equipped with an AOA indicator, it should be airfoil shape) is that lift varies with the AOA and airspeed. referenced to help monitor the proximity to the critical AOA.

Therefore, a large AOA at low airspeeds produces an equal amount of lift at high airspeeds with a low AOA. The speed Some aircraft have the ability to change the direction of the regimes of flight can be grouped in three categories: low- thrust rather than changing the AOA. This is accomplished speed flight, cruising flight, and high-speed flight. either by pivoting the engines or by vectoring the exhaust gases. [Figure 5-4] When the airspeed is low, the AOA must be relatively high Lift if the balance between lift and weight is to be maintained.

[Figure 5-3] If thrust decreases and airspeed decreases, lift The pilot can control the lift. Any time the control yoke will become less than weight and the aircraft will start to or stick is moved fore or aft, the AOA is changed. As the descend. To maintain level flight, the pilot can increase the AOA increases, lift increases (all other factors being equal).

AOA an amount that generates a lift force again equal to the When the aircraft reaches the maximum AOA, lift begins weight of the aircraft. While the aircraft will be flying more to diminish rapidly. This is the stalling AOA, known as slowly, it will still maintain level flight. The AOA is adjusted C critical AOA. Examine Figure 5-5, noting how the L-MAX to maintain lift equal weight. The airspeed will naturally C increases until the critical AOA is reached, then decreases L adjust until drag equals thrust and then maintain that airspeed rapidly with any further increase in the AOA.

(assumes the pilot is not trying to hold an exact speed).

Before proceeding further with the topic of lift and how it Straight-and-level flight in the slow-speed regime provides can be controlled, velocity must be discussed. The shape of some interesting conditions relative to the equilibrium of the wing or rotor cannot be effective unless it continually forces. With the aircraft in a nose-high attitude, there is a keeps “attacking” new air. If an aircraft is to keep flying, the vertical component of thrust that helps support it. For one lift-producing airfoil must keep moving. In a helicopter or thing, wing loading tends to be less than would be expected.

gyroplane, this is accomplished by the rotation of the rotor blades. For other types of aircraft, such as airplanes, weight- Level high speed Level cruise speed Level low speed Level high speed Level cruise speed Level low speed ° ° ° 6 Flight path Flight path Flight path Relative wind Relative wind Relative wind Figure 5-3. Angle of attack at various speeds.

5-3 Figure 5-4. Some aircraft have the ability to change the direction of thrust.

shift control, or gliders, air must be moving across the lifting Taking the equation further, one can see an aircraft could surface. This is accomplished by the forward speed of the not continue to travel in level flight at a constant altitude and aircraft. Lift is proportional to the square of the aircraft’s maintain the same AOA if the velocity is increased. The lift velocity. For example, an airplane traveling at 200 knots has would increase and the aircraft would climb as a result of four times the lift as the same airplane traveling at 100 knots, the increased lift force or speed up. Therefore, to keep the if the AOA and other factors remain constant. aircraft straight and level (not accelerating upward) and in a state of equilibrium, as velocity is increased, lift must be kept . . 2 .

C ρ V S constant. This is normally accomplished by reducing the AOA L L = 2 by lowering the nose. Conversely, as the aircraft is slowed, the decreasing velocity requires increasing the AOA to maintain The above lift equation exemplifies this mathematically lift sufficient to maintain flight. There is, of course, a limit to and supports that doubling of the airspeed will result in four how far the AOA can be increased, if a stall is to be avoided.

times the lift. As a result, one can see that velocity is an important component to the production of lift, which itself All other factors being constant, for every AOA there is can be affected through varying AOA. When examining the a corresponding airspeed required to maintain altitude in equation, lift (L) is determined through the relationship of the steady, unaccelerated flight (true only if maintaining level air density ( ρ ), the airfoil velocity (V), the surface area of the flight). Since an airfoil always stalls at the same AOA, if wing (S) and the coefficient of lift (C ) for a given airfoil. increasing weight, lift must also be increased. The only L CL .2000 C 18 1.8 .1800 L MAX 16 1.6 .1600 ) D L/ D MAX 1.4 14 .1400 1.2 .1200 C L 10 1.0 .1000 Lift/drag L/ 8 0.8 .0800 D Coefficient of drag (C 0.6 6 .0600 C D 0.4 4 .0400 Stall 2 .0200 0.2 0 0 0° 2° 4° 6° 8° 10° 12° 14° 16° 18° 20° 22° Angle of attack Figure 5-5. Coefficients of lift and drag at various angles of attack.

5-4 method of increasing lift is by increasing velocity if the AOA flow around the body, and a reference area associated with is held constant just short of the “critical,” or stalling, AOA the body. The coefficient of drag is also dimensionless and is (assuming no flaps or other high lift devices). used to quantify the drag of an object in a fluid environment, such as air, and is always associated with a particular surface Lift and drag also vary directly with the density of the air. area.

Density is affected by several factors: pressure, temperature, and humidity. At an altitude of 18,000 feet, the density of The L/D ratio is determined by dividing the C by the C , L D the air has one-half the density of air at sea level. In order to which is the same as dividing the lift equation by the drag maintain its lift at a higher altitude, an aircraft must fly at a equation as all of the variables, aside from the coefficients, greater true airspeed for any given AOA. cancel out. The lift and drag equations are as follows (L = Lift in pounds; D = Drag; C = coefficient of lift; ρ = density L Warm air is less dense than cool air, and moist air is less (expressed in slugs per cubic feet); V = velocity (in feet per 1 2 dense than dry air. Thus, on a hot humid day, an aircraft second); q = dynamic pressure per square foot (q = ⁄ 2 ρ v ); must be flown at a greater true airspeed for any given AOA S = the area of the lifting body (in square feet); and than on a cool, dry day. C = Ratio of drag pressure to dynamic pressure): D . . 2 .

If the density factor is decreased and the total lift must equal C ρ V S D D = the total weight to remain in flight, it follows that one of the 2 other factors must be increased. The factor usually increased is the airspeed or the AOA because these are controlled Typically at low AOA, the coefficient of drag is low and directly by the pilot. small changes in AOA create only slight changes in the coefficient of drag. At high AOA, small changes in the AOA Lift varies directly with the wing area, provided there is no cause significant changes in drag. The shape of an airfoil, as change in the wing’s planform. If the wings have the same well as changes in the AOA, affects the production of lift.

proportion and airfoil sections, a wing with a planform area of 200 square feet lifts twice as much at the same AOA as a Notice in Figure 5-5 that the coefficient of lift curve (red) wing with an area of 100 square feet. reaches its maximum for this particular wing section at 20° AOA and then rapidly decreases. 20° AOA is therefore the Two major aerodynamic factors from the pilot’s viewpoint critical angle of attack. The coefficient of drag curve (orange) are lift and airspeed because they can be controlled readily increases very rapidly from 14° AOA and completely and accurately. Of course, the pilot can also control density by overcomes the lift curve at 21° AOA. The lift/drag ratio adjusting the altitude and can control wing area if the aircraft (green) reaches its maximum at 6° AOA, meaning that at this happens to have flaps of the type that enlarge wing area. angle, the most lift is obtained for the least amount of drag.

However, for most situations, the pilot controls lift and airspeed to maneuver an aircraft. For instance, in straight-and-level flight, Note that the maximum lift/drag ratio (L/D ) occurs at MAX cruising along at a constant altitude, altitude is maintained by one specific C and AOA. If the aircraft is operated in steady L adjusting lift to match the aircraft’s velocity or cruise airspeed, flight at L/D , the total drag is at a minimum. Any AOA MAX while maintaining a state of equilibrium in which lift equals lower or higher than that for L/D reduces the L/D and MAX weight. In an approach to landing, when the pilot wishes to consequently increases the total drag for a given aircraft’s land as slowly as practical, it is necessary to increase AOA near maximum to maintain lift equal to the weight of the aircraft.

Lift/Drag Ratio g The lift-to-drag ratio (L/D) is the amount of lift generated by a r d a wing or airfoil compared to its drag. A ratio of L/D indicates e Drag t i airfoil efficiency. Aircraft with higher L/D ratios are more s Total drag a r efficient than those with lower L/D ratios. In unaccelerated a p flight with the lift and drag data steady, the proportions of Minimum I n d the coefficient of lift (C ) and coefficient of drag (C ) can u drag c L D e d d r a g be calculated for specific AOA. [Figure 5-5] Airspeed The coefficient of lift is dimensionless and relates the lift Figure 5-6. Drag versus speed.

generated by a lifting body, the dynamic pressure of the fluid 5-5 lift. Figure 5-6 depicts the L/D by the lowest portion of drag is the easiest to reduce when designing an aircraft. The MAX the blue line labeled “total drag.” The configuration of an solution is to streamline as many of the parts as possible.

aircraft has a great effect on the L/D.

Interference Drag Drag Interference drag comes from the intersection of airstreams Drag is the force that resists movement of an aircraft through that creates eddy currents, turbulence, or restricts smooth the air. There are two basic types: parasite drag and induced airflow. For example, the intersection of the wing and the drag. The first is called parasite because it in no way functions fuselage at the wing root has significant interference drag.

to aid flight, while the second, induced drag, is a result of an Air flowing around the fuselage collides with air flowing over airfoil developing lift.

the wing, merging into a current of air different from the two original currents. The most interference drag is observed when Parasite Drag two surfaces meet at perpendicular angles. Fairings are used to reduce this tendency. If a jet fighter carries two identical Parasite drag is comprised of all the forces that work to slow wing tanks, the overall drag is greater than the sum of the an aircraft’s movement. As the term parasite implies, it is the individual tanks because both of these create and generate drag that is not associated with the production of lift. This interference drag. Fairings and distance between lifting includes the displacement of the air by the aircraft, turbulence surfaces and external components (such as radar antennas generated in the airstream, or a hindrance of air moving over hung from wings) reduce interference drag. [Figure 5-8] the surface of the aircraft and airfoil. There are three types of parasite drag: form drag, interference drag, and skin friction.

Skin Friction Drag Form Drag Skin friction drag is the aerodynamic resistance due to the contact of moving air with the surface of an aircraft. Every Form drag is the portion of parasite drag generated by the surface, no matter how apparently smooth, has a rough, aircraft due to its shape and airflow around it. Examples include ragged surface when viewed under a microscope. The air the engine cowlings, antennas, and the aerodynamic shape of molecules, which come in direct contact with the surface of other components. When the air has to separate to move around the wing, are virtually motionless. Each layer of molecules a moving aircraft and its components, it eventually rejoins above the surface moves slightly faster until the molecules after passing the body. How quickly and smoothly it rejoins is are moving at the velocity of the air moving around the representative of the resistance that it creates, which requires aircraft. This speed is called the free-stream velocity. The area additional force to overcome. [Figure 5-7] between the wing and the free-stream velocity level is about as wide as a playing card and is called the boundary layer. At the Notice how the flat plate in Figure 5-7 causes the air to swirl top of the boundary layer, the molecules increase velocity and around the edges until it eventually rejoins downstream. Form move at the same speed as the molecules outside the boundary layer. The actual speed at which the molecules move depends upon the shape of the wing, the viscosity (stickiness) of FLAT PLATE the air through which the wing or airfoil is moving, and its compressibility (how much it can be compacted).

SPHERE SPHERE WITH A FAIRING SPHERE INSIDE A HOUSING Figure 5-8. A wing root can cause interference drag.

Figure 5-7. Form drag.

5-6 The airflow outside of the boundary layer reacts to the shape of the edge of the boundary layer just as it would to the physical surface of an object. The boundary layer gives any object an “effective” shape that is usually slightly different from the physical shape. The boundary layer may also separate from the body, thus creating an effective shape much different from the physical shape of the object. This change in the physical shape of the boundary layer causes a dramatic decrease in lift and an increase in drag. When this happens, the airfoil has stalled.

In order to reduce the effect of skin friction drag, aircraft designers utilize flush mount rivets and remove any irregularities that may protrude above the wing surface. In addition, a smooth and glossy finish aids in transition of air across the surface of the wing. Since dirt on an aircraft Figure 5-9. Wingtip vortex from a crop duster.

disrupts the free flow of air and increases drag, keep the surfaces of an aircraft clean and waxed.

altitude versus near the ground. Bearing in mind the direction of rotation of these vortices, it can be seen that they induce Induced Drag an upward flow of air beyond the tip and a downwash flow The second basic type of drag is induced drag. It is an behind the wing’s trailing edge. This induced downwash has established physical fact that no system that does work in the nothing in common with the downwash that is necessary to mechanical sense can be 100 percent efficient. This means produce lift. It is, in fact, the source of induced drag.

that whatever the nature of the system, the required work is obtained at the expense of certain additional work that is Downwash points the relative wind downward, so the more dissipated or lost in the system. The more efficient the system, downwash you have, the more your relative wind points the smaller this loss.

downward. That's important for one very good reason: lift is always perpendicular to the relative wind. In Figure 5-11, you In level flight, the aerodynamic properties of a wing or rotor can see that when you have less downwash, your lift vector produce a required lift, but this can be obtained only at the is more vertical, opposing gravity. And when you have more expense of a certain penalty. The name given to this penalty downwash, your lift vector points back more, causing induced is induced drag. Induced drag is inherent whenever an airfoil drag. On top of that, it takes energy for your wings to create is producing lift and, in fact, this type of drag is inseparable downwash and vortices, and that energy creates drag.

from the production of lift. Consequently, it is always present if lift is produced.

An airfoil (wing or rotor blade) produces the lift force by making use of the energy of the free airstream. Whenever an airfoil is producing lift, the pressure on the lower surface of it is greater than that on the upper surface (Bernoulli’s Principle). As a result, the air tends to flow from the high pressure area below the tip upward to the low pressure area on the upper surface. In the vicinity of the tips, there is a tendency for these pressures to equalize, resulting in a lateral flow outward from the underside to the upper surface. This lateral flow imparts a rotational velocity to the air at the tips, creating vortices that trail behind the airfoil.

When the aircraft is viewed from the tail, these vortices circulate counterclockwise about the right tip and clockwise about the left tip. [Figure 5-9] As the air (and vortices) roll off Figure 5-10. The difference in wingtip vortex size at altitude versus the back of your wing, they angle down, which is known as near the ground.

downwash. Figure 5-10 shows the difference in downwash at 5-7 Weight Gravity is the pulling force that tends to draw all bodies to the center of the earth. The CG may be considered as a point at which all the weight of the aircraft is concentrated. If the aircraft were supported at its exact CG, it would balance in any attitude. It will be noted that CG is of major importance in an aircraft, for its position has a great bearing upon stability.

The allowable location of the CG is determined by the general design of each particular aircraft. The designers determine how far the center of pressure (CP) will travel. It is important to understand that an aircraft’s weight is concentrated at the CG and the aerodynamic forces of lift occur at the CP. When the CG is forward of the CP, there is a natural tendency for the aircraft to want to pitch nose down. If the CP is forward of the CG, a nose up pitching moment is created. Therefore, designers fix the aft limit of the CG forward of the CP for the corresponding flight speed in order to retain flight equilibrium.

Weight has a definite relationship to lift. This relationship is simple, but important in understanding the aerodynamics Figure 5-11. The difference in downwash at altitude versus near of flying. Lift is the upward force on the wing acting the ground.

perpendicular to the relative wind and perpendicular to the aircraft’s lateral axis. Lift is required to counteract the The greater the size and strength of the vortices and aircraft’s weight. In stabilized level flight, when the lift force is consequent downwash component on the net airflow over equal to the weight force, the aircraft is in a state of equilibrium the airfoil, the greater the induced drag effect becomes. This and neither accelerates upward or downward. If lift becomes downwash over the top of the airfoil at the tip has the same less than weight, the vertical speed will decrease. When lift is effect as bending the lift vector rearward; therefore, the lift greater than weight, the vertical speed will increase.

is slightly aft of perpendicular to the relative wind, creating a rearward lift component. This is induced drag.

Wingtip Vortices Formation of Vortices In order to create a greater negative pressure on the top of an The action of the airfoil that gives an aircraft lift also causes airfoil, the airfoil can be inclined to a higher AOA. If the AOA induced drag. When an airfoil is flown at a positive AOA, of a symmetrical airfoil were zero, there would be no pressure a pressure differential exists between the upper and lower differential, and consequently, no downwash component and surfaces of the airfoil. The pressure above the wing is less no induced drag. In any case, as AOA increases, induced than atmospheric pressure and the pressure below the wing drag increases proportionally. To state this another way—the is equal to or greater than atmospheric pressure. Since air lower the airspeed, the greater the AOA required to produce always moves from high pressure toward low pressure, lift equal to the aircraft’s weight and, therefore, the greater and the path of least resistance is toward the airfoil’s tips, induced drag. The amount of induced drag varies inversely there is a spanwise movement of air from the bottom of the with the square of the airspeed.

airfoil outward from the fuselage around the tips. This flow of air results in “spillage” over the tips, thereby setting up a Conversely, parasite drag increases as the square of the whirlpool of air called a vortex. [Figure 5-12] airspeed. Thus, in steady state, as airspeed decreases to near the stalling speed, the total drag becomes greater, due At the same time, the air on the upper surface has a tendency mainly to the sharp rise in induced drag. Similarly, as the to flow in toward the fuselage and off the trailing edge. This aircraft reaches its never-exceed speed (V ), the total drag NE air current forms a similar vortex at the inboard portion of the increases rapidly due to the sharp increase of parasite drag.

trailing edge of the airfoil, but because the fuselage limits the As seen in Figure 5-6, at some given airspeed, total drag is inward flow, the vortex is insignificant. Consequently, the at its minimum amount. In figuring the maximum range of deviation in flow direction is greatest at the outer tips where aircraft, the thrust required to overcome drag is at a minimum the unrestricted lateral flow is the strongest.

if drag is at a minimum. The minimum power and maximum endurance occur at a different point.

5-8 vortices lead to a particularly dangerous hazard to flight, wake turbulence.

Avoiding Wake Turbulence Wingtip vortices are greatest when the generating aircraft is “heavy, clean, and slow.” This condition is most commonly encountered during approaches or departures because an aircraft’s AOA is at the highest to produce the lift necessary to land or take off. To minimize the chances of flying through an aircraft’s wake turbulence:

Vortex

• Avoid flying through another aircraft’s flight path.

• Rotate prior to the point at which the preceding aircraft rotated when taking off behind another aircraft.

• Avoid following another aircraft on a similar flight path at an altitude within 1,000 feet. [Figure 5-13] • Approach the runway above a preceding aircraft’s Figure 5-12. Wingtip vortices.

path when landing behind another aircraft and touch down after the point at which the other aircraft wheels As the air curls upward around the tip, it combines with the contacted the runway. [Figure 5-14] downwash to form a fast-spinning trailing vortex. These vortices increase drag because of energy spent in producing A hovering helicopter generates a down wash from its main the turbulence. Whenever an airfoil is producing lift, induced rotor(s) similar to the vortices of an airplane. Pilots of small drag occurs and wingtip vortices are created.

aircraft should avoid a hovering helicopter by at least three rotor disc diameters to avoid the effects of this down wash. In Just as lift increases with an increase in AOA, induced forward flight, this energy is transformed into a pair of strong, drag also increases. This occurs because as the AOA is high-speed trailing vortices similar to wing-tip vortices of larger increased, there is a greater pressure difference between the fixed-wing aircraft. Helicopter vortices should be avoided top and bottom of the airfoil, and a greater lateral flow of air; because helicopter forward flight airspeeds are often very consequently, this causes more violent vortices to be set up, slow and can generate exceptionally strong wake turbulence.

resulting in more turbulence and more induced drag.

Wind is an important factor in avoiding wake turbulence In Figure 5-12, it is easy to see the formation of wingtip because wingtip vortices drift with the wind at the speed of the vortices. The intensity or strength of the vortices is directly wind. For example, a wind speed of 10 knots causes the vortices proportional to the weight of the aircraft and inversely to drift at about 1,000 feet in a minute in the wind direction.

proportional to the wingspan and speed of the aircraft. The When following another aircraft, a pilot should consider wind heavier and slower the aircraft, the greater the AOA and the speed and direction when selecting an intended takeoff or stronger the wingtip vortices. Thus, an aircraft will create landing point. If a pilot is unsure of the other aircraft’s takeoff wingtip vortices with maximum strength occurring during or landing point, approximately 3 minutes provides a margin of the takeoff, climb, and landing phases of flight. These Nominally 500–1,000 ft AVOID Sink rate several hundred ft/min Figure 5-13. Avoid following another aircraft at an altitude within 1,000 feet.

5-9 Wake ends Wake begins Touchdown Rotation Figure 5-14. Avoid turbulence from another aircraft.

3K 3K No Wind Vortex Movement Near Ground - No Wind 3K Wind 6K 0 (3K - 3K) (3K + 3K) Vortex Movement Near Ground - with Cross Winds Figure 5-15. When the vortices of larger aircraft sink close to the ground (within 100 to 200 feet), they tend to move laterally over the ground at a speed of 2 or 3 knots (top). A crosswind will decrease the lateral movement of the upwind vortex and increase the movement of the downwind vortex. Thus a light wind with a cross runway component of 1 to 5 knots could result in the upwind vortex remaining in the touchdown zone for a period of time and hasten the drift of the downwind vortex toward another runway (bottom).

5-10 safety that allows wake turbulence dissipation. [Figure 5-15] For more information on wake turbulence, see Advisory Circular (AC) 90-23, Aircraft Wake Turbulence.

Ground Effect Ever since the beginning of manned flight, pilots realized that just before touchdown it would suddenly feel like the aircraft did not want to go lower, and it would just want to go Figure 5-16. Ground effect changes airflow.

on and on. This is due to the air that is trapped between the wing and the landing surface, as if there were an air cushion.

the spanwise lift distribution and reduces the induced AOA This phenomenon is called ground effect.

and induced drag. Therefore, the wing will require a lower AOA in ground effect to produce the same C . If a constant L When an aircraft in flight comes within several feet of the AOA is maintained, an increase in C results. [Figure 5-17] L surface, ground or water, a change occurs in the three- dimensional flow pattern around the aircraft because the Ground effect also alters the thrust required versus velocity.

vertical component of the airflow around the wing is Since induced drag predominates at low speeds, the reduction restricted by the surface. This alters the wing’s upwash, of induced drag due to ground effect will cause a significant downwash, and wingtip vortices. [Figure 5-16] Ground reduction of thrust required (parasite plus induced drag) at low effect, then, is due to the interference of the ground (or water) speeds. Due to the change in upwash, downwash, and wingtip surface with the airflow patterns about the aircraft in flight.

vortices, there may be a change in position (installation) error While the aerodynamic characteristics of the tail surfaces of the airspeed system associated with ground effect. In the and the fuselage are altered by ground effect, the principal majority of cases, ground effect causes an increase in the local effects due to proximity of the ground are the changes in pressure at the static source and produces a lower indication the aerodynamic characteristics of the wing. As the wing of airspeed and altitude. Thus, an aircraft may be airborne at encounters ground effect and is maintained at a constant an indicated airspeed less than that normally required.

AOA, there is consequent reduction in the upwash, downwash, and wingtip vortices.

In order for ground effect to be of significant magnitude, the wing must be quite close to the ground. One of the direct Induced drag is a result of the airfoil’s work of sustaining results of ground effect is the variation of induced drag with the aircraft, and a wing or rotor lifts the aircraft simply by wing height above the ground at a constant C . When the L accelerating a mass of air downward. It is true that reduced wing is at a height equal to its span, the reduction in induced pressure on top of an airfoil is essential to lift, but that is drag is only 1.4 percent. However, when the wing is at a only one of the things contributing to the overall effect of height equal to one-fourth its span, the reduction in induced pushing an air mass downward. The more downwash there drag is 23.5 percent and, when the wing is at a height equal is, the harder the wing pushes the mass of air down. At high to one-tenth its span, the reduction in induced drag is 47.6 angles of attack, the amount of induced drag is high; since this percent. Thus, a large reduction in induced drag takes place corresponds to lower airspeeds in actual flight, it can be said only when the wing is very close to the ground. Because of that induced drag predominates at low speed. However, the this variation, ground effect is most usually recognized during reduction of the wingtip vortices due to ground effect alters the liftoff for takeoff or just prior to touchdown when landing.

In ground effect L Out of ground effect Out of ground effect Thrust required Lift coefficient C In ground effect Velocity Angle of attack Figure 5-17. Ground effect changes drag and lift.

5-11 During the takeoff phase of flight, ground effect produces establishing a positive rate of climb and only after achieving some important relationships. An aircraft leaving ground a safe altitude.

effect after takeoff encounters just the reverse of an aircraft entering ground effect during landing. The aircraft leaving If, during the landing phase of flight, the aircraft is brought ground effect will: into ground effect with a constant AOA, the aircraft experiences an increase in C and a reduction in the thrust L • Require an increase in AOA to maintain the same C L required, and a “floating” effect may occur. Because of the • Experience an increase in induced drag and thrust reduced drag and lack of power-off deceleration in ground required effect, any excess speed at the point of flare may incur a considerable “float” distance. As the aircraft nears the point • Experience a decrease in stability and a nose-up of touchdown, ground effect is most realized at altitudes less change in moment than the wingspan. During the final phases of the approach • Experience a reduction in static source pressure and as the aircraft nears the ground, a reduction of power is increase in indicated airspeed necessary to offset the increase in lift caused from ground effect otherwise the aircraft will have a tendency to climb Ground effect must be considered during takeoffs and landings.

above the desired glidepath (GP).

For example, if a pilot fails to understand the relationship between the aircraft and ground effect during takeoff, a Axes of an Aircraft hazardous situation is possible because the recommended The axes of an aircraft are three imaginary lines that pass takeoff speed may not be achieved. Due to the reduced drag through an aircraft’s CG. The axes can be considered as in ground effect, the aircraft may seem capable of takeoff well imaginary axles around which the aircraft turns. The three below the recommended speed. As the aircraft rises out of axes pass through the CG at 90° angles to each other. The ground effect with a deficiency of speed, the greater induced axis passes through the CG and parallel to a line from nose drag may result in marginal initial climb performance. In to tail is the longitudinal axis, the axis that passes parallel extreme conditions, such as high gross weight, high density to a line from wingtip to wingtip is the lateral axis, and the altitude, and high temperature, a deficiency of airspeed during axis that passes through the CG at right angles to the other takeoff may permit the aircraft to become airborne but be two axes is the vertical axis. Whenever an aircraft changes incapable of sustaining flight out of ground effect. In this case, its flight attitude or position in flight, it rotates about one or the aircraft may become airborne initially with a deficiency more of the three axes. [Figure 5-18] of speed and then settle back to the runway.

The aircraft’s motion about its longitudinal axis resembles A pilot should not attempt to force an aircraft to become the roll of a ship from side to side. In fact, the names airborne with a deficiency of speed. The manufacturer’s used to describe the motion about an aircraft’s three axes recommended takeoff speed is necessary to provide adequate were originally nautical terms. They have been adapted to initial climb performance. It is also important that a definite aeronautical terminology due to the similarity of motion of climb be established before a pilot retracts the landing gear aircraft and seagoing ships. The motion about the aircraft’s or flaps. Never retract the landing gear or flaps prior to longitudinal axis is “roll,” the motion about its lateral axis is Pitching Rolling Yawing Lateral axis Longitudinal axis Vertical axis Figure 5-18. Axes of an airplane.

5-12 “pitch,” and the motion about its vertical axis is “yaw.” Yaw is the left and right movement of the aircraft’s nose.

The three motions of the conventional airplane (roll, pitch, and yaw) are controlled by three control surfaces. Roll is controlled by the ailerons; pitch is controlled by the elevators; yaw is controlled by the rudder. The use of these controls is explained in Chapter 6, Flight Controls. Other types of aircraft may utilize different methods of controlling the movements about the various axes.

For example, weight-shift control aircraft control two axes (roll and pitch) using an “A” frame suspended from the flexible wing attached to a three-wheeled carriage. These Figure 5-20. A powered parachute.

aircraft are controlled by moving a horizontal bar (called a control bar) in roughly the same way hang glider pilots fly.

Moment and Moment Arm [Figure 5-19] They are termed weight-shift control aircraft A study of physics shows that a body that is free to rotate because the pilot controls the aircraft by shifting the CG.

will always turn about its CG. In aerodynamic terms, the For more information on weight-shift control aircraft, see mathematical measure of an aircraft’s tendency to rotate the Federal Aviation Administration (FAA) Weight-Shift about its CG is called a “moment.” A moment is said to be Control Flying Handbook, FAA-H-8083-5. In the case of equal to the product of the force applied and the distance at powered parachutes, aircraft control is accomplished by which the force is applied. (A moment arm is the distance altering the airfoil via steering lines.

from a datum [reference point or line] to the applied force.)

For aircraft weight and balance computations, “moments” A powered parachute wing is a parachute that has a cambered are expressed in terms of the distance of the arm times the upper surface and a flatter under surface. The two surfaces are aircraft’s weight, or simply, inch-pounds.

separated by ribs that act as cells, which open to the airflow at the leading edge and have internal ports to allow lateral Aircraft designers locate the fore and aft position of the airflow. The principle at work holds that the cell pressure is aircraft’s CG as nearly as possible to the 20 percent point greater than the outside pressure, thereby forming a wing that of the mean aerodynamic chord (MAC). If the thrust line maintains its airfoil shape in flight. The pilot and passenger is designed to pass horizontally through the CG, it will not sit in tandem in front of the engine, which is located at the cause the aircraft to pitch when power is changed, and there rear of a vehicle. The airframe is attached to the parachute will be no difference in moment due to thrust for a power-on via two attachment points and lines. Control is accomplished or power-off condition of flight. Although designers have by both power and the changing of the airfoil via the control some control over the location of the drag forces, they are not lines. [Figure 5-20] always able to make the resultant drag forces pass through the CG of the aircraft. However, the one item over which they have the greatest control is the size and location of the tail.

The objective is to make the moments (due to thrust, drag, and lift) as small as possible and, by proper location of the tail, to provide the means of balancing an aircraft longitudinally for any condition of flight.

The pilot has no direct control over the location of forces acting on the aircraft in flight, except for controlling the center of lift by changing the AOA. The pilot can control the magnitude of the forces. Such a change, however, immediately involves changes in other forces. Therefore, the pilot cannot independently change the location of one force without changing the effect of others. For example, a change in airspeed involves a change in lift, as well as a Figure 5-19. A weight-shift control aircraft.

change in drag and a change in the up or down force on the 5-13 tail. As forces such as turbulence and gusts act to displace maneuverability of the aircraft. If the aircraft is to provide the aircraft, the pilot reacts by providing opposing control maximum utility, it must be safely controllable to the full forces to counteract this displacement. extent of these limits without exceeding the pilot’s strength or requiring exceptional flying ability. If an aircraft is to fly Some aircraft are subject to changes in the location of the CG straight and steady along any arbitrary flight path, the forces with variations of load. Trimming devices, such as elevator acting on it must be in static equilibrium. The reaction of trim tabs and adjustable horizontal stabilizers, are used to any body when its equilibrium is disturbed is referred to as counteract the moments set up by fuel burnoff and loading stability. The two types of stability are static and dynamic.

or off-loading of passengers or cargo.

Static Stability Aircraft Design Characteristics Static stability refers to the initial tendency, or direction of Each aircraft handles somewhat differently because each movement, back to equilibrium. In aviation, it refers to the resists or responds to control pressures in its own way. For aircraft’s initial response when disturbed from a given pitch, example, a training aircraft is quick to respond to control yaw, or bank.

applications, while a transport aircraft feels heavy on the • Positive static stability—the initial tendency of the controls and responds to control pressures more slowly.

aircraft to return to the original state of equilibrium These features can be designed into an aircraft to facilitate after being disturbed. [Figure 5-21] the particular purpose of the aircraft by considering certain • Neutral static stability—the initial tendency of stability and maneuvering requirements. The following the aircraft to remain in a new condition after its discussion summarizes the more important aspects of an equilibrium has been disturbed. [Figure 5-21] aircraft’s stability, maneuverability, and controllability qualities; how they are analyzed; and their relationship to • Negative static stability—the initial tendency of the various flight conditions.

aircraft to continue away from the original state of equilibrium after being disturbed. [Figure 5-21] Stability Stability is the inherent quality of an aircraft to correct for Dynamic Stability conditions that may disturb its equilibrium and to return to Static stability has been defined as the initial tendency to or to continue on the original flight path. It is primarily an return to equilibrium that the aircraft displays after being aircraft design characteristic. The flight paths and attitudes an disturbed from its trimmed condition. Occasionally, the aircraft flies are limited by the aerodynamic characteristics of initial tendency is different or opposite from the overall the aircraft, its propulsion system, and its structural strength.

tendency, so a distinction must be made between the two.

These limitations indicate the maximum performance and Dynamic stability refers to the aircraft response over time Positive Static Stability Neutral Static Stability Negative Static Stability Applied Applied Applied force force force CG CG CG CG Figure 5-21. Types of static stability.

5-14 when disturbed from a given pitch, yaw, or bank. This type considered to be the most affected by certain variables in of stability also has three subtypes: [Figure 5-22] various flight conditions.

• Positive dynamic stability—over time, the motion Longitudinal stability is the quality that makes an aircraft of the displaced object decreases in amplitude and, stable about its lateral axis. It involves the pitching motion because it is positive, the object displaced returns as the aircraft’s nose moves up and down in flight. A toward the equilibrium state.

longitudinally unstable aircraft has a tendency to dive or • Neutral dynamic stability—once displaced, the climb progressively into a very steep dive or climb, or even displaced object neither decreases nor increases in a stall. Thus, an aircraft with longitudinal instability becomes amplitude. A worn automobile shock absorber exhibits difficult and sometimes dangerous to fly.

this tendency.

Static longitudinal stability, or instability in an aircraft, is • Negative dynamic stability—over time, the motion dependent upon three factors: of the displaced object increases and becomes more divergent.

1. Location of the wing with respect to the CG 2. Location of the horizontal tail surfaces with respect Stability in an aircraft affects two areas significantly: to the CG • Maneuverability—the quality of an aircraft that 3. Area or size of the tail surfaces permits it to be maneuvered easily and to withstand the stresses imposed by maneuvers. It is governed by In analyzing stability, it should be recalled that a body free the aircraft’s weight, inertia, size and location of flight to rotate always turns about its CG.

controls, structural strength, and powerplant. It too is an aircraft design characteristic.

To obtain static longitudinal stability, the relation of the • Controllability—the capability of an aircraft to wing and tail moments must be such that, if the moments respond to the pilot’s control, especially with regard are initially balanced and the aircraft is suddenly nose up, to flight path and attitude. It is the quality of the the wing moments and tail moments change so that the sum aircraft’s response to the pilot’s control application of their forces provides an unbalanced but restoring moment when maneuvering the aircraft, regardless of its which, in turn, brings the nose down again. Similarly, if the stability characteristics.

aircraft is nose down, the resulting change in moments brings the nose back up.

Longitudinal Stability (Pitching) In designing an aircraft, a great deal of effort is spent in The Center of Lift (CL) in most asymmetrical airfoils has a developing the desired degree of stability around all three tendency to change its fore and aft positions with a change in axes. But longitudinal stability about the lateral axis is the AOA. The CL tends to move forward with an increase in AOA and to move aft with a decrease in AOA. This means Damped oscillation Undamped oscillation Divergent oscillation Positive static (positive dynamic) Time Displacement Positive Static Positive static (negative dynamic) (neutral dynamic) Figure 5-22. Damped versus undamped stability.

5-15 that when the AOA of an airfoil is increased, the CL, by Cruise Speed moving forward, tends to lift the leading edge of the wing still more. This tendency gives the wing an inherent quality CG of instability. (NOTE: CL is also known as the center of pressure (CP).)

Balanced tail load Figure 5-23 shows an aircraft in straight-and-level flight. The Low Speed line CG-CL-T represents the aircraft’s longitudinal axis from the CG to a point T on the horizontal stabilizer.

CG Most aircraft are designed so that the wing’s CL is to the rear of the CG. This makes the aircraft “nose heavy” and requires that there be a slight downward force on the horizontal Lesser downward tail load stabilizer in order to balance the aircraft and keep the nose from continually pitching downward. Compensation for this nose heaviness is provided by setting the horizontal stabilizer High Speed at a slight negative AOA. The downward force thus produced CG holds the tail down, counterbalancing the “heavy” nose. It is as if the line CG-CL-T were a lever with an upward force Greater downward tail load at CL and two downward forces balancing each other, one a strong force at the CG point and the other, a much lesser force, at point T (downward air pressure on the stabilizer).

Figure 5-24. Effect of speed on downwash.

To better visualize this physics principle: If an iron bar were suspended at point CL, with a heavy weight hanging on it at flow of air over the wing, the downwash is reduced, causing the CG, it would take downward pressure at point T to keep a lesser downward force on the horizontal stabilizer. In turn, the “lever” in balance.

the characteristic nose heaviness is accentuated, causing the aircraft’s nose to pitch down more. [Figure 5-25] This places Even though the horizontal stabilizer may be level when the the aircraft in a nose-low attitude, lessening the wing’s AOA aircraft is in level flight, there is a downwash of air from the and drag and allowing the airspeed to increase. As the aircraft wings. This downwash strikes the top of the stabilizer and continues in the nose-low attitude and its speed increases, produces a downward pressure, which at a certain speed is the downward force on the horizontal stabilizer is once again just enough to balance the “lever.” The faster the aircraft increased. Consequently, the tail is again pushed downward is flying, the greater this downwash and the greater the and the nose rises into a climbing attitude.

downward force on the horizontal stabilizer (except T-tails).

[Figure 5-24] In aircraft with fixed-position horizontal stabilizers, the aircraft manufacturer sets the stabilizer at an Lift angle that provides the best stability (or balance) during flight at the design cruising speed and power setting.

Thrust CG Weight If the aircraft’s speed decreases, the speed of the airflow over the wing is decreased. As a result of this decreased Normal downwash CL Lift CG Thrust CG Weight CL Reduced downwash CG Figure 5-25. Reduced power allows pitch down.

Figure 5-23. Longitudinal stability.

5-16 As this climb continues, the airspeed again decreases, causing Lift the downward force on the tail to decrease until the nose lowers once more. Because the aircraft is dynamically stable, CG the nose does not lower as far this time as it did before. The Thrust aircraft acquires enough speed in this more gradual dive to start it into another climb, but the climb is not as steep as the preceding one.

Cruise power Lift After several of these diminishing oscillations, in which the nose alternately rises and lowers, the aircraft finally settles down to a speed at which the downward force on the CG Thrust tail exactly counteracts the tendency of the aircraft to dive.

When this condition is attained, the aircraft is once again in balanced flight and continues in stabilized flight as long as Idle power this attitude and airspeed are not changed.

Lift A similar effect is noted upon closing the throttle. The downwash of the wings is reduced and the force at T in Thrust CG Figure 5-23 is not enough to hold the horizontal stabilizer down. It seems as if the force at T on the lever were allowing the force of gravity to pull the nose down. This is a desirable Full power characteristic because the aircraft is inherently trying to regain airspeed and reestablish the proper balance.

Figure 5-27. Power changes affect longitudinal stability.

Power or thrust can also have a destabilizing effect in that increased a moment is produced to counteract the down load an increase of power may tend to make the nose rise. The on the tail. On the other hand, a very “low thrust line” would aircraft designer can offset this by establishing a “high tend to add to the nose-up effect of the horizontal tail surface.

thrust line” wherein the line of thrust passes above the CG.

Conclusion: with CG forward of the CL and with an [Figures 5-26 and 5-27] In this case, as power or thrust is aerodynamic tail-down force, the aircraft usually tries to return to a safe flying attitude.

The following is a simple demonstration of longitudinal CG Thrust stability. Trim the aircraft for “hands off” control in level flight. Then, momentarily give the controls a slight push to nose the aircraft down. If, within a brief period, the nose rises towards the original position, the aircraft is statically stable.

Below center of gravity Ordinarily, the nose passes the original position (that of level flight) and a series of slow pitching oscillations follows. If the oscillations gradually cease, the aircraft has positive stability; if they continue unevenly, the aircraft has neutral stability; Thrust CG if they increase, the aircraft is unstable.

Lateral Stability (Rolling) Through center of gravity Stability about the aircraft’s longitudinal axis, which extends from the nose of the aircraft to its tail, is called lateral stability. Positive lateral stability helps to stabilize the lateral or “rolling effect” when one wing gets lower than the wing Thrust on the opposite side of the aircraft. There are four main CG design factors that make an aircraft laterally stable: dihedral, sweepback, keel effect, and weight distribution.

Above center of gravity Figure 5-26. Thrust line affects longitudinal stability.

5-17 Dihedral Some aircraft are designed so that the outer tips of the wings are higher than the wing roots. The upward angle thus formed by the wings is called dihedral. [Figure 5-28] When a gust causes a roll, a sideslip will result. This sideslip causes the Restoring lift relative wind affecting the entire airplane to be from the direction of the slip. When the relative wind comes from the side, the wing slipping into the wind is subject to an increase in AOA and develops an increase in lift. The wing away Wing has decreased from the wind is subject to a decrease in angle of attack, and AOA, hence reduced lift develops a decrease in lift. The changes in lift effect a rolling due to sideslip.

moment tending to raise the windward wing, hence dihedral Sideslip contributes to a stable roll due to sideslip. [Figure 5-29] Wing has increased AOA, hence increased lift due to sideslip.

Sweepback and Wing Location Many aspects of an aircraft's configuration can affect its effective dihedral, but two major components are wing Figure 5-29. Sideslip causing different AOA on each blade.

sweepback and the wing location with respect to the fuselage (such as a low wing or high wing). As a rough estimation, 10° of sweepback on a wing provides about 1° of effective dihedral, while a high wing configuration can provide about 5° of effective dihedral over a low wing configuration.

A sweptback wing is one in which the leading edge slopes backward. [Figure 5-30] When a disturbance causes an aircraft with sweepback to slip or drop a wing, the low wing presents its leading edge at an angle that is more perpendicular to the relative airflow. As a result, the low wing acquires more lift, rises, and the aircraft is restored to its original flight attitude.

Keel Effect and Weight Distribution Figure 5-30. Sweepback wings.

A high wing aircraft always has the tendency to turn the longitudinal axis of the aircraft into the relative wind, which is disturbed and one wing dips, the fuselage weight acts like a often ref e rred to as the keel effect. These aircraft are laterally pendulum returning the aircraft to the horizontal level.

stable simply because the wings are attached in a high position on the fuselage, making the fuselage behave like a Laterally stable aircraft are constructed so that the greater keel exerting a steadying influence on the aircraft laterally portion of the keel area is above the CG. [Figure 5-31] Thus, about the longitudinal axis. When a high-winged aircraft is when the aircraft slips to one side, the combination of the Dihedral Dihedral Figure 5-28. Dihedral is the upward angle of the wings from a horizontal (front/rear view) axis of the plane as shown in the graphic depiction and the rear view of a Ryanair Boeing 737.

5-18 CG CG CG centerline CG Area forward Area aft of CG of CG Figure 5-31. Keel area for lateral stability.

w CG a y aircraft’s weight and the pressure of the airflow against the Y upper portion of the keel area (both acting about the CG) a w tends to roll the aircraft back to wings-level flight.

R e l a t i v e w i n d Directional Stability (Yawing) Stability about the aircraft’s vertical axis (the sideways moment) is called yawing or directional stability. Yawing or directional stability is the most easily achieved stability in aircraft design. The area of the vertical fin and the sides of the fuselage aft of the CG are the prime contributors that Figure 5-32. Fuselage and fin for directional stability.

make the aircraft act like the well known weather vane or arrow, pointing its nose into the relative wind.

to the right, there is a brief moment when the aircraft is still moving along its original path, but its longitudinal axis is In examining a weather vane, it can be seen that if exactly the pointed slightly to the right.

same amount of surface were exposed to the wind in front of the pivot point as behind it, the forces fore and aft would The aircraft is then momentarily skidding sideways and, be in balance and little or no directional movement would during that moment (since it is assumed that although the result. Consequently, it is necessary to have a greater surface yawing motion has stopped, the excess pressure on the left aft of the pivot point than forward of it.

side of the fin still persists), there is necessarily a tendency for the aircraft to be turned partially back to the left. That is, Similarly, the aircraft designer must ensure positive there is a momentary restoring tendency caused by the fin.

directional stability by making the side surface greater aft than ahead of the CG. [Figure 5-32] To provide additional This restoring tendency is relatively slow in developing and positive stability to that provided by the fuselage, a vertical ceases when the aircraft stops skidding. When it ceases, the fin is added. The fin acts similar to the feather on an arrow aircraft is flying in a direction slightly different from the in maintaining straight flight. Like the weather vane and the original direction. In other words, it will not return of its own arrow, the farther aft this fin is placed and the larger its size, accord to the original heading; the pilot must reestablish the the greater the aircraft’s directional stability.

initial heading.

If an aircraft is flying in a straight line, and a sideward gust A minor improvement of directional stability may be obtained of air gives the aircraft a slight rotation about its vertical through sweepback. Sweepback is incorporated in the design axis (i.e., the right), the motion is retarded and stopped by of the wing primarily to delay the onset of compressibility the fin because while the aircraft is rotating to the right, the during high-speed flight. In lighter and slower aircraft, air is striking the left side of the fin at an angle. This causes sweepback aids in locating the center of pressure in the pressure on the left side of the fin, which resists the turning correct relationship with the CG. A longitudinally stable motion and slows down the aircraft’s yaw. In doing so, it aircraft is built with the center of pressure aft of the CG.

acts somewhat like the weather vane by turning the aircraft into the relative wind. The initial change in direction of the Because of structural reasons, aircraft designers sometimes aircraft’s flight path is generally slightly behind its change cannot attach the wings to the fuselage at the exact desired of heading. Therefore, after a slight yawing of the aircraft 5-19 point. If they had to mount the wings too far forward, and at comparatively weak dihedral lags in restoring the lateral right angles to the fuselage, the center of pressure would not balance. Due to this yaw, the wing on the outside of the be far enough to the rear to result in the desired amount of turning moment travels forward faster than the inside wing longitudinal stability. By building sweepback into the wings, and, as a consequence, its lift becomes greater. This produces however, the designers can move the center of pressure toward an overbanking tendency which, if not corrected by the pilot, the rear. The amount of sweepback and the position of the results in the bank angle becoming steeper and steeper. At wings then place the center of pressure in the correct location. the same time, the strong directional stability that yaws the aircraft into the relative wind is actually forcing the nose When turbulence or rudder application causes the aircraft to to a lower pitch attitude. A slow downward spiral begins yaw to one side, the opposite wing presents a longer leading which, if not counteracted by the pilot, gradually increases edge perpendicular to the relative airflow. The airspeed of into a steep spiral dive. Usually the rate of divergence in the the forward wing increases and it acquires more drag than spiral motion is so gradual the pilot can control the tendency the back wing. The additional drag on the forward wing pulls without any difficulty.

the wing back, turning the aircraft back to its original path.

Many aircraft are affected to some degree by this characteristic, The contribution of the wing to static directional stability is although they may be inherently stable in all other normal usually small. The swept wing provides a stable contribution parameters. This tendency explains why an aircraft cannot depending on the amount of sweepback, but the contribution be flown “hands off” indefinitely.

is relatively small when compared with other components.

Much research has gone into the development of control Free Directional Oscillations (Dutch Roll) devices (wing leveler) to correct or eliminate this instability.

The pilot must be careful in application of recovery controls Dutch roll is a coupled lateral/directional oscillation that is usually dynamically stable but is unsafe in an aircraft because during advanced stages of this spiral condition or excessive loads may be imposed on the structure. Improper recovery of the oscillatory nature. The damping of the oscillatory mode may be weak or strong depending on the properties of the from spiral instability leading to inflight structural failures has probably contributed to more fatalities in general aviation particular aircraft.

aircraft than any other factor. Since the airspeed in the spiral condition builds up rapidly, the application of back elevator If the aircraft has a right wing pushed down, the positive sideslip angle corrects the wing laterally before the nose is force to reduce this speed and to pull the nose up only “tightens the turn,” increasing the load factor. The results realigned with the relative wind. As the wing corrects the position, a lateral directional oscillation can occur resulting in of the prolonged uncontrolled spiral are inflight structural failure, crashing into the ground, or both. Common recorded the nose of the aircraft making a figure eight on the horizon as a result of two oscillations (roll and yaw), which, although of causes for pilots who get into this situation are loss of horizon reference, inability to control the aircraft by reference to about the same magnitude, are out of phase with each other.

instruments, or a combination of both.

In most modern aircraft, except high-speed swept wing Effect of Wing Planform designs, these free directional oscillations usually die out automatically in very few cycles unless the air continues to Understanding the effects of different wing planforms be gusty or turbulent. Those aircraft with continuing Dutch is important when learning about wing performance and roll tendencies are usually equipped with gyro-stabilized yaw airplane flight characteristics. A planform is the shape of the dampers. Manufacturers try to reach a midpoint between too wing as viewed from directly above and deals with airflow much and too little directional stability. Because it is more in three dimensions. Aspect ratio, taper ratio, and sweepback desirable for the aircraft to have “spiral instability” than are factors in planform design that are very important to the Dutch roll tendencies, most aircraft are designed with that overall aerodynamic characteristic of a wing. [Figure 5-33] characteristic.

Aspect ratio is the ratio of wing span to wing chord. Taper Spiral Instability ratio can be either in planform or thickness, or both. In its Spiral instability exists when the static directional stability simplest terms, it is a decrease from wing root to wingtip in of the aircraft is very strong as compared to the effect of its wing chord or wing thickness. Sweepback is the rearward dihedral in maintaining lateral equilibrium. When the lateral slant of a wing, horizontal tail, or other airfoil surface.

equilibrium of the aircraft is disturbed by a gust of air and a sideslip is introduced, the strong directional stability tends There are two general means by which the designer can to yaw the nose into the resultant relative wind while the change the planform of a wing and both will affect the 5-20 Elliptical wing Regular wing Moderate taper wing High taper wing Pointed tip wing Sweepback wing Figure 5-33. Different types of wing planforms.

aerodynamic characteristics of the wing. The first is to effect A decrease in aspect ratio will give a corresponding increase a change in the aspect ratio. Aspect ratio is the primary factor in drag. It should be noted, however, that with an increase in in determining the three dimensional characteristics of the aspect ratio there is an increase in the length of span, with a ordinary wing and its lift/drag ratio. An increase in aspect corresponding increase in the weight of the wing structure, ratio with constant velocity will decrease the drag, especially which means the wing must be heavier to carry the same load.

at high angles of attack, improving the performance of the For this reason, part of the gain (due to a decrease in drag) is wing when in a climbing attitude. lost because of the increased weight, and a compromise in 5-21 design is necessary to obtain the best results from these two In comparison, the rectangular wing has a tendency to stall conflicting conditions. first at the wing root and provides adequate stall warning, adequate aileron effectiveness, and is usually quite stable.

The second means of changing the planform is by tapering It is, therefore, favored in the design of low cost, low speed (decreasing the length of chord from the root to the tip of the airplanes.

wing). In general, tapering causes a decrease in drag (most Aerodynamic Forces in Flight Maneuvers effective at high speeds) and an increase in lift. There is also a structural benefit due to a saving in weight of the wing.

Forces in Turns If an aircraft were viewed in straight-and-level flight from the Most training and general aviation type airplanes are operated front [Figure 5-34], and if the forces acting on the aircraft at high coefficients of lift, and therefore require comparatively could be seen, lift and weight would be apparent: two forces.

high aspect ratios. Airplanes that are developed to operate at If the aircraft were in a bank it would be apparent that lift very high speeds demand greater aerodynamic cleanness and did not act directly opposite to the weight, rather it now acts greater strength, which require low aspect ratios. Very low in the direction of the bank. A basic truth about turns is that aspect ratios result in high wing loadings and high stall speeds.

when the aircraft banks, lift acts inward toward the center of When sweepback is combined with low aspect ratio, it results the turn, perpendicular to the lateral axis as well as upward.

in flying qualities very different from a more conventional high aspect ratio airplane configuration. Such airplanes Newton’s First Law of Motion, the Law of Inertia, states that require very precise and professional flying techniques, an object at rest or moving in a straight line remains at rest especially at slow speeds, while airplanes with a high aspect or continues to move in a straight line until acted on by some ratio are usually more forgiving of improper pilot techniques.

other force. An aircraft, like any moving object, requires a sideward force to make it turn. In a normal turn, this force The elliptical wing is the ideal subsonic planform since it is supplied by banking the aircraft so that lift is exerted provides for a minimum of induced drag for a given aspect inward, as well as upward. The force of lift during a turn is ratio, though as we shall see, its stall characteristics in separated into two components at right angles to each other.

some respects are inferior to the rectangular wing. It is also One component, which acts vertically and opposite to the comparatively difficult to construct. The tapered airfoil is weight (gravity), is called the “vertical component of lift.” desirable from the standpoint of weight and stiffness, but The other, which acts horizontally toward the center of the again is not as efficient aerodynamically as the elliptical turn, is called the “horizontal component of lift” or centripetal wing. In order to preserve the aerodynamic efficiency of the force. The horizontal component of lift is the force that elliptical wing, rectangular and tapered wings are sometimes pulls the aircraft from a straight flight path to make it turn.

tailored through use of wing twist and variation in airfoil Centrifugal force is the “equal and opposite reaction” of the sections until they provide as nearly as possible the elliptical aircraft to the change in direction and acts equal and opposite wing’s lift distribution. While it is true that the elliptical to the horizontal component of lift. This explains why, in a wing provides the best coefficients of lift before reaching an correctly executed turn, the force that turns the aircraft is incipient stall, it gives little advance warning of a complete not supplied by the rudder. The rudder is used to correct any stall, and lateral control may be difficult because of poor deviation between the straight track of the nose and tail of the aileron effectiveness.

aircraft into the relative wind. A good turn is one in which the Level flight Medium banked turn Steeply banked turn Vertical component Vertical component Total lift Total lift Lift Centrifugal force Horizontal Centrifugal component force Horizontal Resultant load Resultant load component Weight Weight Weight Figure 5-34. Forces during normal, coordinated turn at constant altitude.

5-22 nose and tail of the aircraft track along the same path. If no decreased, or the angle of bank increased, if a constant rudder is used in a turn, the nose of the aircraft yaws to the altitude is to be maintained. If the angle of bank is held outside of the turn. The rudder is used rolling into the turn constant and the AOA decreased, the ROT decreases. In order to bring the nose back in line with the relative wind. Once to maintain a constant ROT as the airspeed is increased, the in the turn, the rudder should not be needed. AOA must remain constant and the angle of bank increased.

An aircraft is not steered like a boat or an automobile. In An increase in airspeed results in an increase of the turn radius, order for an aircraft to turn, it must be banked. If it is not and centrifugal force is directly proportional to the radius of banked, there is no force available to cause it to deviate the turn. In a correctly executed turn, the horizontal component from a straight flight path. Conversely, when an aircraft is of lift must be exactly equal and opposite to the centrifugal banked, it turns provided it is not slipping to the inside of the force. As the airspeed is increased in a constant-rate level turn, turn. Good directional control is based on the fact that the the radius of the turn increases. This increase in the radius of aircraft attempts to turn whenever it is banked. Pilots should turn causes an increase in the centrifugal force, which must keep this fact in mind when attempting to hold the aircraft be balanced by an increase in the horizontal component of lift, in straight-and-level flight. which can only be increased by increasing the angle of bank.

Merely banking the aircraft into a turn produces no change in In a slipping turn, the aircraft is not turning at the rate the total amount of lift developed. Since the lift during the bank appropriate to the bank being used, since the aircraft is yawed is divided into vertical and horizontal components, the amount toward the outside of the turning flight path. The aircraft is of lift opposing gravity and supporting the aircraft’s weight banked too much for the ROT, so the horizontal lift component is reduced. Consequently, the aircraft loses altitude unless is greater than the centrifugal force. [Figure 5-35] Equilibrium additional lift is created. This is done by increasing the AOA between the horizontal lift component and centrifugal force until the vertical component of lift is again equal to the weight. is reestablished by either decreasing the bank, increasing the Since the vertical component of lift decreases as the bank ROT, or a combination of the two changes.

angle increases, the AOA must be progressively increased to produce sufficient vertical lift to support the aircraft’s A skidding turn results from an excess of centrifugal force weight. An important fact for pilots to remember when making over the horizontal lift component, pulling the aircraft constant altitude turns is that the vertical component of lift toward the outside of the turn. The ROT is too great for the must be equal to the weight to maintain altitude. angle of bank. Correction of a skidding turn thus involves a reduction in the ROT, an increase in bank, or a combination At a given airspeed, the rate at which an aircraft turns of the two changes.

depends upon the magnitude of the horizontal component of lift. It is found that the horizontal component of lift is To maintain a given ROT, the angle of bank must be varied proportional to the angle of bank—that is, it increases or with the airspeed. This becomes particularly important in decreases respectively as the angle of bank increases or high-speed aircraft. For instance, at 400 miles per hour (mph), decreases. As the angle of bank is increased, the horizontal an aircraft must be banked approximately 44° to execute a component of lift increases, thereby increasing the rate of standard-rate turn (3° per second). At this angle of bank, turn (ROT). Consequently, at any given airspeed, the ROT only about 79 percent of the lift of the aircraft comprises the can be controlled by adjusting the angle of bank. vertical component of the lift. This causes a loss of altitude unless the AOA is increased sufficiently to compensate for To provide a vertical component of lift sufficient to hold the loss of vertical lift.

altitude in a level turn, an increase in the AOA is required.

Forces in Climbs Since the drag of the airfoil is directly proportional to its AOA, induced drag increases as the lift is increased. This, in turn, For all practical purposes, the wing’s lift in a steady state causes a loss of airspeed in proportion to the angle of bank. normal climb is the same as it is in a steady level flight at the A small angle of bank results in a small reduction in airspeed same airspeed. Although the aircraft’s flight path changed while a large angle of bank results in a large reduction in when the climb was established, the AOA of the wing with airspeed. Additional thrust (power) must be applied to prevent respect to the inclined flight path reverts to practically the a reduction in airspeed in level turns. The required amount of same values, as does the lift. There is an initial momentary additional thrust is proportional to the angle of bank.

change as shown in Figure 5-36. During the transition from straight-and-level flight to a climb, a change in lift occurs To compensate for added lift, which would result if the when back elevator pressure is first applied. Raising the airspeed were increased during a turn, the AOA must be aircraft’s nose increases the AOA and momentarily increases 5-23 Normal turn Slipping turn Skidding turn Vertical lift Vertical lift Vertical lift Lift Lift Lift Centrifugal Centrifugal force Centrifugal force force Horizontal Horizontal Horizontal lift lift Load lift Weight Weight Weight Load Centrifugal Centrifugal Centrifugal force Load force equals force less than greater than horizontal lift horizontal lift horizontal lift Figure 5-35. Normal, slipping, and skidding turns at a constant altitude.

the lift. Lift at this moment is now greater than weight and a value lower than in straight-and-level flight at the same starts the aircraft climbing. After the flight path is stabilized power setting. Since the aircraft’s weight is acting not only on the upward incline, the AOA and lift again revert to about downward but rearward with drag while in a climb, additional the level flight values. power is required to maintain the same airspeed as in level flight. The amount of power depends on the angle of climb.

If the climb is entered with no change in power setting, the When the climb is established steep enough that there is airspeed gradually diminishes because the thrust required insufficient power available, a slower speed results.

to maintain a given airspeed in level flight is insufficient to maintain the same airspeed in a climb. When the flight path The thrust required for a stabilized climb equals drag plus a is inclined upward, a component of the aircraft’s weight percentage of weight dependent on the angle of climb. For acts in the same direction as, and parallel to, the total drag example, a 10° climb would require thrust to equal drag plus of the aircraft, thereby increasing the total effective drag. 17 percent of weight. To climb straight up would require Consequently, the total effective drag is greater than the thrust to equal all of weight and drag. Therefore, the angle power, and the airspeed decreases. The reduction in airspeed of climb for climb performance is dependent on the amount gradually results in a corresponding decrease in drag until of excess thrust available to overcome a portion of weight.

the total drag (including the component of weight acting Note that aircraft are able to sustain a climb due to excess in the same direction) equals the thrust. [Figure 5-37] Due thrust. When the excess thrust is gone, the aircraft is no to momentum, the change in airspeed is gradual, varying longer able to climb. At this point, the aircraft has reached considerably with differences in aircraft size, weight, total its “absolute ceiling.” drag, and other factors. Consequently, the total effective drag Forces in Descents is greater than the thrust, and the airspeed decreases.

As in climbs, the forces that act on the aircraft go through Generally, the forces of thrust and drag, and lift and weight, definite changes when a descent is entered from straight again become balanced when the airspeed stabilizes but at and-level flight. For the following example, the aircraft Level flight forces balanced T L constant speed L W D L L T L L D W L D T W Steady climb Climb entry drag forces balanced greater than thrust Steady climb Climb entry Level flight normal lift constant speed speed slowing increased lift normal lift Figure 5-37. Changes in speed during climb entry.

Figure 5-36. Changes in lift during climb entry.

5-24 is descending at the same power as used in straight-and drop during a stall, reducing the AOA and “unstalling” the level flight. wing. The nose-down tendency is due to the CL being aft of the CG. The CG range is very important when it comes to As forward pressure is applied to the control yoke to initiate stall recovery characteristics. If an aircraft is allowed to be the descent, the AOA is decreased momentarily. Initially, operated outside of the CG range, the pilot may have difficulty the momentum of the aircraft causes the aircraft to briefly recovering from a stall. The most critical CG violation would continue along the same flight path. For this instant, the AOA occur when operating with a CG that exceeds the rear limit.

decreases causing the total lift to decrease. With weight now In this situation, a pilot may not be able to generate sufficient being greater than lift, the aircraft begins to descend. At the force with the elevator to counteract the excess weight aft of same time, the flight path goes from level to a descending the CG. Without the ability to decrease the AOA, the aircraft flight path. Do not confuse a reduction in lift with the inability continues in a stalled condition until it contacts the ground.

to generate sufficient lift to maintain level flight. The flight path is being manipulated with available thrust in reserve The stalling speed of a particular aircraft is not a fixed value and with the elevator. for all flight situations, but a given aircraft always stalls at the same AOA regardless of airspeed, weight, load factor, or To descend at the same airspeed as used in straight-and density altitude. Each aircraft has a particular AOA where the level flight, the power must be reduced as the descent is airflow separates from the upper surface of the wing and the entered. Entering the descent, the component of weight stall occurs. This critical AOA varies from approximately 16° acting forward along the flight path increases as the angle to 20° depending on the aircraft’s design. But each aircraft of descent increases and, conversely, when leveling off, the has only one specific AOA where the stall occurs.

component of weight acting along the flight path decreases as the angle of descent decreases. There are three flight situations in which the critical AOA is most frequently exceeded: low speed, high speed, and turning.

Stalls One way the aircraft can be stalled in straight-and-level flight An aircraft stall results from a rapid decrease in lift caused by by flying too slowly. As the airspeed decreases, the AOA the separation of airflow from the wing’s surface brought on must be increased to retain the lift required for maintaining by exceeding the critical AOA. A stall can occur at any pitch altitude. The lower the airspeed becomes, the more the AOA attitude or airspeed. Stalls are one of the most misunderstood must be increased. Eventually, an AOA is reached that results areas of aerodynamics because pilots often believe an airfoil in the wing not producing enough lift to support the aircraft, stops producing lift when it stalls. In a stall, the wing does which then starts settling. If the airspeed is reduced further, not totally stop producing lift. Rather, it cannot generate the aircraft stalls because the AOA has exceeded the critical adequate lift to sustain level flight.

angle and the airflow over the wing is disrupted.

Since the C increases with an increase in AOA, at some L Low speed is not necessary to produce a stall. The wing point the C peaks and then begins to drop off. This peak is L can be brought into an excessive AOA at any speed. For called the C . The amount of lift the wing produces drops L-MAX example, an aircraft is in a dive with an airspeed of 100 dramatically after exceeding the C or critical AOA, but L-MAX knots when the pilot pulls back sharply on the elevator as stated above, it does not completely stop producing lift.

control. [Figure 5-38] Gravity and centrifugal force prevent an immediate alteration of the flight path, but the aircraft’s In most straight-wing aircraft, the wing is designed to stall AOA changes abruptly from quite low to very high. Since the wing root first. The wing root reaches its critical AOA the flight path of the aircraft in relation to the oncoming air first making the stall progress outward toward the wingtip.

determines the direction of the relative wind, the AOA is By having the wing root stall first, aileron effectiveness is suddenly increased, and the aircraft would reach the stalling maintained at the wingtips, maintaining controllability of angle at a speed much greater than the normal stall speed.

the aircraft. Various design methods are used to achieve the stalling of the wing root first. In one design, the wing is The stalling speed of an aircraft is also higher in a level turn “twisted” to a higher AOA at the wing root. Installing stall than in straight-and-level flight. [Figure 5-39] Centrifugal strips on the first 20–25 percent of the wing’s leading edge force is added to the aircraft’s weight and the wing must is another method to introduce a stall prematurely.

produce sufficient additional lift to counterbalance the load imposed by the combination of centrifugal force and weight.

The wing never completely stops producing lift in a stalled In a turn, the necessary additional lift is acquired by applying condition. If it did, the aircraft would fall to the Earth. Most back pressure to the elevator control. This increases the wing’s training aircraft are designed for the nose of the aircraft to 5-25 Airfoil shape and degradation of that shape must also be considered in a discussion of stalls. For example, if ice, snow, and frost are allowed to accumulate on the surface of an aircraft, L the smooth airflow over the wing is disrupted. This causes the CF W boundary layer to separate at an AOA lower than that of the critical angle. Lift is greatly reduced, altering expected aircraft performance. If ice is allowed to accumulate on the aircraft L during flight , the weight of the aircraft is increased while the CF L ability to generate lift is decreased. [Figure 5-40] As little as W L 0.8 millimeter of ice on the upper wing surface increases drag and reduces aircraft lift by 25 percent.

W W Pilots can encounter icing in any season, anywhere in the CF CF country, at altitudes of up to 18,000 feet and sometimes higher. Small aircraft, including commuter planes, are most vulnerable because they fly at lower altitudes where ice is more prevalent. They also lack mechanisms common on jet aircraft Figure 5-38. Forces exerted when pulling out of a dive.

that prevent ice buildup by heating the front edges of wings.

AOA and results in increased lift. The AOA must increase Icing can occur in clouds any time the temperature drops as the bank angle increases to counteract the increasing load below freezing and super-cooled droplets build up on an caused by centrifugal force. If at any time during a turn the aircraft and freeze. (Super-cooled droplets are still liquid AOA becomes excessive, the aircraft stalls.

even though the temperature is below 32 °Fahrenheit (F), or 0 °Celsius (C).

At this point, the action of the aircraft during a stall should be examined. To balance the aircraft aerodynamically, the CL Angle of Attack Indicators is normally located aft of the CG. Although this makes the aircraft inherently nose-heavy, downwash on the horizontal The FAA along with the General Aviation Joint Steering stabilizer counteracts this condition. At the point of stall, Committee (GAJSC) is promoting AOA indicators as one when the upward force of the wing’s lift diminishes below of the many safety initiatives aimed at reducing the general that required for sustained flight and the downward tail aviation accident rate. AOA indicators will specifically target force decreases to a point of ineffectiveness, or causes it to Loss of Control (LOC) accidents. Loss of control is the have an upward force, an unbalanced condition exists. This number one root cause of fatalities in both general aviation causes the aircraft to pitch down abruptly, rotating about its and commercial aviation. More than 25 percent of general CG. During this nose-down attitude, the AOA decreases and aviation fatal accidents occur during the maneuvering phase the airspeed again increases. The smooth flow of air over of flight. Of those accidents, half involve stall/spin scenarios.

the wing begins again, lift returns, and the aircraft begins Technology such as AOA indicators can have a tremendous to fly again. Considerable altitude may be lost before this impact on reversing this trend and are increasingly affordable cycle is complete.

for general aviation airplanes. [Figure 5-41] The purpose of an AOA indicator is to give the pilot better 13 situation awareness pertaining to the aerodynamic health e r s 80 9 o a t e c r a c f n i d d a e o e L p s 40 l Load factor or “G” l a t S Percent increase in stall speed 0° 10° 20° 30° 40° 50° 60° 70° 80° 90° Bank Angle Figure 5-40. Inflight ice formation.

Figure 5-39. Increase in stall speed and load factor.

5-26 of the airfoil. This can also be referred to as stall margin state of an airplane is the balance between airspeed, altitude, awareness. More simply explained, it is the margin that exists drag, and thrust and represents how efficiently the airfoil is between the current AOA that the airfoil is operating at, and operating. The more efficiently the airfoil operates; the larger the AOA at which the airfoil will stall (critical AOA). stall margin that is present. With this increased situational awareness pertaining to the energy condition of the airplane, Angle of attack is taught to student pilots as theory in ground pilots will have information that they need to aid in preventing training. When beginning flight training, students typically a LOC scenario resulting from a stall/spin. Additionally, the rely solely on airspeed and the published 1G stall speed to less energy that is utilized to maintain flight means greater avoid stalls. This creates problems since this speed is only overall efficiency of the airplane, which is typically realized in valid when the following conditions are met: fuel savings. This equates to a lower operating cost to the pilot.

• Unaccelerated flight (a 1G load factor) Just as training is required for any system on an aircraft, • Coordinated flight (inclinometer centered) AOA indicators have training considerations also. A more comprehensive understanding of AOA in general should be • At one weight (typically maximum gross weight) the goal of this training along with the specific operating characteristics and limitations of the installed AOA indicator.

Speed by itself is not a reliable parameter to avoid a stall.

Ground and flight instructors should make every attempt An airplane can stall at any speed. Angle of attack is a better to receive training from an instructor knowledgeable about parameter to use to avoid a stall. For a given configuration, AOA indicators prior to giving instruction pertaining to or in the airplane always stalls at the same AOA, referred to as airplanes equipped with AOA indicators. Pilot schools should the critical AOA. This critical AOA does not change with: incorporate training on AOA indicators in their syllabi, • Weight whether their training aircraft are equipped with them or not.

• Bank angle Installation of AOA indicators not required by type • Temperature certification in general aviation airplanes has recently been • Density altitude streamlined by the FAA. The FAA established policy in • Center of gravity February 2014 pertaining to non-required AOA systems and how they may be installed as a minor alteration, depending An AOA indicator can have several benefits when installed upon their installation requirements and operational utilization, and the procedures to take for certification of in general aviation aircraft, not the least of which is increased situational awareness. Without an AOA indicator, the AOA these installations. For updated information, reference the FAA website at www.faa.gov .

is “invisible” to pilots. These devices measure several parameters simultaneously and determine the current AOA While AOA indicators provide a simple visual representation providing a visual image to the pilot of the current AOA along with representations of the proximity to the critical AOA. of the current AOA and its proximity to the critical AOA, they are not without their limitations. These limitations should [Figure 5-42] These devices can give a visual representation of the energy management state of the airplane. The energy be understood by operators of general aviation airplanes Figure 5-41. A variety of AOA indicators.

5-27 Coefficient of Lift Curve Direction of Relative Wind Direction of Relative Wind Direction of Relative Wind C L Direction of Relative Wind Calibration Set Points: Ground (Zero Set Point) Optimum Alpha Angle (OAA) (1.3 x V ) s Cruise Alpha (Va or Maneuvering Speed) 3 Alpha (angle of attack) Figure 5-42. An AOA indicator has several benefits when installed in general aviation aircraft.

equipped with these devices. Like advanced automation, and produce forces that create the thrust to pull, or push, such as autopilots and moving maps, the misunderstanding the aircraft through the air. The engine furnishes the power or misuse of the equipment can have disastrous results. Some needed to rotate the propeller blades through the air at high items which may limit the effectiveness of an AOA indicator speeds, and the propeller transforms the rotary power of the are listed below: engine into forward thrust.

• Calibration techniques A cross-section of a typical propeller blade is shown in • Probes or vanes not being heated Figure 5-43. This section or blade element is an airfoil comparable to a cross-section of an aircraft wing. One • The type of indicator itself surface of the blade is cambered or curved, similar to the • Flap setting upper surface of an aircraft wing, while the other surface is • Wing contamination flat like the bottom surface of a wing. The chord line is an imaginary line drawn through the blade from its leading edge Pilots of general aviation airplanes equipped with AOA to its trailing edge. As in a wing, the leading edge is the thick indicators should contact the manufacturer for specific edge of the blade that meets the air as the propeller rotates.

limitations applicable to that installation.

Blade angle, usually measured in degrees, is the angle between the chord of the blade and the plane of rotation Basic Propeller Principles and is measured at a specific point along the length of the blade. [Figure 5-44] Because most propellers have a flat The aircraft propeller consists of two or more blades and a blade “face,” the chord line is often drawn along the face central hub to which the blades are attached. Each blade of of the propeller blade. Pitch is not blade angle, but because an aircraft propeller is essentially a rotating wing. As a result pitch is largely determined by blade angle, the two terms are of their construction, the propeller blades are like airfoils 5-28 the vectors of propeller forces in Figure 5-44, each section of a propeller blade moves downward and forward. The angle at which this air (relative wind) strikes the propeller blade is its AOA. The air deflection produced by this angle causes the dynamic pressure at the engine side of the propeller blade to be greater than atmospheric pressure, thus creating thrust.

The shape of the blade also creates thrust because it is cambered like the airfoil shape of a wing. As the air flows past the propeller, the pressure on one side is less than that on the other. As in a wing, a reaction force is produced in the Figure 5-43. Airfoil sections of propeller blade.

direction of the lesser pressure. The airflow over the wing has less pressure, and the force (lift) is upward. In the case often used interchangeably. An increase or decrease in one is of the propeller, which is mounted in a vertical instead of a usually associated with an increase or decrease in the other.

horizontal plane, the area of decreased pressure is in front of The pitch of a propeller may be designated in inches. A the propeller, and the force (thrust) is in a forward direction.

propeller designated as a “74–48” would be 74 inches in Aerodynamically, thrust is the result of the propeller shape length and have an effective pitch of 48 inches. The pitch and the AOA of the blade.

is the distance in inches, which the propeller would screw through the air in one revolution if there were no slippage.

Thrust can be considered also in terms of the mass of air handled by the propeller. In these terms, thrust equals mass When specifying a fixed-pitch propeller for a new type of of air handled multiplied by slipstream velocity minus aircraft, the manufacturer usually selects one with a pitch velocity of the aircraft. The power expended in producing that operates efficiently at the expected cruising speed of the thrust depends on the rate of air mass movement. On average, aircraft. Every fixed-pitch propeller must be a compromise thrust constitutes approximately 80 percent of the torque (total because it can be efficient at only a given combination of horsepower absorbed by the propeller). The other 20 percent airspeed and revolutions per minute (rpm). Pilots cannot is lost in friction and slippage. For any speed of rotation, change this combination in flight.

the horsepower absorbed by the propeller balances the horsepower delivered by the engine. For any single revolution When the aircraft is at rest on the ground with the engine of the propeller, the amount of air handled depends on the operating, or moving slowly at the beginning of takeoff, blade angle, which determines how big a “bite” of air the the propeller efficiency is very low because the propeller is propeller takes. Thus, the blade angle is an excellent means of restrained from advancing with sufficient speed to permit adjusting the load on the propeller to control the engine rpm.

its fixed-pitch blades to reach their full efficiency. In this situation, each propeller blade is turning through the air at The blade angle is also an excellent method of adjusting the an AOA that produces relatively little thrust for the amount AOA of the propeller. On constant-speed propellers, the blade of power required to turn it.

angle must be adjusted to provide the most efficient AOA at all engine and aircraft speeds. Lift versus drag curves, which To understand the action of a propeller, consider first its are drawn for propellers as well as wings, indicate that the motion, which is both rotational and forward. As shown by most efficient AOA is small, varying from +2° to +4°. The actual blade angle necessary to maintain this small AOA varies with the forward speed of the aircraft.

Ro tational veloc Fixed-pitch and ground-adjustable propellers are designed Thrust for best efficiency at one rotation and forward speed. They are designed for a given aircraft and engine combination. A r o e l h t c i g P n ity a propeller may be used that provides the maximum efficiency e d l e l a b g n A for takeoff, climb, cruise, or high-speed flight. Any change in f k o c a t t a these conditions results in lowering the efficiency of both the Chord line propeller and the engine. Since the efficiency of any machine Forward velocity is the ratio of the useful power output to the actual power Relative wind input, propeller efficiency is the ratio of thrust horsepower Figure 5-44. Propeller blade angle.

to brake horsepower. Propeller efficiency varies from 50 to 5-29 87 percent, depending on how much the propeller “slips.” e l d i s t a n r a v c e r t — e v Propeller slip is the difference between the geometric pitch of t e a r e y r G h i g h s p the propeller and its effective pitch. [Figure 5-45] Geometric e e d — pitch is the theoretical distance a propeller should advance i s t a n c e — d 9 e l m v o d r a k t e r in one revolution; effective pitch is the distance it actually a n t e t a e o r s t e p s d e advances. Thus, geometric or theoretical pitch is based on o e M d — no slippage, but actual or effective pitch includes propeller n c e t a — s s 9 i d l o l w k slippage in the air. e v n s a p o r t e t t e s r d o h S The reason a propeller is “twisted” is that the outer parts of the — propeller blades, like all things that turn about a central point, 20 in.

travel faster than the portions near the hub. [Figure 5-46] If the k n o 2 t , 5 m s 0 r p blades had the same geometric pitch throughout their lengths, portions near the hub could have negative AOAs while the 40 in.

propeller tips would be stalled at cruise speed. Twisting or , 5 0 0 r p m variations in the geometric pitch of the blades permits the propeller to operate with a relatively constant AOA along its 60 in.

length when in cruising flight. Propeller blades are twisted 2 , 5 0 0 r p m to change the blade angle in proportion to the differences in speed of rotation along the length of the propeller, keeping Figure 5-46. Propeller tips travel faster than the hub.

thrust more nearly equalized along this length.

high, and with the low aircraft speed, there is maximum thrust.

Usually 1° to 4° provides the most efficient lift/drag ratio, After liftoff, as the speed of the aircraft increases, the constant- but in flight the propeller AOA of a fixed-pitch propeller speed propeller automatically changes to a higher angle (or varies—normally from 0° to 15°. This variation is caused pitch). Again, the higher blade angle keeps the AOA small by changes in the relative airstream, which in turn results and efficient with respect to the relative wind. The higher from changes in aircraft speed. Thus, propeller AOA is the blade angle increases the mass of air handled per revolution.

product of two motions: propeller rotation about its axis and This decreases the engine rpm, reducing fuel consumption its forward motion.

and engine wear, and keeps thrust at a maximum.

A constant-speed propeller automatically keeps the blade After the takeoff climb is established in an aircraft having a angle adjusted for maximum efficiency for most conditions controllable-pitch propeller, the pilot reduces the power output encountered in flight. During takeoff, when maximum power of the engine to climb power by first decreasing the manifold and thrust are required, the constant-speed propeller is at a pressure and then increasing the blade angle to lower the rpm.

low propeller blade angle or pitch. The low blade angle keeps the AOA small and efficient with respect to the relative wind.

At cruising altitude, when the aircraft is in level flight and At the same time, it allows the propeller to handle a smaller less power is required than is used in takeoff or climb, the mass of air per revolution. This light load allows the engine to pilot again reduces engine power by reducing the manifold turn at high rpm and to convert the maximum amount of fuel pressure and then increasing the blade angle to decrease the into heat energy in a given time. The high rpm also creates rpm. Again, this provides a torque requirement to match the maximum thrust because, although the mass of air handled reduced engine power. Although the mass of air handled per per revolution is small, the rpm and slipstream velocity are revolution is greater, it is more than offset by a decrease in slipstream velocity and an increase in airspeed. The AOA is Slip still small because the blade angle has been increased with an increase in airspeed.

Torque and P-Factor To the pilot, “torque” (the left turning tendency of the Effective pitch airplane) is made up of four elements that cause or produce Geometric pitch a twisting or rotating motion around at least one of the airplane’s three axes. These four elements are: Figure 5-45. Propeller slippage.

1. Torque reaction from engine and propeller 5-30 2. Corkscrewing effect of the slipstream This yawing moment on the takeoff roll is corrected by the pilot’s proper use of the rudder or rudder trim.

3. Gyroscopic action of the propeller 4. Asymmetric loading of the propeller (P-factor) Corkscrew Effect The high-speed rotation of an aircraft propeller gives a Torque Reaction corkscrew or spiraling rotation to the slipstream. At high Torque reaction involves Newton’s Third Law of Physics— propeller speeds and low forward speed (as in the takeoffs for every action, there is an equal and opposite reaction. As and approaches to power-on stalls), this spiraling rotation applied to the aircraft, this means that as the internal engine is very compact and exerts a strong sideward force on the parts and propeller are revolving in one direction, an equal aircraft’s vertical tail surface. [Figure 5-48] force is trying to rotate the aircraft in the opposite direction.

[Figure 5-47] When this spiraling slipstream strikes the vertical fin, it causes a yawing moment about the aircraft’s vertical axis.

When the aircraft is airborne, this force is acting around The more compact the spiral, the more prominent this force the longitudinal axis, tending to make the aircraft roll. To is. As the forward speed increases, however, the spiral compensate for roll tendency, some of the older aircraft are elongates and becomes less effective. The corkscrew rigged in a manner to create more lift on the wing that is being flow of the slipstream also causes a rolling moment forced downward. The more modern aircraft are designed around the longitudinal axis.

with the engine offset to counteract this effect of torque.

Note that this rolling moment caused by the corkscrew flow NOTE: Most United States built aircraft engines rotate the of the slipstream is to the right, while the yawing moment propeller clockwise, as viewed from the pilot’s seat. The caused by torque reaction is to the left—in effect one may discussion here is with reference to those engines.

be counteracting the other. However, these forces vary greatly and it is the pilot’s responsibility to apply proper Generally, the compensating factors are permanently set so corrective action by use of the flight controls at all times.

that they compensate for this force at cruising speed, since These forces must be counteracted regardless of which is most of the aircraft’s operating time is at that speed. However, the most prominent at the time.

aileron trim tabs permit further adjustment for other speeds.

When the aircraft’s wheels are on the ground during the Gyroscopic Action takeoff roll, an additional turning moment around the vertical Before the gyroscopic effects of the propeller can be axis is induced by torque reaction. As the left side of the understood, it is necessary to understand the basic principle aircraft is being forced down by torque reaction, more weight of a gyroscope. All practical applications of the gyroscope is being placed on the left main landing gear. This results in are based upon two fundamental properties of gyroscopic more ground friction, or drag, on the left tire than on the right, action: rigidity in space and precession. The one of interest causing a further turning moment to the left. The magnitude for this discussion is precession.

of this moment is dependent on many variables. Some of these variables are: Precession is the resultant action, or deflection, of a spinning rotor when a deflecting force is applied to its rim. As can be 1. Size and horsepower of engine seen in Figure 5-49, when a force is applied, the resulting 2. Size of propeller and the rpm force takes effect 90° ahead of and in the direction of rotation.

3. Size of the aircraft The rotating propeller of an airplane makes a very good 4. Condition of the ground surface R e a c t i o Yaw n m a e r s t l i p S e c r o F n o i t c A Figure 5-48. Corkscrewing slipstream.

Figure 5-47. Torque reaction.

5-31 Asymmetric Loading (P-Factor) Effective Resultant force 90° force When an aircraft is flying with a high AOA, the “bite” of Yaw the downward moving blade is greater than the “bite” of the upward moving blade. This moves the center of thrust to the right of the prop disc area, causing a yawing moment toward 1. Intake the left around the vertical axis. Proving this explanation is complex because it would be necessary to work wind vector Applied force problems on each blade while considering both the AOA of the aircraft and the AOA of each blade.

Figure 5-49. Gyroscopic precession.

This asymmetric loading is caused by the resultant velocity, gyroscope and thus has similar properties. Any time a force which is generated by the combination of the velocity of the is applied to deflect the propeller out of its plane of rotation, propeller blade in its plane of rotation and the velocity of the the resulting force is 90° ahead of and in the direction of air passing horizontally through the propeller disc. With the rotation and in the direction of application, causing a pitching aircraft being flown at positive AOAs, the right (viewed from moment, a yawing moment, or a combination of the two the rear) or downswinging blade, is passing through an area of depending upon the point at which the force was applied.

resultant velocity, which is greater than that affecting the left or upswinging blade. Since the propeller blade is an airfoil, This element of torque effect has always been associated with increased velocity means increased lift. The downswinging and considered more prominent in tailwheel-type aircraft blade has more lift and tends to pull (yaw) the aircraft’s nose and most often occurs when the tail is being raised during to the left.

the takeoff roll. [Figure 5-50] This change in pitch attitude has the same effect as applying a force to the top of the When the aircraft is flying at a high AOA, the downward propeller’s plane of rotation. The resultant force acting 90° moving blade has a higher resultant velocity, creating more ahead causes a yawing moment to the left around the vertical lift than the upward moving blade. [Figure 5-51] This might axis. The magnitude of this moment depends on several be easier to visualize if the propeller shaft was mounted variables, one of which is the abruptness with which the tail perpendicular to the ground (like a helicopter). If there is raised (amount of force applied). However, precession, were no air movement at all, except that generated by the or gyroscopic action, occurs when a force is applied to any propeller itself, identical sections of each blade would have point on the rim of the propeller’s plane of rotation; the the same airspeed. With air moving horizontally across this resultant force will still be 90° from the point of application vertically mounted propeller, the blade proceeding forward in the direction of rotation. Depending on where the force is into the flow of air has a higher airspeed than the blade applied, the airplane is caused to yaw left or right, to pitch retreating with the airflow. Thus, the blade proceeding into up or down, or a combination of pitching and yawing.

the horizontal airflow is creating more lift, or thrust, moving the center of thrust toward that blade. Visualize rotating the It can be said that, as a result of gyroscopic action, any yawing vertically mounted propeller shaft to shallower angles relative around the vertical axis results in a pitching moment, and any to the moving air (as on an aircraft). This unbalanced thrust pitching around the lateral axis results in a yawing moment.

then becomes proportionately smaller and continues getting To correct for the effect of gyroscopic action, it is necessary smaller until it reaches the value of zero when the propeller for the pilot to properly use elevator and rudder to prevent shaft is exactly horizontal in relation to the moving air.

undesired pitching and yawing.

The effects of each of these four elements of torque vary in value with changes in flight situations. In one phase of flight, one of these elements may be more prominent than another. In another phase of flight, another element may be Applied force Effective more prominent. The relationship of these values to each force other varies with different aircraft depending on the airframe, engine, and propeller combinations, as well as other design Yaw Resultant features. To maintain positive control of the aircraft in all force flight conditions, the pilot must apply the flight controls as necessary to compensate for these varying values.

Figure 5-50. Raising tail produces gyroscopic precession.

5-32 Load Factors in Aircraft Design Load on Load on upward moving upward moving The answer to the question “How strong should an aircraft propeller blade propeller blade be?” is determined largely by the use to which the aircraft is subjected. This is a difficult problem because the maximum possible loads are much too high for use in efficient design.

It is true that any pilot can make a very hard landing or an extremely sharp pull up from a dive, which would result in abnormal loads. However, such extremely abnormal loads must be dismissed somewhat if aircraft are built that take off Load on Load on downward moving downward moving quickly, land slowly, and carry worthwhile payloads.

propeller blade propeller blade Low angle of attack High angle of attack The problem of load factors in aircraft design becomes how to determine the highest load factors that can be expected in Figure 5-51. Asymmetrical loading of propeller (P-factor).

normal operation under various operational situations. These load factors are called “limit load factors.” For reasons of safety, it is required that the aircraft be designed to withstand Load Factors these load factors without any structural damage. Although In aerodynamics, the maximum load factor (at given bank the Code of Federal Regulations (CFR) requires the aircraft angle) is a proportion between lift and weight and has a structure be capable of supporting one and one-half times trigonometric relationship. The load factor is measured in these limit load factors without failure, it is accepted that Gs (acceleration of gravity), a unit of force equal to the force parts of the aircraft may bend or twist under these loads and exerted by gravity on a body at rest and indicates the force to that some structural damage may occur.

which a body is subjected when it is accelerated. Any force applied to an aircraft to deflect its flight from a straight line This 1.5 load limit factor is called the “factor of safety” and produces a stress on its structure. The amount of this force provides, to some extent, for loads higher than those expected is the load factor. While a course in aerodynamics is not a under normal and reasonable operation. This strength reserve prerequisite for obtaining a pilot’s license, the competent is not something that pilots should willfully abuse; rather, it is pilot should have a solid understanding of the forces that act there for protection when encountering unexpected conditions.

on the aircraft, the advantageous use of these forces, and the operating limitations of the aircraft being flown.

The above considerations apply to all loading conditions, whether they be due to gusts, maneuvers, or landings. The For example, a load factor of 3 means the total load on an gust load factor requirements now in effect are substantially aircraft’s structure is three times its weight. Since load factors the same as those that have been in existence for years.

are expressed in terms of Gs, a load factor of 3 may be spoken Hundreds of thousands of operational hours have proven of as 3 Gs, or a load factor of 4 as 4 Gs.

them adequate for safety. Since the pilot has little control over gust load factors (except to reduce the aircraft’s speed when If an aircraft is pulled up from a dive, subjecting the pilot to rough air is encountered), the gust loading requirements are 3 Gs, he or she would be pressed down into the seat with a substantially the same for most general aviation type aircraft force equal to three times his or her weight. Since modern regardless of their operational use. Generally, the gust load aircraft operate at significantly higher speeds than older factors control the design of aircraft which are intended for aircraft, increasing the potential for large load factors, this strictly nonacrobatic usage.

effect has become a primary consideration in the design of the structure of all aircraft.

An entirely different situation exists in aircraft design with maneuvering load factors. It is necessary to discuss this matter With the structural design of aircraft planned to withstand separately with respect to: (1) aircraft designed in accordance only a certain amount of overload, a knowledge of load with the category system (i.e., normal, utility, acrobatic); and factors has become essential for all pilots. Load factors are (2) older designs built according to requirements that did not important for two reasons: provide for operational categories.

1. It is possible for a pilot to impose a dangerous overload on the aircraft structures.

Aircraft designed under the category system are readily identified by a placard in the flight deck, which states the 2. An increased load factor increases the stalling speed and operational category (or categories) in which the aircraft makes stalls possible at seemingly safe flight speeds.

5-33 is certificated. The maximum safe load factors (limit load slower the ROT. This compensates for added centrifugal factors) specified for aircraft in the various categories are: force, allowing the load factor to remain the same.

Figure 5-53 reveals an important fact about turns—the load CATEGORY LIMIT LOAD FACTOR factor increases at a terrific rate after a bank has reached Normal 3.8 to –1.52 45° or 50°. The load factor for any aircraft in a coordinated Utility (mild acrobatics, 4.4 to –1.76 level turn at 60° bank is 2 Gs. The load factor in an 80° bank including spins) is 5.76 Gs. The wing must produce lift equal to these load Acrobatic 6.0 to –3.00 factors if altitude is to be maintained.

For aircraft with gross weight of more than 4,000 pounds, It should be noted how rapidly the line denoting load factor the limit load factor is reduced. To the limit loads given rises as it approaches the 90° bank line, which it never quite above, a safety factor of 50 percent is added.

reaches because a 90° banked, constant altitude turn is not mathematically possible. An aircraft may be banked to 90° There is an upward graduation in load factor with the in a coordinated turn if not trying to hold altitude. An aircraft increasing severity of maneuvers. The category system that can be held in a 90° banked slipping turn is capable of provides for maximum utility of an aircraft. If normal straight knife-edged flight. At slightly more than 80°, the operation alone is intended, the required load factor (and load factor exceeds the limit of 6 Gs, the limit load factor of consequently the weight of the aircraft) is less than if the an acrobatic aircraft.

aircraft is to be employed in training or acrobatic maneuvers as they result in higher maneuvering loads.

For a coordinated, constant altitude turn, the approximate maximum bank for the average general aviation aircraft is 60°.

Aircraft that do not have the category placard are designs that This bank and its resultant necessary power setting reach the were constructed under earlier engineering requirements in limit of this type of aircraft. An additional 10° bank increases which no operational restrictions were specifically given to the load factor by approximately 1 G, bringing it close to the the pilots. For aircraft of this type (up to weights of about yield point established for these aircraft. [Figure 5-54] 4,000 pounds), the required strength is comparable to present- day utility category aircraft, and the same types of operation Load Factors and Stalling Speeds are permissible. For aircraft of this type over 4,000 pounds, Any aircraft, within the limits of its structure, may be stalled the load factors decrease with weight. These aircraft should at any airspeed. When a sufficiently high AOA is imposed, be regarded as being comparable to the normal category the smooth flow of air over an airfoil breaks up and separates, aircraft designed under the category system, and they should producing an abrupt change of flight characteristics and a be operated accordingly.

sudden loss of lift, which results in a stall.

Load Factors in Steep Turns A study of this effect has revealed that an aircraft’s stalling At a constant altitude, during a coordinated turn in any speed increases in proportion to the square root of the aircraft, the load factor is the result of two forces: centrifugal force and weight. [Figure 5-52] For any given bank angle, the ROT varies with the airspeed—the higher the speed, the ° ° 0 5 ° ° 0 4 ° Centrifugal ° force = 1.73 Gs Load factor (G units) Load factor = 2 Gs 0° 10° 20° 30° 40° 50° 60° 70° 80° 90° Gravity = 1G Bank angle Figure 5-52. Two forces cause load factor during turns.

Figure 5-53. Angle of bank changes load factor in level flight.

5-34 load factor. This means that an aircraft with a normal This speed is called the “design maneuvering speed” (V ), A unaccelerated stalling speed of 50 knots can be stalled at 100 which is the speed below which you can move a single knots by inducing a load factor of 4 Gs. If it were possible flight control, one time, to its full deflection, for one axis for this aircraft to withstand a load factor of nine, it could of airplane rotation only (pitch, roll or yaw), in smooth be stalled at a speed of 150 knots. A pilot should be aware air, without risk of damage to the airplane. V must be A of the following: entered in the FAA-approved Airplane Flight Manual/ Pilot’s Operating Handbook (AFM/POH) of all recently • The danger of inadvertently stalling the aircraft by designed airplanes. For older general aviation airplanes, increasing the load factor, as in a steep turn or spiral; this speed is approximately 1.7 times the normal stalling • When intentionally stalling an aircraft above its speed. Thus, an older airplane that normally stalls at 60 design maneuvering speed, a tremendous load factor knots must never be stalled at above 102 knots (60 knots × is imposed.

1.7 = 102 knots). An airplane with a normal stalling speed of 60 knots stalled at 102 knots undergoes a load factor Figures 5-53 and 5-54 show that banking an aircraft greater equal to the square of the increase in speed, or 2.89 Gs (1.7 than 72° in a steep turn produces a load factor of 3, and the × 1.7 = 2.89 Gs). (The above figures are approximations to stalling speed is increased significantly. If this turn is made be considered as a guide, and are not the exact answers to in an aircraft with a normal unaccelerated stalling speed of any set of problems. The design maneuvering speed should 45 knots, the airspeed must be kept greater than 75 knots to be determined from the particular airplane’s operating prevent inducing a stall. A similar effect is experienced in a limitations provided by the manufacturer.) Operating at or quick pull up or any maneuver producing load factors above below design maneuvering speed does not provide structural 1 G. This sudden, unexpected loss of control, particularly in protection against multiple full control inputs in one axis or a steep turn or abrupt application of the back elevator control full control inputs in more than one axis at the same time.

near the ground, has caused many accidents.

Since the leverage in the control system varies with different Since the load factor is squared as the stalling speed doubles, aircraft (some types employ “balanced” control surfaces while tremendous loads may be imposed on structures by stalling others do not), the pressure exerted by the pilot on the controls an aircraft at relatively high airspeeds.

cannot be accepted as an index of the load factors produced in different aircraft. In most cases, load factors can be judged The following information primarily applies to fixed-wing by the experienced pilot from the feel of seat pressure. Load airplanes. The maximum speed at which an airplane may factors can also be measured by an instrument called an be stalled safely is now determined for all new designs.

“accelerometer,” but this instrument is not common in general 40 40 s 5 50 50 60 60 70 70 80 80 s 100 100 120 120 150 150 Unaccelerated stall speed Ratio of acceleration V to unaccelerated V 0 1 2 3 4 5 6 7 8 20 40 60 80 100 120 140 160 180 200 220 240 260 “G” Load Accelerated stall speed Figure 5-54. Load factor changes stall speed.

5-35 aviation training aircraft. The development of the ability to factor. Abrupt pull ups at high diving speeds may impose judge load factors from the feel of their effect on the body is critical loads on aircraft structures and may produce recurrent important. A knowledge of these principles is essential to the or secondary stalls by increasing the AOA to that of stalling.

development of the ability to estimate load factors.

As a generalization, a recovery from a stall made by diving A thorough knowledge of load factors induced by varying only to cruising or design maneuvering airspeed, with a degrees of bank and the V aids in the prevention of two of gradual pull up as soon as the airspeed is safely above stalling, A the most serious types of accidents: can be effected with a load factor not to exceed 2 or 2.5 Gs. A higher load factor should never be necessary unless recovery 1. Stalls from steep turns or excessive maneuvering near has been effected with the aircraft’s nose near or beyond the the ground vertical attitude or at extremely low altitudes to avoid diving 2. Structural failures during acrobatics or other violent into the ground.

maneuvers resulting from loss of control Spins Load Factors and Flight Maneuvers A stabilized spin is not different from a stall in any element Critical load factors apply to all flight maneuvers except other than rotation and the same load factor considerations unaccelerated straight flight where a load factor of 1 G is apply to spin recovery as apply to stall recovery. Since spin always present. Certain maneuvers considered in this section recoveries are usually effected with the nose much lower than is are known to involve relatively high load factors. Full common in stall recoveries, higher airspeeds and consequently application of pitch, roll, or yaw controls should be confined higher load factors are to be expected. The load factor in a to speeds below the maneuvering speed. Avoid rapid and proper spin recovery usually is found to be about 2.5 Gs.

large alternating control inputs, especially in combination with large changes in pitch, roll, or yaw (e.g., large sideslip The load factor during a spin varies with the spin characteristics angles) as they may result in structural failures at any speed, of each aircraft, but is usually found to be slightly above the including below V .

A 1 G of level flight. There are two reasons for this: 1. Airspeed in a spin is very low, usually within 2 knots Turns of the unaccelerated stalling speeds.

Increased load factors are a characteristic of all banked 2. An aircraft pivots, rather than turns, while it is in a spin.

turns. As noted in the section on load factors in steep turns, load factors become significant to both flight performance and load on wing structure as the bank increases beyond High Speed Stalls approximately 45°.

The average light plane is not built to withstand the repeated application of load factors common to high speed stalls.

The yield factor of the average light plane is reached The load factor necessary for these maneuvers produces a at a bank of approximately 70° to 75°, and the stalling stress on the wings and tail structure, which does not leave speed is increased by approximately one-half at a bank of a reasonable margin of safety in most light aircraft.

approximately 63°.

The only way this stall can be induced at an airspeed above Stalls normal stalling involves the imposition of an added load The normal stall entered from straight-and-level flight, or an factor, which may be accomplished by a severe pull on the unaccelerated straight climb, does not produce added load elevator control. A speed of 1.7 times stalling speed (about factors beyond the 1 G of straight-and-level flight. As the 102 knots in a light aircraft with a stalling speed of 60 knots) stall occurs, however, this load factor may be reduced toward produces a load factor of 3 Gs. Only a very narrow margin zero, the factor at which nothing seems to have weight. The for error can be allowed for acrobatics in light aircraft. To pilot experiences a sensation of “floating free in space.” If illustrate how rapidly the load factor increases with airspeed, recovery is effected by snapping the elevator control forward, a high-speed stall at 112 knots in the same aircraft would negative load factors (or those that impose a down load on produce a load factor of 4 Gs.

the wings and raise the pilot from the seat) may be produced.

Chandelles and Lazy Eights During the pull up following stall recovery, significant A chandelle is a maximum performance climbing turn load factors are sometimes induced. These may be further beginning from approximately straight-and-level flight, increased inadvertently during excessive diving (and and ending at the completion of a precise 180° turn in a consequently high airspeed) and abrupt pull ups to level wings-level, nose-high attitude at the minimum controllable flight. One usually leads to the other, thus increasing the load 5-36 airspeed. In this flight maneuver, the aircraft is in a steep capable of a wide range of speeds and altitudes. It is important climbing turn and almost stalls to gain altitude while changing for the pilot to remember that the maximum “never-exceed” direction. A lazy eight derives its name from the manner in placard dive speeds are determined for smooth air only. High which the extended longitudinal axis of the aircraft is made speed dives or acrobatics involving speed above the known to trace a flight pattern in the form of a figure “8” lying on maneuvering speed should never be practiced in rough or its side. It would be difficult to make a definite statement turbulent air.

concerning load factors in these maneuvers as both involve smooth, shallow dives and pull-ups. The load factors incurred Vg Diagram depend directly on the speed of the dives and the abruptness The flight operating strength of an aircraft is presented of the pull-ups during these maneuvers.

on a graph whose vertical scale is based on load factor.

[Figure 5-55] The diagram is called a Vg diagram—velocity Generally, the better the maneuver is performed, the less versus G loads or load factor. Each aircraft has its own Vg extreme the load factor induced. A chandelle or lazy eight diagram that is valid at a certain weight and altitude.

in which the pull-up produces a load factor greater than 2 Gs will not result in as great a gain in altitude; in low-powered The lines of maximum lift capability (curved lines) are the aircraft, it may result in a net loss of altitude.

first items of importance on the Vg diagram. The aircraft in Figure 5-53 is capable of developing no more than +1 G at The smoothest pull-up possible, with a moderate load factor, 64 mph, the wing level stall speed of the aircraft. Since the delivers the greatest gain in altitude in a chandelle and results maximum load factor varies with the square of the airspeed, in a better overall performance in both chandelles and lazy the maximum positive lift capability of this aircraft is 2 G at eights. The recommended entry speed for these maneuvers 92 mph, 3 G at 112 mph, 4.4 G at 137 mph, and so forth. Any is generally near the manufacturer’s design maneuvering load factor above this line is unavailable aerodynamically speed, which allows maximum development of load factors (i.e., the aircraft cannot fly above the line of maximum lift without exceeding the load limits.

capability because it stalls). The same situation exists for negative lift flight with the exception that the speed necessary Rough Air to produce a given negative load factor is higher than that to All standard certificated aircraft are designed to withstand produce the same positive load factor.

loads imposed by gusts of considerable intensity. Gust load factors increase with increasing airspeed, and the strength used If the aircraft is flown at a positive load factor greater than the for design purposes usually corresponds to the highest level positive limit load factor of 4.4, structural damage is possible.

flight speed. In extremely rough air, as in thunderstorms or When the aircraft is operated in this region, objectionable frontal conditions, it is wise to reduce the speed to the design permanent deformation of the primary structure may take place maneuvering speed. Regardless of the speed held, there may and a high rate of fatigue damage is incurred. Operation above be gusts that can produce loads that exceed the load limits.

the limit load factor must be avoided in normal operation.

Each specific aircraft is designed with a specific G loading There are two other points of importance on the Vg diagram.

that can be imposed on the aircraft without causing structural One point is the intersection of the positive limit load factor damage. There are two types of load factors factored into and the line of maximum positive lift capability. The airspeed aircraft design: limit load and ultimate load. The limit load at this point is the minimum airspeed at which the limit load is a force applied to an aircraft that causes a bending of the can be developed aerodynamically. Any airspeed greater than aircraft structure that does not return to the original shape. this provides a positive lift capability sufficient to damage The ultimate load is the load factor applied to the aircraft the aircraft. Conversely, any airspeed less than this does not beyond the limit load and at which point the aircraft material provide positive lift capability sufficient to cause damage experiences structural failure (breakage). Load factors lower from excessive flight loads. The usual term given to this speed than the limit load can be sustained without compromising is “maneuvering speed,” since consideration of subsonic the integrity of the aircraft structure.

aerodynamics would predict minimum usable turn radius or maneuverability to occur at this condition. The maneuver Speeds up to, but not exceeding, the maneuvering speed speed is a valuable reference point, since an aircraft operating allow an aircraft to stall prior to experiencing an increase in below this point cannot produce a damaging positive flight load factor that would exceed the limit load of the aircraft.

load. Any combination of maneuver and gust cannot create damage due to excess airload when the aircraft is below the Most AFM/POH now include turbulent air penetration maneuver speed.

information, which help today’s pilots safely fly aircraft 5-37 Structural damage Maneuvering speed Structural failure l l a t Never exceed speed 3 s d e t a r e l e c c A Caution range Normal operating range Normal stall speed 1 Level flight at 1 G Load factor –1 –2 Structural Damage –3 20 40 60 80 100 120 140 160 180 200 220 240 Indicated airspeed (mph) Figure 5-55. Typical Vg diagram.

The other point of importance on the Vg diagram is the Rate of Turn intersection of the negative limit load factor and line of The rate of turn (ROT) is the number of degrees (expressed in maximum negative lift capability. Any airspeed greater than degrees per second) of heading change that an aircraft makes.

this provides a negative lift capability sufficient to damage The ROT can be determined by taking the constant of 1,091, the aircraft; any airspeed less than this does not provide multiplying it by the tangent of any bank angle and dividing negative lift capability sufficient to damage the aircraft from that product by a given airspeed in knots as illustrated in excessive flight loads.

Figure 5-55. If the airspeed is increased and the ROT desired is to be constant, the angle of bank must be increased, The limit airspeed (or redline speed) is a design reference point otherwise, the ROT decreases. Likewise, if the airspeed is for the aircraft—this aircraft is limited to 225 mph. If flight held constant, an aircraft’s ROT increases if the bank angle is attempted beyond the limit airspeed, structural damage or is increased. The formula in Figures 5-56 through 5-58 structural failure may result from a variety of phenomena.

depicts the relationship between bank angle and airspeed as they affect the ROT.

The aircraft in flight is limited to a regime of airspeeds and Gs that do not exceed the limit (or redline) speed, do NOTE: All airspeed discussed in this section is true airspeed not exceed the limit load factor, and cannot exceed the (TAS).

maximum lift capability. The aircraft must be operated within this “envelope” to prevent structural damage and Airspeed significantly effects an aircraft’s ROT. If airspeed is ensure the anticipated service lift of the aircraft is obtained.

increased, the ROT is reduced if using the same angle of bank The pilot must appreciate the Vg diagram as describing the used at the lower speed. Therefore, if airspeed is increased allowable combination of airspeeds and load factors for as illustrated in Figure 5-57, it can be inferred that the angle safe operation. Any maneuver, gust, or gust plus maneuver of bank must be increased in order to achieve the same ROT outside the structural envelope can cause structural damage achieved in Figure 5-58.

and effectively shorten the service life of the aircraft.

5-38 Example Suppose we wanted to know what bank angle 1,091 x tangent of the bank angle ROT = would give us a rate of turn of 5.25 ° per second airspeed (in knots) at 240 knots. A slight rearrangement of the formula would indicate it will take a 49 ° angle of bank to Example The rate of turn for an aircraft in a achieve the same ROT used at the lower airspeed coordinated turn of 30 ° and traveling at of 120 knots.

120 knots would have a ROT as follows.

1,091 x tangent of 30° 1,091 x tangent of X ROT = ROT (5.25) = 120 knots 240 knots 1,091 x 0.5773 (tangent of 30°) 240 x 5.25 = 1,091 x tangent of X ROT = 120 knots 240 x 5.25 = tangent of X 1,091 1.1549 = tangent of X ROT = 5.25 degrees per second 49° = X Figure 5-56. Rate of turn for a given airspeed (knots, TAS) and Figure 5-58. To achieve the same rate of turn of an aircraft traveling bank angle.

at 120 knots, an increase of bank angle is required.

What does this mean on a practicable side? If a given arc due to a greater speed. An aircraft traveling at 120 knots airspeed and bank angle produces a specific ROT, additional is able to turn a 360° circle in a tighter radius than an aircraft conclusions can be made. Knowing the ROT is a given number traveling at 240 knots. In order to compensate for the increase of degrees of change per second, the number of seconds it in airspeed, the bank angle would need to be increased.

takes to travel 360° (a circle) can be determined by simple division. For example, if moving at 120 knots with a 30° bank The radius of turn (R) can be computed using a simple angle, the ROT is 5.25° per second and it takes 68.6 seconds formula. The radius of turn is equal to the velocity squared (360° divided by 5.25 = 68.6 seconds) to make a complete (V ) divided by 11.26 times the tangent of the bank angle.

circle. Likewise, if flying at 240 knots TAS and using a 30° angle of bank, the ROT is only about 2.63° per second and it V takes about 137 seconds to complete a 360° circle. Looking at R = 11.26 × tangent of bank angle the formula, any increase in airspeed is directly proportional to the time the aircraft takes to travel an arc.

Using the examples provided in Figures 5-56 through 5-58, the turn radius for each of the two speeds can be computed.

So why is this important to understand? Once the ROT is understood, a pilot can determine the distance required to Note that if the speed is doubled, the radius is quadrupled.

make that particular turn, which is explained in radius of turn.

[Figures 5-59 and 5-60] Radius of Turn Another way to determine the radius of turn is speed using The radius of turn is directly linked to the ROT, which feet per second (fps), π (3.1415), and the ROT. In one of the explained earlier is a function of both bank angle and previous examples, it was determined that an aircraft with airspeed. If the bank angle is held constant and the airspeed a ROT of 5.25 degrees per second required 68.6 seconds to is increased, the radius of the turn changes (increases). A make a complete circle. An aircraft’s speed (in knots) can higher airspeed causes the aircraft to travel through a longer V R = 120 knots Example Suppose we were to increase the speed to 240 11.26 x tangent of bank angle knots, what is the ROT? Using the same formula from above we see that: R = 11.26 x tangent of 30° 1,091 x tangent of 30° 14,400 ROT = R = 240 knots 11.26 x 0.5773 ROT = 2.62 degrees per second R = 2,215 feet The radius of a turn required by an aircraft traveling at 120 knots An increase in speed causes a decrease in the and using a bank angle of 30° is 2,215 feet ROT when using the same bank angle.

Figure 5-59. Radius at 120 knots with bank angle of 30 ° .

Figure 5-57. Rate of turn when increasing speed.

5-39 of equal weight. Instead, do a full computation of all items V R = to be loaded on the aircraft, including baggage, as well as 240 knots 11.26 x tangent of bank angle the pilot and passenger. It is recommended that all bags be weighed to make a precise computation of how the aircraft R = 11.26 x tangent of 30° CG is positioned.

57,600 R = 11.26 x 0.57735 The importance of the CG was stressed in the discussion R = 8,861 feet of stability, controllability, and performance. Unequal load (four times the radius at 120 knots) distribution causes accidents. A competent pilot understands The radius of a turn required by an aircraft traveling at 240 knots and respects the effects of CG on an aircraft.

using the same bank angle in Figure 4-51 is 8,861 feet. Speed is a major factor in a turn.

Weight and balance are critical components in the utilization Figure 5-60. Radius at 240 knots.

of an aircraft to its fullest potential. The pilot must know how much fuel can be loaded onto the aircraft without violating CG limits, as well as weight limits to conduct be converted to fps by multiplying it by a constant of 1.69.

long or short flights with or without a full complement of Therefore, an aircraft traveling at 120 knots (TAS) travels allowable passengers. For example, an aircraft has four seats at 202.8 fps. Knowing the speed in fps (202.8) multiplied by and can carry 60 gallons of fuel. How many passengers can the time an aircraft takes to complete a circle (68.6 seconds) the aircraft safely carry? Can all those seats be occupied at can determine the size of the circle; 202.8 times 68.6 equals all times with the varying fuel loads? Four people who each 13,912 feet. Dividing by π yields a diameter of 4,428 feet, weigh 150 pounds leads to a different weight and balance which when divided by 2 equals a radius of 2,214 feet computation than four people who each weigh 200 pounds.

[Figure 5-61], a foot within that determined through use of The second scenario loads an additional 200 pounds onto the the formula in Figure 5-59.

aircraft and is equal to about 30 gallons of fuel.

In Figure 5-62, the pilot enters a canyon and decides to turn The additional weight may or may not place the CG outside 180° to exit. The pilot uses a 30° bank angle in his turn.

of the CG envelope, but the maximum gross weight could be exceeded. The excess weight can overstress the aircraft Weight and Balance and degrade the performance.

The aircraft’s weight and balance data is important information for a pilot that must be frequently reevaluated.

Aircraft are certificated for weight and balance for two Although the aircraft was weighed during the certification principal reasons: process, this information is not valid indefinitely. Equipment 1. The effect of the weight on the aircraft’s primary changes or modifications affect the weight and balance data.

Too often pilots reduce the aircraft weight and balance into structure and its performance characteristics a rule of thumb, such as: “If I have three passengers, I can 2. The effect of the location of this weight on flight load only 100 gallons of fuel; four passengers, 70 gallons.” characteristics, particularly in stall and spin recovery and stability Weight and balance computations should be part of every preflight briefing. Never assume three passengers are always Aircraft, such as balloons and weight-shift control, do not require weight and balance computations because the load is suspended below the lifting mechanism. The CG range r = speed (fps) x in these types of aircraft is such that it is difficult to exceed ROT Pi ( π ) loading limits. For example, the rear seat position and fuel of a weight-shift control aircraft are as close as possible to 202.8 x 68.6 the hang point with the aircraft in a suspended attitude. Thus, π r = load variations have little effect on the CG. This also holds true for the balloon basket or gondola. While it is difficult 13,912 to exceed CG limits in these aircraft, pilots should never π r = overload an aircraft because overloading causes structural damage and failures. Weight and balance computations are 4,428 r = = 2,214 feet not required, but pilots should calculate weight and remain within the manufacturer’s established limit.

Figure 5-61. Another formula that can be used for radius.

5-40

120 knots

I0 I0 I0 I0 TEST STBY PWR 4,430 feet 2,215 feet 5,000 feet 120 14,400 V R = = = 2,215 feet R = 11.26 x 0.5773 6.50096 11.26 x tangent of the bank angle 30°

140 knots

I0 I0 I0 I0 TEST STBY PWR 6,028 feet 3,014 feet f e e t 5 , 0 0 0 140 19,600 V R = = = 3,014 feet R = 11.26 x 0.5773 6.50096 11.26 x tangent of the bank angle 30° Figure 5-62. Two aircraft have flown into a canyon by error. The canyon is 5,000 feet across and has sheer cliffs on both sides. The pilot in the top image is flying at 120 knots. After realizing the error, the pilot banks hard and uses a 30 ° bank angle to reverse course. This aircraft requires about 4,000 feet to turn 180 ° , and makes it out of the canyon safely. The pilot in the bottom image is flying at 140 knots and also uses a 30 ° angle of bank in an attempt to reverse course. The aircraft, although flying just 20 knots faster than the aircraft in the top image, requires over 6,000 feet to reverse course to safety. Unfortunately, the canyon is only 5,000 feet across and the aircraft will hit the canyon wall. The point is that airspeed is the most influential factor in determining how much distance is required to turn. Many pilots have made the error of increasing the steepness of their bank angle when a simple reduction of speed would have been more appropriate.

5-41 Effect of Weight on Flight Performance a load of 3.8 times the approved gross weight of the aircraft without structural failure occurring. If this is accepted as The takeoff/climb and landing performance of an aircraft are indicative of the load factors that may be imposed during determined on the basis of its maximum allowable takeoff and operations for which the aircraft is intended, a 100-pound landing weights. A heavier gross weight results in a longer overload imposes a potential structural overload of 380 takeoff run and shallower climb, and a faster touchdown pounds. The same consideration is even more impressive speed and longer landing roll. Even a minor overload may in the case of utility and acrobatic category aircraft, which make it impossible for the aircraft to clear an obstacle that have load factor requirements of 4.4 and 6.0, respectively.

normally would not be a problem during takeoff under more favorable conditions.

Structural failures that result from overloading may be dramatic and catastrophic, but more often they affect The detrimental effects of overloading on performance are structural components progressively in a manner that not limited to the immediate hazards involved with takeoffs is difficult to detect and expensive to repair. Habitual and landings. Overloading has an adverse effect on all overloading tends to cause cumulative stress and damage climb and cruise performance, which leads to overheating that may not be detected during preflight inspections and during climbs, added wear on engine parts, increased fuel result in structural failure later during completely normal consumption, slower cruising speeds, and reduced range.

operations. The additional stress placed on structural parts by overloading is believed to accelerate the occurrence of The manufacturers of modern aircraft furnish weight and metallic fatigue failures.

balance data with each aircraft produced. Generally, this information may be found in the FAA-approved AFM/POH A knowledge of load factors imposed by flight maneuvers and easy-to-read charts for determining weight and balance and gusts emphasizes the consequences of an increase in the data are now provided. Increased performance and load- gross weight of an aircraft. The structure of an aircraft about to carrying capability of these aircraft require strict adherence undergo a load factor of 3 Gs, as in recovery from a steep dive, to the operating limitations prescribed by the manufacturer.

must be prepared to withstand an added load of 300 pounds Deviations from the recommendations can result in structural for each 100-pound increase in weight. It should be noted that damage or complete failure of the aircraft’s structure. Even this would be imposed by the addition of about 16 gallons if an aircraft is loaded well within the maximum weight of unneeded fuel in a particular aircraft. FAA-certificated limitations, it is imperative that weight distribution be civil aircraft have been analyzed structurally and tested for within the limits of CG location. The preceding brief study flight at the maximum gross weight authorized and within the of aerodynamics and load factors points out the reasons for speeds posted for the type of flights to be performed. Flights at this precaution. The following discussion is background weights in excess of this amount are quite possible and often information into some of the reasons why weight and balance are well within the performance capabilities of an aircraft.

conditions are important to the safe flight of an aircraft.

This fact should not mislead the pilot, as the pilot may not realize that loads for which the aircraft was not designed are In some aircraft, it is not possible to fill all seats, baggage being imposed on all or some part of the structure.

compartments, and fuel tanks, and still remain within approved weight or balance limits. For example, in several In loading an aircraft with either passengers or cargo, the popular four-place aircraft, the fuel tanks may not be filled to structure must be considered. Seats, baggage compartments, capacity when four occupants and their baggage are carried.

and cabin floors are designed for a certain load or In a certain two-place aircraft, no baggage may be carried concentration of load and no more. For example, a light in the compartment aft of the seats when spins are to be plane baggage compartment may be placarded for 20 pounds practiced. It is important for a pilot to be aware of the weight because of the limited strength of its supporting structure and balance limitations of the aircraft being flown and the even though the aircraft may not be overloaded or out of CG reasons for these limitations.

limits with more weight at that location.

Effect of Weight on Aircraft Structure Effect of Weight on Stability and Controllability The effect of additional weight on the wing structure of an Overloading also a ffects stability. An aircraft that is stable aircraft is not readily apparent. Airworthiness requirements and controllable when loaded normally may have very prescribe that the structure of an aircraft certificated in the different flight characteristics when overloaded. Although normal category (in which acrobatics are prohibited) must the distribution of weight has the most direct effect on this, be strong enough to withstand a load factor of 3.8 Gs to take an increase in the aircraft’s gross weight may be expected care of dynamic loads caused by maneuvering and gusts. This to have an adverse effect on stability, regardless of location means that the primary structure of the aircraft can withstand 5-42 of the CG. The stability of many certificated aircraft is permissible gross weight. Important among these effects completely unsatisfactory if the gross weight is exceeded. are changes in controllability, stability, and the actual load imposed on the wing.

Effect of Load Distribution The effect of the position of the CG on the load imposed Generally, an aircraft becomes less controllable, especially at slow flight speeds, as the CG is moved further aft. An on an aircraft’s wing in flight is significant to climb and cruising performance. An aircraft with forward loading is aircraft that cleanly recovers from a prolonged spin with the CG at one position may fail completely to respond to “heavier” and consequently, slower than the same aircraft with the CG further aft. normal recovery attempts when the CG is moved aft by one or two inches.

Figure 5-63 illustrates why this is true. With forward loading, It is common practice for aircraft designers to establish “nose-up” trim is required in most aircraft to maintain level cruising flight. Nose-up trim involves setting the tail surfaces an aft CG limit that is within one inch of the maximum, which allows normal recovery from a one-turn spin. When to produce a greater down load on the aft portion of the fuselage, which adds to the wing loading and the total lift certificating an aircraft in the utility category to permit intentional spins, the aft CG limit is usually established required from the wing if altitude is to be maintained. This requires a higher AOA of the wing, which results in more at a point several inches forward of that permissible for certification in the normal category.

drag and, in turn, produces a higher stalling speed.

Another factor affecting controllability, which has become With aft loading and “nose-down” trim, the tail surfaces exert less down load, relieving the wing of that much wing more important in current designs of large aircraft, is the effect of long moment arms to the positions of heavy loading and lift required to maintain altitude. The required AOA of the wing is less, so the drag is less, allowing for a equipment and cargo. The same aircraft may be loaded to maximum gross weight within its CG limits by concentrating faster cruise speed. Theoretically, a neutral load on the tail surfaces in cruising flight would produce the most efficient fuel, passengers, and cargo near the design CG, or by dispersing fuel and cargo loads in wingtip tanks and cargo overall performance and fastest cruising speed, but it would also result in instability. Modern aircraft are designed to bins forward and aft of the cabin.

require a down load on the tail for stability and controllability.

A zero indication on the trim tab control is not necessarily With the same total weight and CG, maneuvering the aircraft or maintaining level flight in turbulent air requires the same as “neutral trim” because of the force exerted by downwash from the wings and the fuselage on the tail surfaces. the application of greater control forces when the load is dispersed. The longer moment arms to the positions of the The effects of the distribution of the aircraft’s useful load heavy fuel and cargo loads must be overcome by the action of the control surfaces. An aircraft with full outboard wing have a significant influence on its flight characteristics, even when the load is within the CG limits and the maximum tanks or tip tanks tends to be sluggish in roll when control situations are marginal, while one with full nose and aft cargo bins tends to be less responsive to the elevator controls.

Load imposed by tail Gross weight The rearward CG limit of an aircraft is determined largely by considerations of stability. The original airworthiness CG requirements for a type certificate specify that an aircraft in flight at a certain speed dampens out vertical displacement of Stronger Center of lift Forward CG Down load on tail the nose within a certain number of oscillations. An aircraft loaded too far rearward may not do this. Instead, when the Load imposed by tail nose is momentarily pulled up, it may alternately climb and Gross weight dive becoming steeper with each oscillation. This instability is not only uncomfortable to occupants, but it could even become dangerous by making the aircraft unmanageable CG under certain conditions.

Lighter Down load on tail AFT CG The recovery from a stall in any aircraft becomes progressively more difficult as its CG moves aft. This is particularly Figure 5-63. Effect of load distribution on balance.

important in spin recovery, as there is a point in rearward 5-43 loading of any aircraft at which a “flat” spin develops. A • A forward CG location increases the need for greater flat spin is one in which centrifugal force, acting through a back elevator pressure. The elevator may no longer CG located well to the rear, pulls the tail of the aircraft out be able to oppose any increase in nose-down pitching.

away from the axis of the spin, making it impossible to get Adequate elevator control is needed to control the the nose down and recover. aircraft throughout the airspeed range down to the stall.

An aircraft loaded to the rear limit of its permissible CG A detailed discussion and additional information relating range handles differently in turns and stall maneuvers and to weight and balance can be found in Chapter 10, Weight has different landing characteristics than when it is loaded and Balance.

near the forward limit.

High Speed Flight The forward CG limit is determined by a number of Subsonic Versus Supersonic Flow considerations. As a safety measure, it is required that the In subsonic aerodynamics, the theory of lift is based upon the trimming device, whether tab or adjustable stabilizer, be forces generated on a body and a moving gas (air) in which capable of holding the aircraft in a normal glide with the power it is immersed. At speeds of approximately 260 knots or off. A conventional aircraft must be capable of a full stall, less, air can be considered incompressible in that, at a fixed power-off landing in order to ensure minimum landing speed altitude, its density remains nearly constant while its pressure in emergencies. A tailwheel-type aircraft loaded excessively varies. Under this assumption, air acts the same as water and nose-heavy is difficult to taxi, particularly in high winds. It is classified as a fluid. Subsonic aerodynamic theory also can be nosed over easily by use of the brakes, and it is difficult assumes the effects of viscosity (the property of a fluid that to land without bouncing since it tends to pitch down on the tends to prevent motion of one part of the fluid with respect wheels as it is slowed down and flared for landing. Steering to another) are negligible and classifies air as an ideal fluid difficulties on the ground may occur in nosewheel-type conforming to the principles of ideal-fluid aerodynamics such aircraft, particularly during the landing roll and takeoff. The as continuity, Bernoulli’s principle, and circulation.

effects of load distribution are summarized as follows: In reality, air is compressible and viscous. While the effects of • The CG position influences the lift and AOA of the wing, the amount and direction of force on the tail, these properties are negligible at low speeds, compressibility effects in particular become increasingly important as speed and the degree of deflection of the stabilizer needed to supply the proper tail force for equilibrium. The increases. Compressibility (and to a lesser extent viscosity) is of paramount importance at speeds approaching the speed of latter is very important because of its relationship to elevator control force. sound. In these speed ranges, compressibility causes a change in the density of the air around an aircraft.

• The aircraft stalls at a higher speed with a forward CG location. This is because the stalling AOA is reached During flight, a wing produces lift by accelerating the airflow at a higher speed due to increased wing loading.

over the upper surface. This accelerated air can, and does, • Higher elevator control forces normally exist with a reach sonic speeds even though the aircraft itself may be flying forward CG location due to the increased stabilizer subsonic. At some extreme AOAs, in some aircraft, the speed deflection required to balance the aircraft.

of the air over the top surface of the wing may be double the aircraft’s speed. It is therefore entirely possible to have both • The aircraft cruises faster with an aft CG location supersonic and subsonic airflow on an aircraft at the same time.

because of reduced drag. The drag is reduced because When flow velocities reach sonic speeds at some location on a smaller AOA and less downward deflection of the an aircraft (such as the area of maximum camber on the wing), stabilizer are required to support the aircraft and further acceleration results in the onset of compressibility overcome the nose-down pitching tendency.

effects, such as shock wave formation, drag increase, buffeting, • The aircraft becomes less stable as the CG is moved stability, and control difficulties. Subsonic flow principles are rearward. This is because when the CG is moved invalid at all speeds above this point. [Figure 5-64] rearward, it causes a decrease in the AOA. Therefore, the wing contribution to the aircraft’s stability is Speed Ranges now decreased, while the tail contribution is still The speed of sound varies with temperature. Under standard stabilizing. When the point is reached that the wing temperature conditions of 15 °C, the speed of sound at sea and tail contributions balance, then neutral stability level is 661 knots. At 40,000 feet, where the temperature is exists. Any CG movement further aft results in an –55 °C, the speed of sound decreases to 574 knots. In high unstable aircraft.

5-44 M is expressed in Mach number. The V limit is usually MO MO associated with operations at lower altitudes and deals with M = 0.50 structural loads and flutter. The M limit is associated with MO Maximum local velocity is less than sonic operations at higher altitudes and is usually more concerned with compressibility effects and flutter. At lower altitudes, Critical mach number structural loads and flutter are of concern; at higher altitudes, M = 0.72 compressibility effects and flutter are of concern.

Maximum local velocity equal to sonic Adherence to these speeds prevents structural problems due i c n o s r e Normal shock wave p w to dynamic pressure or flutter, degradation in aircraft control u o l f S Subsonic response due to compressibility effects (e.g., Mach Tuck, P o s s i b l e s e p M = 0.77 a r a t aileron reversal, or buzz), and separated airflow due to shock i o n waves resulting in loss of lift or vibration and buffet. Any of these phenomena could prevent the pilot from being able to Figure 5-64. Wing airflow.

adequately control the aircraft.

speed flight and/or high-altitude flight, the measurement of For example, an early civilian jet aircraft had a V limit of MO speed is expressed in terms of a “Mach number”—the ratio 306 KCAS up to approximately FL 310 (on a standard day).

of the true airspeed of the aircraft to the speed of sound in At this altitude (FL 310), an M of 0.82 was approximately MO the same atmospheric conditions. An aircraft traveling at equal to 306 KCAS. Above this altitude, an M of 0.82 MO the speed of sound is traveling at Mach 1.0. Aircraft speed always equaled a KCAS less than 306 KCAS and, thus, regimes are defined approximately as follows: became the operating limit as you could not reach the V MO Subsonic—Mach numbers below 0.75 limit without first reaching the M limit. For example, at MO FL 380, an M of 0.82 is equal to 261 KCAS.

Transonic—Mach numbers from 0.75 to 1.20 MO Supersonic—Mach numbers from 1.20 to 5.00 Mach Number Versus Airspeed Hypersonic—Mach numbers above 5.00 It is important to understand how airspeed varies with Mach number. As an example, consider how the stall speed of a While flights in the transonic and supersonic ranges are jet transport aircraft varies with an increase in altitude. The common occurrences for military aircraft, civilian jet aircraft increase in altitude results in a corresponding drop in air normally operate in a cruise speed range of Mach 0.7 to density and outside temperature. Suppose this jet transport Mach 0.90.

is in the clean configuration (gear and flaps up) and weighs 550,000 pounds. The aircraft might stall at approximately 152 The speed of an aircraft in which airflow over any part of KCAS at sea level. This is equal to (on a standard day) a true the aircraft or structure under consideration first reaches velocity of 152 KTAS and a Mach number of 0.23. At FL 380, (but does not exceed) Mach 1.0 is termed “critical Mach the aircraft will still stall at approximately 152 KCAS, but the number” or “Mach Crit.” Thus, critical Mach number is true velocity is about 287 KTAS with a Mach number of 0.50.

the boundary between subsonic and transonic flight and is largely dependent on the wing and airfoil design. Critical Mach number is an important point in transonic flight. When shock waves form on the aircraft, airflow separation followed by buffet and aircraft control difficulties can occur. Shock waves, buffet, and airflow separation take place above critical Mach number. A jet aircraft typically is most efficient when Force divergence Mach number cruising at or near its critical Mach number. At speeds 5–10 percent above the critical Mach number, compressibility (Drag coefficient) D Critical Mach number C = 0.3 effects begin. Drag begins to rise sharply. Associated with C L the “drag rise” are buffet, trim, and stability changes and a decrease in control surface effectiveness. This is the point 0.5 1.0 of “drag divergence.” [Figure 5-65] M (Mach number) V /M is defined as the maximum operating limit speed.

MO MO Figure 5-65. Critical Mach.

V is expressed in knots calibrated airspeed (KCAS), while MO 5-45 Although the stalling speed has remained the same for our earlier in the chapter, the layer of air over the wing’s surface purposes, both the Mach number and TAS have increased. that is slowed down or stopped by viscosity is the boundary With increasing altitude, the air density has decreased; this layer. There are two different types of boundary layer flow: requires a faster true airspeed in order to have the same laminar and turbulent.

pressure sensed by the pitot tube for the same KCAS, or KIAS (for our purposes, KCAS and KIAS are relatively close to Laminar Boundary Layer Flow each other). The dynamic pressure the wing experiences at The laminar boundary layer is a very smooth flow, while FL 380 at 287 KTAS is the same as at sea level at 152 KTAS.

the turbulent boundary layer contains swirls or eddies.

However, it is flying at higher Mach number.

The laminar flow creates less skin friction drag than the turbulent flow but is less stable. Boundary layer flow over a Another factor to consider is the speed of sound. A decrease wing surface begins as a smooth laminar flow. As the flow in temperature in a gas results in a decrease in the speed of continues back from the leading edge, the laminar boundary sound. Thus, as the aircraft climbs in altitude with outside layer increases in thickness.

temperature dropping, the speed of sound is dropping. At sea level, the speed of sound is approximately 661 KCAS, Turbulent Boundary Layer Flow while at FL 380 it is 574 KCAS. Thus, for our jet transport At some distance back from the leading edge, the smooth aircraft, the stall speed (in KTAS) has gone from 152 at sea laminar flow breaks down and transitions to a turbulent flow.

level to 287 at FL 380. Simultaneously, the speed of sound From a drag standpoint, it is advisable to have the transition (in KCAS) has decreased from 661 to 574 and the Mach from laminar to turbulent flow as far aft on the wing as number has increased from 0.23 (152 KTAS divided by 661 possible or have a large amount of the wing surface within KTAS) to 0.50 (287 KTAS divided by 574 KTAS). All the the laminar portion of the boundary layer. The low energy while, the KCAS for stall has remained constant at 152. This laminar flow, however, tends to break down more suddenly describes what happens when the aircraft is at a constant than the turbulent layer.

KCAS with increasing altitude, but what happens when the pilot keeps Mach constant during the climb? In normal jet Boundary Layer Separation flight operations, the climb is at 250 KIAS (or higher (e.g.

Another phenomenon associated with viscous flow is heavy)) to 10,000 feet and then at a specified en route climb separation. Separation occurs when the airflow breaks away airspeed (about 330 if a DC10) until reaching an altitude in from an airfoil. The natural progression is from laminar the “mid-twenties” where the pilot then climbs at a constant boundary layer to turbulent boundary layer and then to Mach number to cruise altitude.

airflow separation. Airflow separation produces high drag and ultimately destroys lift. The boundary layer separation Assuming for illustration purposes that the pilot climbs at a point moves forward on the wing as the AOA is increased.

M of 0.82 from sea level up to FL 380. KCAS goes from MO [Figure 5-66] 543 to 261. The KIAS at each altitude would follow the same behavior and just differ by a few knots. Recall from Vortex generators are used to delay or prevent shock wave the earlier discussion that the speed of sound is decreasing induced boundary layer separation encountered in transonic with the drop in temperature as the aircraft climbs. The Mach flight. They are small low aspect ratio airfoils placed at a 12° number is simply the ratio of the true airspeed to the speed to 15° AOA to the airstream. Usually spaced a few inches of sound at flight conditions. The significance of this is that apart along the wing ahead of the ailerons or other control at a constant Mach number climb, the KCAS (and KTAS or surfaces, vortex generators create a vortex that mixes the KIAS as well) is falling off.

boundary airflow with the high energy airflow just above the surface. This produces higher surface velocities and increases If the aircraft climbed high enough at this constant M MO the energy of the boundary layer. Thus, a stronger shock wave with decreasing KIAS, KCAS, and KTAS, it would begin to is necessary to produce airflow separation.

approach its stall speed. At some point, the stall speed of the aircraft in Mach number could equal the M of the aircraft, MO Shock Waves and the pilot could neither slow down (without stalling) nor When an airplane flies at subsonic speeds, the air ahead is speed up (without exceeding the max operating speed of the “warned” of the airplane’s coming by a pressure change aircraft). This has been dubbed the “coffin corner.” transmitted ahead of the airplane at the speed of sound.

Because of this warning, the air begins to move aside before Boundary Layer the airplane arrives and is prepared to let it pass easily. When The viscous nature of airflow reduces the local velocities on the airplane’s speed reaches the speed of sound, the pressure a surface and is responsible for skin friction. As discussed 5-46 Turbulent boundary layer Transition region Laminar boundary layer Laminar sublayer Figure 5-66. Boundary layer.

change can no longer warn the air ahead because the airplane part of the velocity energy of the airstream is converted to is keeping up with its own pressure waves. Rather, the air heat as it flows through the wave, is a contributing factor particles pile up in front of the airplane causing a sharp in the drag increase, but the drag resulting from airflow decrease in the flow velocity directly in front of the airplane separation is much greater. If the shock wave is strong, with a corresponding increase in air pressure and density. the boundary layer may not have sufficient kinetic energy to withstand airflow separation. The drag incurred in the As the airplane’s speed increases beyond the speed of sound, transonic region due to shock wave formation and airflow the pressure and density of the compressed air ahead of it separation is known as “wave drag.” When speed exceeds increase, the area of compression extending some distance the critical Mach number by about 10 percent, wave drag ahead of the airplane. At some point in the airstream, the air increases sharply. A considerable increase in thrust (power) particles are completely undisturbed, having had no advanced is required to increase flight speed beyond this point into the warning of the airplane’s approach, and in the next instant the supersonic range where, depending on the airfoil shape and same air particles are forced to undergo sudden and drastic the AOA, the boundary layer may reattach.

changes in temperature, pressure, density, and velocity.

The boundary between the undisturbed air and the region Normal shock waves form on the wing’s upper surface and of compressed air is called a shock or “compression” wave. form an additional area of supersonic flow and a normal shock This same type of wave is formed whenever a supersonic wave on the lower surface. As flight speed approaches the airstream is slowed to subsonic without a change in direction, speed of sound, the areas of supersonic flow enlarge and the such as when the airstream is accelerated to sonic speed shock waves move nearer the trailing edge. [Figure 5-67] over the cambered portion of a wing, and then decelerated to subsonic speed as the area of maximum camber is passed.

w l o f c i n o Normal shock wave s r A shock wave forms as a boundary between the supersonic e p u S and subsonic ranges.

M = 0.82 Whenever a shock wave forms perpendicular to the airflow, it Normal shock wave is termed a “normal” shock wave, and the flow immediately behind the wave is subsonic. A supersonic airstream passing w l o f c i through a normal shock wave experiences these changes: n o s r e p u S • The airstream is slowed to subsonic.

M = 0.95 • The airflow immediately behind the shock wave does not change direction.

• The static pressure and density of the airstream behind Bow wave the wave is greatly increased.

M = 1.05 • The energy of the airstream (indicated by total pressure—dynamic plus static) is greatly reduced.

Subsonic airflow Shock wave formation causes an increase in drag. One of the principal effects of a shock wave is the formation of a dense high pressure region immediately behind the wave. Figure 5-67. Shock waves.

The instability of the high pressure region, and the fact that 5-47 Associated with “drag rise” are buffet (known as Mach buffet), trim, and stability changes and a decrease in control force effectiveness. The loss of lift due to airflow separation results in a loss of downwash and a change in the position of the center pressure on the wing. Airflow separation produces a turbulent wake behind the wing, which causes the tail surfaces to buffet (vibrate). The nose-up and nose-down pitch control provided by the horizontal tail is dependent on the downwash behind the wing. Thus, an increase in downwash decreases the horizontal tail’s pitch control effectiveness since it effectively increases the AOA that the tail surface is seeing. Movement of the wing CP affects the wing pitching moment. If the CP moves aft, a diving moment referred to Spanwise flow as “Mach tuck” or “tuck under” is produced, and if it moves forward, a nose-up moment is produced. This is the primary reason for the development of the T-tail configuration on many turbine-powered aircraft, which places the horizontal stabilizer as far as practical from the turbulence of the wings.

Sweepback Most of the difficulties of transonic flight are associated with shock wave induced flow separation. Therefore, any means of delaying or alleviating the shock induced separation improves aerodynamic performance. One method is wing sweepback.

Airspeed sensed Sweepback theory is based upon the concept that it is only the by wing Mach 0.70 component of the airflow perpendicular to the leading edge True airspeed of the wing that affects pressure distribution and formation Mach 0.85 of shock waves. [Figure 5-68] On a straight wing aircraft, the airflow strikes the wing leading edge at 90°, and its full impact produces pressure and Figure 5-68. Sweepback effect.

lift. A wing with sweepback is struck by the same airflow at an angle smaller than 90°. This airflow on the swept wing has because the boundary layer tends to flow spanwise toward the effect of persuading the wing into believing that it is flying slower than it really is; thus the formation of shock waves is the tips and to separate near the leading edges. Because the tips of a swept wing are on the aft part of the wing (behind delayed. Advantages of wing sweep include an increase in critical Mach number, force divergence Mach number, and the CL), a wingtip stall causes the CL to move forward on the wing, forcing the nose to rise further. The tendency for the Mach number at which drag rise peaks. In other words, sweep delays the onset of compressibility effects. tip stall is greatest when wing sweep and taper are combined.

The Mach number that produces a sharp change in coefficient The stall situation can be aggravated by a T-tail configuration, which affords little or no pre-stall warning in the form of tail of drag is termed the “force divergence” Mach number and, for most airfoils, usually exceeds the critical Mach number by control surface buffet. [Figure 5-70] The T-tail, being above the wing wake remains effective even after the wing has begun 5 to 10 percent. At this speed, the airflow separation induced by shock wave formation can create significant variations in to stall, allowing the pilot to inadvertently drive the wing into a deeper stall at a much greater AOA. If the horizontal the drag, lift, or pitching moment coefficients. In addition to the delay of the onset of compressibility effects, sweepback tail surfaces then become buried in the wing’s wake, the elevator may lose all effectiveness, making it impossible to reduces the magnitude in the changes of drag, lift, or moment coefficients. In other words, the use of sweepback “softens” reduce pitch attitude and break the stall. In the pre-stall and immediate post-stall regimes, the lift/drag qualities of a swept the force divergence.

wing aircraft (specifically the enormous increase in drag at low speeds) can cause an increasingly descending flight A disadvantage of swept wings is that they tend to stall at the wingtips rather than at the wing roots. [Figure 5-69] This is path with no change in pitch attitude, further increasing the 5-48 to cause a low-speed Mach buffet. This very high AOA has the effect of increasing airflow velocity over the upper surface of the wing until the same effects of the shock waves and buffet occur as in the high-speed buffet situation. The AOA of the wing has the greatest effect on inducing the Mach buffet at either the high-speed or low-speed boundaries for the aircraft. The conditions that increase the AOA, the speed of the airflow over the wing, and chances of Mach buffet are: • High altitudes—the higher an aircraft flies, the thinner Pre-stall the air and the greater the AOA required to produce Prestall the lift needed to maintain level flight.

Figure 5-69. Wingtip pre-stall.

• Heavy weights—the heavier the aircraft, the greater the lift required of the wing, and all other factors being equal, the greater the AOA.

• G loading—an increase in the G loading on the aircraft has the same effect as increasing the weight of the aircraft. Whether the increase in G forces is caused by turns, rough control usage, or turbulence, the effect of increasing the wing’s AOA is the same.

Stalled Stalled High Speed Flight Controls On high-speed aircraft, flight controls are divided into Figure 5-70. T-tail stall.

primary flight controls and secondary or auxiliary flight controls. The primary flight controls maneuver the aircraft AOA. In this situation, without reliable AOA information, about the pitch, roll, and yaw axes. They include the ailerons, a nose-down pitch attitude with an increasing airspeed is no elevator, and rudder. Secondary or auxiliary flight controls guarantee that recovery has been affected, and up-elevator include tabs, leading edge flaps, trailing edge flaps, spoilers, movement at this stage may merely keep the aircraft stalled.

and slats.

It is a characteristic of T-tail aircraft to pitch up viciously Spoilers are used on the upper surface of the wing to spoil or when stalled in extreme nose-high attitudes, making reduce lift. High speed aircraft, due to their clean low drag recovery difficult or violent. The stick pusher inhibits this design, use spoilers as speed brakes to slow them down.

type of stall. At approximately one knot above stall speed, Spoilers are extended immediately after touchdown to dump pre-programmed stick forces automatically move the stick lift and thus transfer the weight of the aircraft from the wings forward, preventing the stall from developing. A G-limiter onto the wheels for better braking performance. [Figure 5-71] may also be incorporated into the system to prevent the pitch down generated by the stick pusher from imposing excessive Jet transport aircraft have small ailerons. The space for loads on the aircraft. A “stick shaker,” on the other hand, ailerons is limited because as much of the wing trailing provides stall warning when the airspeed is five to seven edge as possible is needed for flaps. Also, a conventional percent above stall speed.

size aileron would cause wing twist at high speed. For that reason, spoilers are used in unison with ailerons to provide Mach Buffet Boundaries additional roll control.

Mach buffet is a function of the speed of the airflow over the wing—not necessarily the speed of the aircraft. Any time that Some jet transports have two sets of ailerons, a pair of outboard too great a lift demand is made on the wing, whether from too low-speed ailerons and a pair of high-speed inboard ailerons.

fast an airspeed or from too high an AOA near the M , the When the flaps are fully retracted after takeoff, the outboard MO “high-speed” buffet occurs. There are also occasions when ailerons are automatically locked out in the faired position.

the buffet can be experienced at much lower speeds known as the “low-speed Mach buffet.” When used for roll control, the spoiler on the side of the up-going aileron extends and reduces the lift on that side, An aircraft flown at a speed too slow for its weight and causing the wing to drop. If the spoilers are extended as speed altitude necessitating a high AOA is the most likely situation brakes, they can still be used for roll control. If they are the 5-49 I n b o a r d w i n g Rudder Elevator Tab b o a r d w i n u t g O Stabilizer Foreflap Midflap Inboard flap Aftflap Flight spoilers Ground spoiler Outboard flap Aileron Tab Landing Flaps Aileron Leading edge slats a r d I n b o w i n g Leading edge flaps 737 Control Surfaces o a r d w i n u t b g O Stabilizer Control tab Elevator Inboard aileron Control tab Leading edge flaps Aileron Upper rudder Takeoff Flaps Anti-balance tabs Lower rudder Foreflap Midflap Aftflap Vortex generators Pitot tubes n b o a r d I w i n g Ground spoilers Inboard flaps o a r d w i n g t b u O Flight spoilers Outboard flap Leading edge slat Balance tab Leading edge flap Outboard aileron Slats Fence Aileron 727 Control Surfaces Flaps Retracted Figure 5-71. Control surfaces.

differential type, they extend further on one side and retract around the wing leading edge. The airflow tends to tear loose on the other side. If they are the non-differential type, they rather suddenly from the upper surface at a moderate AOA.

extend further on one side but do not retract on the other side. To utilize trailing edge flaps, and thus increase the C , L-MAX When fully extended as speed brakes, the non-differential the wing must go to a higher AOA without airflow separation.

spoilers remain extended and do not supplement the ailerons. Therefore, leading edge slots, slats, and flaps are used to improve the low-speed characteristics during takeoff, climb, To obtain a smooth stall and a higher AOA without airflow and landing. Although these devices are not as powerful as separation, the wing’s leading edge should have a well- trailing edge flaps, they are effective when used full span in rounded almost blunt shape that the airflow can adhere to combination with high-lift trailing edge flaps. With the aid at the higher AOA. With this shape, the airflow separation of these sophisticated high-lift devices, airflow separation is starts at the trailing edge and progresses forward gradually delayed and the C is increased considerably. In fact, a L-MAX as AOA is increased. 50 knot reduction in stall speed is not uncommon.

The pointed leading edge necessary for high-speed flight results in an abrupt stall and restricts the use of trailing edge flaps because the airflow cannot follow the sharp curve 5-50 The operational requirements of a large jet transport aircraft Chapter Summary necessitate large pitch trim changes. Some requirements are: In order to sustain an aircraft in flight, a pilot must understand • A large CG range how thrust, drag, lift, and weight act on the aircraft. By understanding the aerodynamics of flight, how design, • A large speed range weight, load factors, and gravity affect an aircraft during • The ability to perform large trim changes due to flight maneuvers from stalls to high speed flight, the pilot wing leading edge and trailing edge high-lift devices learns how to control the balance between these forces. For without limiting the amount of elevator remaining information on stall speeds, load factors, and other important • Maintaining trim drag to a minimum aircraft data, always consult the AFM/POH for specific information pertaining to the aircraft being flown.

These requirements are met by the use of a variable incidence horizontal stabilizer. Large trim changes on a fixed-tail aircraft require large elevator deflections. At these large deflections, little further elevator movement remains in the same direction. A variable incidence horizontal stabilizer is designed to take out the trim changes. The stabilizer is larger than the elevator, and consequently does not need to be moved through as large an angle. This leaves the elevator streamlining the tail plane with a full range of movement up and down. The variable incidence horizontal stabilizer can be set to handle the bulk of the pitch control demand, with the elevator handling the rest. On aircraft equipped with a variable incidence horizontal stabilizer, the elevator is smaller and less effective in isolation than it is on a fixed-tail aircraft.

In comparison to other flight controls, the variable incidence horizontal stabilizer is enormously powerful in its effect.

Because of the size and high speeds of jet transport aircraft, the forces required to move the control surfaces can be beyond the strength of the pilot. Consequently, the control surfaces are actuated by hydraulic or electrical power units. Moving the controls in the flight deck signals the control angle required, and the power unit positions the actual control surface. In the event of complete power unit failure, movement of the control surface can be affected by manually controlling the control tabs. Moving the control tab upsets the aerodynamic balance, which causes the control surface to move.

5-51

Chapter 6

Flight Controls

Introduction This chapter focuses on the flight control systems a pilot uses to control the forces of flight and the aircraft’s direction and attitude. It should be noted that flight control systems and characteristics can vary greatly depending on the type of aircraft flown. The most basic flight control system designs are mechanical and date back to early aircraft. They operate with a collection of mechanical parts, such as rods, cables, pulleys, and sometimes chains to transmit the forces of the flight deck controls to the control surfaces. Mechanical flight control systems are still used today in small general and sport category aircraft where the aerodynamic forces are not excessive. [Figure 6-1] 6-1 of this project is to develop an adaptive neural network-based Control stick flight control system. Applied directly to flight control system feedback errors, IFCS provides adjustments to improve Elevator aircraft performance in normal flight, as well as with system failures. With IFCS, a pilot is able to maintain control and Pulleys safely land an aircraft that has suffered a failure to a control surface or damage to the airframe. It also improves mission capability, increases the reliability and safety of flight, and eases the pilot workload.

Today’s aircraft employ a variety of flight control systems.

Cable Push rod For example, some aircraft in the sport pilot category rely on weight-shift control to fly while balloons use a standard burn Figure 6-1. Mechanical flight control system.

technique. Helicopters utilize a cyclic to tilt the rotor in the desired direction along with a collective to manipulate rotor pitch and anti-torque pedals to control yaw. [Figure 6-3] As aviation matured and aircraft designers learned more about aerodynamics, the industry produced larger and faster aircraft.

For additional information on flight control systems, refer Therefore, the aerodynamic forces acting upon the control to the appropriate handbook for information related to the surfaces increased exponentially. To make the control force flight control systems and characteristics of specific types required by pilots manageable, aircraft engineers designed of aircraft.

more complex systems. At first, hydromechanical designs, consisting of a mechanical circuit and a hydraulic circuit, were used to reduce the complexity, weight, and limitations Flight Control Systems of mechanical flight controls systems. [Figure 6-2] Flight Controls Aircraft flight control systems consist of primary and As aircraft became more sophisticated, the control surfaces secondary systems. The ailerons, elevator (or stabilator), were actuated by electric motors, digital computers, or fiber and rudder constitute the primary control system and are optic cables. Called “fly-by-wire,” this flight control system required to control an aircraft safely during flight. Wing flaps, replaces the physical connection between pilot controls and leading edge devices, spoilers, and trim systems constitute the flight control surfaces with an electrical interface. In the secondary control system and improve the performance addition, in some large and fast aircraft, controls are boosted characteristics of the airplane or relieve the pilot of excessive by hydraulically or electrically actuated systems. In both control forces.

the fly-by-wire and boosted controls, the feel of the control reaction is fed back to the pilot by simulated means.

Primary Flight Controls Aircraft control systems are carefully designed to provide Current research at the National Aeronautics and Space adequate responsiveness to control inputs while allowing a Administration (NASA) Dryden Flight Research Center involves Intelligent Flight Control Systems (IFCS). The goal Yaw Yaw Neutral Cyclic Cyclic Control stick (AFT—nose up) Collective Collective Cyclic stick LEGEND Hydraulic pressure Hydraulic return Pivot point Yaw Yaw Cyclic Elevator (UP) Control cables Control valves Cyclic Collective Collective Neutral Anti-torque pedals Collective lever Power cylinder Neutral Power disconnect linkage Figure 6-2. Hydromechanical flight control system. Figure 6-3. Helicopter flight control system.

6-2 natural feel. At low airspeeds, the controls usually feel soft Ailerons and sluggish, and the aircraft responds slowly to control Ailerons control roll about the longitudinal axis. The ailerons applications. At higher airspeeds, the controls become are attached to the outboard trailing edge of each wing and increasingly firm and aircraft response is more rapid.

move in the opposite direction from each other. Ailerons are connected by cables, bellcranks, pulleys, and/or push-pull Movement of any of the three primary flight control surfaces tubes to a control wheel or control stick.

(ailerons, elevator or stabilator, or rudder), changes the airflow and pressure distribution over and around the airfoil.

Moving the control wheel, or control stick, to the right These changes affect the lift and drag produced by the airfoil/ causes the right aileron to deflect upward and the left aileron control surface combination, and allow a pilot to control the to deflect downward. The upward deflection of the right aircraft about its three axes of rotation. aileron decreases the camber resulting in decreased lift on the right wing. The corresponding downward deflection of Design features limit the amount of deflection of flight the left aileron increases the camber resulting in increased control surfaces. For example, control-stop mechanisms may lift on the left wing. Thus, the increased lift on the left wing be incorporated into the flight control linkages, or movement and the decreased lift on the right wing causes the aircraft of the control column and/or rudder pedals may be limited.

to roll to the right.

The purpose of these design limits is to prevent the pilot from inadvertently overcontrolling and overstressing the aircraft Adverse Yaw during normal maneuvers.

Since the downward deflected aileron produces more lift as evidenced by the wing raising, it also produces more drag.

A properly designed aircraft is stable and easily controlled This added drag causes the wing to slow down slightly.

during normal maneuvering. Control surface inputs cause This results in the aircraft yawing toward the wing which movement about the three axes of rotation. The types of had experienced an increase in lift (and drag). From the stability an aircraft exhibits also relate to the three axes of pilot’s perspective, the yaw is opposite the direction of the rotation. [Figure 6-4] bank. The adverse yaw is a result of differential drag and the slight difference in the velocity of the left and right wings.

Rudder—Yaw Elevator—Pitch [Figure 6-5] Lateral axis Vertical axis (directional (longitudinal Adverse yaw becomes more pronounced at low airspeeds.

stability) stability) At these slower airspeeds, aerodynamic pressure on control Aileron—Roll surfaces are low, and larger control inputs are required to Longitudinal axis (lateral stability) Lift Drag Primary Airplane Axes of Type of Lift Control Movement Rotation Stability Drag A Surface d v e r w y a s e Aileron Roll Longitudinal Lateral Elevator/ Pitch Lateral Longitudinal Stabilator Rudder Yaw Vertical Directional Figure 6-5. Adverse yaw is caused by higher drag on the outside Figure 6-4. Airplane controls, movement, axes of rotation, and wing that is producing more lift.

type of stability.

6-3 effectively maneuver the aircraft. As a result, the increase in aileron deflection causes an increase in adverse yaw. The A i l e r o n d e f l e c t e d u p yaw is especially evident in aircraft with long wing spans.

Application of the rudder is used to counteract adverse yaw. The amount of rudder control required is greatest at Differential aileron low airspeeds, high angles of attack, and with large aileron deflections. Like all control surfaces at lower airspeeds, the vertical stabilizer/rudder becomes less effective and magnifies the control problems associated with adverse yaw.

Aileron deflected down All turns are coordinated by use of ailerons, rudder, and Figure 6-6 . Differential ailerons.

elevator. Applying aileron pressure is necessary to place the aircraft in the desired angle of bank, while simultaneous the drag created by the lowered aileron on the opposite wing application of rudder pressure is necessary to counteract the and reduces adverse yaw. [Figure 6-7] resultant adverse yaw. Additionally, because more lift is required during a turn than during straight-and-level flight, The frise-type aileron also forms a slot so air flows smoothly the angle of attack (AOA) must be increased by applying over the lowered aileron, making it more effective at high elevator back pressure. The steeper the turn, the more elevator angles of attack. Frise-type ailerons may also be designed back pressure that is needed.

to function differentially. Like the differential aileron, the frise-type aileron does not eliminate adverse yaw entirely.

As the desired angle of bank is established, aileron and Coordinated rudder application is still needed when ailerons rudder pressures should be relaxed. This stops the angle of are applied.

bank from increasing, because the aileron and rudder control surfaces are in a neutral and streamlined position. Elevator Coupled Ailerons and Rudder back pressure should be held constant to maintain altitude.

Coupled ailerons and rudder are linked controls. This is The roll-out from a turn is similar to the roll-in, except the accomplished with rudder-aileron interconnect springs, which flight controls are applied in the opposite direction. The help correct for aileron drag by automatically deflecting aileron and rudder are applied in the direction of the roll-out the rudder at the same time the ailerons are deflected. For or toward the high wing. As the angle of bank decreases, the elevator back pressure should be relaxed as necessary Neutral to maintain altitude.

In an attempt to reduce the effects of adverse yaw, manufacturers have engineered four systems: differential ailerons, frise-type ailerons, coupled ailerons and rudder, and flaperons.

Raised Differential Ailerons With differential ailerons, one aileron is raised a greater distance than the other aileron and is lowered for a given movement of the control wheel or control stick. This produces an increase in drag on the descending wing. The greater drag results from deflecting the up aileron on the descending wing Drag to a greater angle than the down aileron on the rising wing.

Lowered While adverse yaw is reduced, it is not eliminated completely.

[Figure 6-6] Frise-Type Ailerons With a frise-type aileron, when pressure is applied to the control wheel, or control stick, the aileron that is being raised pivots on an offset hinge. This projects the leading edge of Figure 5-4. Frise-type ailerons.

Figure 6-7. Frise-type ailerons.

the aileron into the airflow and creates drag. It helps equalize 6-4 example, when the control wheel, or control stick, is moved to produce a left roll, the interconnect cable and spring pulls forward on the left rudder pedal just enough to prevent the nose of the aircraft from yawing to the right. The force applied to the rudder by the springs can be overridden if it becomes necessary to slip the aircraft. [Figure 6-8] Flaperons Flaperons combine both aspects of flaps and ailerons. In addition to controlling the bank angle of an aircraft like conventional ailerons, flaperons can be lowered together to function much the same as a dedicated set of flaps. The Figure 6-9. Flaperons on a Skystar Kitfox MK 7.

pilot retains separate controls for ailerons and flaps. A mixer is used to combine the separate pilot inputs into this single linkages. Aft movement of the control column deflects set of control surfaces called flaperons. Many designs that the trailing edge of the elevator surface up. This is usually incorporate flaperons mount the control surfaces away from referred to as the up-elevator position. [Figure 6-10] the wing to provide undisturbed airflow at high angles of attack and/or low airspeeds. [Figure 6-9] The up-elevator position decreases the camber of the elevator and creates a downward aerodynamic force, which is greater Elevator than the normal tail-down force that exists in straight-and The elevator controls pitch about the lateral axis. Like the level flight. The overall effect causes the tail of the aircraft ailerons on small aircraft, the elevator is connected to the to move down and the nose to pitch up. The pitching moment control column in the flight deck by a series of mechanical occurs about the center of gravity (CG). The strength of the pitching moment is determined by the distance between the CG and the horizontal tail surface, as well as by the Rudder deflects with ailerons aerodynamic effectiveness of the horizontal tail surface.

Moving the control column forward has the opposite effect.

In this case, elevator camber increases, creating more lift (less tail-down force) on the horizontal stabilizer/elevator.

This moves the tail upward and pitches the nose down. Again, the pitching moment occurs about the CG.

As mentioned earlier, stability, power, thrustline, and the position of the horizontal tail surfaces on the empennage are factors in elevator effectiveness controlling pitch. For n w Control column o aft d l i Up elevator a T CG N o s e u p Downward aerodynamic force Rudder/Aileron interconnecting springs Figure 6-10. The elevator is the primary control for changing the Figure 6-8. Coupled ailerons and rudder.

pitch attitude of an aircraft.

6-5 example, the horizontal tail surfaces may be attached near similar recovery problems are also found with conventional the lower part of the vertical stabilizer, at the midpoint, or tail aircraft with an aft CG. [Figure 6-11] Deep stalls can at the high point, as in the T-tail design. occur on any aircraft but are more likely to occur on aircraft with “T” tails as a high AOA may be more likely to place T-Tail the wings separated airflow into the path of the horizontal surface of the tail. Additionally, the distance between the In a T-tail configuration, the elevator is above most of the wings and the tail, the position of the engines (such as being effects of downwash from the propeller, as well as airflow mounted on the tail) may increase the susceptibility of deep around the fuselage and/or wings during normal flight stall events. Therefore a deep stall may be more prevalent conditions. Operation of the elevators in this undisturbed air on transport versus general aviation aircraft.

allows control movements that are consistent throughout most flight regimes. T-tail designs have become popular on many Since flight at a high AOA with a low airspeed and an aft light and large aircraft, especially those with aft fuselage- CG position can be dangerous, many aircraft have systems to mounted engines because the T-tail configuration removes compensate for this situation. The systems range from control the tail from the exhaust blast of the engines. Seaplanes and stops to elevator down springs. On transport category jets, stick amphibians often have T-tails in order to keep the horizontal pushers are commonly used. An elevator down spring assists in surfaces as far from the water as possible. An additional lowering the nose of the aircraft to prevent a stall caused by the benefit is reduced noise and vibration inside the aircraft.

aft CG position. The stall occurs because the properly trimmed airplane is flying with the elevator in a trailing edge down In comparison with conventional-tail aircraft, the elevator on a position, forcing the tail up and the nose down. In this unstable T-tail aircraft must be moved a greater distance to raise the nose condition, if the aircraft encounters turbulence and slows down a given amount when traveling at slow speeds. This is because further, the trim tab no longer positions the elevator in the nose- the conventional-tail aircraft has the downwash from the down position. The elevator then streamlines, and the nose of propeller pushing down on the tail to assist in raising the nose.

the aircraft pitches upward, possibly resulting in a stall.

Aircraft controls are rigged so that an increase in control force The elevator down spring produces a mechanical load on the is required to increase control travel. The forces required to elevator, causing it to move toward the nose-down position if not raise the nose of a T-tail aircraft are greater than the forces otherwise balanced. The elevator trim tab balances the elevator required to raise the nose of a conventional-tail aircraft.

down spring to position the elevator in a trimmed position.

Longitudinal stability of a trimmed aircraft is the same for When the trim tab becomes ineffective, the down spring drives both types of configuration, but the pilot must be aware that the elevator to a nose-down position. The nose of the aircraft the required control forces are greater at slow speeds during lowers, speed builds up, and a stall is prevented. [Figure 6-12] takeoffs, landings, or stalls than for similar size aircraft equipped with conventional tails.

The elevator must also have sufficient authority to hold the nose of the aircraft up during the roundout for a landing. In T-tail aircraft also require additional design considerations this case, a forward CG may cause a problem. During the to counter the problem of flutter. Since the weight of the landing flare, power is usually reduced, which decreases the horizontal surfaces is at the top of the vertical stabilizer, the moment arm created causes high loads on the vertical stabilizer that can result in flutter. Engineers must compensate for this by increasing the design stiffness of the vertical stabilizer, usually resulting in a weight penalty over conventional tail designs.

When flying at a very high AOA with a low airspeed and an aft CG, the T-tail aircraft may be more susceptible to a CG deep stall. In this condition, the wake of the wing impinges on the tail surface and renders it almost ineffective. The wing, if fully stalled, allows its airflow to separate right after the leading edge. The wide wake of decelerated, turbulent air blankets the horizontal tail and hence its effectiveness diminished significantly. In these circumstances, elevator or stabilator control is reduced (or perhaps eliminated) making it difficult to recover from the stall. It should be noted that an Figure 6-11. Aircraft with a T-tail design at a high AOA and an aft CG.

aft CG is often a contributing factor in these incidents, since 6-6 Antiservo tab Down spring Stabilator Pivot points Elevator Balance weight Pivot point Bell crank Figure 6-13. The stabilator is a one-piece horizontal tail surface that pivots up and down about a central hinge point.

Figure 6-12. When the aerodynamic efficiency of the horizontal tail surface is inadequate due to an aft CG condition, an elevator down of the main wings. In effect, the canard is an airfoil similar to spring may be used to supply a mechanical load to lower the nose.

the horizontal surface on a conventional aft-tail design. The difference is that the canard actually creates lift and holds airflow over the empennage. This, coupled with the reduced the nose up, as opposed to the aft-tail design which exerts landing speed, makes the elevator less effective.

downward force on the tail to prevent the nose from rotating downward. [Figure 6-14] As this discussion demonstrates, pilots must understand and follow proper loading procedures, particularly with regard The canard design dates back to the pioneer days of aviation.

to the CG position. More information on aircraft loading, Most notably, it was used on the Wright Flyer. Recently, the as well as weight and balance, is included in Chapter 10, canard configuration has regained popularity and is appearing Weight and Balance.

on newer aircraft. Canard designs include two types–one with a horizontal surface of about the same size as a normal aft-tail Stabilator design, and the other with a surface of the same approximate As mentioned in Chapter 3, Aircraft Structure, a stabilator is size and airfoil of the aft-mounted wing known as a tandem essentially a one-piece horizontal stabilizer that pivots from wing configuration. Theoretically, the canard is considered a central hinge point. When the control column is pulled more efficient because using the horizontal surface to help back, it raises the stabilator’s trailing edge, pulling the nose lift the weight of the aircraft should result in less drag for a of the aircraft. Pushing the control column forward lowers given amount of lift.

the trailing edge of the stabilator and pitches the nose of the aircraft down.

Because stabilators pivot around a central hinge point, they are extremely sensitive to control inputs and aerodynamic loads. Antiservo tabs are incorporated on the trailing edge to decrease sensitivity. They deflect in the same direction as the stabilator. This results in an increase in the force required to move the stabilator, thus making it less prone to pilot-induced overcontrolling. In addition, a balance weight is usually incorporated in front of the main spar. The balance weight may project into the empennage or may be incorporated on the forward portion of the stabilator tips. [Figure 6-13] Canard Figure 6-14. The Piaggio P180 includes a variable-sweep canard The canard design utilizes the concept of two lifting surfaces.

design that provides longitudinal stability about the lateral axis.

The canard functions as a horizontal stabilizer located in front 6-7 Rudder The rudder controls movement of the aircraft about its vertical axis. This motion is called yaw. Like the other primary control surfaces, the rudder is a movable surface hinged to a fixed surface in this case, to the vertical stabilizer or fin. The rudder is controlled by the left and right rudder pedals.

When the rudder is deflected into the airflow, a horizontal force is exerted in the opposite direction. [Figure 6-15] By pushing the left pedal, the rudder moves left. This alters the airflow around the vertical stabilizer/rudder and creates a sideward lift that moves the tail to the right and yaws the nose of the airplane to the left. Rudder effectiveness increases with speed; therefore, large deflections at low speeds and small Figure 6-16. Beechcraft Bonanza V35.

deflections at high speeds may be required to provide the desired reaction. In propeller-driven aircraft, any slipstream appropriate amount. The control system for the V-tail is more flowing over the rudder increases its effectiveness.

complex than the control system for a conventional tail. In addition, the V-tail design is more susceptible to Dutch roll V-Tail tendencies than a conventional tail, and total reduction in The V-tail design utilizes two slanted tail surfaces to perform drag is minimal.

the same functions as the surfaces of a conventional elevator and rudder configuration. The fixed surfaces act as both Secondary Flight Controls horizontal and vertical stabilizers. [Figure 6-16] Secondary flight control systems may consist of wing flaps, leading edge devices, spoilers, and trim systems.

The movable surfaces, which are usually called ruddervators, are connected through a special linkage that allows the control Flaps wheel to move both surfaces simultaneously. On the other Flaps are the most common high-lift devices used on aircraft.

hand, displacement of the rudder pedals moves the surfaces These surfaces, which are attached to the trailing edge of differentially, thereby providing directional control.

the wing, increase both lift and induced drag for any given AOA. Flaps allow a compromise between high cruising When both rudder and elevator controls are moved by the speed and low landing speed because they may be extended pilot, a control mixing mechanism moves each surface the when needed and retracted into the wing’s structure when not needed. There are four common types of flaps: plain, split, slotted, and Fowler flaps. [Figure 6-17] w Y a The plain flap is the simplest of the four types. It increases the airfoil camber, resulting in a significant increase in the coefficient of lift (C ) at a given AOA. At the same time, it L greatly increases drag and moves the center of pressure (CP) aft on the airfoil, resulting in a nose-down pitching moment.

Left rudder forward CG The split flap is deflected from the lower surface of the airfoil and produces a slightly greater increase in lift than the plain flap. More drag is created because of the turbulent air pattern produced behind the airfoil. When fully extended, both plain and split flaps produce high drag with little additional lift.

The most popular flap on aircraft today is the slotted flap.

Variations of this design are used for small aircraft, as well as for large ones. Slotted flaps increase the lift coefficient Left rudder A e r o e d c r y f o n a i c m significantly more than plain or split flaps. On small aircraft, the hinge is located below the lower surface of the flap, and Figure 6-15. The effect of left rudder pressure.

6-8 when the flap is lowered, a duct forms between the flap well Fowler flaps are a type of slotted flap. This flap design not in the wing and the leading edge of the flap. When the slotted only changes the camber of the wing, it also increases the flap is lowered, high energy air from the lower surface is wing area. Instead of rotating down on a hinge, it slides ducted to the flap’s upper surface. The high energy air from backwards on tracks. In the first portion of its extension, it the slot accelerates the upper surface boundary layer and increases the drag very little, but increases the lift a great delays airflow separation, providing a higher C . Thus, the deal as it increases both the area and camber. Pilots should L slotted flap produces much greater increases in maximum be aware that flap extension may cause a nose-up or down coefficient of lift (C ) than the plain or split flap. While pitching moment, depending on the type of aircraft, which L-MAX there are many types of slotted flaps, large aircraft often the pilot will need to compensate for, usually with a trim have double- and even triple-slotted flaps. These allow the adjustment. As the extension continues, the flap deflects maximum increase in drag without the airflow over the flaps downward. During the last portion of its travel, the flap separating and destroying the lift they produce. increases the drag with little additional increase in lift.

Leading Edge Devices Basic section High-lift devices also can be applied to the leading edge of the airfoil. The most common types are fixed slots, movable slats, leading edge flaps, and cuffs. [Figure 6-18] Fixed slots direct airflow to the upper wing surface and delay airflow separation at higher angles of attack. The slot does not Plain flap Fixed slot Split flap Movable slot Slotted flap Leading edge flap Fowler flap Leading edge cuff Slotted Fowler flap Figure 6-18. Leading edge high lift devices.

Figure 6-17. Five common types of flaps.

6-9 increase the wing camber, but allows a higher maximum C L because the stall is delayed until the wing reaches a greater AOA.

Movable slats consist of leading edge segments that move on tracks. At low angles of attack, each slat is held flush against the wing’s leading edge by the high pressure that forms at the wing’s leading edge. As the AOA increases, the high- pressure area moves aft below the lower surface of the wing, allowing the slats to move forward. Some slats, however, are pilot operated and can be deployed at any AOA. Opening a slat allows the air below the wing to flow over the wing’s upper surface, delaying airflow separation.

Leading edge flaps, like trailing edge flaps, are used to Figure 6-19. Spoilers reduce lift and increase drag during descent increase both C and the camber of the wings. This type and landing.

L-MAX of leading edge device is frequently used in conjunction with trailing edge flaps and can reduce the nose-down pitching variables. Trim systems are used to relieve the pilot of the movement produced by the latter. As is true with trailing edge need to maintain constant pressure on the flight controls, and flaps, a small increment of leading edge flaps increases lift usually consist of flight deck controls and small hinged devices to a much greater extent than drag. As flaps are extended, attached to the trailing edge of one or more of the primary flight drag increases at a greater rate than lift.

control surfaces. Designed to help minimize a pilot’s workload, trim systems aerodynamically assist movement and position of Leading edge cuffs, like leading edge flaps and trailing edge the flight control surface to which they are attached. Common flaps are used to increase both C and the camber of L-MAX types of trim systems include trim tabs, balance tabs, antiservo the wings. Unlike leading edge flaps and trailing edge flaps, tabs, ground adjustable tabs, and an adjustable stabilizer.

leading edge cuffs are fixed aerodynamic devices. In most cases, leading edge cuffs extend the leading edge down and Trim Tabs forward. This causes the airflow to attach better to the upper The most common installation on small aircraft is a single surface of the wing at higher angles of attack, thus lowering trim tab attached to the trailing edge of the elevator. Most trim an aircraft’s stall speed. The fixed nature of leading edge cuffs tabs are manually operated by a small, vertically mounted extracts a penalty in maximum cruise airspeed, but recent control wheel. However, a trim crank may be found in some advances in design and technology have reduced this penalty.

aircraft. The flight deck control includes a trim tab position indicator. Placing the trim control in the full nose-down Spoilers position moves the trim tab to its full up position. With Found on some fixed-wing aircraft, high drag devices called the trim tab up and into the airstream, the airflow over the spoilers are deployed from the wings to spoil the smooth horizontal tail surface tends to force the trailing edge of the airflow, reducing lift and increasing drag. On gliders, spoilers elevator down. This causes the tail of the aircraft to move are most often used to control rate of descent for accurate up and the nose to move down. [Figure 6-20] landings. On other aircraft, spoilers are often used for roll control, an advantage of which is the elimination of adverse If the trim tab is set to the full nose-up position, the tab moves yaw. To turn right, for example, the spoiler on the right wing to its full down position. In this case, the air flowing under the is raised, destroying some of the lift and creating more drag horizontal tail surface hits the tab and forces the trailing edge on the right. The right wing drops, and the aircraft banks of the elevator up, reducing the elevator’s AOA. This causes and yaws to the right. Deploying spoilers on both wings at the tail of the aircraft to move down and the nose to move up.

the same time allows the aircraft to descend without gaining speed. Spoilers are also deployed to help reduce ground roll In spite of the opposing directional movement of the trim after landing. By destroying lift, they transfer weight to the tab and the elevator, control of trim is natural to a pilot. If wheels, improving braking effectiveness. [Figure 6-19] the pilot needs to exert constant back pressure on a control column, the need for nose-up trim is indicated. The normal Trim Systems trim procedure is to continue trimming until the aircraft is Although an aircraft can be operated throughout a wide range balanced and the nose-heavy condition is no longer apparent.

of attitudes, airspeeds, and power settings, it can be designed to Pilots normally establish the desired power, pitch attitude, fly hands-off within only a very limited combination of these and configuration first, and then trim the aircraft to relieve 6-10 helps to move the entire flight control surface in the direction Nose-down trim that the pilot wishes it to go. A servo tab is a dynamic device that deploys to decrease the pilots work load and de-stabilize Elevator the aircraft. Servo tabs are sometimes referred to as flight tabs Trim tab and are used primarily on large aircraft. They aid the pilot in moving the control surface and in holding it in the desired position. Only the servo tab moves in response to movement of the pilot’s flight control, and the force of the airflow on the servo tab then moves the primary control surface.

Tab up—elevator down Antiservo Tabs Antiservo tabs work in the same manner as balance tabs Nose-up trim except, instead of moving in the opposite direction, they move in the same direction as the trailing edge of the stabilator.

Elevator In addition to decreasing the sensitivity of the stabilator, an Trim tab antiservo tab also functions as a trim device to relieve control pressure and maintain the stabilator in the desired position.

The fixed end of the linkage is on the opposite side of the surface from the horn on the tab; when the trailing edge of the stabilator moves up, the linkage forces the trailing edge of the tab up. When the stabilator moves down, the tab also moves Tab up—elevator up down. Conversely, trim tabs on elevators move opposite of the control surface. [Figure 6-21] Figure 6-20. The movement of the elevator is opposite to the direction of movement of the elevator trim tab.

Figure 5-16. The movement of the elevator is opposite to the Ground Adjustable Tabs direction of movement of the elevator trim tab.

Many small aircraft have a nonmovable metal trim tab on the control pressures that may exist for that flight condition. As rudder. This tab is bent in one direction or the other while on power, pitch attitude, or configuration changes, retrimming the ground to apply a trim force to the rudder. The correct is necessary to relieve the control pressures for the new displacement is determined by trial and error. Usually, small flight condition.

Balance Tabs The control forces may be excessively high in some aircraft, and, in order to decrease them, the manufacturer may use balance tabs. They look like trim tabs and are hinged in approximately the same places as trim tabs. The essential difference between the two is that the balancing tab is coupled to the control surface rod so that when the primary control surface is moved in any direction, the tab automatically moves in the opposite direction. The airflow striking the tab Stabilator counterbalances some of the air pressure against the primary control surface and enables the pilot to move the control more Pivot point easily and hold the control surface in position.

If the linkage between the balance tab and the fixed Antiservo tab surface is adjustable from the flight deck, the tab acts as a combination trim and balance tab that can be adjusted to a desired deflection.

Servo Tabs Figure 6-21. An antiservo tab attempts to streamline the control Servo tabs are very similar in operation and appearance to the surface and is used to make the stabilator less sensitive by opposing trim tabs previously discussed. A servo tab is a small portion the force exerted by the pilot.

of a flight control surface that deploys in such a way that it 6-11 adjustments are necessary until the aircraft no longer skids Adjustable stabilizer left or right during normal cruising flight. [Figure 6-22] Nose down Adjustable Stabilizer Nose up Rather than using a movable tab on the trailing edge of the Jackscrew elevator, some aircraft have an adjustable stabilizer. With this arrangement, linkages pivot the horizontal stabilizer about Pivot its rear spar. This is accomplished by the use of a jackscrew mounted on the leading edge of the stabilator. [Figure 6-23] On small aircraft, the jackscrew is cable operated with a trim Trim motor or trim cable wheel or crank. On larger aircraft, it is motor driven. The trimming effect and flight deck indications for an adjustable Figure 6-23. Some aircraft, including most jet transports, use an stabilizer are similar to those of a trim tab.

adjustable stabilizer to provide the required pitch trim forces.

Autopilot The autopilot system also incorporates a disconnect safety Autopilot is an automatic flight control system that keeps an feature to disengage the system automatically or manually.

aircraft in level flight or on a set course. It can be directed by These autopilots work with inertial navigation systems, the pilot, or it may be coupled to a radio navigation signal.

global positioning systems (GPS), and flight computers to Autopilot reduces the physical and mental demands on a pilot control the aircraft. In fly-by-wire systems, the autopilot is and increases safety. The common features available on an an integrated component.

autopilot are altitude and heading hold.

Additionally, autopilots can be manually overridden. Because The simplest systems use gyroscopic attitude indicators and autopilot systems differ widely in their operation, refer to magnetic compasses to control servos connected to the flight the autopilot operating instructions in the Airplane Flight control system. [Figure 6-24] The number and location of Manual (AFM) or the Pilot’s Operating Handbook (POH).

these servos depends on the complexity of the system. For example, a single-axis autopilot controls the aircraft about the Chapter Summary longitudinal axis and a servo actuates the ailerons. A three-axis Because flight control systems and aerodynamic autopilot controls the aircraft about the longitudinal, lateral, and characteristics vary greatly between aircraft, it is essential vertical axes. Three different servos actuate ailerons, elevator, that a pilot become familiar with the primary and secondary and rudder. More advanced systems often include a vertical flight control systems of the aircraft being flown. The speed and/or indicated airspeed hold mode. Advanced autopilot primary source of this information is the AFM or the POH.

systems are coupled to navigational aids through a flight director.

Various manufacturer and owner group websites can also be a valuable source of additional information.

Figure 6-24. Basic autopilot system integrated into the flight control system.

Figure 6-22. A ground adjustable tab is used on the rudder of many small airplanes to correct for a tendency to fly with the fuselage slightly misaligned with the relative wind.

6-12

Chapter 7

Aircraft Systems

Introduction This chapter covers the primary systems found on most aircraft. These include the engine, propeller, induction, ignition, as well as the fuel, lubrication, cooling, electrical, landing gear, and environmental control systems.

Powerplant An aircraft engine, or powerplant, produces thrust to propel an aircraft. Reciprocating engines and turboprop engines work in combination with a propeller to produce thrust.

Turbojet and turbofan engines produce thrust by increasing the velocity of air flowing through the engine. All of these powerplants also drive the various systems that support the operation of an aircraft.

7-1 Reciprocating Engines Most small aircraft are designed with reciprocating engines. The name is derived from the back-and-forth, or reciprocating, movement of the pistons that produces the mechanical energy necessary to accomplish work.

Driven by a revitalization of the general aviation (GA) industry and advances in both material and engine design, reciprocating engine technology has improved dramatically over the past two decades. The integration of computerized engine management systems has improved fuel efficiency, decreased emissions, and reduced pilot workload.

Reciprocating engines operate on the basic principle of converting chemical energy (fuel) into mechanical energy.

Figure 7-1. Radial engine.

This conversion occurs within the cylinders of the engine through the process of combustion. The two primary reciprocating engine designs are the spark ignition and the In-line engines have a comparatively small frontal area, but compression ignition. The spark ignition reciprocating engine their power-to-weight ratios are relatively low. In addition, has served as the powerplant of choice for many years. In the rearmost cylinders of an air-cooled, in-line engine an effort to reduce operating costs, simplify design, and receive very little cooling air, so these engines are normally improve reliability, several engine manufacturers are turning limited to four or six cylinders. V-type engines provide to compression ignition as a viable alternative. Often referred more horsepower than in-line engines and still retain a small to as jet fuel piston engines, compression ignition engines frontal area.

have the added advantage of utilizing readily available and lower cost diesel or jet fuel.

Continued improvements in engine design led to the development of the horizontally-opposed engine, which The main mechanical components of the spark ignition and remains the most popular reciprocating engines used on the compression ignition engine are essentially the same.

smaller aircraft. These engines always have an even number Both use cylindrical combustion chambers and pistons that of cylinders, since a cylinder on one side of the crankcase travel the length of the cylinders to convert linear motion “opposes” a cylinder on the other side. [Figure 7-2] The into the rotary motion of the crankshaft. The main difference majority of these engines are air cooled and usually are between spark ignition and compression ignition is the mounted in a horizontal position when installed on fixed-wing process of igniting the fuel. Spark ignition engines use a airplanes. Opposed-type engines have high power-to-weight spark plug to ignite a pre-mixed fuel-air mixture. (Fuel-air ratios because they have a comparatively small, lightweight mixture is the ratio of the “weight” of fuel to the “weight” crankcase. In addition, the compact cylinder arrangement of air in the mixture to be burned.) A compression ignition reduces the engine’s frontal area and allows a streamlined engine first compresses the air in the cylinder, raising its installation that minimizes aerodynamic drag.

temperature to a degree necessary for automatic ignition when fuel is injected into the cylinder.

These two engine designs can be further classified as: 1. Cylinder arrangement with respect to the crankshaft— radial, in-line, v-type, or opposed 2. Operating cycle—two or four 3. Method of cooling—liquid or air Radial engines were widely used during World War II and many are still in service today. With these engines, a row or Opposed cylinders rows of cylinders are arranged in a circular pattern around the crankcase. The main advantage of a radial engine is the favorable power-to-weight ratio. [Figure 7-1] Figure 7-2. Horizontally opposed engine.

7-2 Depending on the engine manufacturer, all of these arrangements can be designed to utilize spark or compression Cylinder ignition and operate on either a two- or four-stroke cycle.

In a two-stroke engine, the conversion of chemical energy into mechanical energy occurs over a two-stroke operating cycle. The intake, compression, power, and exhaust processes occur in only two strokes of the piston rather than the more common four strokes. Because a two-stroke engine has a power stroke upon each revolution of the crankshaft, it typically has higher power-to-weight ratio than a comparable Exhaust valve four-stroke engine. Due to the inherent inefficiency and Intake valve disproportionate emissions of the earliest designs, use of the two-stroke engine has been limited in aviation.

Recent advances in material and engine design have reduced many of the negative characteristics associated with two-stroke engines. Modern two-stroke engines often Spark plug use conventional oil sumps, oil pumps, and full pressure Piston fed lubrication systems. The use of direct fuel injection Crankcase and pressurized air, characteristic of advanced compression ignition engines, make two-stroke compression ignition engines a viable alternative to the more common four-stroke spark ignition designs. [Figure 7-3] Spark ignition four-stroke engines remain the most common design used in GA today. [Figure 7-4] The main parts of a Crankshaft Connecting rod spark ignition reciprocating engine include the cylinders, crankcase, and accessory housing. The intake/exhaust valves, spark plugs, and pistons are located in the cylinders. The Figure 7-4. Main components of a spark ignition reciprocating crankshaft and connecting rods are located in the crankcase.

engine.

The magnetos are normally located on the engine accessory housing.

In a four-stroke engine, the conversion of chemical energy into mechanical energy occurs over a four-stroke operating cycle.

The intake, compression, power, and exhaust processes occur Exhaust valve Fuel injector Forced air in four separate strokes of the piston in the following order.

1. The intake stroke begins as the piston starts its downward travel. When this happens, the intake valve opens and the fuel-air mixture is drawn into the cylinder.

2. The compression stroke begins when the intake valve closes, and the piston starts moving back to the top of Piston the cylinder. This phase of the cycle is used to obtain a much greater power output from the fuel-air mixture once it is ignited.

3. The power stroke begins when the fuel-air mixture is 1. Intake/compression ignited. This causes a tremendous pressure increase and exhaust 2. Power stroke in the cylinder and forces the piston downward away from the cylinder head, creating the power that turns Figure 7-3. Two-stroke compression ignition.

the crankshaft.

7-3 4. The exhaust stroke is used to purge the cylinder of of a diesel-fueled reciprocating engine lies in the physical burned gases. It begins when the exhaust valve opens, similarity of diesel and kerosene. Aircraft equipped with a and the piston starts to move toward the cylinder head diesel piston engine runs on standard aviation fuel kerosene, once again. which provides more independence, higher reliability, lower consumption, and operational cost saving.

Even when the engine is operated at a fairly low speed, the four-stroke cycle takes place several hundred times In 1999, Thielert formed Thielert Aircraft Engines (TAE) each minute. [Figure 7-5] In a four-cylinder engine, each to design, develop, certify, and manufacture a brand-new cylinder operates on a different stroke. Continuous rotation Jet-A-burning diesel cycle engine (also known as jet-fueled of a crankshaft is maintained by the precise timing of the piston engine) for the GA industry. By March 2001, the first power strokes in each cylinder. Continuous operation of the prototype engine became the first certified diesel engine engine depends on the simultaneous function of auxiliary since World War II. TAE continues to design and develop systems, including the induction, ignition, fuel, oil, cooling, diesel cycle engines and other engine manufacturers, such as and exhaust systems. Société de Motorisations Aéronautiques (SMA), now offer jet-fueled piston engines as well. TAE engines can be found The latest advance in aircraft reciprocating engines was on the Diamond DA40 single and the DA42 Twin Star; the pioneered in the mid-1960s by Frank Thielert, who looked first diesel engine to be part of the type certificate of a new to the automotive industry for answers on how to integrate original equipment manufacturer (OEM) aircraft.

diesel technology into an aircraft engine. The advantage These engines have also gained a toehold in the retrofit market with a supplemental type certificate (STC) to re- Exhaust valve Intake valve engine the Cessna 172 models and the Piper PA-28 family.

The jet-fueled piston engine’s technology has continued to progress and a full authority digital engine control (FADEC, discussed more fully later in the chapter) is standard on such equipped aircraft, which minimizes complication of engine control. By 2007, various jet-fueled piston aircraft had logged well over 600,000 hours of service.

Piston Spark plug Propeller The propeller is a rotating airfoil, subject to induced drag, stalls, and other aerodynamic principles that apply to any airfoil. It provides the necessary thrust to pull, or in some cases push, the aircraft through the air. The engine power is Crankshaft Connecting rod used to rotate the propeller, which in turn generates thrust very similar to the manner in which a wing produces lift.

1. Intake 2. Compression The amount of thrust produced depends on the shape of the airfoil, the angle of attack (AOA) of the propeller blade, and the revolutions per minute (rpm) of the engine. The propeller itself is twisted so the blade angle changes from hub to tip.

The greatest angle of incidence, or the highest pitch, is at the hub while the smallest angle of incidence or smallest pitch is at the tip. [Figure 7-6] The reason for the twist is to produce uniform lift from the hub to the tip. As the blade rotates, there is a difference in the actual speed of the various portions of the blade. The tip of the blade travels faster than the part near the hub, because the tip travels a greater distance than the hub in the same 3. Power 4. Exhaust length of time. [Figure 7-7] Changing the angle of incidence (pitch) from the hub to the tip to correspond with the speed produces uniform lift throughout the length of the blade. A Figure 7-5. The arrows in this illustration indicate the direction of propeller blade designed with the same angle of incidence motion of the crankshaft and piston during the four-stroke cycle.

7-4 installed depends upon its intended use. The climb propeller has a lower pitch, therefore less drag. Less drag results in higher rpm and more horsepower capability, which increases performance during takeoffs and climbs but decreases performance during cruising flight.

The cruise propeller has a higher pitch, therefore more drag. More drag results in lower rpm and less horsepower capability, which decreases performance during takeoffs and climbs but increases efficiency during cruising flight.

Figure 7-6. Changes in propeller blade angle from hub to tip.

The propeller is usually mounted on a shaft, which may be an extension of the engine crankshaft. In this case, the rpm throughout its entire length would be inefficient because as of the propeller would be the same as the crankshaft rpm. On airspeed increases in flight, the portion near the hub would some engines, the propeller is mounted on a shaft geared to have a negative AOA while the blade tip would be stalled.

the engine crankshaft. In this type, the rpm of the propeller Small aircraft are equipped with either one of two types of is different than that of the engine.

propellers: fixed-pitch or adjustable-pitch.

In a fixed-pitch propeller, the tachometer is the indicator of Fixed-Pitch Propeller engine power. [Figure 7-8] A tachometer is calibrated in A propeller with fixed blade angles is a fixed-pitch propeller.

hundreds of rpm and gives a direct indication of the engine The pitch of this propeller is set by the manufacturer and and propeller rpm. The instrument is color coded with a green cannot be changed. Since a fixed-pitch propeller achieves arc denoting the maximum continuous operating rpm. Some the best efficiency only at a given combination of airspeed tachometers have additional markings to reflect engine and/or and rpm, the pitch setting is ideal for neither cruise nor propeller limitations. The manufacturer’s recommendations climb. Thus, the aircraft suffers a bit in each performance should be used as a reference to clarify any misunderstanding category. The fixed-pitch propeller is used when low weight, of tachometer markings.

simplicity, and low cost are needed.

The rpm is regulated by the throttle, which controls the fuel- There are two types of fixed-pitch propellers: climb and air flow to the engine. At a given altitude, the higher the cruise. Whether the airplane has a climb or cruise propeller tachometer reading, the higher the power output of the engine.

a n c e — v e i s t r y l d h When operating altitude increases, the tachometer may not e i g v h a r s t p r e e t e a d e — show correct power output of the engine. For example, 2,300 r G 3 k n rpm at 5,000 feet produces less horsepower than 2,300 rpm o t c e — m o s a n d s t e i r a d l t e at sea level because power output depends on air density. Air e s v p a r e t e e d t — density decreases as altitude increases and a decrease in air a r e d o M k n n c e — t a s s o i l d o t l w s e v s a p r t e t e r d o h S

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CONTINUOUS 60 in. OPERATION BETWEEN 2250 AND 2350 RPM , 5 0 0 r p m Figure 7-7. Relationship of travel distance and speed of various Figure 7-8. Engine rpm is indicated on the tachometer.

portions of propeller blade.

7-5 density (higher density altitude) decreases the power output will increase or decrease as appropriate, with changes in of the engine. As altitude changes, the position of the throttle airspeed and propeller load. For example, once a specific must be changed to maintain the same rpm. As altitude is rpm has been selected, if aircraft speed decreases enough to increased, the throttle must be opened further to indicate the rotate the propeller blades until they contact the low pitch same rpm as at a lower altitude. stop, any further decrease in airspeed will cause engine rpm to decrease the same way as if a fixed-pitch propeller were Adjustable-Pitch Propeller installed. The same holds true when an aircraft equipped with a constant-speed propeller accelerates to a faster airspeed. As The adjustable-pitch propeller was the forerunner of the the aircraft accelerates, the propeller blade angle increases to constant-speed propeller. It is a propeller with blades whose maintain the selected rpm until the high pitch stop is reached.

pitch can be adjusted on the ground with the engine not Once this occurs, the blade angle cannot increase any further running, but which cannot be adjusted in flight. It is also and engine rpm increases.

referred to as a ground adjustable propeller. By the 1930s, pioneer aviation inventors were laying the ground work for On aircraft equipped with a constant-speed propeller, power automatic pitch-change mechanisms, which is why the term output is controlled by the throttle and indicated by a manifold sometimes refers to modern constant-speed propellers that pressure gauge. The gauge measures the absolute pressure of are adjustable in flight.

the fuel-air mixture inside the intake manifold and is more correctly a measure of manifold absolute pressure (MAP). At The first adjustable-pitch propeller systems provided only two a constant rpm and altitude, the amount of power produced pitch settings: low and high. Today, most adjustable-pitch is directly related to the fuel-air mixture being delivered to propeller systems are capable of a range of pitch settings.

the combustion chamber. As the throttle setting is increased, more fuel and air flows to the engine and MAP increases.

A constant-speed propeller is a controllable-pitch propeller When the engine is not running, the manifold pressure gauge whose pitch is automatically varied in flight by a governor indicates ambient air pressure (i.e., 29.92 inches mercury maintaining constant rpm despite varying air loads. It is the (29.92 "Hg)). When the engine is started, the manifold most common type of adjustable-pitch propeller. The main pressure indication decreases to a value less than ambient advantage of a constant-speed propeller is that it converts pressure (i.e., idle at 12 "Hg). Engine failure or power loss a high percentage of brake horsepower (BHP) into thrust is indicated on the manifold gauge as an increase in manifold horsepower (THP) over a wide range of rpm and airspeed pressure to a value corresponding to the ambient air pressure combinations. A constant-speed propeller is more efficient at the altitude where the failure occurred. [Figure 7-9] than other propellers because it allows selection of the most efficient engine rpm for the given conditions.

The manifold pressure gauge is color coded to indicate the engine’s operating range. The face of the manifold pressure An aircraft with a constant-speed propeller has two controls: gauge contains a green arc to show the normal operating the throttle and the propeller control. The throttle controls range and a red radial line to indicate the upper limit of power output, and the propeller control regulates engine manifold pressure.

rpm. This regulates propeller rpm, which is registered on the tachometer.

Once a specific rpm is selected, a governor automatically adjusts the propeller blade angle as necessary to maintain 30 30 the selected rpm. For example, after setting the desired rpm 35 25 35 25 MANIFOLD during cruising flight, an increase in airspeed or decrease in PRESS propeller load causes the propeller blade angle to increase 20 20 40 40 as necessary to maintain the selected rpm. A reduction in IN Hg airspeed or increase in propeller load causes the propeller ALg.

15 15 45 45 blade angle to decrease.

10 10 50 50 The propeller’s constant-speed range, defined by the high and low pitch stops, is the range of possible blade angles for a constant-speed propeller. As long as the propeller blade angle is within the constant-speed range and not against Figure 7-9. Engine power output is indicated on the manifold either pitch stop, a constant engine rpm is maintained. If pressure gauge.

the propeller blades contact a pitch stop, the engine rpm 7-6 For any given rpm, there is a manifold pressure that should Operating Handbook (POH), but was unable to reach the not be exceeded. If manifold pressure is excessive for a given airport and was forced to conduct an off-field landing.

rpm, the pressure within the cylinders could be exceeded, placing undue stress on the cylinders. If repeated too It was further explained that a determination was made that the frequently, this stress can weaken the cylinder components propeller experienced a failure causing the blade pitch change and eventually cause engine failure. mechanism to move to the low pitch stop position. This caused the propeller to operate as a fixed-pitch propeller such that it A pilot can avoid conditions that overstress the cylinders changes rpm with changes in power and airspeed. The low by being constantly aware of the rpm, especially when pitch setting allows for maximum power during takeoff but increasing the manifold pressure. Consult the manufacturer’s can result in a propeller overspeed at a higher airspeed.

recommendations for power settings of a particular engine to maintain the proper relationship between manifold pressure A performance evaluation of the flight condition was and rpm. performed for the particular aircraft model involved in this incident. This evaluation indicated that an airspeed lower When both manifold pressure and rpm need to be changed, than the best glide speed would have resulted in increased avoid engine overstress by making power adjustments in thrust enabling the pilot to maintain level flight. There are the proper order: numerous variables in aircraft, engines, and propellers that affect aircraft performance. For some aircraft models, • When power settings are being decreased, reduce the published best glide speed may not be low enough to manifold pressure before reducing rpm. If rpm is generate adequate thrust for a given propeller installation in reduced before manifold pressure, manifold pressure this situation (propeller blades at low pitch stop position).

automatically increases, possibly exceeding the manufacturer’s tolerances.

The operators of aircraft with variable pitch propellers should • When power settings are being increased, reverse the be aware that in certain instances of propeller overspeed, the order—increase rpm first, then manifold pressure.

airspeed necessary to maintain level flight may be different than the speed associated with engine-out best glide speed.

• To prevent damage to radial engines, minimize The appropriate emergency procedures should be followed to operating time at maximum rpm and manifold mitigate the emergency situation in the event of a propeller pressure, and avoid operation at maximum rpm and overspeed; however, pilots should be aware that some low manifold pressure.

reduction in airspeed may result in the ability for continued safe flight and landing. The determination of an airspeed that The engine and/or airframe manufacturer’s recommendations is more suitable than engine-out best glide speed should only should be followed to prevent severe wear, fatigue, and be conducted at a safe altitude when the pilot has time to damage to high-performance reciprocating engines.

determine an alternative course of action other than landing immediately.

Propeller Overspeed in Piston Engine Aircraft On March 17, 2010, the Federal Aviation Administration Induction Systems (FAA) issued Special Airworthiness Information Bulletin The induction system brings in air from the outside, mixes (SAIB) CE-10-21. The subject was Propellers/Propulsers; it with fuel, and delivers the fuel-air mixture to the cylinder Propeller Overspeed in Piston Engine Aircraft to alert where combustion occurs. Outside air enters the induction operators, pilots, and aircraft manufacturers of concerns system through an intake port on the front of the engine for an optimum response to a propeller overspeed in piston cowling. This port normally contains an air filter that inhibits engine aircraft with variable pitch propellers. Although a the entry of dust and other foreign objects. Since the filter SAIB is not regulatory in nature, the FAA recommends that may occasionally become clogged, an alternate source of the information be read and taken into consideration for the air must be available. Usually, the alternate air comes from safety of flight.

inside the engine cowling, where it bypasses a clogged air filter. Some alternate air sources function automatically, The document explains that a single-engine aircraft while others operate manually.

experienced a propeller overspeed during cruise flight at 7,000 feet. The pilot reported that the application of throttle resulted in a propeller overspeed with no appreciable thrust.

The pilot attempted to glide to a nearby airport and established the “best glide” speed of 110 knots, as published in the Pilot’s 7-7 Two types of induction systems are commonly used in small fuel to flow through a main fuel jet located at the throat. The aircraft engines: fuel then flows into the airstream where it is mixed with the flowing air. [Figure 7-10] 1. The carburetor system mixes the fuel and air in the carburetor before this mixture enters the intake The fuel-air mixture is then drawn through the intake manifold.

manifold and into the combustion chambers where it is 2. The fuel injection system mixes the fuel and air ignited. The float-type carburetor acquires its name from a immediately before entry into each cylinder or injects float that rests on fuel within the float chamber. A needle fuel directly into each cylinder.

attached to the float opens and closes an opening at the bottom of the carburetor bowl. This meters the amount of Carburetor Systems fuel entering into the carburetor, depending upon the position Aircraft carburetors are separated into two categories: float- of the float, which is controlled by the level of fuel in the type carburetors and pressure-type carburetors. Float-type float chamber. When the level of the fuel forces the float carburetors, complete with idling, accelerating, mixture to rise, the needle valve closes the fuel opening and shuts control, idle cutoff, and power enrichment systems, are the off the fuel flow to the carburetor. The needle valve opens most common of the two carburetor types. Pressure-type again when the engine requires additional fuel. The flow of carburetors are usually not found on small aircraft. The basic the fuel-air mixture to the combustion chambers is regulated difference between a float-type and a pressure-type carburetor by the throttle valve, which is controlled by the throttle in is the delivery of fuel. The pressure-type carburetor delivers the flight deck.

fuel under pressure by a fuel pump.

The float-type carburetor has several distinct disadvantages.

In the operation of the float-type carburetor system, the First, they do not function well during abrupt maneuvers.

outside air first flows through an air filter, usually located Secondly, the discharge of fuel at low pressure leads to at an air intake in the front part of the engine cowling. This incomplete vaporization and difficulty in discharging filtered air flows into the carburetor and through a venturi, a fuel into some types of supercharged systems. The chief narrow throat in the carburetor. When the air flows through disadvantage of the float-type carburetor, however, is its the venturi, a low-pressure area is created that forces the icing tendency. Since the float-type carburetor must discharge Fuel inlet Fuel-air mixture Float chamber Fuel level is maintained Fuel is received into The blend of fuel and by a float-type device. the carburetor through air is routed to the the fuel inlet. combustion chambers to be burned.

Throttle valve The flow of the fuel-air mixture is controlled by the throttle valve. The throttle valve is adjusted from the flight deck by the throttle.

Fuel Venturi The shape of the venturi creates an area of low pressure.

Mixture needle The mixture needle Discharge nozzle controls fuel to the discharge nozzle. Fuel is forced through Mixture needle position the discharge nozzle can be adjusted using into the venturi by the mixture control. greater atmospheric pressure in the float Air bleed chamber.

Air inlet The air bleed allows air to be mixed with fuel being drawn out of the Air enters the carburetor discharge nozzle to decrease fuel through the air inlet.

density and promote fuel vaporization.

Figure 7-10. Float-type carburetor.

7-8 fuel at a point of low pressure, the discharge nozzle must be Carburetor Icing located at the venturi throat, and the throttle valve must be As mentioned earlier, one disadvantage of the float-type on the engine side of the discharge nozzle. This means that carburetor is its icing tendency. Carburetor ice occurs due the drop in temperature due to fuel vaporization takes place to the effect of fuel vaporization and the decrease in air within the venturi. As a result, ice readily forms in the venturi pressure in the venturi, which causes a sharp temperature and on the throttle valve.

drop in the carburetor. If water vapor in the air condenses when the carburetor temperature is at or below freezing, ice A pressure-type carburetor discharges fuel into the airstream may form on internal surfaces of the carburetor, including at a pressure well above atmospheric pressure. This results the throttle valve. [Figure 7-11] in better vaporization and permits the discharge of fuel into the airstream on the engine side of the throttle valve. With the The reduced air pressure, as well as the vaporization of fuel, discharge nozzle in this position fuel vaporization takes place contributes to the temperature decrease in the carburetor. Ice after the air has passed through the throttle valve and at a point generally forms in the vicinity of the throttle valve and in the where the drop in temperature is offset by heat from the engine.

venturi throat. This restricts the flow of the fuel-air mixture Thus, the danger of fuel vaporization icing is practically and reduces power. If enough ice builds up, the engine may eliminated. The effects of rapid maneuvers and rough air on cease to operate. Carburetor ice is most likely to occur when the pressure-type carburetors are negligible, since their fuel temperatures are below 70 degrees Fahrenheit (°F) or 21 chambers remain filled under all operating conditions.

degrees Celsius (°C) and the relative humidity is above 80 percent. Due to the sudden cooling that takes place in the Mixture Control carburetor, icing can occur even in outside air temperatures Carburetors are normally calibrated at sea-level air pressure as high as 100 °F (38 °C) and humidity as low as 50 percent.

where the correct fuel-air mixture ratio is established with the This temperature drop can be as much as 60 to 70 absolute mixture control set in the FULL RICH position. However, as (versus relative) Fahrenheit degrees (70 x 100/180 = 38.89 altitude increases, the density of air entering the carburetor decreases, while the density of the fuel remains the same. This To engine Fuel-air mixture creates a progressively richer mixture that can result in engine roughness and an appreciable loss of power. The roughness normally is due to spark plug fouling from excessive carbon buildup on the plugs. Carbon buildup occurs because the rich mixture lowers the temperature inside the cylinder, inhibiting complete combustion of the fuel. This condition may occur during the runup prior to takeoff at high-elevation Ice airports and during climbs or cruise flight at high altitudes.

To maintain the correct fuel-air mixture, the mixture must be leaned using the mixture control. Leaning the mixture Ice decreases fuel flow, which compensates for the decreased Ice air density at high altitude.

Venturi During a descent from high altitude, the fuel-air mixture must be enriched, or it may become too lean. An overly lean mixture causes detonation, which may result in rough engine operation, overheating, and/or a loss of power. The best way to maintain the proper fuel-air mixture is to monitor the engine temperature and enrich the mixture as needed. Proper mixture control and better fuel economy for fuel-injected engines can be achieved by using an exhaust gas temperature Incoming air (EGT) gauge. Since the process of adjusting the mixture can vary from one aircraft to another, it is important to refer to Figure 7-11. The formation of carburetor ice may reduce or block the airplane flight manual (AFM) or the POH to determine fuel-air flow to the engine.

the specific procedures for a given aircraft.

7-9 Celsius degrees) (Remember there are 180 Fahrenheit degrees presence. If detected, full carburetor heat should be applied from freezing to boiling versus 100 degrees for the Celsius immediately, and it should be left in the ON position until scale.) Therefore, an outside air temperature of 100 F (38 C), the pilot is certain that all the ice has been removed. If ice a temperature drop of an absolute 70 F degrees (38.89 Celsius is present, applying partial heat or leaving heat on for an degrees) results in an air temperature in the carburetor of 30 insufficient time might aggravate the situation. In extreme F (-1 C). [Figure 7-12] cases of carburetor icing, even after the ice has been removed, full carburetor heat should be used to prevent further ice The first indication of carburetor icing in an aircraft with formation. If installed, a carburetor temperature gauge is a fixed-pitch propeller is a decrease in engine rpm, which useful in determining when to use carburetor heat.

may be followed by engine roughness. In an aircraft with a constant-speed propeller, carburetor icing is usually indicated Whenever the throttle is closed during flight, the engine cools by a decrease in manifold pressure, but no reduction in rpm. rapidly and vaporization of the fuel is less complete than if Propeller pitch is automatically adjusted to compensate for the engine is warm. Also, in this condition, the engine is more loss of power. Thus, a constant rpm is maintained. Although susceptible to carburetor icing. If carburetor icing conditions carburetor ice can occur during any phase of flight, it is are suspected and closed-throttle operation anticipated, adjust particularly dangerous when using reduced power during a the carburetor heat to the full ON position before closing the descent. Under certain conditions, carburetor ice could build throttle and leave it on during the closed-throttle operation.

unnoticed until power is added. To combat the effects of The heat aids in vaporizing the fuel and helps prevent the carburetor ice, engines with float-type carburetors employ a formation of carburetor ice. Periodically, open the throttle carburetor heat system. smoothly for a few seconds to keep the engine warm; otherwise, the carburetor heater may not provide enough heat to prevent icing.

Carburetor Heat Carburetor heat is an anti-icing system that preheats the air The use of carburetor heat causes a decrease in engine before it reaches the carburetor and is intended to keep the power, sometimes up to 15 percent, because the heated fuel-air mixture above freezing to prevent the formation of air is less dense than the outside air that had been entering carburetor ice. Carburetor heat can be used to melt ice that has the engine. This enriches the mixture. When ice is present already formed in the carburetor if the accumulation is not too in an aircraft with a fixed-pitch propeller and carburetor great, but using carburetor heat as a preventative measure is heat is being used, there is a decrease in rpm, followed by the better option. Additionally, carburetor heat may be used a gradual increase in rpm as the ice melts. The engine also as an alternate air source if the intake filter clogs, such as in should run more smoothly after the ice has been removed.

sudden or unexpected airframe icing conditions. The carburetor If ice is not present, the rpm decreases and then remains heat should be checked during the engine runup. When using constant. When carburetor heat is used on an aircraft with a carburetor heat, follow the manufacturer’s recommendations.

constant-speed propeller and ice is present, a decrease in the manifold pressure is noticed, followed by a gradual increase.

When conditions are conducive to carburetor icing during If carburetor icing is not present, the gradual increase in flight, periodic checks should be made to detect its manifold pressure is not apparent until the carburetor heat is turned off.

100% High carburetor 90% It is imperative for a pilot to recognize carburetor ice when it icing potential forms during flight to prevent a loss in power, altitude, and/or 80% airspeed. These symptoms may sometimes be accompanied by vibration or engine roughness. Once a power loss is 70% noticed, immediate action should be taken to eliminate ice Carburetor icing possible Relative humidity already formed in the carburetor and to prevent further ice 60% formation. This is accomplished by applying full carburetor heat, which will further reduce power and may cause engine 50% roughness as melted ice goes through the engine. These 20°F/-7°C 32°F/0°C 70°F/21°C 100°F/38°C symptoms may last from 30 seconds to several minutes, Outside air temperature depending on the severity of the icing. During this period, the pilot must resist the temptation to decrease the carburetor heat Figure 7-12. Although carburetor ice is most likely to form when usage. Carburetor heat must remain in the full-hot position the temperature and humidity are in ranges indicated by this chart, until normal power returns.

carburetor icing is possible under conditions not depicted.

7-10 Since the use of carburetor heat tends to reduce the output Celsius and Fahrenheit. It provides the outside or ambient of the engine and to increase the operating temperature, air temperature for calculating true airspeed and is useful in carburetor heat should not be used when full power is required detecting potential icing conditions.

(as during takeoff) or during normal engine operation, except Fuel Injection Systems to check for the presence of, or to remove, carburetor ice.

In a fuel injection system, the fuel is injected directly into Carburetor Air Temperature Gauge the cylinders, or just ahead of the intake valve. The air intake for the fuel injection system is similar to that used Some aircraft are equipped with a carburetor air temperature in a carburetor system, with an alternate air source located gauge, which is useful in detecting potential icing conditions.

within the engine cowling. This source is used if the external Usually, the face of the gauge is calibrated in degrees Celsius air source is obstructed. The alternate air source is usually with a yellow arc indicating the carburetor air temperatures operated automatically, with a backup manual system that where icing may occur. This yellow arc typically ranges can be used if the automatic feature malfunctions.

between –15 °C and +5 °C (5 °F and 41 °F). If the air temperature and moisture content of the air are such that A fuel injection system usually incorporates six basic carburetor icing is improbable, the engine can be operated components: an engine-driven fuel pump, a fuel-air control with the indicator in the yellow range with no adverse effects.

unit, a fuel manifold (fuel distributor), discharge nozzles, If the atmospheric conditions are conducive to carburetor an auxiliary fuel pump, and fuel pressure/flow indicators.

icing, the indicator must be kept outside the yellow arc by [Figure 7-13] application of carburetor heat.

The auxiliary fuel pump provides fuel under pressure to the Certain carburetor air temperature gauges have a red radial fuel-air control unit for engine starting and/or emergency that indicates the maximum permissible carburetor inlet air use. After starting, the engine-driven fuel pump provides fuel temperature recommended by the engine manufacturer. If under pressure from the fuel tank to the fuel-air control unit.

present, a green arc indicates the normal operating range.

This control unit, which essentially replaces the carburetor, Outside Air Temperature Gauge meters fuel based on the mixture control setting and sends it Most aircraft are also equipped with an outside air to the fuel manifold valve at a rate controlled by the throttle.

temperature (OAT) gauge calibrated in both degrees Fuel tank Auxiliary fuel pump Engine-driven fuel pump Fuel-air control unit Fuel manifold valve Fuel lines Figure 7-13. Fuel injection system.

7-11 After reaching the fuel manifold valve, the fuel is distributed or boosted, by either a supercharger or a turbosupercharger, to the individual fuel discharge nozzles. The discharge the aircraft’s service ceiling can be increased. With these nozzles, which are located in each cylinder head, inject the systems, an aircraft can fly at higher altitudes with the fuel-air mixture directly into each cylinder intake port. advantage of higher true airspeeds and the increased ability to circumnavigate adverse weather.

A fuel injection system is considered to be less susceptible Superchargers to icing than a carburetor system, but impact icing on the air intake is a possibility in either system. Impact icing occurs A supercharger is an engine-driven air pump or compressor when ice forms on the exterior of the aircraft and blocks that provides compressed air to the engine to provide openings, such as the air intake for the injection system.

additional pressure to the induction air so that the engine can produce additional power. It increases manifold pressure and The following are advantages of using fuel injection: forces the fuel-air mixture into the cylinders. Higher manifold pressure increases the density of the fuel-air mixture and • Reduction in evaporative icing increases the power an engine can produce. With a normally • Better fuel flow aspirated engine, it is not possible to have manifold pressure • Faster throttle response higher than the existing atmospheric pressure. A supercharger is capable of boosting manifold pressure above 30 "Hg.

• Precise control of mixture • Better fuel distribution For example, at 8,000 feet, a typical engine may be able to produce 75 percent of the power it could produce at mean • Easier cold weather starts sea level (MSL) because the air is less dense at the higher altitude. The supercharger compresses the air to a higher The following are disadvantages of using fuel injection: density allowing a supercharged engine to produce the same • Difficulty in starting a hot engine manifold pressure at higher altitudes as it could produce • Vapor locks during ground operations on hot days at sea level. Thus, an engine at 8,000 feet MSL could still produce 25 "Hg of manifold pressure whereas, without a • Problems associated with restarting an engine that supercharger, it could only produce 22 "Hg. Superchargers quits because of fuel starvation are especially valuable at high altitudes (such as 18,000 feet) where the air density is 50 percent that of sea level. The use Superchargers and Turbosuperchargers of a supercharger in many cases will supply air to the engine To increase an engine’s horsepower, manufacturers have at the same density it did at sea level.

developed forced induction systems called supercharger and turbosupercharger systems. They both compress the The components in a supercharged induction system are similar intake air to increase its density. The key difference lies in to those in a normally aspirated system, with the addition of the power supply. A supercharger relies on an engine-driven a supercharger between the fuel metering device and intake air pump or compressor, while a turbocharger gets its power manifold. A supercharger is driven by the engine through a from the exhaust stream that runs through a turbine, which in gear train at one speed, two speeds, or variable speeds. In turn spins the compressor. Aircraft with these systems have addition, superchargers can have one or more stages. Each a manifold pressure gauge, which displays MAP within the stage also provides an increase in pressure and superchargers engine’s intake manifold.

may be classified as single stage, two stage, or multistage, depending on the number of times compression occurs.

On a standard day at sea level with the engine shut down, the manifold pressure gauge indicates the ambient An early version of a single-stage, single-speed supercharger absolute air pressure of 29.92 "Hg. Because atmospheric may be referred to as a sea-level supercharger. An engine pressure decreases approximately 1 "Hg per 1,000 feet of equipped with this type of supercharger is called a sea-level altitude increase, the manifold pressure gauge indicates engine. With this type of supercharger, a single gear-driven approximately 24.92 "Hg at an airport that is 5,000 feet above impeller is used to increase the power produced by an engine sea level with standard day conditions.

at all altitudes. The drawback with this type of supercharger is a decrease in engine power output with an increase in altitude.

As a normally aspirated aircraft climbs, it eventually reaches an altitude where the MAP is insufficient for a normal climb.

Single-stage, single-speed superchargers are found on many This altitude limit is known as the aircraft’s service ceiling, high-powered radial engines and use an air intake that faces and it is directly affected by the engine’s ability to produce forward so the induction system can take full advantage of power. If the induction air entering the engine is pressurized, 7-12 the ram air. Intake air passes through ducts to a carburetor, Installed on an engine, this booster uses the engine’s exhaust where fuel is metered in proportion to the airflow. The gases to drive an air compressor to increase the pressure of fuel-air charge is then ducted to the supercharger, or blower the air going into the engine through the carburetor or fuel impeller, which accelerates the fuel-air mixture outward. injection system to boost power at higher altitude.

Once accelerated, the fuel-air mixture passes through a diffuser, where air velocity is traded for pressure energy. The major disadvantage of the gear-driven supercharger––use After compression, the resulting high pressure fuel-air of a large amount of the engine’s power output for the amount mixture is directed to the cylinders. of power increase produced––is avoided with a turbocharger because turbochargers are powered by an engine’s exhaust Some of the large radial engines developed during World gases. This means a turbocharger recovers energy from hot War II have a single-stage, two-speed supercharger. With exhaust gases that would otherwise be lost.

this type of supercharger, a single impeller may be operated at two speeds. The low impeller speed is often referred to A second advantage of turbochargers over superchargers is as the low blower setting, while the high impeller speed is the ability to maintain control over an engine’s rated sea- called the high blower setting. On engines equipped with a level horsepower from sea level up to the engine’s critical two-speed supercharger, a lever or switch in the flight deck altitude. Critical altitude is the maximum altitude at which activates an oil-operated clutch that switches from one speed a turbocharged engine can produce its rated horsepower.

to the other. Above the critical altitude, power output begins to decrease like it does for a normally aspirated engine.

Under normal operations, takeoff is made with the supercharger in the low blower position. In this mode, the Turbochargers increase the pressure of the engine’s induction engine performs as a ground-boosted engine, and the power air, which allows the engine to develop sea level or greater output decreases as the aircraft gains altitude. However, once horsepower at higher altitudes. A turbocharger is comprised the aircraft reaches a specified altitude, a power reduction is of two main elements: a compressor and turbine. The made, and the supercharger control is switched to the high compressor section houses an impeller that turns at a high rate blower position. The throttle is then reset to the desired of speed. As induction air is drawn across the impeller blades, manifold pressure. An engine equipped with this type of the impeller accelerates the air, allowing a large volume of supercharger is called an altitude engine. [Figure 7-14] air to be drawn into the compressor housing. The impeller’s action subsequently produces high-pressure, high-density Turbosuperchargers air that is delivered to the engine. To turn the impeller, the The most efficient method of increasing horsepower in an engine’s exhaust gases are used to drive a turbine wheel that is mounted on the opposite end of the impeller’s drive engine is by using a turbosupercharger or turbocharger.

shaft. By directing different amounts of exhaust gases to flow over the turbine, more energy can be extracted, causing the Two-speed supercharged engine impeller to deliver more compressed air to the engine. The waste gate, essentially an adjustable butterfly valve installed Lo w High blower b l o we in the exhaust system, is used to vary the mass of exhaust gas r flowing into the turbine. When closed, most of the exhaust gases from the engine are forced to flow through the turbine.

N When open, the exhaust gases are allowed to bypass the o r m a l l y a s p turbine by flowing directly out through the engine’s exhaust i r a t e d e n g i n e pipe. [Figure 7-15] Brake horsepower Since the temperature of a gas rises when it is compressed, turbocharging causes the temperature of the induction air to increase. To reduce this temperature and lower the risk of detonation, many turbocharged engines use an intercooler.

This small heat exchanger uses outside air to cool the hot compressed air before it enters the fuel metering device.

Sea level Density altitude Figure 7-14. Power output of normally aspirated engine compared to a single-stage, two-speed supercharged engine.

7-13 Intake manifold Turbocharger Throttle body Pressurized air from the The turbocharger in This regulates airflow turbocharger is supplied corporates a turbine, to the engine.

to the cylinders. which is driven by ex haust gases and a com pressor that pressurizes the incoming air.

Waste gas Exhaust manifold This controls the amount Exhaust gas is ducted Air intake of exhaust through the through the exhaust man Intake air is ducted to the turbine. Waste gate ifold and is used to turn turbocharger where it is position is actuated by the turbine which drives compressed.

Exhaust gas discharge engine oil pressure. the compressor.

Figure 7-15. Turbocharger components.

waste gate actuator quickly enough to prevent an overboost.

System Operation To help prevent overboosting, advance the throttle cautiously On most modern turbocharged engines, the position of to prevent exceeding the maximum manifold pressure limits.

the waste gate is governed by a pressure-sensing control mechanism coupled to an actuator. Engine oil directed into A pilot flying an aircraft with a turbocharger should be aware or away from this actuator moves the waste gate position.

of system limitations. For example, a turbocharger turbine On these systems, the actuator is automatically positioned to and impeller can operate at rotational speeds in excess of produce the desired MAP simply by changing the position 80,000 rpm while at extremely high temperatures. To achieve of the throttle control.

high rotational speed, the bearings within the system must be constantly supplied with engine oil to reduce the frictional Other turbocharging system designs use a separate manual forces and high temperature. To obtain adequate lubrication, control to position the waste gate. With manual control, the oil temperature should be in the normal operating range the manifold pressure gauge must be closely monitored to before high throttle settings are applied. In addition, allow determine when the desired MAP has been achieved. Manual the turbocharger to cool and the turbine to slow down before systems are often found on aircraft that have been modified shutting the engine down. Otherwise, the oil remaining in with aftermarket turbocharging systems. These systems the bearing housing will boil, causing hard carbon deposits require special operating considerations. For example, if the to form on the bearings and shaft. These deposits rapidly waste gate is left closed after descending from a high altitude, deteriorate the turbocharger’s efficiency and service life. For it is possible to produce a manifold pressure that exceeds the further limitations, refer to the AFM/POH.

engine’s limitations. This condition, called an overboost, may produce severe detonation because of the leaning effect High Altitude Performance resulting from increased air density during descent.

As an aircraft equipped with a turbocharging system climbs, Although an automatic waste gate system is less likely to the waste gate is gradually closed to maintain the maximum allowable manifold pressure. At some point, the waste gate experience an overboost condition, it can still occur. If takeoff power is applied while the engine oil temperature is below its is fully closed and further increases in altitude cause the manifold pressure to decrease. This is the critical altitude, normal operating range, the cold oil may not flow out of the 7-14 which is established by the aircraft or engine manufacturer. slightly higher power output. If one of the magnetos fails, the When evaluating the performance of the turbocharging other is unaffected. The engine continues to operate normally, system, be aware that if the manifold pressure begins although a slight decrease in engine power can be expected.

decreasing before the specified critical altitude, the engine The same is true if one of the two spark plugs in a cylinder fails.

and turbocharging system should be inspected by a qualified aviation maintenance technician (AMT) to verify that the The operation of the magneto is controlled in the flight deck system is operating properly. by the ignition switch. The switch has five positions: 1. OFF Ignition System 2. R (right) In a spark ignition engine, the ignition system provides a 3. L (left) spark that ignites the fuel-air mixture in the cylinders and is made up of magnetos, spark plugs, high-tension leads, and 4. BOTH an ignition switch. [Figure 7-16] 5. START A magneto uses a permanent magnet to generate an electrical With RIGHT or LEFT selected, only the associated magneto current completely independent of the aircraft’s electrical is activated. The system operates on both magnetos when system. The magneto generates sufficiently high voltage BOTH is selected.

to jump a spark across the spark plug gap in each cylinder.

The system begins to fire when the starter is engaged and the A malfunctioning ignition system can be identified during crankshaft begins to turn. It continues to operate whenever the pretakeoff check by observing the decrease in rpm that the crankshaft is rotating.

occurs when the ignition switch is first moved from BOTH to RIGHT and then from BOTH to LEFT. A small decrease Most standard certificated aircraft incorporate a dual ignition in engine rpm is normal during this check. The permissible system with two individual magnetos, separate sets of wires, decrease is listed in the AFM or POH. If the engine stops and spark plugs to increase reliability of the ignition system.

running when switched to one magneto or if the rpm drop Each magneto operates independently to fire one of the two exceeds the allowable limit, do not fly the aircraft until spark plugs in each cylinder. The firing of two spark plugs the problem is corrected. The cause could be fouled plugs, improves combustion of the fuel-air mixture and results in a Upper magneto wires Upper spark plugs Lower spark plugs Lower magneto wires

2 1

Right magneto Left magneto Figure 7-16. Ignition system components.

7-15 broken or shorted wires between the magneto and the plugs, Reciprocating engines use either a wet-sump or a dry-sump or improperly timed firing of the plugs. It should be noted oil system. In a wet-sump system, the oil is located in a sump that “no drop” in rpm is not normal, and in that instance, the that is an integral part of the engine. In a dry-sump system, aircraft should not be flown. the oil is contained in a separate tank and circulated through the engine by pumps. [Figure 7-17] Following engine shutdown, turn the ignition switch to the OFF position. Even with the battery and master switches The main component of a wet-sump system is the oil pump, OFF, the engine can fire and turn over if the ignition switch which draws oil from the sump and routes it to the engine. After is left ON and the propeller is moved because the magneto the oil passes through the engine, it returns to the sump. In requires no outside source of electrical power. Be aware of some engines, additional lubrication is supplied by the rotating the potential for serious injury in this situation. crankshaft, which splashes oil onto portions of the engine.

Even with the ignition switch in the OFF position, if An oil pump also supplies oil pressure in a dry-sump the ground wire between the magneto and the ignition system, but the source of the oil is located external to the switch becomes disconnected or broken, the engine could engine in a separate oil tank. After oil is routed through accidentally start if the propeller is moved with residual fuel the engine, it is pumped from the various locations in the in the cylinder. If this occurs, the only way to stop the engine engine back to the oil tank by scavenge pumps. Dry-sump is to move the mixture lever to the idle cutoff position, then systems allow for a greater volume of oil to be supplied to have the system checked by a qualified AMT. the engine, which makes them more suitable for very large reciprocating engines.

Oil Systems The oil pressure gauge provides a direct indication of the oil The engine oil system performs several important functions: system operation. It ensures the pressure in pounds per square • Lubrication of the engine’s moving parts inch (psi) of the oil supplied to the engine. Green indicates • Cooling of the engine by reducing friction the normal operating range, while red indicates the minimum and maximum pressures. There should be an indication of • Removing heat from the cylinders oil pressure during engine start. Refer to the AFM/POH for • Providing a seal between the cylinder walls and pistons manufacturer limitations.

• Carrying away contaminants Oil filler cap and dipstick Engine and Sump oil and return Accessory oil from relief valve Bearings Pressure oil from Oil sump oil pump Low pressure oil screen Oil pressure relief valve Oil pump High pressure oil screen 245 II5 P I00 T P R E °F S 60 E Oil cooler and filter I50 I M S I00 P S OIL Figure 7-17. Wet-sump oil system.

7-16 The oil temperature gauge measures the temperature of oil. Air cooling is accomplished by air flowing into the engine A green area shows the normal operating range, and the red compartment through openings in front of the engine line indicates the maximum allowable temperature. Unlike cowling. Baffles route this air over fins attached to the engine oil pressure, changes in oil temperature occur more slowly. cylinders, and other parts of the engine, where the air absorbs This is particularly noticeable after starting a cold engine, the engine heat. Expulsion of the hot air takes place through when it may take several minutes or longer for the gauge to one or more openings in the lower, aft portion of the engine show any increase in oil temperature. cowling. [Figure 7-19] Check oil temperature periodically during flight especially The outside air enters the engine compartment through an when operating in high or low ambient air temperature. inlet behind the propeller hub. Baffles direct it to the hottest High oil temperature indications may signal a plugged oil parts of the engine, primarily the cylinders, which have fins line, a low oil quantity, a blocked oil cooler, or a defective that increase the area exposed to the airflow.

temperature gauge. Low oil temperature indications may signal improper oil viscosity during cold weather operations. The air cooling system is less effective during ground operations, takeoffs, go-arounds, and other periods of high- The oil filler cap and dipstick (for measuring the oil quantity) power, low-airspeed operation. Conversely, high-speed are usually accessible through a panel in the engine cowling. If descents provide excess air and can shock cool the engine, the quantity does not meet the manufacturer’s recommended subjecting it to abrupt temperature fluctuations.

operating levels, oil should be added. The AFM/POH or placards near the access panel provide information about Operating the engine at higher than its designed temperature the correct oil type and weight, as well as the minimum and can cause loss of power, excessive oil consumption, and maximum oil quantity. [Figure 7-18] detonation. It will also lead to serious permanent damage, such as scoring the cylinder walls, damaging the pistons and Engine Cooling Systems rings, and burning and warping the valves. Monitoring the flight deck engine temperature instruments aids in avoiding The burning fuel within the cylinders produces intense high operating temperature.

heat, most of which is expelled through the exhaust system.

Much of the remaining heat, however, must be removed, or Under normal operating conditions in aircraft not equipped at least dissipated, to prevent the engine from overheating.

with cowl flaps, the engine temperature can be controlled Otherwise, the extremely high engine temperatures can lead to loss of power, excessive oil consumption, detonation, and serious engine damage.

Cylinders While the oil system is vital to the internal cooling of the engine, an additional method of cooling is necessary for the Baffle Air inlet engine’s external surface. Most small aircraft are air cooled, although some are liquid cooled.

Baffle Fixed cowl opening Figure 7-18. Always check the engine oil level during the preflight Figure 7-19. Outside air aids in cooling the engine.

inspection.

7-17 by changing the airspeed or the power output of the engine. Some exhaust systems have an EGT probe. This probe High engine temperatures can be decreased by increasing the transmits the EGT to an instrument in the flight deck. The airspeed and/or reducing the power. EGT gauge measures the temperature of the gases at the exhaust manifold. This temperature varies with the ratio of The oil temperature gauge gives an indirect and delayed fuel to air entering the cylinders and can be used as a basis indication of rising engine temperature, but can be used for regulating the fuel-air mixture. The EGT gauge is highly for determining engine temperature if this is the only accurate in indicating the correct fuel-air mixture setting.

means available. When using the EGT to aid in leaning the fuel-air mixture, fuel consumption can be reduced. For specific procedures, Most aircraft are equipped with a cylinder-head temperature refer to the manufacturer’s recommendations for leaning the gauge that indicates a direct and immediate cylinder fuel-air mixture.

temperature change. This instrument is calibrated in degrees Starting System Celsius or Fahrenheit and is usually color coded with a green arc to indicate the normal operating range. A red line on Most small aircraft use a direct-cranking electric starter the instrument indicates maximum allowable cylinder head system. This system consists of a source of electricity, wiring, temperature.

switches, and solenoids to operate the starter and a starter motor. Most aircraft have starters that automatically engage To avoid excessive cylinder head temperatures, increase and disengage when operated, but some older aircraft have airspeed, enrich the fuel-air mixture, and/or reduce starters that are mechanically engaged by a lever actuated by power. Any of these procedures help to reduce the engine the pilot. The starter engages the aircraft flywheel, rotating temperature. On aircraft equipped with cowl flaps, use the the engine at a speed that allows the engine to start and cowl flap positions to control the temperature. Cowl flaps maintain operation.

are hinged covers that fit over the opening through which the hot air is expelled. If the engine temperature is low, the cowl Electrical power for starting is usually supplied by an onboard flaps can be closed, thereby restricting the flow of expelled battery, but can also be supplied by external power through hot air and increasing engine temperature. If the engine an external power receptacle. When the battery switch is temperature is high, the cowl flaps can be opened to permit turned on, electricity is supplied to the main power bus bar a greater flow of air through the system, thereby decreasing through the battery solenoid. Both the starter and the starter the engine temperature.

switch draw current from the main bus bar, but the starter will not operate until the starting solenoid is energized by Exhaust Systems the starter switch being turned to the “start” position. When Engine exhaust systems vent the burned combustion gases the starter switch is released from the “start” position, the overboard, provide heat for the cabin, and defrost the solenoid removes power from the starter motor. The starter windscreen. An exhaust system has exhaust piping attached motor is protected from being driven by the engine through a to the cylinders, as well as a muffler and a muffler shroud. clutch in the starter drive that allows the engine to run faster The exhaust gases are pushed out of the cylinder through than the starter motor. [Figure 7-20] the exhaust valve and then through the exhaust pipe system to the atmosphere. When starting an engine, the rules of safety and courtesy should be strictly observed. One of the most important safety For cabin heat, outside air is drawn into the air inlet and is rules is to ensure there is no one near the propeller prior to ducted through a shroud around the muffler. The muffler is starting the engine. In addition, the wheels should be chocked heated by the exiting exhaust gases and, in turn, heats the and the brakes set to avoid hazards caused by unintentional air around the muffler. This heated air is then ducted to the movement. To avoid damage to the propeller and property, cabin for heat and defrost applications. The heat and defrost the aircraft should be in an area where the propeller will not are controlled in the flight deck and can be adjusted to the stir up gravel or dust.

desired level.

Combustion Exhaust gases contain large amounts of carbon monoxide, During normal combustion, the fuel-air mixture burns in a which is odorless and colorless. Carbon monoxide is deadly, very controlled and predictable manner. In a spark ignition and its presence is virtually impossible to detect. To ensure engine, the process occurs in a fraction of a second. The that exhaust gases are properly expelled, the exhaust system mixture actually begins to burn at the point where it is ignited must be in good condition and free of cracks.

7-18 External External power plug power relay + + M A Starter I N Battery B Explosion Normal combustion U S Figure 7-21. Normal combustion and explosive combustion.

Battery • Maintaining extended ground operations or steep Starter contactor contactor (solenoid) climbs in which cylinder cooling is reduced Detonation may be avoided by following these basic R B L B guidelines during the various phases of ground and flight A A OFF operations: L S T T • Ensure that the proper grade of fuel is used.

Ignition switch • Keep the cowl flaps (if available) in the full-open position while on the ground to provide the maximum Figure 7-20. Typical starting circuit.

airflow through the cowling.

• Use an enriched fuel mixture, as well as a shallow by the spark plugs. It then burns away from the plugs until it climb angle, to increase cylinder cooling during is completely consumed. This type of combustion causes a takeoff and initial climb.

smooth build-up of temperature and pressure and ensures that • Avoid extended, high power, steep climbs.

the expanding gases deliver the maximum force to the piston at exactly the right time in the power stroke. [Figure 7-21] • Develop the habit of monitoring the engine instruments Detonation is an uncontrolled, explosive ignition of the to verify proper operation according to procedures fuel-air mixture within the cylinder’s combustion chamber.

established by the manufacturer.

It causes excessive temperatures and pressures which, if not corrected, can quickly lead to failure of the piston, cylinder, Preignition occurs when the fuel-air mixture ignites prior or valves. In less severe cases, detonation causes engine to the engine’s normal ignition event. Premature burning overheating, roughness, or loss of power.

is usually caused by a residual hot spot in the combustion chamber, often created by a small carbon deposit on a spark Detonation is characterized by high cylinder head temperatures plug, a cracked spark plug insulator, or other damage in the and is most likely to occur when operating at high power cylinder that causes a part to heat sufficiently to ignite the settings. Common operational causes of detonation are: fuel-air charge. Preignition causes the engine to lose power and produces high operating temperature. As with detonation, • Use of a lower fuel grade than that specified by the preignition may also cause severe engine damage because aircraft manufacturer the expanding gases exert excessive pressure on the piston • Operation of the engine with extremely high manifold while still on its compression stroke.

pressures in conjunction with low rpm • Operation of the engine at high power settings with an excessively lean mixture 7-19 Detonation and preignition often occur simultaneously and Turbine Engines one may cause the other. Since either condition causes high An aircraft turbine engine consists of an air inlet, compressor, engine temperature accompanied by a decrease in engine combustion chambers, a turbine section, and exhaust. Thrust performance, it is often difficult to distinguish between the is produced by increasing the velocity of the air flowing two. Using the recommended grade of fuel and operating through the engine. Turbine engines are highly desirable the engine within its proper temperature, pressure, and rpm aircraft powerplants. They are characterized by smooth ranges reduce the chance of detonation or preignition.

operation and a high power-to-weight ratio, and they use readily available jet fuel. Prior to recent advances in Full Authority Digital Engine Control material, engine design, and manufacturing processes, the (FADEC) use of turbine engines in small/light production aircraft was FADEC is a system consisting of a digital computer and cost prohibitive. Today, several aviation manufacturers are ancillary components that control an aircraft’s engine producing or plan to produce small/light turbine-powered and propeller. First used in turbine-powered aircraft, and aircraft. These smaller turbine-powered aircraft typically referred to as full authority digital electronic control, these seat between three and seven passengers and are referred to sophisticated control systems are increasingly being used in as very light jets (VLJs) or microjets. [Figure 7-22] piston powered aircraft.

Types of Turbine Engines In a spark-ignition reciprocating engine, the FADEC uses Turbine engines are classified according to the type of speed, temperature, and pressure sensors to monitor the status compressors they use. There are three types of compressors— of each cylinder. A digital computer calculates the ideal pulse centrifugal flow, axial flow, and centrifugal-axial flow.

for each injector and adjusts ignition timing as necessary Compression of inlet air is achieved in a centrifugal flow to achieve optimal performance. In a compression-ignition engine by accelerating air outward perpendicular to the engine, the FADEC operates similarly and performs all of longitudinal axis of the machine. The axial-flow engine the same functions, excluding those specifically related to compresses air by a series of rotating and stationary the spark ignition process.

airfoils moving the air parallel to the longitudinal axis. The centrifugal-axial flow design uses both kinds of compressors FADEC systems eliminate the need for magnetos, carburetor to achieve the desired compression.

heat, mixture controls, and engine priming. A single throttle lever is characteristic of an aircraft equipped with a FADEC The path the air takes through the engine and how power is system. The pilot simply positions the throttle lever to a produced determines the type of engine. There are four types desired detent, such as start, idle, cruise power, or max power, of aircraft turbine engines—turbojet, turboprop, turbofan, and the FADEC system adjusts the engine and propeller and turboshaft.

automatically for the mode selected. There is no need for the pilot to monitor or control the fuel-air mixture.

Turbojet The turbojet engine consists of four sections—compressor, During aircraft starting, the FADEC primes the cylinders, combustion chamber, turbine section, and exhaust. The adjusts the mixture, and positions the throttle based on engine compressor section passes inlet air at a high rate of speed to temperature and ambient pressure. During cruise flight, the FADEC constantly monitors the engine and adjusts fuel flow and ignition timing individually in each cylinder. This precise control of the combustion process often results in decreased fuel consumption and increased horsepower.

FADEC systems are considered an essential part of the engine and propeller control and may be powered by the aircraft’s main electrical system. In many aircraft, FADEC uses power from a separate generator connected to the engine.

In either case, there must be a backup electrical source available because failure of a FADEC system could result in a complete loss of engine thrust. To prevent loss of thrust, two separate and identical digital channels are incorporated for redundancy. Each channel is capable of providing all engine Figure 7-22. Eclipse 500 VLJ.

and propeller functions without limitations.

7-20 the combustion chamber. The combustion chamber contains of the turboprop engine is normally available in the altitude the fuel inlet and igniter for combustion. The expanding range of 25,000 feet to the tropopause. [Figure 7-24] air drives a turbine, which is connected by a shaft to the compressor, sustaining engine operation. The accelerated Turbofan exhaust gases from the engine provide thrust. This is a basic Turbofans were developed to combine some of the best application of compressing air, igniting the fuel-air mixture, features of the turbojet and the turboprop. Turbofan engines producing power to self-sustain the engine operation, and are designed to create additional thrust by diverting a exhaust for propulsion. [Figure 7-23] secondary airflow around the combustion chamber. The turbofan bypass air generates increased thrust, cools the Turbojet engines are limited in range and endurance. They engine, and aids in exhaust noise suppression. This provides are also slow to respond to throttle applications at slow turbojet-type cruise speed and lower fuel consumption.

compressor speeds.

The inlet air that passes through a turbofan engine is usually Turboprop divided into two separate streams of air. One stream passes A turboprop engine is a turbine engine that drives a propeller through the engine core, while a second stream bypasses the through a reduction gear. The exhaust gases drive a power engine core. It is this bypass stream of air that is responsible turbine connected by a shaft that drives the reduction gear for the term “bypass engine.” A turbofan’s bypass ratio refers assembly. Reduction gearing is necessary in turboprop to the ratio of the mass airflow that passes through the fan engines because optimum propeller performance is achieved divided by the mass airflow that passes through the engine at much slower speeds than the engine’s operating rpm. core. [Figure 7-25] Turboprop engines are a compromise between turbojet engines and reciprocating powerplants. Turboprop engines Turboshaft are most efficient at speeds between 250 and 400 mph and The fourth common type of jet engine is the turboshaft.

altitudes between 18,000 and 30,000 feet. They also perform [Figure 7-26] It delivers power to a shaft that drives well at the slow airspeeds required for takeoff and landing and something other than a propeller. The biggest difference are fuel efficient. The minimum specific fuel consumption between a turbojet and turboshaft engine is that on a Fuel injector Turbine Inlet Hot gases Combustion chamber Compressor Nozzle Figure 7-23. Turbojet engine.

Combustion chamber Compressor Gear box Exhaust Inlet Fuel injector Prop Turbine Figure 7-24. Turboprop engine.

7-21 Fuel injector Inlet Turbine Duct fan Hot gases Primary air stream Secondary air stream Combustion chamber Compressor Nozzle Figure 7-25. Turbofan engine.

Combustion chamber Compressor Exhaust Inlet Power shaft Compressor turbine Free (power) turbine Figure 7-26. Turboshaft engine.

turboshaft engine, most of the energy produced by the EPR system design automatically compensates for the effects expanding gases is used to drive a turbine rather than produce of airspeed and altitude. Changes in ambient temperature thrust. Many helicopters use a turboshaft gas turbine engine. require a correction be applied to EPR indications to provide In addition, turboshaft engines are widely used as auxiliary accurate engine power settings.

power units on large aircraft.

Exhaust Gas Temperature (EGT) Turbine Engine Instruments A limiting factor in a gas turbine engine is the temperature Engine instruments that indicate oil pressure, oil temperature, of the turbine section. The temperature of a turbine section engine speed, exhaust gas temperature, and fuel flow are must be monitored closely to prevent overheating the turbine common to both turbine and reciprocating engines. However, blades and other exhaust section components. One common there are some instruments that are unique to turbine engines.

way of monitoring the temperature of a turbine section is These instruments provide indications of engine pressure with an EGT gauge. EGT is an engine operating limit used ratio, turbine discharge pressure, and torque. In addition, to monitor overall engine operating conditions.

most gas turbine engines have multiple temperature-sensing instruments, called thermocouples, which provide pilots with Variations of EGT systems bear different names based on temperature readings in and around the turbine section.

the location of the temperature sensors. Common turbine temperature sensing gauges include the turbine inlet Engine Pressure Ratio (EPR) temperature (TIT) gauge, turbine outlet temperature (TOT) gauge, interstage turbine temperature (ITT) gauge, and An engine pressure ratio (EPR) gauge is used to indicate the power output of a turbojet/turbofan engine. EPR is the ratio turbine gas temperature (TGT) gauge.

of turbine discharge to compressor inlet pressure. Pressure measurements are recorded by probes installed in the engine Torquemeter inlet and at the exhaust. Once collected, the data is sent to Turboprop/turboshaft engine power output is measured a differential pressure transducer, which is indicated on a by the torquemeter. Torque is a twisting force applied to a flight deck EPR gauge.

shaft. The torquemeter measures power applied to the shaft.

7-22 Turboprop and turboshaft engines are designed to produce temperatures also results in decreased thrust. While both torque for driving a propeller. Torquemeters are calibrated turbine and reciprocating powered engines are affected to in percentage units, foot-pounds, or psi. some degree by high relative humidity, turbine engines will experience a negligible loss of thrust, while reciprocating N Indicator engines a significant loss of brake horsepower.

N represents the rotational speed of the low pressure Foreign Object Damage (FOD) compressor and is presented on the indicator as a percentage of design rpm. After start, the speed of the low pressure Due to the design and function of a turbine engine’s air inlet, compressor is governed by the N turbine wheel. The N the possibility of ingestion of debris always exists. This 1 1 turbine wheel is connected to the low pressure compressor causes significant damage, particularly to the compressor through a concentric shaft. and turbine sections. When ingestion of debris occurs, it is called foreign object damage (FOD). Typical FOD consists of small nicks and dents caused by ingestion of small objects N Indicator from the ramp, taxiway, or runway, but FOD damage caused N represents the rotational speed of the high pressure by bird strikes or ice ingestion also occur. Sometimes FOD compressor and is presented on the indicator as a percentage of results in total destruction of an engine.

design rpm. The high pressure compressor is governed by the N turbine wheel. The N turbine wheel is connected to the high 2 2 Prevention of FOD is a high priority. Some engine inlets pressure compressor through a concentric shaft. [Figure 7-27] have a tendency to form a vortex between the ground and the inlet during ground operations. A vortex dissipater may Turbine Engine Operational Considerations be installed on these engines. Other devices, such as screens The great variety of turbine engines makes it impractical to and/or deflectors, may also be utilized. Preflight procedures cover specific operational procedures, but there are certain include a visual inspection for any sign of FOD.

operational considerations common to all turbine engines.

They are engine temperature limits, foreign object damage, Turbine Engine Hot/Hung Start hot start, compressor stall, and flameout.

When the EGT exceeds the safe limit of an aircraft, it experiences a “hot start.” This is caused by too much fuel Engine Temperature Limitations entering the combustion chamber or insufficient turbine rpm.

The highest temperature in any turbine engine occurs at the Any time an engine has a hot start, refer to the AFM/POH or an turbine inlet. TIT is therefore usually the limiting factor in appropriate maintenance manual for inspection requirements.

turbine engine operation.

If the engine fails to accelerate to the proper speed after Thrust Variations ignition or does not accelerate to idle rpm, a hung or false start Turbine engine thrust varies directly with air density. As air has occurred. A hung start may be caused by an insufficient density decreases, so does thrust. Additionally, because air starting power source or fuel control malfunction.

density decreases with an increase in temperature, increased Compressor Stalls Low pressure High pressure Compressor blades are small airfoils and are subject to the compressor (N ) compressor (N ) 1 2 same aerodynamic principles that apply to any airfoil. A compressor blade has an AOA that is a result of inlet air velocity and the compressor’s rotational velocity. These two forces combine to form a vector, which defines the airfoil’s actual AOA to the approaching inlet air.

A compressor stall is an imbalance between the two vector quantities, inlet velocity, and compressor rotational speed.

Compressor stalls occur when the compressor blades’ AOA exceeds the critical AOA. At this point, smooth airflow High pressure compressor drive shaft is interrupted and turbulence is created with pressure fluctuations. Compressor stalls cause air flowing in the Low pressure compressor drive shaft compressor to slow down and stagnate, sometimes reversing direction. [Figure 7-28] Figure 7-27. Dual-spool axial-flow compressor.

7-23 A more common flameout occurrence is due to low fuel pressure and low engine speeds, which typically are associated with high-altitude flight. This situation may also occur with the engine throttled back during a descent, which Normal inlet airflow can set up the lean-condition flameout. A weak mixture can easily cause the flame to die out, even with a normal airflow through the engine.

Distorted inlet airflow Any interruption of the fuel supply can result in a flameout. This may be due to prolonged unusual attitudes, a malfunctioning fuel control system, turbulence, icing, or running out of fuel.

Symptoms of a flameout normally are the same as those following an engine failure. If the flameout is due to a Figure 7-28. Comparison of normal and distorted airflow into the transitory condition, such as an imbalance between fuel compressor section.

flow and engine speed, an airstart may be attempted once the condition is corrected. In any case, pilots must follow Compressor stalls can be transient and intermittent or steady the applicable emergency procedures outlined in the AFM/ and severe. Indications of a transient/intermittent stall are POH. Generally these procedures contain recommendations usually an intermittent “bang” as backfire and flow reversal concerning altitude and airspeed where the airstart is most take place. If the stall develops and becomes steady, strong likely to be successful.

vibration and a loud roar may develop from the continuous flow reversal. Often, the flight deck gauges do not show Performance Comparison a mild or transient stall, but they do indicate a developed It is possible to compare the performance of a reciprocating stall. Typical instrument indications include fluctuations powerplant and different types of turbine engines. For in rpm and an increase in exhaust gas temperature. Most the comparison to be accurate, thrust horsepower (usable transient stalls are not harmful to the engine and often correct horsepower) for the reciprocating powerplant must be used themselves after one or two pulsations. The possibility of rather than brake horsepower, and net thrust must be used severe engine damage from a steady state stall is immediate.

for the turbine-powered engines. In addition, aircraft design Recovery must be accomplished by quickly reducing power, configuration and size must be approximately the same.

decreasing the aircraft’s AOA, and increasing airspeed.

When comparing performance, the following definitions Although all gas turbine engines are subject to compressor are useful: stalls, most models have systems that inhibit them. One system uses a variable inlet guide vane (VIGV) and variable • Brake horsepower (BHP)—the horsepower actually stator vanes that direct the incoming air into the rotor blades delivered to the output shaft. Brake horsepower is the at an appropriate angle. To prevent air pressure stalls, actual usable horsepower.

operate the aircraft within the parameters established by the • Net thrust—the thrust produced by a turbojet or manufacturer. If a compressor stall does develop, follow the turbofan engine.

procedures recommended in the AFM/POH.

• Thrust horsepower (THP)—the horsepower equivalent of the thrust produced by a turbojet or turbofan engine.

Flameout A flameout occurs in the operation of a gas turbine engine in Equivalent shaft horsepower (ESHP)—with respect which the fire in the engine unintentionally goes out. If the to turboprop engines, the sum of the shaft horsepower rich limit of the fuel-air ratio is exceeded in the combustion (SHP) delivered to the propeller and THP produced by the chamber, the flame will blow out. This condition is often exhaust gases.

referred to as a rich flameout. It generally results from very fast engine acceleration where an overly rich mixture Figure 7-29 shows how four types of engines compare in net causes the fuel temperature to drop below the combustion thrust as airspeed is increased. This figure is for explanatory temperature. It may also be caused by insufficient airflow to support combustion.

7-24 maximum speed than aircraft equipped with a turboprop or reciprocating powerplant.

Reciprocating Turboprop Airframe Systems Turbofan g Fuel, electrical, hydraulic, and oxygen systems make up the a r d Turbojet t airframe systems.

f a r c r i A Fuel Systems The fuel system is designed to provide an uninterrupted flow of clean fuel from the fuel tanks to the engine. The Net thrust fuel must be available to the engine under all conditions of engine power, altitude, attitude, and during all approved flight maneuvers. Two common classifications apply to fuel systems in small aircraft: gravity-feed and fuel-pump systems.

A B C D E F Gravity-Feed System Airspeed The gravity-feed system utilizes the force of gravity to transfer the fuel from the tanks to the engine. For example, on Figure 7-29. Engine net thrust versus aircraft speed and drag. Points high-wing airplanes, the fuel tanks are installed in the wings.

a through f are explained in the text below.

This places the fuel tanks above the carburetor, and the fuel is gravity fed through the system and into the carburetor. If purposes only and is not for specific models of engines. The the design of the aircraft is such that gravity cannot be used following are the four types of engines: to transfer fuel, fuel pumps are installed. For example, on • Reciprocating powerplant low-wing airplanes, the fuel tanks in the wings are located below the carburetor. [Figure 7-30] • Turbine, propeller combination (turboprop) • Turbine engine incorporating a fan (turbofan) Fuel-Pump System Aircraft with fuel-pump systems have two fuel pumps. The • Turbojet (pure jet) main pump system is engine driven with an electrically- driven auxiliary pump provided for use in engine starting By plotting the performance curve for each engine, a comparison can be made of maximum aircraft speed variation and in the event the engine pump fails. The auxiliary pump, also known as a boost pump, provides added reliability to with the type of engine used. Since the graph is only a means of comparison, numerical values for net thrust, aircraft speed, the fuel system. The electrically-driven auxiliary pump is controlled by a switch in the flight deck.

and drag are not included.

Fuel Primer Comparison of the four powerplants on the basis of net thrust makes certain performance capabilities evident. In the speed Both gravity-feed and fuel-pump systems may incorporate a range shown to the left of line A, the reciprocating powerplant fuel primer into the system. The fuel primer is used to draw outperforms the other three types. The turboprop outperforms fuel from the tanks to vaporize fuel directly into the cylinders the turbofan in the range to the left of line C. The turbofan prior to starting the engine. During cold weather, when engine outperforms the turbojet in the range to the left of engines are difficult to start, the fuel primer helps because line F. The turbofan engine outperforms the reciprocating there is not enough heat available to vaporize the fuel in the powerplant to the right of line B and the turboprop to the carburetor. It is important to lock the primer in place when right of line C. The turbojet outperforms the reciprocating it is not in use. If the knob is free to move, it may vibrate powerplant to the right of line D, the turboprop to the right out of position during flight which may cause an excessively of line E, and the turbofan to the right of line F. rich fuel-air mixture. To avoid overpriming, read the priming instructions for the aircraft.

The points where the aircraft drag curve intersects the net thrust curves are the maximum aircraft speeds. The vertical Fuel Tanks lines from each of the points to the baseline of the graph The fuel tanks, normally located inside the wings of an indicate that the turbojet aircraft can attain a higher maximum airplane, have a filler opening on top of the wing through speed than aircraft equipped with the other types of engines. which they can be filled. A filler cap covers this opening.

Aircraft equipped with the turbofan engine attains a higher 7-25 accuracy in fuel gauges only when they read “empty.” Any reading other than “empty” should be verified. Do not depend solely on the accuracy of the fuel quantity gauges. Always Right tank visually check the fuel level in each tank during the preflight inspection, and then compare it with the corresponding fuel BOTH quantity indication.

Left tank RIGHT LEFT If a fuel pump is installed in the fuel system, a fuel pressure OFF Strainer Vent gauge is also included. This gauge indicates the pressure in the fuel lines. The normal operating pressure can be found Selector valve in the AFM/POH or on the gauge by color coding.

Fuel Selectors The fuel selector valve allows selection of fuel from various tanks. A common type of selector valve contains four Carburetor positions: LEFT, RIGHT, BOTH, and OFF. Selecting the Primer LEFT or RIGHT position allows fuel to feed only from the Gravity-feed system respective tank, while selecting the BOTH position feeds fuel from both tanks. The LEFT or RIGHT position may be Engine-driven pump Carburetor used to balance the amount of fuel remaining in each wing tank. [Figure 7-31] Fuel placards show any limitations on fuel tank usage, such as “level flight only” and/or “both” for landings and takeoffs.

Strainer Regardless of the type of fuel selector in use, fuel Electric pump consumption should be monitored closely to ensure that a Primer tank does not run completely out of fuel. Running a fuel tank dry does not only cause the engine to stop, but running for Selector valve prolonged periods on one tank causes an unbalanced fuel load between tanks. Running a tank completely dry may allow air BOTH to enter the fuel system and cause vapor lock, which makes RIGHT Right tank LEFT it difficult to restart the engine. On fuel-injected engines, the Left tank OFF fuel becomes so hot it vaporizes in the fuel line, not allowing fuel to reach the cylinders.

Fuel-pump system Figure 7-30. Gravity-feed and fuel-pump systems.

B O T H F L F A N O D E I N T 3 8 G A L K G H A G T A I T I T L T F U D L E L S A The tanks are vented to the outside to maintain atmospheric pressure inside the tank. They may be vented through the filler cap or through a tube extending through the surface LEFT RIGHT 19 gal 19 gal of the wing. Fuel tanks also include an overflow drain that LEVEL LEVEL FLIGHT FLIGHT may stand alone or be collocated with the fuel tank vent.

ONLY ONLY This allows fuel to expand with increases in temperature without damage to the tank itself. If the tanks have been filled on a hot day, it is not unusual to see fuel coming from OFF the overflow drain.

Fuel Gauges The fuel quantity gauges indicate the amount of fuel Figure 7-31. Fuel selector valve.

measured by a sensing unit in each fuel tank and is displayed in gallons or pounds. Aircraft certification rules require 7-26 Fuel Strainers, Sumps, and Drains performs the same as grade 100, the “LL” indicates it has a low lead content. Fuel for aircraft with turbine engines is After leaving the fuel tank and before it enters the carburetor, classified as JET A, JET A-1, and JET B. Jet fuel is basically the fuel passes through a strainer that removes any moisture kerosene and has a distinctive kerosene smell. Since use of and other sediments in the system. Since these contaminants the correct fuel is critical, dyes are added to help identify the are heavier than aviation fuel, they settle in a sump at the type and grade of fuel. [Figure 7-32] bottom of the strainer assembly. A sump is a low point in a fuel system and/or fuel tank. The fuel system may contain a sump, In addition to the color of the fuel itself, the color-coding a fuel strainer, and fuel tank drains, which may be collocated.

system extends to decals and various airport fuel handling equipment. For example, all AVGAS is identified by name, The fuel strainer should be drained before each flight. Fuel using white letters on a red background. In contrast, turbine samples should be drained and checked visually for water fuels are identified by white letters on a black background.

and contaminants.

Special Airworthiness Information Bulleting (SAIB) Water in the sump is hazardous because in cold weather the NE-11-15 advises that grade 100VLL AVGAS is acceptable water can freeze and block fuel lines. In warm weather, it for use on aircraft and engines. 100VLL meets all can flow into the carburetor and stop the engine. If water is performance requirements of grades 80, 91, 100, and 100LL; present in the sump, more water in the fuel tanks is probable, meets the approved operating limitations for aircraft and and they should be drained until there is no evidence of water.

engines certificated to operate with these other grades of Never take off until all water and contaminants have been AVGAS; and is basically identical to 100LL AVGAS. The removed from the engine fuel system.

lead content of 100VLL is reduced by about 19 percent.

100VLL is blue like 100LL and virtually indistinguishable.

Because of the variation in fuel systems, become thoroughly familiar with the systems that apply to the aircraft being flown.

Fuel Contamination Consult the AFM/POH for specific operating procedures.

Accidents attributed to powerplant failure from fuel Fuel Grades contamination have often been traced to: Aviation gasoline (AVGAS) is identified by an octane or • Inadequate preflight inspection by the pilot performance number (grade), which designates the antiknock • Servicing aircraft with improperly filtered fuel from value or knock resistance of the fuel mixture in the engine small tanks or drums cylinder. The higher the grade of gasoline, the more pressure • Storing aircraft with partially filled fuel tanks the fuel can withstand without detonating. Lower grades of fuel are used in lower-compression engines because these • Lack of proper maintenance fuels ignite at a lower temperature. Higher grades are used in higher-compression engines because they ignite at higher Fuel should be drained from the fuel strainer quick drain and temperatures, but not prematurely. If the proper grade of fuel from each fuel tank sump into a transparent container and is not available, use the next higher grade as a substitute. Never then checked for dirt and water. When the fuel strainer is use a grade lower than recommended. This can cause the being drained, water in the tank may not appear until all the cylinder head temperature and engine oil temperature to exceed fuel has been drained from the lines leading to the tank. This their normal operating ranges, which may result in detonation.

indicates that water remains in the tank and is not forcing the fuel out of the fuel lines leading to the fuel strainer. Therefore, Several grades of AVGAS are available. Care must be drain enough fuel from the fuel strainer to be certain that exercised to ensure that the correct aviation grade is being fuel is being drained from the tank. The amount depends on used for the specific type of engine. The proper fuel grade is stated in the AFM/POH, on placards in the flight deck, and next to the filler caps. Automobile gas should NEVER be 80 100 100LL JET used in aircraft engines unless the aircraft has been modified AVGAS AVGAS AVGAS A with a Supplemental Type Certificate (STC) issued by the Federal Aviation Administration (FAA).

COLORLESS RED GREEN BLUE OR STRAW The current method identifies AVGAS for aircraft with AVGAS AVGAS AVGAS JET A reciprocating engines by the octane and performance number, 100LL 80 100 along with the abbreviation AVGAS. These aircraft use Figure 7-32. Aviation fuel color-coding system.

AVGAS 80, 100, and 100LL. Although AVGAS 100LL 7-27 the length of fuel line from the tank to the drain. If water or Another condition of undissolved water is free water that other contaminants are found in the first sample, drain further may be introduced as a result of refueling or the settling of samples until no trace appears. entrained water that collects at the bottom of a fuel tank. Free water is usually present in easily detected quantities at the Water may also remain in the fuel tanks after the drainage bottom of the tank, separated by a continuous interface from from the fuel strainer has ceased to show any trace of water. the fuel above. Free water can be drained from a fuel tank This residual water can be removed only by draining the fuel through the sump drains, which are provided for that purpose.

tank sump drains. Free water, frozen on the bottom of reservoirs, such as the fuel tanks and fuel filter, may render water drains useless Water is the principal fuel contaminant. Suspended water and can later melt releasing the water into the system thereby droplets in the fuel can be identified by a cloudy appearance causing engine malfunction or stoppage. If such a condition of the fuel, or by the clear separation of water from the colored is detected, the aircraft may be placed in a warm hangar to fuel, which occurs after the water has settled to the bottom reestablish proper draining of these reservoirs, and all sumps of the tank. As a safety measure, the fuel sumps should be and drains should be activated and checked prior to flight.

drained before every flight during the preflight inspection.

Entrained water (i.e., water in solution with petroleum fuels) Fuel tanks should be filled after each flight or after the last constitutes a relatively small part of the total potential water flight of the day to prevent moisture condensation within the in a particular system, the quantity dissolved being dependent tank. To prevent fuel contamination, avoid refueling from on fuel temperature and the existing pressure and the water cans and drums. volubility characteristics of the fuel. Entrained water freezes in mid fuel and tends to stay in suspension longer since the In remote areas or in emergency situations, there may be no specific gravity of ice is approximately the same as that of alternative to refueling from sources with inadequate anti- AVGAS.

contamination systems. While a chamois skin and funnel may be the only possible means of filtering fuel, using Water in suspension may freeze and form ice crystals of them is hazardous. Remember, the use of a chamois does sufficient size such that fuel screens, strainers, and filters not always ensure decontaminated fuel. Worn-out chamois may be blocked. Some of this water may be cooled further as do not filter water; neither will a new, clean chamois that is the fuel enters carburetor air passages and causes carburetor already water-wet or damp. Most imitation chamois skins metering component icing, when conditions are not otherwise do not filter water. conducive to this form of icing.

Fuel System Icing Prevention Procedures Ice formation in the aircraft fuel system results from the The use of anti-icing additives for some aircraft has been presence of water in the fuel system. This water may be approved as a means of preventing problems with water undissolved or dissolved. One condition of undissolved and ice in AVGAS. Some laboratory and flight testing water is entrained water that consists of minute water indicates that the use of hexylene glycol, certain methanol particles suspended in the fuel. This may occur as a result of derivatives, and ethylene glycol mononethyl ether (EGME) mechanical agitation of free water or conversion of dissolved in small concentrations inhibit fuel system icing. These tests water through temperature reduction. Entrained water settles indicate that the use of EGME at a maximum 0.15 percent out in time under static conditions and may or may not be by volume concentration substantially inhibits fuel system drained during normal servicing, depending on the rate at icing under most operating conditions. The concentration which it is converted to free water. In general, it is not likely of additives in the fuel is critical. Marked deterioration in that all entrained water can ever be separated from fuel under additive effectiveness may result from too little or too much field conditions. The settling rate depends on a series of additive. Pilots should recognize that anti-icing additives are factors including temperature, quiescence, and droplet size.

in no way a substitute or replacement for carburetor heat.

Aircraft operating instructions involving the use of carburetor The droplet size varies depending upon the mechanics heat should be adhered to at all times when operating under of formation. Usually, the particles are so small as to be atmospheric conditions conducive to icing.

invisible to the naked eye, but in extreme cases, can cause slight haziness in the fuel. Water in solution cannot be removed except by dehydration or by converting it through temperature reduction to entrained, then to free water.

7-28 switch prevents fuel from flowing unless the fan is working.

Refueling Procedures Outside the combustion chamber, a second, larger diameter Static electricity is formed by the friction of air passing tube conducts air around the combustion tube’s outer surface, over the surfaces of an aircraft in flight and by the flow of and a second fan blows the warmed air into tubing to direct fuel through the hose and nozzle during refueling. Nylon, it towards the interior of the aircraft. Most gasoline heaters Dacron, or wool clothing is especially prone to accumulate can produce between 5,000 and 50,000 British Thermal Units and discharge static electricity from the person to the funnel (BTU) per hour.

or nozzle. To guard against the possibility of static electricity igniting fuel fumes, a ground wire should be attached to the Fuel fired heaters require electricity to operate and are aircraft before the fuel cap is removed from the tank. Because compatible with a 12-volt and 24-volt aircraft electrical both the aircraft and refueler have different static charges, system. The heater requires routine maintenance, such as bonding both components to each other is critical. By bonding regular inspection of the combustion tube and replacement of both components to each other, the static differential charge is the igniter at periodic intervals. Because gasoline heaters are equalized. The refueling nozzle should be bonded to the aircraft required to be vented, special care must be made to ensure the before refueling begins and should remain bonded throughout vents do not leak into the interior of the aircraft. Combustion the refueling process. When a fuel truck is used, it should be byproducts include soot, sulfur dioxide, carbon dioxide, and grounded prior to the fuel nozzle contacting the aircraft.

some carbon monoxide. An improperly adjusted, fueled, or poorly maintained fuel heater can be dangerous.

If fueling from drums or cans is necessary, proper bonding and grounding connections are important. Drums should be Exhaust Heating Systems placed near grounding posts, and the following sequence of Exhaust heating systems are the simplest type of aircraft connections observed: heating system and are used on most light aircraft. Exhaust 1. Drum to ground heating systems are used to route exhaust gases away from the engine and fuselage while reducing engine noise. The 2. Ground to aircraft exhaust systems also serve as a heat source for the cabin 3. Drum to aircraft or nozzle to aircraft before removing and carburetor.

the fuel cap The risks of operating an aircraft with a defective exhaust When disconnecting, reverse the order.

heating system include carbon monoxide poisoning, a decrease in engine performance, and an increased potential The passage of fuel through a chamois increases the charge for fire. Because of these risks, technicians should be aware of static electricity and the danger of sparks. The aircraft of the rate of exhaust heating system deterioration and should must be properly grounded and the nozzle, chamois filter, thoroughly inspect all areas of the exhaust heating system to and funnel bonded to the aircraft. If a can is used, it should look for deficiencies inside and out.

be connected to either the grounding post or the funnel.

Under no circumstances should a plastic bucket or similar Combustion Heater Systems nonconductive container be used in this operation.

Combustion heaters or surface combustion heaters are often used to heat the cabin of larger, more expensive aircraft.

Heating System This type of heater burns the aircraft’s fuel in a combustion There are many different types of aircraft heating systems that chamber or tube to develop required heat, and the air are available depending on the type of aircraft. Regardless of flowing around the tube is heated and ducted to the cabin.

which type or the safety features that accompany them, it is A combustion heater is an airtight burner chamber with a always important to reference the specific aircraft operator’s stainless-steel jacket. Fuel from the aircraft fuel system is manual and become knowledgeable about the heating system.

ignited and burns to provide heat. Ventilation air is forced Each has different repair and inspection criteria that should over the airtight burn chamber picking up heat, which is then be precisely followed.

dispersed into the cabin area.

Fuel Fired Heaters When the heater control switch is turned on, airflow, ignition, A fuel fired heater is a small mounted or portable space- and fuel are supplied to the heater. Airflow and ignition are heating device. The fuel is brought to the heater by using constant within the burner chamber while the heater control piping from a fuel tank, or taps into the aircraft’s fuel system.

switch is on. When heat is required, the temperature control A fan blows air into a combustion chamber, and a spark plug is advanced, activating the thermostat. The thermostat (which or ignition device lights the fuel-air mixture. A built-in safety 7-29 senses ventilation air temperature) turns on the fuel solenoid • Battery allowing fuel to spray into the burner chamber. Fuel mixes • Master/battery switch with air inside the chamber and is ignited by the spark plug, • Alternator/generator switch producing heat.

• Bus bar, fuses, and circuit breakers The by-product, carbon monoxide, leaves the aircraft through • Voltage regulator the heater exhaust pipe. Air flowing over the outside of the • Ammeter/loadmeter burner chamber and inside the jacket of the heater absorbs the heat and carries it through ducts into the cabin. As the • Associated electrical wiring thermostat reaches its preset temperature, it turns off the fuel solenoid and stops the flow of fuel into the burner chamber.

Engine-driven alternators or generators supply electric When ventilation air cools to the point that the thermostat current to the electrical system. They also maintain a again turns the fuel solenoid on, the burner starts again.

sufficient electrical charge in the battery. Electrical energy stored in a battery provides a source of electrical power for This method of heat is very safe as an overheat switch is starting the engine and a limited supply of electrical power provided on all combustion heaters, which is wired into for use in the event the alternator or generator fails.

the heater’s electrical system to shut off the fuel in the case of malfunction. In the unlikely event that the heater fuel Most DC generators do not produce a sufficient amount of solenoid, located at the heater, remains open or the control electrical current at low engine rpm to operate the entire switches fail, the remote fuel solenoid and/or fuel pump is electrical system. During operations at low engine rpm, the shut off by the mechanical overheat switch, stopping all fuel electrical needs must be drawn from the battery, which can flow to the system.

quickly be depleted.

As opposed to the fuel fired cabin heaters that are used Alternators have several advantages over generators.

on most single-engine aircraft, it is unlikely for carbon Alternators produce sufficient current to operate the entire monoxide poisoning to occur in combustion heaters.

electrical system, even at slower engine speeds, by producing Combustion heaters have low pressure in the combustion alternating current (AC), which is converted to DC. The tube that is vented through its exhaust into the air stream. The electrical output of an alternator is more constant throughout ventilation air on the outside of the combustion chamber is a wide range of engine speeds.

of higher pressure than on the inside, and ram air increases the pressure on the outside of the combustion tube. In the Some aircraft have receptacles to which an external ground event a leak would develop in the combustion chamber, the power unit (GPU) may be connected to provide electrical higher-pressure air outside the chamber would travel into the energy for starting. These are very useful, especially chamber and out the exhaust.

during cold weather starting. Follow the manufacturer’s recommendations for engine starting using a GPU.

Bleed Air Heating Systems Bleed air heating systems are used on turbine-engine The electrical system is turned on or off with a master switch.

aircraft. Extremely hot compressor bleed air is ducted into Turning the master switch to the ON position provides a chamber where it is mixed with ambient or re-circulated electrical energy to all the electrical equipment circuits air to cool the air to a useable temperature. The air mixture except the ignition system. Equipment that commonly uses is then ducted into the cabin. This type of system contains the electrical system for its source of energy includes: several safety features to include temperature sensors that • Position lights prevent excessive heat from entering the cabin, check • Anticollision lights valves to prevent a loss of compressor bleed air when starting the engine and when full power is required, and • Landing lights engine sensors to eliminate the bleed system if the engine • Taxi lights becomes inoperative.

• Interior cabin lights Electrical System • Instrument lights Most aircraft are equipped with either a 14- or a 28-volt direct • Radio equipment current (DC) electrical system. A basic aircraft electrical • Turn indicator system consists of the following components: • Fuel gauges • Alternator/generator 7-30 • Electric fuel pump An ammeter is used to monitor the performance of the aircraft electrical system. The ammeter shows if the alternator/ • Stall warning system generator is producing an adequate supply of electrical power.

• Pitot heat It also indicates whether or not the battery is receiving an electrical charge.

• Starting motor Ammeters are designed with the zero point in the center Many aircraft are equipped with a battery switch that of the face and a negative or positive indication on either controls the electrical power to the aircraft in a manner side. [Figure 7-35] When the pointer of the ammeter is similar to the master switch. In addition, an alternator switch on the plus side, it shows the charging rate of the battery.

is installed that permits the pilot to exclude the alternator A minus indication means more current is being drawn from the electrical system in the event of alternator failure.

from the battery than is being replaced. A full-scale minus [Figure 7-33] deflection indicates a malfunction of the alternator/generator.

A full-scale positive deflection indicates a malfunction of With the alternator half of the switch in the OFF position, the the regulator. In either case, consult the AFM/POH for entire electrical load is placed on the battery. All nonessential appropriate action to be taken.

electrical equipment should be turned off to conserve battery power.

Not all aircraft are equipped with an ammeter. Some have a warning light that, when lighted, indicates a discharge in A bus bar is used as a terminal in the aircraft electrical system the system as a generator/alternator malfunction. Refer to the to connect the main electrical system to the equipment using AFM/POH for appropriate action to be taken.

electricity as a source of power. This simplifies the wiring system and provides a common point from which voltage can Another electrical monitoring indicator is a loadmeter.

be distributed throughout the system. [Figure 7-34] This type of gauge has a scale beginning with zero and shows the load being placed on the alternator/generator.

Fuses or circuit breakers are used in the electrical system to [Figure 7-35] The loadmeter reflects the total percentage of protect the circuits and equipment from electrical overload.

the load placed on the generating capacity of the electrical Spare fuses of the proper amperage limit should be carried in system by the electrical accessories and battery. When all the aircraft to replace defective or blown fuses. Circuit breakers electrical components are turned off, it reflects only the have the same function as a fuse but can be manually reset, amount of charging current demanded by the battery.

rather than replaced, if an overload condition occurs in the electrical system. Placards at the fuse or circuit breaker panel A voltage regulator controls the rate of charge to the battery identify the circuit by name and show the amperage limit.

by stabilizing the generator or alternator electrical output. The generator/alternator voltage output should be higher than the battery voltage. For example, a 12-volt battery would be fed by a generator/alternator system of approximately 14 volts.

The difference in voltage keeps the battery charged.

Hydraulic Systems There are multiple applications for hydraulic use in aircraft, depending on the complexity of the aircraft. For example, a hydraulic system is often used on small airplanes to operate wheel brakes, retractable landing gear, and some constant- speed propellers. On large airplanes, a hydraulic system is used for flight control surfaces, wing flaps, spoilers, and other systems.

A basic hydraulic system consists of a reservoir, pump (either hand, electric, or engine-driven), a filter to keep the fluid clean, a selector valve to control the direction of flow, a relief valve to relieve excess pressure, and an actuator.

Figure 7-33. On this master switch, the left half is for the alternator [Figure 7-36] and the right half is for the battery.

7-31 Low-voltage Alternator warning light control unit To inst Low volt out LTS To fuel quantity indicators circuit P Power in breaker FUEL IND.

R To flashing beacon Sense (+) I Alternator F To pitot heat Field M BCN PITOT A Sense (-) To radio cooling fan B G R PULL Ground OFF To strobe lights STROBE Y RADIO FAN B Pull off To landing and taxi lights B LDG LTS ALT U To ignition switch S B Alternator field To wing flap system A FLAP A circuit breaker L Clock T To red doorpost maplight T -30 +30 To low-voltage warning light Ammeter + 60 - 60 INST LTS Master To instrument, radio, compass A M P switch and post lights To oil temperature gauge Starter Oil pressure switch To turn coordinator To low-vacuum warning light A Switch/circuit breaker to V standby vacuum pump I STBY VAC To white doorpost light O To wing To audio muting relay N flap circuit Starter I Flight hour breaker To control wheel maplight contactor recorder C NAV To navigation lights DOME S To dome light B To radio U Battery RADIO 1 S contactor Magnetos To radio Ground service Battery plug receptacle RADIO 2 L R To radio or transponder and encoding altimeter RADIO 3 Fuse Diode Circuit breaker (auto-reset) Resistor To radio RADIO 4 Circuit breaker (push to reset) CODE Circuit breaker (pull—off, Capacitor (Noise Filter) push to reset) Figure 7-34. Electrical system schematic.

The hydraulic fluid is pumped through the system to an or both sides of the servo, depending on the servo type. A actuator or servo. A servo is a cylinder with a piston inside single-acting servo provides power in one direction. The that turns fluid power into work and creates the power needed selector valve allows the fluid direction to be controlled.

to move an aircraft system or flight control. Servos can be This is necessary for operations such as the extension and either single-acting or double-acting, based on the needs of retraction of landing gear during which the fluid must work the system. This means that the fluid can be applied to one in two different directions. The relief valve provides an outlet 7-32 -30 +30 0 30 60 + 60 - 60 ALT AMPS A M P Loadmeter Ammeter Figure 7-35. Ammeter and loadmeter.

for the system in the event of excessive fluid pressure in the system. Each system incorporates different components to meet the individual needs of different aircraft.

Figure 7-37. The landing gear supports the airplane during the takeoff run, landing, taxiing, and when parked.

A mineral-based hydraulic fluid is the most widely used type for small aircraft. This type of hydraulic fluid, a kerosene-like airplane. Landing gear employing a rear-mounted wheel is petroleum product, has good lubricating properties, as well called conventional landing gear. Airplanes with conventional as additives to inhibit foaming and prevent the formation landing gear are often referred to as tailwheel airplanes. When of corrosion. It is chemically stable, has very little viscosity the third wheel is located on the nose, it is called a nosewheel, change with temperature, and is dyed for identification. Since and the design is referred to as a tricycle gear. A steerable several types of hydraulic fluids are commonly used, an aircraft nosewheel or tailwheel permits the airplane to be controlled must be serviced with the type specified by the manufacturer.

throughout all operations while on the ground.

Refer to the AFM/POH or the Maintenance Manual.

Tricycle Landing Gear Landing Gear There are three advantages to using tricycle landing gear: The landing gear forms the principal support of an aircraft on the surface. The most common type of landing gear consists 1. It allows more forceful application of the brakes during of wheels, but aircraft can also be equipped with floats for landings at high speeds without causing the aircraft to water operations or skis for landing on snow. [Figure 7-37] nose over.

The landing gear on small aircraft consists of three wheels: 2. It permits better forward visibility for the pilot during two main wheels (one located on each side of the fuselage) takeoff, landing, and taxiing.

and a third wheel positioned either at the front or rear of the 3. It tends to prevent ground looping (swerving) by providing more directional stability during ground Hydraulic fluid supply operation since the aircraft’s center of gravity (CG) is forward of the main wheels. The forward CG keeps Return fluid the airplane moving forward in a straight line rather Hydraulic pressure than ground looping.

Nosewheels are either steerable or castering. Steerable nosewheels are linked to the rudders by cables or rods, while castering nosewheels are free to swivel. In both cases, the BOTH aircraft is steered using the rudder pedals. Airplanes with a RIGHT Pump castering nosewheel may require the pilot to combine the LEFT Motion OFF use of the rudder pedals with independent use of the brakes.

Tailwheel Landing Gear System relief valve Tailwheel landing gear airplanes have two main wheels attached to the airframe ahead of its CG that support most of Selector valve Double acting cylinder the weight of the structure. A tailwheel at the very back of the fuselage provides a third point of support. This arrangement Figure 7-36. Basic hydraulic system.

7-33 allows adequate ground clearance for a larger propeller maintenance. Retractable landing gear is designed to and is more desirable for operations on unimproved fields. streamline the airplane by allowing the landing gear to [Figure 7-38] be stowed inside the structure during cruising flight.

[Figure 7-39] With the CG located behind the main landing gear, directional control using this type of landing gear is more difficult while Brakes on the ground. This is the main disadvantage of the tailwheel Airplane brakes are located on the main wheels and are landing gear. For example, if the pilot allows the aircraft to applied by either a hand control or by foot pedals (toe or heel).

swerve while rolling on the ground at a low speed, he or Foot pedals operate independently and allow for differential she may not have sufficient rudder control and the CG will braking. During ground operations, differential braking can attempt to get ahead of the main gear, which may cause the supplement nosewheel/tailwheel steering.

airplane to ground loop.

Pressurized Aircraft Diminished forward visibility when the tailwheel is on or near Aircraft are flown at high altitudes for two reasons. First, an the ground is a second disadvantage of tailwheel landing gear aircraft flown at high altitude consumes less fuel for a given airplanes. Because of these disadvantages, specific training airspeed than it does for the same speed at a lower altitude is required to operate tailwheel airplanes.

because the aircraft is more efficient at a high altitude.

Second, bad weather and turbulence may be avoided by flying Fixed and Retractable Landing Gear in relatively smooth air above the storms. Many modern Landing gear can also be classified as either fixed or aircraft are being designed to operate at high altitudes, retractable. Fixed landing gear always remains extended taking advantage of that environment. In order to fly at and has the advantage of simplicity combined with low higher altitudes, the aircraft must be pressurized or suitable supplemental oxygen must be provided for each occupant.

It is important for pilots who fly these aircraft to be familiar with the basic operating principles.

In a typical pressurization system, the cabin, flight compartment, and baggage compartments are incorporated into a sealed unit capable of containing air under a pressure higher than outside atmospheric pressure. On aircraft powered by turbine engines, bleed air from the engine compressor section is used to pressurize the cabin. Superchargers may be used on older model turbine-powered aircraft to pump air into the sealed fuselage. Piston-powered aircraft may use air supplied from each engine turbocharger through a sonic venturi (flow limiter). Air is released from the fuselage by Figure 7-38. Tailwheel landing gear.

Figure 7-39. Fixed (left) and retractable (right) gear airplanes.

7-34 a device called an outflow valve. By regulating the air exit, Atmosphere pressure the outflow valve allows for a constant inflow of air to the Altitude (ft) Pressure (psi) pressurized area. [Figure 7-40] Sea level 14.7 2,000 13.7 A cabin pressurization system typically maintains a cabin 4,000 12.7 The altitude at which the pressure altitude of approximately 8,000 feet at the maximum 6,000 11.8 standard air pressure is designed cruising altitude of an aircraft. This prevents rapid 8,000 10.9 equal to 10.9 psi can be changes of cabin altitude that may be uncomfortable or cause 10,000 10.1 found at 8,000 feet.

12,000 9.4 injury to passengers and crew. In addition, the pressurization 14,000 8.6 system permits a reasonably fast exchange of air from At an altitude of 28,000 16,000 8.0 feet, standard atmo the inside to the outside of the cabin. This is necessary to 18,000 7.3 spheric pressure is 4.8 eliminate odors and to remove stale air. [Figure 7-41] psi. By adding this 20,000 6.8 pressure to the cabin 22,000 6.2 pressure differential of Pressurization of the aircraft cabin is necessary in order to 24,000 5.7 6.1 psi difference (psid), protect occupants against hypoxia. Within a pressurized 26,000 5.2 a total air pressure of 28,000 4.8 cabin, occupants can be transported comfortably and safely 10.9 psi is obtained.

30,000 4.4 for long periods of time, particularly if the cabin altitude is maintained at 8,000 feet or below, where the use of Figure 7-41. Standard atmospheric pressure chart.

oxygen equipment is not required. The flight crew in this type of aircraft must be aware of the danger of accidental The following terms will aid in understanding the operating loss of cabin pressure and be prepared to deal with such an principles of pressurization and air conditioning systems: emergency whenever it occurs.

• Aircraft altitude—the actual height above sea level at which the aircraft is flying • Ambient temperature—the temperature in the area Cabin heat Air scoops valve immediately surrounding the aircraft • Ambient pressure—the pressure in the area Heat exchanger Heat shroud immediately surrounding the aircraft Turbocharger • Cabin altitude—cabin pressure in terms of equivalent compressor altitude above sea level Forward section air outlets • Differential pressure—the difference in pressure Flow control between the pressure acting on one side of a wall venturi and the pressure acting on the other side of the Floor level outlets wall. In aircraft air-conditioning and pressurizing systems, it is the difference between cabin pressure To cabin altitude controller and atmospheric pressure.

The cabin pressure control system provides cabin pressure regulation, pressure relief, vacuum relief, and the means for selecting the desired cabin altitude in the isobaric and Safety/dump valve Outflow valve differential range. In addition, dumping of the cabin pressure is a function of the pressure control system. A cabin pressure regulator, an outflow valve, and a safety valve are used to accomplish these functions.

Ambient air Compressor discharge air The cabin pressure regulator controls cabin pressure to a Pressurization air selected value in the isobaric range and limits cabin pressure Pre-heated ambient air to a preset differential value in the differential range. When an CODE Conditioned pressurization air aircraft reaches the altitude at which the difference between Pressurized cabin the pressure inside and outside the cabin is equal to the highest differential pressure for which the fuselage structure is designed, a further increase in aircraft altitude will result Figure 7-40. High performance airplane pressurization system.

7-35 in a corresponding increase in cabin altitude. Differential Decompression is defined as the inability of the aircraft’s control is used to prevent the maximum differential pressure, pressurization system to maintain its designed pressure for which the fuselage was designed, from being exceeded. differential. This can be caused by a malfunction in the This differential pressure is determined by the structural pressurization system or structural damage to the aircraft.

strength of the cabin and often by the relationship of the cabin size to the probable areas of rupture, such as window Physiologically, decompressions fall into the following two areas and doors. categories: • Explosive decompression—a change in cabin pressure The cabin air pressure safety valve is a combination faster than the lungs can decompress, possibly pressure relief, vacuum relief, and dump valve. The pressure resulting in lung damage. Normally, the time required relief valve prevents cabin pressure from exceeding a to release air from the lungs without restrictions, such predetermined differential pressure above ambient pressure.

as masks, is 0.2 seconds. Most authorities consider any The vacuum relief prevents ambient pressure from exceeding decompression that occurs in less than 0.5 seconds to cabin pressure by allowing external air to enter the cabin be explosive and potentially dangerous.

when ambient pressure exceeds cabin pressure. The flight • Rapid decompression—a change in cabin pressure in deck control switch actuates the dump valve. When this which the lungs decompress faster than the cabin.

switch is positioned to ram, a solenoid valve opens, causing the valve to dump cabin air into the atmosphere.

During an explosive decompression, there may be noise, and one may feel dazed for a moment. The cabin air fills The degree of pressurization and the operating altitude of with fog, dust, or flying debris. Fog occurs due to the rapid the aircraft are limited by several critical design factors.

drop in temperature and the change of relative humidity.

Primarily, the fuselage is designed to withstand a particular Normally, the ears clear automatically. Air rushes from the maximum cabin differential pressure.

mouth and nose due to the escape of air from the lungs and may be noticed by some individuals.

Several instruments are used in conjunction with the pressurization controller. The cabin differential pressure gauge Rapid decompression decreases the period of useful indicates the difference between inside and outside pressure.

consciousness because oxygen in the lungs is exhaled rapidly, This gauge should be monitored to assure that the cabin does reducing pressure on the body. This decreases the partial not exceed the maximum allowable differential pressure. A pressure of oxygen in the blood and reduces the pilot’s cabin altimeter is also provided as a check on the performance effective performance time by one-third to one-fourth its of the system. In some cases, these two instruments are normal time. For this reason, an oxygen mask should be combined into one. A third instrument indicates the cabin rate worn when flying at very high altitudes (35,000 feet or of climb or descent. A cabin rate-of-climb instrument and a higher). It is recommended that the crewmembers select the cabin altimeter are illustrated in Figure 7-42.

100 percent oxygen setting on the oxygen regulator at high altitude if the aircraft is equipped with a demand or pressure demand oxygen system.

Cabin differential L T A N I pressure indicator B t e A e F 0 C 0 (pounds per square

4 inch differential)

I

DIFF CABIN CLIMB .5 PRESS THOUSAND FT PER MIN 30 Cabin pressure PSI .5 altitude indicator 4 (thousands of feet)

I

Maximum cabin differential pressure limit Cabin rate-of-climb indicator Cabin/differential pressure indicator Figure 7-42. Cabin pressurization instruments.

7-36 The primary danger of decompression is hypoxia. Quick, being stored in an unheated area of the aircraft rather than proper utilization of oxygen equipment is necessary to avoid an actual depletion of the oxygen supply. High pressure unconsciousness. Another potential danger that pilots, crew, oxygen containers should be marked with the psi tolerance and passengers face during high altitude decompressions is (i.e., 1,800 psi) before filling the container to that pressure.

evolved gas decompression sickness. This occurs when the The containers should be supplied with oxygen that meets pressure on the body drops sufficiently, nitrogen comes out or exceeds SAE AS8010 (as revised), Aviator’s Breathing of solution, and forms bubbles inside the person that can have Oxygen Purity Standard. To assure safety, periodic inspection adverse effects on some body tissues. and servicing of the oxygen system should be performed.

Decompression caused by structural damage to the aircraft An oxygen system consists of a mask or cannula and a presents another type of danger to pilots, crew, and regulator that supplies a flow of oxygen dependent upon passengers––being tossed or blown out of the aircraft if cabin altitude. Most regulators approved for use up to 40,000 they are located near openings. Individuals near openings feet are designed to provide zero percent cylinder oxygen should wear safety harnesses or seatbelts at all times when and 100 percent cabin air at cabin altitudes of 8,000 feet or the aircraft is pressurized and they are seated. Structural less, with the ratio changing to 100 percent oxygen and zero damage also has the potential to expose them to wind blasts percent cabin air at approximately 34,000 feet cabin altitude.

and extremely cold temperatures. [Figure 7-43] Most regulators approved up to 45,000 feet are designed to provide 40 percent cylinder oxygen and 60 Rapid descent from altitude is necessary in order to minimize percent cabin air at lower altitudes, with the ratio changing these problems. Automatic visual and aural warning systems to 100 percent at the higher altitude.

are included in the equipment of all pressurized aircraft.

Pilots should be aware of the danger of fire when using Oxygen Systems oxygen. Materials that are nearly fireproof in ordinary air may be susceptible to combustion in oxygen. Oils and greases may Crew and passengers use oxygen systems, in conjunction ignite if exposed to oxygen and cannot be used for sealing with pressurization systems, to prevent hypoxia. Regulations the valves and fittings of oxygen equipment. Smoking during require, at a minimum, flight crews have and use supplemental any kind of oxygen equipment use is prohibited. Before oxygen after 30 minutes exposure to cabin pressure altitudes each flight, the pilot should thoroughly inspect and test all between 12,500 and 14,000 feet. Use of supplemental oxygen equipment. The inspection should include a thorough oxygen is required immediately upon exposure to cabin examination of the aircraft oxygen equipment, including pressure altitudes above 14,000 feet. Every aircraft occupant, available supply, an operational check of the system, and above 15,000 feet cabin pressure altitude, must have assurance that the supplemental oxygen is readily accessible.

supplemental oxygen. However, based on a person’s physical The inspection should be accomplished with clean hands and characteristics and condition, a person may feel the effects should include a visual inspection of the mask and tubing of oxygen deprivation at much lower altitudes. Some people for tears, cracks, or deterioration; the regulator for valve flying above 10,000 feet during the day may experience and lever condition and positions; oxygen quantity; and the disorientation due to the lack of adequate oxygen. At night, location and functioning of oxygen pressure gauges, flow especially when fatigued, these effects may occur as low indicators, and connections. The mask should be donned and as 5,000 feet. Therefore, for optimum protection, pilots are the system should be tested. After any oxygen use, verify that encouraged to use supplemental oxygen above 10,000 feet all components and valves are shut off.

cabin altitude during the day and above 5,000 feet at night.

Most high altitude aircraft come equipped with some type of fixed oxygen installation. If the aircraft does not have a fixed installation, portable oxygen equipment must be readily accessible during flight. The portable equipment usually consists of a container, regulator, mask outlet, and pressure gauge. Aircraft oxygen is usually stored in high pressure system containers of 1,800–2,200 psi. When the ambient temperature surrounding an oxygen cylinder decreases, pressure within that cylinder decreases because pressure varies directly with temperature if the volume of a gas remains constant. A drop in the indicated pressure of a Figure 7-43. Oxygen system regulator.

supplemental oxygen cylinder may be due to the container 7-37 Oxygen Masks oxygen system. However, current regulations require aircraft with oxygen systems installed and certified for operations There are numerous types and designs of oxygen masks in above 18,000 feet to be equipped with oxygen masks instead use. The most important factor in oxygen mask use is to of cannulas. Many cannulas have a flow meter in the oxygen ensure that the masks and oxygen system are compatible.

supply line. If equipped, a periodic check of the green flow Crew masks are fitted to the user’s face with a minimum of detector should be a part of the pilot’s regular scan.

leakage and usually contain a microphone. Most masks are the oronasal type that covers only the mouth and nose.

Diluter-Demand Oxygen Systems Diluter-demand oxygen systems supply oxygen only when A passenger mask may be a simple, cup-shaped rubber the user inhales through the mask. An automix lever allows molding sufficiently flexible to obviate individual fitting. It the regulators to automatically mix cabin air and oxygen or may have a simple elastic head strap or the passenger may supply 100 percent oxygen, depending on the altitude. The hold it to his or her face.

demand mask provides a tight seal over the face to prevent dilution with outside air and can be used safely up to 40,000 All oxygen masks should be kept clean to reduce the danger feet. A pilot who has a beard or mustache should be sure it is of infection and prolong the life of the mask. To clean the trimmed in a manner that will not interfere with the sealing mask, wash it with a mild soap and water solution and rinse of the oxygen mask. The fit of the mask around the beard or it with clear water. If a microphone is installed, use a clean mustache should be checked on the ground for proper sealing.

swab, instead of running water, to wipe off the soapy solution.

The mask should also be disinfected. A gauze pad that has Pressure-Demand Oxygen Systems been soaked in a water solution of Merthiolate can be used Pressure-demand oxygen systems are similar to diluter to swab out the mask. This solution used should contain demand oxygen equipment, except that oxygen is supplied to one-fifth teaspoon of Merthiolate per quart of water. Wipe the mask under pressure at cabin altitudes above 34,000 feet.

the mask with a clean cloth and air dry.

Pressure-demand regulators create airtight and oxygen-tight seals, but they also provide a positive pressure application of Cannula oxygen to the mask face piece that allows the user’s lungs A cannula is an ergonomic piece of plastic tubing that runs to be pressurized with oxygen. This feature makes pressure under the nose to administer oxygen to the user. [Figure 7-44] demand regulators safe at altitudes above 40,000 feet. Some Cannulas are typically more comfortable than masks, but systems may have a pressure demand mask with the regulator may not provide an adequate flow of oxygen as reliably as attached directly to the mask, rather than mounted on the masks when operating at higher altitudes. Airplanes certified instrument panel or other area within the flight deck. The to older regulations had cannulas installed with an on-board mask-mounted regulator eliminates the problem of a long hose that must be purged of air before 100 percent oxygen begins flowing into the mask.

Continuous-Flow Oxygen System Continuous-flow oxygen systems are usually provided for passengers. The passenger mask typically has a reservoir bag that collects oxygen from the continuous-flow oxygen system during the time when the mask user is exhaling.

The oxygen collected in the reservoir bag allows a higher aspiratory flow rate during the inhalation cycle, which reduces the amount of air dilution. Ambient air is added to the supplied oxygen during inhalation after the reservoir bag oxygen supply is depleted. The exhaled air is released to the cabin. [Figure 7-45] Electrical Pulse-Demand Oxygen System Portable electrical pulse-demand oxygen systems deliver oxygen by detecting an individual’s inhalation effort and provide oxygen flow during the initial portion of inhalation.

Pulse demand systems do not waste oxygen during the Figure 7-44. Cannula with green flow detector.

7-38 Figure 7-45. Continuous flow mask and rebreather bag.

breathing cycle because oxygen is only delivered during inhalation. Compared to continuous-flow systems, the pulse- Figure 7-46. EDS-011 portable pulse-demand oxygen system.

demand method of oxygen delivery can reduce the amount of oxygen needed by 50–85 percent. Most pulse-demand systems are to be serviced. Oxygen system servicing should oxygen systems also incorporate an internal barometer be accomplished only when the aircraft is located outside that automatically compensates for changes in altitude by of the hangars. Personal cleanliness and good housekeeping increasing the amount of oxygen delivered for each pulse as are imperative when working with oxygen. Oxygen under altitude is increased. [Figure 7-46] pressure creates spontaneous results when brought in contact with petroleum products. Service people should be certain to Pulse Oximeters wash dirt, oil, and grease (including lip salves and hair oil) A pulse oximeter is a device that measures the amount of from their hands before working around oxygen equipment. It oxygen in an individual’s blood, in addition to heart rate.

is also essential that clothing and tools are free of oil, grease, This non-invasive device measures the color changes that red blood cells undergo when they become saturated with oxygen. By transmitting a special light beam through a fingertip to evaluate the color of the red cells, a pulse oximeter can calculate the degree of oxygen saturation within one percent of directly measured blood oxygen.

Because of their portability and speed, pulse oximeters are very useful for pilots operating in nonpressurized aircraft above 12,500 feet where supplemental oxygen is required.

A pulse oximeter permits crewmembers and passengers of an aircraft to evaluate their actual need for supplemental oxygen. [Figure 7-47] Servicing of Oxygen Systems Before servicing any aircraft with oxygen, consult the specific aircraft service manual to determine the type of Figure 7-47. Onyx pulse oximeter.

equipment required and procedures to be used. Certain precautions should be observed whenever aircraft oxygen 7-39 and dirt. Aircraft with permanently installed oxygen tanks usually require two persons to accomplish servicing of the system. One should be stationed at the service equipment control valves, and the other stationed where he or she can observe the aircraft system pressure gauges. Oxygen system servicing is not recommended during aircraft fueling operations or while other work is performed that could provide a source of ignition. Oxygen system servicing while passengers are on board the aircraft is not recommended.

Anti-Ice and Deice Systems Tubes deflated Anti-icing equipment is designed to prevent the formation of ice, while deicing equipment is designed to remove ice once it has formed. These systems protect the leading edge of wing and tail surfaces, pitot and static port openings, fuel tank vents, stall warning devices, windshields, and propeller blades. Ice detection lighting may also be installed on some aircraft to determine the extent of structural icing during night flights.

Most light aircraft have only a heated pitot tube and are not certified for flight in icing. These light aircraft have limited cross-country capability in the cooler climates during late fall, winter, and early spring. Noncertificated aircraft must Tubes inflated exit icing conditions immediately. Refer to the AFM/POH for details.

Figure 6-48. Deicing boots on the leading edge of the wing.

Airfoil Anti-Ice and Deice also incorporate an annunciator light to indicate proper boot Inflatable deicing boots consist of a rubber sheet bonded to operation.

the leading edge of the airfoil. When ice builds up on the leading edge, an engine-driven pneumatic pump inflates the Proper maintenance and care of deicing boots are important rubber boots. Many turboprop aircraft divert engine bleed for continued operation of this system. They need to be air to the wing to inflate the rubber boots. Upon inflation, carefully inspected during preflight.

the ice is cracked and should fall off the leading edge of the wing. Deicing boots are controlled from the flight deck by Another type of leading edge protection is the thermal anti-ice a switch and can be operated in a single cycle or allowed to system. Heat provides one of the most effective methods for cycle at automatic, timed intervals. [Figure 7-48] preventing ice accumulation on an airfoil. High performance turbine aircraft often direct hot air from the compressor In the past, it was believed that if the boots were cycled section of the engine to the leading edge surfaces. The hot too soon after encountering ice, the ice layer would expand air heats the leading edge surfaces sufficiently to prevent the instead of breaking off, resulting in a condition referred to as formation of ice. A newer type of thermal anti-ice system ice “bridging.” Consequently, subsequent deice boot cycles referred to as ThermaWing uses electrically heated graphite would be ineffective at removing the ice buildup. Although foil laminate applied to the leading edge of the wing and some residual ice may remain after a boot cycle, “bridging” horizontal stabilizer. ThermaWing systems typically have does not occur with any modern boots. Pilots can cycle the two zones of heat application. One zone on the leading edge boots as soon as an ice accumulation is observed. Consult receives continuous heat; the second zone further aft receives the AFM/POH for information on the operation of deice heat in cycles to dislodge the ice allowing aerodynamic forces boots on an aircraft.

to remove it. Thermal anti-ice systems should be activated prior to entering icing conditions.

Many deicing boot systems use the instrument system suction gauge and a pneumatic pressure gauge to indicate proper boot An alternate type of leading edge protection that is not as operation. These gauges have range markings that indicate common as thermal anti-ice and deicing boots is known the operating limits for boot operation. Some systems may 7-40 as a weeping wing. The weeping-wing design uses small inboard and the outboard sections. The boots are imbedded holes located in the leading edge of the wing to prevent with electrical wires that carry current for heating the the formation and build-up of ice. An antifreeze solution propeller. The prop anti-ice system can be monitored for is pumped to the leading edge and weeps out through the proper operation by monitoring the prop anti-ice ammeter.

holes. Additionally, the weeping wing is capable of deicing During the preflight inspection, check the propeller boots for an aircraft. When ice has accumulated on the leading edges, proper operation. If a boot fails to heat one blade, an unequal application of the antifreeze solution chemically breaks down blade loading can result and may cause severe propeller the bond between the ice and airframe, allowing aerodynamic vibration. [Figure 7-50] forces to remove the ice. [Figure 7-49] Other Anti-Ice and Deice Systems Windscreen Anti-Ice Pitot and static ports, fuel vents, stall-warning sensors, There are two main types of windscreen anti-ice systems.

and other optional equipment may be heated by electrical The first system directs a flow of alcohol to the windscreen.

elements. Operational checks of the electrically heated If used early enough, the alcohol prevents ice from building systems are to be checked in accordance with the AFM /POH.

up on the windscreen. The rate of alcohol flow can be controlled by a dial in the flight deck according to procedures Operation of aircraft anti-icing and deicing systems should be recommended by the aircraft manufacturer.

checked prior to encountering icing conditions. Encounters with structural ice require immediate action. Anti-icing and Another effective method of anti-icing equipment is the deicing equipment are not intended to sustain long-term flight electric heating method. Small wires or other conductive in icing conditions.

material is imbedded in the windscreen. The heater can be turned on by a switch in the flight deck, causing an electrical Chapter Summary current to be passed across the shield through the wires to All aircraft have a requirement for essential systems such provide sufficient heat to prevent the formation of ice on as the engine, propeller, induction, ignition systems as well the windscreen. The heated windscreen should only be used as the fuel, lubrication, cooling, electrical, landing gear, and during flight. Do not leave it on during ground operations, as it can overheat and cause damage to the windscreen. Warning: the electrical current can cause compass deviation errors by as much as 40°.

Prop anti-ice ammeter When the system is operating, Propeller Anti-Ice the prop ammeter indicates Propellers are protected from icing by the use of alcohol or normal operating range. As each boot section cycles, the ammeter PROP DEICER electrically heated elements. Some propellers are equipped fluctuates.

AMPS with a discharge nozzle that is pointed toward the root of the blade. Alcohol is discharged from the nozzles, and centrifugal force drives the alcohol down the leading edge of the blade.

The boots are also grooved to help direct the flow of alcohol.

This prevents ice from forming on the leading edge of the propeller. Propellers can also be fitted with propeller anti-ice boots. The propeller boot is divided into two sections—the Outboard section Inboard section Prop anti-ice boot The boot is divided into two sections: inboard and outboard.

When the anti-ice is operating, the inboard section heats on each blade, and then cycles to the outboard section. If a boot fails to heat properly on one blade, unequal ice loading may result causing severe vibration.

Figure 7-49. TKS weeping wing anti-ice/deicing system. Figure 7-50. Prop ammeter and anti-ice boots.

7-41 environmental control systems to support flight. Understanding the aircraft systems of the aircraft being flown is critical to its safe operation and proper maintenance. Consult the AFM/ POH for specific information pertaining to the aircraft being flown. Various manufacturer and owners group websites can also be a valuable source of additional information.

7-42

Chapter 8

Flight

Instruments

Introduction In order to safely fly any aircraft, a pilot must understand how to interpret and operate the flight instruments. The pilot also needs to be able to recognize associated errors and malfunctions of these instruments. This chapter addresses the pitot-static system and associated instruments, the vacuum system and related instruments, gyroscopic instruments, and the magnetic compass. When a pilot understands how each instrument works and recognizes when an instrument is malfunctioning, he or she can safely utilize the instruments to their fullest potential.

Pitot-Static Flight Instruments The pitot-static system is a combined system that utilizes the static air pressure and the dynamic pressure due to the motion of the aircraft through the air. These combined pressures are utilized for the operation of the airspeed indicator (ASI), altimeter, and vertical speed indicator (VSI). [Figure 8-1] 8-1 Altimeter Vertical speed indicator (VSI) Airspeed indicator (ASI) 29.8 29.9 30.0 Pressure chamber Static port Static chamber Baffle plate Pitot tube Drain hole Static hole Ram air Heater (35 watts) Pitot heater switch Alternate static source Heater (100 watts) Figure 8-1. Pitot-static system and instruments.

Impact Pressure Chamber and Lines precipitation. Both openings in the pitot tube must be checked prior to flight to ensure that neither is blocked. Many aircraft The pitot tube is utilized to measure the total combined have pitot tube covers installed when they sit for extended pressures that are present when an aircraft moves through periods of time. This helps to keep bugs and other objects the air. Static pressure, also known as ambient pressure, is from becoming lodged in the opening of the pitot tube.

always present whether an aircraft is moving or at rest. It is simply the barometric pressure in the local area. Dynamic The one instrument that utilizes the pitot tube is the ASI. The pressure is present only when an aircraft is in motion; total pressure is transmitted to the ASI from the pitot tube’s therefore, it can be thought of as a pressure due to motion.

pressure chamber via a small tube. The static pressure is Wind also generates dynamic pressure. It does not matter if also delivered to the opposite side of the ASI, which serves the aircraft is moving through still air at 70 knots or if the to cancel out the two static pressures, thereby leaving the aircraft is facing a wind with a speed of 70 knots, the same dynamic pressure to be indicated on the instrument. When dynamic pressure is generated.

the dynamic pressure changes, the ASI shows either increase or decrease, corresponding to the direction of change. The When the wind blows from an angle less than 90° off the two remaining instruments (altimeter and VSI) utilize only nose of the aircraft, dynamic pressure can be depicted on the the static pressure that is derived from the static port.

ASI. The wind moving across the airfoil at 20 knots is the same as the aircraft moving through calm air at 20 knots.

Static Pressure Chamber and Lines The pitot tube captures the dynamic pressure, as well as the The static chamber is vented through small holes to the static pressure that is always present.

free undisturbed air on the side(s) of the aircraft. As the atmospheric pressure changes, the pressure is able to move The pitot tube has a small opening at the front that allows freely in and out of the instruments through the small lines the total pressure to enter the pressure chamber. The total that connect the instruments to the static system. An alternate pressure is made up of dynamic pressure plus static pressure.

static source is provided in some aircraft to provide static In addition to the larger hole in the front of the pitot tube, pressure should the primary static source become blocked.

there is a small hole in the back of the chamber that allows The alternate static source is normally found inside the flight moisture to drain from the system should the aircraft enter 8-2 deck. Due to the venturi effect of the air flowing around the 100 ft. pointer fuselage, the air pressure inside the flight deck is lower than the exterior pressure.

10,000 ft. pointer When the alternate static source pressure is used, the 1,000 ft. pointer Aneroid wafers following instrument indications are observed: 1. The altimeter indicates a slightly higher altitude than actual.

2. The ASI indicates an airspeed greater than the actual airspeed.

3. The VSI shows a momentary climb and then stabilizes if the altitude is held constant.

Each pilot is responsible for consulting the Aircraft Flight Crosshatch flag Manual (AFM) or the Pilot’s Operating Handbook (POH) Static port A crosshatched area appears on to determine the amount of error that is introduced into the some altimeters when displaying an altitude below 10 , 000 feet MSL.

system when utilizing the alternate static source. In an aircraft not equipped with an alternate static source, an alternate Barometric scale adjustment knob method of introducing static pressure into the system should a blockage occur is to break the glass face of the VSI. This Altimeter setting window most likely renders the VSI inoperative. The reason for choosing the VSI as the instrument to break is that it is the Figure 8-2. Altimeter.

least important static source instrument for flight.

until the pressure inside the wafers is equal to the surrounding Altimeter static pressure. Conversely, if the static pressure is less than The altimeter is an instrument that measures the height of the pressure inside of the wafers, the wafers are able to expand an aircraft above a given pressure level. Pressure levels which increases the volume. The expansion and contraction are discussed later in detail. Since the altimeter is the only of the wafers moves the mechanical linkage which drives the instrument that is capable of indicating altitude, this is one of needles on the face of the altimeter.

the most vital instruments installed in the aircraft. To use the altimeter effectively, the pilot must understand the operation Principle of Operation of the instrument, as well as the errors associated with the The pressure altimeter is an aneroid barometer that measures altimeter and how each affect the indication.

the pressure of the atmosphere at the level where the altimeter is located and presents an altitude indication in feet. The altimeter A stack of sealed aneroid wafers comprise the main uses static pressure as its source of operation. Air is denser component of the altimeter. An aneroid wafer is a sealed at sea level than aloft—as altitude increases, atmospheric wafer that is evacuated to an internal pressure of 29.92 pressure decreases. This difference in pressure at various levels inches of mercury ("Hg). These wafers are free to expand causes the altimeter to indicate changes in altitude.

and contract with changes to the static pressure. A higher static pressure presses down on the wafers and causes them The presentation of altitude varies considerably between to collapse. A lower static pressure (less than 29.92 "Hg) different types of altimeters. Some have one pointer while allows the wafers to expand. A mechanical linkage connects others have two or more. Only the multipointer type is the wafer movement to the needles on the indicator face, discussed in this handbook. The dial of a typical altimeter which translates compression of the wafers into a decrease is graduated with numerals arranged clockwise from zero in altitude and translates an expansion of the wafers into an to nine. Movement of the aneroid element is transmitted increase in altitude. [Figure 8-2] through gears to the three hands that indicate altitude. In Figure 8-2 , the long, thin needle with the inverted triangle Notice how the static pressure is introduced into the rear of the at the end indicates tens of thousands of feet; the short, wide sealed altimeter case. The altimeter’s outer chamber is sealed, needle indicates thousands of feet; and the long needle on which allows the static pressure to surround the aneroid top indicates hundreds of feet.

wafers. If the static pressure is higher than the pressure in the aneroid wafers (29.92 "Hg), then the wafers are compressed 8-3 This indicated altitude is correct, however, only when the be lower then the indicated altitude. There is an old aviation sea level barometric pressure is standard (29.92 "Hg), the sea axiom: “GOING FROM A HIGH TO A LOW, LOOK OUT level free air temperature is standard (+15 degrees Celsius BELOW.” Conversely, if an aircraft is flown from a low (°C) or 59 degrees Fahrenheit (°F)), and the pressure and pressure area to a high pressure area without an adjustment temperature decrease at a standard rate with an increase of the altimeter, the actual altitude of the aircraft is higher in altitude. Adjustments for nonstandard pressures are than the indicated altitude. Once in flight, it is important to accomplished by setting the corrected pressure into a frequently obtain current altimeter settings en route to ensure barometric scale located on the face of the altimeter. The terrain and obstruction clearance.

barometric pressure window is sometimes referred to as the Kollsman window; only after the altimeter is set does it Many altimeters do not have an accurate means of being indicate the correct altitude. The word “correct” will need adjusted for barometric pressures in excess of 31.00 to be better explained when referring to types of altitudes, "Hg. When the altimeter cannot be set to the higher but is commonly used in this case to denote the approximate pressure setting, the aircraft actual altitude is higher than altitude above sea level. In other words, the indicated the altimeter indicates. When low barometric pressure altitude refers to the altitude read off of the altitude which is conditions occur (below 28.00), flight operations by uncorrected, after the barometric pressure setting is dialed aircraft unable to set the actual altimeter setting are into the Kollsman window. The additional types of altitudes not recommended.

are further explained later.

Adjustments to compensate for nonstandard pressure do not compensate for nonstandard temperature. Since cold Effect of Nonstandard Pressure and Temperature air is denser than warm air, when operating in temperatures It is easy to maintain a consistent height above ground if that are colder than standard, the altitude is lower than the the barometric pressure and temperature remain constant, altimeter indication. [Figure 8-3] It is the magnitude of this but this is rarely the case. The pressure and temperature can “difference” that determines the magnitude of the error. It is change between takeoff and landing even on a local flight.

the difference due to colder temperatures that concerns the If these changes are not taken into consideration, flight pilot. When flying into a cooler air mass while maintaining a becomes dangerous.

constant indicated altitude, true altitude is lower. If terrain or obstacle clearance is a factor in selecting a cruising altitude, If altimeters could not be adjusted for nonstandard pressure, a particularly in mountainous terrain, remember to anticipate hazardous situation could occur. For example, if an aircraft is that a colder-than-standard temperature places the aircraft flown from a high pressure area to a low pressure area without lower than the altimeter indicates. Therefore, a higher adjusting the altimeter, a constant altitude will be displayed, indicated altitude may be required to provide adequate terrain but the actual height of the aircraft above the ground would clearance. A variation of the memory aid used for pressure 5,000 foot pressure level 4,000 foot pressure level 3,000 foot pressure level 2,000 foot pressure level 1,000 foot pressure level Sea level ° ° ° 30 C 15 C 0 C Figure 8-3. Effects of nonstandard temperature on an altimeter.

8-4 can be employed: “FROM HOT TO COLD, LOOK OUT at higher levels, particularly the effect of nonstandard BELOW.” When the air is warmer than standard, the aircraft temperature. If each pilot in a given area is using the same is higher than the altimeter indicates. Altitude corrections for altimeter setting, each altimeter should be equally affected temperature can be computed on the navigation computer. by temperature and pressure variation errors, making it possible to maintain the desired vertical separation between Extremely cold temperatures also affect altimeter indications. aircraft. This does not guarantee vertical separation though.

Figure 8-4, which was derived from ICAO formulas, It is still imperative to maintain a regimented visual scan for indicates how much error can exist when the temperature is intruding air traffic.

extremely cold.

When flying over high, mountainous terrain, certain Setting the Altimeter atmospheric conditions cause the altimeter to indicate an altitude of 1,000 feet or more higher than the actual altitude.

Most altimeters are equipped with a barometric pressure For this reason, a generous margin of altitude should be setting window (or Kollsman window) providing a means allowed—not only for possible altimeter error, but also for to adjust the altimeter. A knob is located at the bottom of the possible downdrafts that might be associated with high winds.

instrument for this adjustment.

To illustrate the use of the altimeter setting system, follow a To adjust the altimeter for variation in atmospheric pressure, flight from Dallas Love Field, Texas, to Abilene Municipal the pressure scale in the altimeter setting window, calibrated Airport, Texas, via Mineral Wells. Before taking off from in inches of mercury ("Hg) and/or millibars (mb), is adjusted Love Field, the pilot receives a current altimeter setting of to match the given altimeter setting. Altimeter setting is 29.85 "Hg from the control tower or ATIS and sets this value defined as station pressure reduced to sea level, but an in the altimeter setting window. The altimeter indication altimeter setting is accurate only in the vicinity of the should then be compared with the known airport elevation of reporting station. Therefore, the altimeter must be adjusted as 487 feet. Since most altimeters are not perfectly calibrated, the flight progresses from one station to the next. Air traffic an error may exist.

control (ATC) will advise when updated altimeter settings are available. If a pilot is not utilizing ATC assistance, When over Mineral Wells, assume the pilot receives a current local altimeter settings can be obtained by monitoring local altimeter setting of 29.94 "Hg and sets this in the altimeter automated weather observing system/automated surface window. Before entering the traffic pattern at Abilene observation system (AWOS/ASOS) or automatic terminal Municipal Airport, a new altimeter setting of 29.69 "Hg information service (ATIS) broadcasts.

is received from the Abilene Control Tower and set in the altimeter setting window. If the pilot desires to fly the Many pilots confidently expect the current altimeter setting traffic pattern at approximately 800 feet above the terrain, will compensate for irregularities in atmospheric pressure at and the field elevation of Abilene is 1,791 feet, an indicated all altitudes, but this is not always true. The altimeter setting altitude of 2,600 feet should be maintained (1,791 feet + broadcast by ground stations is the station pressure corrected 800 feet = 2,591 feet, rounded to 2,600 feet).

to mean sea level. It does not account for the irregularities The importance of properly setting the altimeter cannot Height Above Airport in Feet be overemphasized. Assume the pilot did not adjust the altimeter at Abilene to the current setting and continued using 200 300 400 500 600 700 800 900 2,000 3,000 4,000 5,000 1,000 1,500 Reported Temp 0 °C the Mineral Wells setting of 29.94 "Hg. When entering the +10 10 10 10 10 20 20 20 20 20 30 40 60 80 90 Abilene traffic pattern at an indicated altitude of 2,600 feet, 0 20 20 30 30 40 40 50 50 60 90 120 170 230 280 the aircraft would be approximately 250 feet below the proper -10 20 30 40 50 60 70 80 90 100 150 200 290 390 490 traffic pattern altitude. Upon landing, the altimeter would -20 30 50 60 70 90 100 120 130 140 210 280 420 570 710 indicate approximately 250 feet higher than the field elevation.

-30 40 60 80 100 120 140 150 170 190 280 380 570 760 950 Mineral Wells altimeter setting 29.94 -40 50 80 100 120 150 170 190 220 240 360 480 720 970 1,210 -50 60 90 120 150 180 210 240 270 300 450 590 890 1,190 1,500 Abilene altimeter setting 29.69 Difference 0.25 Figure 8-4. Look at the chart using a temperature of –10 °C and an aircraft altitude of 1,000 feet above the airport elevation. The (Since 1 inch of pressure is equal to approximately 1,000 feet chart shows that the reported current altimeter setting may place of altitude, 0.25 × 1,000 feet = 250 feet.)

the aircraft as much as 100 feet below the altitude indicated by the altimeter.

8-5 When determining whether to add or subtract the amount of A decrease in pressure causes the altimeter to indicate an altimeter error, remember that when the actual pressure is lower increase in altitude, and an increase in pressure causes the than what is set in the altimeter window, the actual altitude altimeter to indicate a decrease in altitude. Accordingly, if of the aircraft is lower than what is indicated on the altimeter. the aircraft is sitting on the ground with a pressure level of 29.98 "Hg and the pressure level changes to 29.68 "Hg, the The following is another method of computing the altitude altimeter would show an increase of approximately 300 feet deviation. Start by subtracting the current altimeter setting in altitude. This pressure change is most noticeable when the from 29.94 "Hg. Always remember to place the original setting aircraft is left parked over night. As the pressure falls, the as the top number. Then subtract the current altimeter setting. altimeter interprets this as a climb. The altimeter indicates an altitude above the actual field elevation. If the barometric Mineral Wells altimeter setting 29.94 pressure setting is reset to the current altimeter setting of 29.68 Abilene altimeter setting 29.69 "Hg, then the field elevation is again indicated on the altimeter.

29.94 – 29.69 = Difference 0.25 This pressure change is not as easily noticed in flight since aircraft fly at specific altitudes. The aircraft steadily decreases (Since 1 inch of pressure is equal to approximately 1,000 feet true altitude while the altimeter is held constant through pilot of altitude, 0.25 × 1,000 feet = 250 feet.) Always subtract action as discussed in the previous section.

the number from the indicated altitude.

2,600 – 250 = 2,350 Knowing the aircraft’s altitude is vitally important to a pilot. The pilot must be sure that the aircraft is flying high Now, try a lower pressure setting. Adjust from altimeter enough to clear the highest terrain or obstruction along the setting 29.94 to 30.56 "Hg.

intended route. It is especially important to have accurate Mineral Wells altimeter setting 29.94 altitude information when visibility is restricted. To clear obstructions, the pilot must constantly be aware of the altitude Altimeter setting 30.56 of the aircraft and the elevation of the surrounding terrain. To 29.94 – 30.56 = Difference –0.62 reduce the possibility of a midair collision, it is essential to maintain altitude in accordance with air traffic rules.

(Since 1 inch of pressure is equal to approximately 1,000 feet of altitude, 0.62 × 1,000 feet = 620 feet.) Always subtract Types of Altitude the number from the indicated altitude.

Altitude in itself is a relevant term only when it is specifically 2,600 – (–620) = 3,220 stated to which type of altitude a pilot is referring. Normally when the term “altitude” is used, it is referring to altitude The pilot will be 620 feet high.

above sea level since this is the altitude which is used to depict obstacles and airspace, as well as to separate air traffic.

Notice the difference is a negative number. Starting with the current indicated altitude of 2,600 feet, subtracting a negative Altitude is vertical distance above some point or level used as number is the same as adding the two numbers. By utilizing a reference. There are as many kinds of altitude as there are this method, a pilot will better understand the importance of reference levels from which altitude is measured, and each using the current altimeter setting (miscalculation of where may be used for specific reasons. Pilots are mainly concerned and in what direction an error lies can affect safety; if altitude with five types of altitudes: is lower than indicated altitude, an aircraft could be in danger 1. Indicated altitude—read directly from the altimeter of colliding with an obstacle).

(uncorrected) when it is set to the current altimeter setting.

Altimeter Operation 2. True altitude—the vertical distance of the aircraft There are two means by which the altimeter pointers can above sea level—the actual altitude. It is often be moved. The first is a change in air pressure, while the expressed as feet above mean sea level (MSL). Airport, other is an adjustment to the barometric scale. When the terrain, and obstacle elevations on aeronautical charts aircraft climbs or descends, changing pressure within the are true altitudes.

altimeter case expands or contracts the aneroid barometer.

This movement is transmitted through mechanical linkage to rotate the pointers.

8-6 3. Absolute altitude—the vertical distance of an aircraft Vertical Speed Indicator (VSI) above the terrain, or above ground level (AGL).

The VSI, which is sometimes called a vertical velocity indicator (VVI), indicates whether the aircraft is climbing, 4. Pressure altitude—the altitude indicated when descending, or in level flight. The rate of climb or descent is the altimeter setting window (barometric scale) is indicated in feet per minute (fpm). If properly calibrated, the adjusted to 29.92 "Hg. This is the altitude above VSI indicates zero in level flight. [Figure 8-5] the standard datum plane, which is a theoretical plane where air pressure (corrected to 15 °C) equals Principle of Operation 29.92 "Hg. Pressure altitude is used to compute density altitude, true altitude, true airspeed (TAS), and other Although the VSI operates solely from static pressure, it is a differential pressure instrument. It contains a diaphragm with performance data.

connecting linkage and gearing to the indicator pointer inside 5. Density altitude—pressure altitude corrected an airtight case. The inside of the diaphragm is connected for variations from standard temperature. When directly to the static line of the pitot-static system. The area conditions are standard, pressure altitude and density outside the diaphragm, which is inside the instrument case, altitude are the same. If the temperature is above is also connected to the static line but through a restricted standard, the density altitude is higher than pressure orifice (calibrated leak).

altitude. If the temperature is below standard, the density altitude is lower than pressure altitude. This Both the diaphragm and the case receive air from the static is an important altitude because it is directly related line at existing atmospheric pressure. The diaphragm receives to the aircraft’s performance.

unrestricted air, while the case receives the static pressure via the metered leak. When the aircraft is on the ground or in level A pilot must understand how the performance of the aircraft flight, the pressures inside the diaphragm and the instrument is directly related to the density of the air. The density of case are equal, and the pointer is at the zero indication.

the air affects how much power a naturally aspirated engine When the aircraft climbs or descends, the pressure inside produces, as well as how efficient the airfoils are. If there are the diaphragm changes immediately, but due to the metering fewer air molecules (lower pressure) to accelerate through action of the restricted passage, the case pressure remains the propeller, the acceleration to rotation speed is longer higher or lower for a short time, causing the diaphragm to and thus produces a longer takeoff roll, which translates to contract or expand. This causes a pressure differential that a decrease in performance.

is indicated on the instrument needle as a climb or descent.

When the pressure differential stabilizes at a definite ratio, As an example, consider an airport with a field elevation the needle indicates the rate of altitude change.

of 5,048 feet MSL where the standard temperature is 5 °C.

Under these conditions, pressure altitude and density altitude are the same—5,048 feet. If the temperature changes to Diaphragm 30 °C, the density altitude increases to 7,855 feet. This means an aircraft would perform on takeoff as though the field elevation were 7,855 feet at standard temperature.

Conversely, a temperature of –25 °C would result in a density 2

I

altitude of 1,232 feet. An aircraft would perform much better VERTICAL SPEED UP THOUSAND FT PER MIN under these conditions.

DOWN Instrument Check

I

Prior to each flight, a pilot should examine the altimeter for proper indications in order to verify its validity. To determine the condition of an altimeter, set the barometric scale to the Direct static pressure current reported altimeter setting transmitted by the local airport traffic control tower, flight service station (FSS), or Calibrated leak any other reliable source, such as ATIS, AWOS, or ASOS.

The altimeter pointers should indicate the surveyed field elevation of the airport. If the indication is off more than Figure 8-5. Vertical speed indicator (VSI).

75 feet from the surveyed field elevation, the instrument should be referred to a certificated instrument repair station for recalibration.

8-7 The VSI displays two different types of information: Airspeed Indicator (ASI) The ASI is a sensitive, differential pressure gauge that • Trend information shows an immediate indication of measures and promptly indicates the difference between pitot an increase or decrease in the aircraft’s rate of climb (impact/dynamic pressure) and static pressure. These two or descent.

pressures are equal when the aircraft is parked on the ground • Rate information shows a stabilized rate of change in in calm air. When the aircraft moves through the air, the altitude.

pressure on the pitot line becomes greater than the pressure in the static lines. This difference in pressure is registered by The trend information is the direction of movement of the the airspeed pointer on the face of the instrument, which is VSI needle. For example, if an aircraft is maintaining level calibrated in miles per hour, knots (nautical miles per hour), flight and the pilot pulls back on the control yoke causing the or both. [Figure 8-7] nose of the aircraft to pitch up, the VSI needle moves upward to indicate a climb. If the pitch attitude is held constant, The ASI is the one instrument that utilizes both the pitot, the needle stabilizes after a short period (6–9 seconds) and as well as the static system. The ASI introduces the static indicates the rate of climb in hundreds of fpm. The time pressure into the airspeed case while the pitot pressure period from the initial change in the rate of climb, until the (dynamic) is introduced into the diaphragm. The dynamic VSI displays an accurate indication of the new rate, is called pressure expands or contracts one side of the diaphragm, the lag. Rough control technique and turbulence can extend which is attached to an indicating system. The system drives the lag period and cause erratic and unstable rate indications.

the mechanical linkage and the airspeed needle.

Some aircraft are equipped with an instantaneous vertical speed indicator (IVSI), which incorporates accelerometers Just as in altitudes, there are multiple types of airspeeds.

to compensate for the lag in the typical VSI. [Figure 8-6] Pilots need to be very familiar with each type.

• Indicated airspeed (IAS)—the direct instrument Instrument Check reading obtained from the ASI, uncorrected for As part of a preflight check, proper operation of the VSI variations in atmospheric density, installation error, must be established. Make sure the VSI indicates a near zero or instrument error. Manufacturers use this airspeed reading prior to leaving the ramp area and again just before as the basis for determining aircraft performance.

takeoff. If the VSI indicates anything other than zero, that Takeoff, landing, and stall speeds listed in the AFM/ indication can be referenced as the zero mark. Normally, if the POH are IAS and do not normally vary with altitude needle is not exactly zero, it is only slightly above or below or temperature.

the zero line. After takeoff, the VSI should trend upward to indicate a positive rate of climb and then, once a stabilized climb is established, a rate of climb can be referenced.

Diaphragm Sector Long lever Accelerometer Pitot connection Pitot tube I UP .5 .5 DOWN I 2 3 Inlet from static port Handstaff pinion Static air line Ram air Calibrated leak Figure 8-7. Airspeed indicator (ASI).

Figure 8-6. An IVSI incorporates accelerometers to help the instrument immediately indicate changes in vertical speed.

8-8 • Calibrated airspeed (CAS)—IAS corrected for installation error and instrument error. Although V (red line) NE manufacturers attempt to keep airspeed errors to a V S0 minimum, it is not possible to eliminate all errors Yellow arc throughout the airspeed operating range. At certain 9 0 6 0 ° 1 2 0 3 0 F - 3 V S1 airspeeds and with certain flap settings, the installation PRESS ALT 5 and instrument errors may total several knots. This 0 AIRSPEED 1 KNOTS error is generally greatest at low airspeeds. In the 5 160 cruising and higher airspeed ranges, IAS and CAS 2 60 140 are approximately the same. Refer to the airspeed V MPH White arc N0 MPH calibration chart to correct for possible airspeed errors.

• True airspeed (TAS)—CAS corrected for altitude 80 T.A.S. 100 KTS and nonstandard temperature. Because air density 80 V decreases with an increase in altitude, an aircraft has FE Green arc to be flown faster at higher altitudes to cause the same pressure difference between pitot impact pressure and static pressure. Therefore, for a given CAS, TAS Figure 8-8. Single engine airspeed indicator (ASI).

increases as altitude increases; or for a given TAS, CAS decreases as altitude increases. A pilot can find speed. Approaches and landings are usually flown at TAS by two methods. The most accurate method is speeds within the white arc.

to use a flight computer. With this method, the CAS is corrected for temperature and pressure variation by • Lower limit of white arc (V )—the stalling speed S0 using the airspeed correction scale on the computer.

or the minimum steady flight speed in the landing Extremely accurate electronic flight computers are configuration. In small aircraft, this is the power-off also available. Just enter the CAS, pressure altitude, stall speed at the maximum landing weight in the and temperature, and the computer calculates the TAS.

landing configuration (gear and flaps down).

A second method, which is a rule of thumb, provides • Upper limit of the white arc (V )—the maximum FE the approximate TAS. Simply add 2 percent to the speed with the flaps extended.

CAS for each 1,000 feet of altitude. The TAS is the • Green arc—the normal operating range of the aircraft.

speed that is used for flight planning and is used when Most flying occurs within this range.

filing a flight plan.

• Lower limit of green arc (V )—the stalling speed • Groundspeed (GS)—the actual speed of the airplane S1 or the minimum steady flight speed obtained in a over the ground. It is TAS adjusted for wind. GS specified configuration. For most aircraft, this is the decreases with a headwind and increases with a power-off stall speed at the maximum takeoff weight tailwind.

in the clean configuration (gear up, if retractable, and flaps up).

Airspeed Indicator Markings Aircraft weighing 12,500 pounds or less, manufactured after • Upper limit of green arc (V )—the maximum N0 1945, and certificated by the FAA are required to have ASIs structural cruising speed. Do not exceed this speed marked in accordance with a standard color-coded marking except in smooth air.

system. This system of color-coded markings enables a pilot • Yellow arc—caution range. Fly within this range only to determine at a glance certain airspeed limitations that are in smooth air and then only with caution.

important to the safe operation of the aircraft. For example, if • Red line (V )—never exceed speed. Operating above NE during the execution of a maneuver, it is noted that the airspeed this speed is prohibited since it may result in damage needle is in the yellow arc and rapidly approaching the red or structural failure.

line, the immediate reaction should be to reduce airspeed.

Other Airspeed Limitations As shown in Figure 8-8, ASIs on single-engine small aircraft include the following standard color-coded markings: Some important airspeed limitations are not marked on the face of the ASI, but are found on placards and in the AFM/ • White arc—commonly referred to as the flap operating POH. These airspeeds include: range since its lower limit represents the full flap stall speed and its upper limit provides the maximum flap 8-9 • Design maneuvering speed (V )—the maximum already in the system vents through the drain hole, and the A speed at which the structural design’s limit load can remaining pressure drops to ambient (outside) air pressure.

be imposed (either by gusts or full deflection of the Under these circumstances, the ASI reading decreases to control surfaces) without causing structural damage. zero because the ASI senses no difference between ram and It is important to consider weight when referencing static air pressure. The ASI no longer operates since dynamic this speed. For example, V may be 100 knots when pressure cannot enter the pitot tube opening. Static pressure A an airplane is heavily loaded, but only 90 knots when is able to equalize on both sides since the pitot drain hole the load is light. is still open. The apparent loss of airspeed is not usually instantaneous but happens very quickly. [Figure 8-9] • Landing gear operating speed (V )—the maximum LO speed for extending or retracting the landing gear if If both the pitot tube opening and the drain hole should flying an aircraft with retractable landing gear.

become clogged simultaneously, then the pressure in the pitot • Landing gear extended speed (V )—the maximum LE tube is trapped. No change is noted on the airspeed indication speed at which an aircraft can be safely flown with should the airspeed increase or decrease. If the static port the landing gear extended.

is unblocked and the aircraft should change altitude, then a change is noted on the ASI. The change is not related to a • Best angle-of-climb speed (V )—the airspeed at X change in airspeed but a change in static pressure. The total which an aircraft gains the greatest amount of altitude pressure in the pitot tube does not change due to the blockage; in a given distance. It is used during a short-field however, the static pressure will change.

takeoff to clear an obstacle.

• Best rate-of-climb speed (V )—the airspeed that Y Because airspeed indications rely upon both static and provides the most altitude gain in a given period of time.

dynamic pressure together, the blockage of either of these • Single-engine best rate-of-climb (V )—the best YSE systems affects the ASI reading. Remember that the ASI has rate-of-climb or minimum rate-of-sink in a light a diaphragm in which dynamic air pressure is entered. Behind twin-engine aircraft with one engine inoperative. It is this diaphragm is a reference pressure called static pressure marked on the ASI with a blue line. V is commonly YSE that comes from the static ports. The diaphragm pressurizes referred to as “Blue Line.” against this static pressure and as a result changes the airspeed indication via levers and indicators. [Figure 8-10] • Minimum control speed (V )—the minimum flight MC speed at which a light, twin-engine aircraft can be For example, take an aircraft and slow it down to zero knots satisfactorily controlled when an engine suddenly at a given altitude. If the static port (providing static pressure) becomes inoperative and the remaining engine is at and the pitot tube (providing dynamic pressure) are both takeoff power.

unobstructed, the following claims can be made: Instrument Check 1. The ASI would be zero.

Prior to takeoff, the ASI should read zero. However, if there 2. Dynamic pressure and static pressure are equal.

is a strong wind blowing directly into the pitot tube, the ASI 3. Because both dynamic and static air pressure are equal may read higher than zero. When beginning the takeoff, at zero speed with increased speed, dynamic pressure make sure the airspeed is increasing at an appropriate rate.

Blockage of the Pitot-Static System Errors almost always indicate blockage of the pitot tube, the static port(s), or both. Blockage may be caused by moisture (including ice), dirt, or even insects. During preflight, make sure the pitot tube cover is removed. Then, check the pitot and static port openings. A blocked pitot tube affects the accuracy Pitot tube Static port of the ASI, but a blockage of the static port not only affects the ASI, but also causes errors in the altimeter and VSI.

Blockage Blocked Pitot System Drain hole The pitot system can become blocked completely or only partially if the pitot tube drain hole remains open. If the pitot tube becomes blocked and its associated drain hole remains Figure 8-9. A blocked pitot tube, but clear drain hole.

clear, ram air is no longer able to enter the pitot system. Air 8-10 diaphragm causing it to compress, thereby resulting in an indication of decreased airspeed. Conversely, if the aircraft were to climb, the static pressure would decrease allowing the diaphragm to expand, thereby showing an indication of greater airspeed. [Figure 8-10] The pitot tube may become blocked during flight due to Blockage Static port visible moisture. Some aircraft may be equipped with pitot heat for flight in visible moisture. Consult the AFM/POH for specific procedures regarding the use of pitot heat.

Pitot tube Drain hole Blocked Static System If the static system becomes blocked but the pitot tube remains clear, the ASI continues to operate; however, it is inaccurate. The airspeed indicates lower than the actual airspeed when the aircraft is operated above the altitude where the static ports became blocked because the trapped Climb static pressure is higher than normal for that altitude. When operating at a lower altitude, a faster than actual airspeed is displayed due to the relatively low static pressure trapped in the system.

Revisiting the ratios that were used to explain a blocked pitot tube, the same principle applies for a blocked static port. If Descent the aircraft descends, the static pressure increases on the pitot side showing an increase on the ASI. This assumes that the aircraft does not actually increase its speed. The increase in static pressure on the pitot side is equivalent to an increase in dynamic pressure since the pressure cannot change on Figure 8-10. Blocked pitot system with clear static system. the static side.

If an aircraft begins to climb after a static port becomes must include two components: static pressure and blocked, the airspeed begins to show a decrease as the dynamic pressure.

aircraft continues to climb. This is due to the decrease in static pressure on the pitot side, while the pressure on the It can be inferred that airspeed indication must be based upon static side is held constant.

a relationship between these two pressures, and indeed it is.

An ASI uses the static pressure as a reference pressure and A blockage of the static system also affects the altimeter and as a result, the ASI’s case is kept at this pressure behind the VSI. Trapped static pressure causes the altimeter to freeze diaphragm. On the other hand, the dynamic pressure through at the altitude where the blockage occurred. In the case of the pitot tube is connected to a highly sensitive diaphragm the VSI, a blocked static system produces a continuous zero within the ASI case. Because an aircraft in zero motion indication. [Figure 8-11] (regardless of altitude) results in a zero airspeed, the pitot tube always provides static pressure in addition to dynamic pressure.

Some aircraft are equipped with an alternate static source in the flight deck. In the case of a blocked static source, opening Therefore, the airspeed indication is the result of two the alternate static source introduces static pressure from the pressures: the pitot tube static and dynamic pressure within flight deck into the system. Flight deck static pressure is lower the diaphragm as measured against the static pressure in the than outside static pressure. Check the aircraft AOM/POH for ASI’s case.

airspeed corrections when utilizing alternate static pressure.

If the aircraft were to descend while the pitot tube is obstructed, the pressure in the pitot system, including the diaphragm, would remain constant. But as the descent is made, the static pressure would increase against the 8-11 available to a pilot, but also how the information is displayed.

Inaccurate airspeed indications In addition to the improvement in system reliability, which increases overall safety, EFDs have decreased the overall cost Constant zero indication on VSI of equipping aircraft with state-of-the-art instrumentation.

Primary electronic instrumentation packages are less prone Frozen altimeter to failure than their analogue counterparts. No longer is it necessary for aircraft designers to create cluttered panel layouts in order to accommodate all necessary flight 29.8 29.9 30.0 instruments. Instead, multi-panel digital flight displays combine all flight instruments onto a single screen that is called a primary flight display (PFD). The traditional “six pack” of instruments is now displayed on one liquid crystal Pitot tube display (LCD) screen.

Blockage Airspeed Tape Configured similarly to traditional panel layouts, the ASI Static port is located on the left side of the screen and is displayed as a vertical speed tape. As the aircraft increases in speed, the larger numbers descend from the top of the tape. The TAS is Figure 8-11. Blocked static system.

displayed at the bottom of the tape through the input to the air data computer (ADC) from the outside air temperature probe.

Electronic Flight Display (EFD) Airspeed markings for V , V , and rotation speed (V ) are X Y R Advances in technology have brought about changes in the displayed for pilot reference. An additional pilot-controlled instrumentation found in all types of aircraft; for example, airspeed bug is available to set at any desired reference speed.

Electronic Flight Displays (EFDs) commonly referred to As on traditional analogue ASIs, the electronic airspeed tape as “glass cockpits.” EFDs include flight displays such as displays the color-coded ranges for the flap operating range, primary flight displays (PFD) and multi-function displays (MFD). This has changed not only what information is _ _ _ _ _ _ _ _ ._ _ _ _ WPT DIS NM DTK °T TRK 360° NAV1 108.00 113.00 134.000 118.000 COM1 Attitude indicator Altimeter Slip skid indicator NAV2 108.00 110.60 123.800 118.000 COM2 4 000 4 300 4 200 Vertical speed indicator (VSI) 4 100 Airspeed indicator 80 9 3 900 3 800 ° TAS 106 KT Turn indicator VOR 1 Slip/skid indicator Horizontal situation indicator 270 ° ° XPDR 5537 IDNT LCL10:12:34 OAT 6° C Turn rate indicator tick marks VOR 1 INSET PFD OBS CDI DME XPDR IDENT TMR/REF NRST ALERTS Turn rate trend vector Figure 8-12. Primary flight display (PFD). Note that the actual location of indications vary depending on manufacturers.

8-12 normal range, and caution range. [Figure 8-12] The number Turn Indicator value changes color to red when the airspeed exceeds V to NE The turn indicator takes a slightly different form than the warn the pilot of exceeding the maximum speed limitation.

traditional instrumentation. A sliding bar moves left and right below the triangle to indicate deflection from coordinated Attitude Indicator flight. [Figure 8-12] Reference for coordinated flight comes One improvement over analogue instrumentation is the from accelerometers contained in the AHRS unit.

larger attitude indicator on EFD. The artificial horizon spans the entire width of the PFD. [Figure 8-12] This expanded Tachometer instrumentation offers better reference through all phases of The sixth instrument normally associated with the “six pack” flight and all flight maneuvers. The attitude indicator receives package is the tachometer. This is the only instrument that is its information from the Attitude Heading and Reference not located on the PFD. The tachometer is normally located System (AHRS).

on the multi-function display (MFD). In the event of a display screen failure, it is displayed on the remaining screen with Altimeter the PFD flight instrumentation. [Figure 8-13] The altimeter is located on the right side of the PFD.

[Figure 8-12] As the altitude increases, the larger numbers Slip/Skid Indicator descend from the top of the display tape, with the current The slip/skid indicator is the horizontal line below the roll altitude being displayed in the black box in the center of the pointer. [Figure 8-12] Like a ball in a turn-and-slip indicator, display tape. The altitude is displayed in increments of 20 feet.

a bar width off center is equal to one ball width displacement.

Vertical Speed Indicator (VSI) Turn Rate Indicator The VSI is displayed to the right of the altimeter tape and can The turn rate indicator, illustrated in Figure 8-12 , is typically take the form of an arced indicator or a vertical speed tape.

found directly above the rotating compass card. Tick marks [Figure 8-12] Both are equipped with a vertical speed bug.

to the left and right of the lub b er line denote the turn (standardrate versus half standard-rate). Typically denoted Heading Indicator by a trend line, if the trend vector is extended to the The heading indicator is located below the artificial horizon second tick mark the aircraft is in a standard-rate turn.

and is normally modeled after a Horizontal Situation Indicator (HSI). [Figure 8-12] As in the case of the attitude Individual panel displays can be configured for a variety indicator, the heading indicator receives its information from of aircraft by installing different software packages.

the magnetometer, which feeds information to the AHRS unit [Figure 8-14] Manufacturers are also able to upgrade existing and then out to the PFD.

instrument displays in a similar manner, eliminating the need to replace individual gauges in order to upgrade.

Figure 8-13. Multi-function display (MFD).

8-13 200 210 220 230 240 250 260 270 U Y 10 10 710 100 6 30.30 00:03:29 U 80 X V S B 10 10 W S 40 7 N E MA239 5800’ IFR APPR 239 2.3NM ANG 239 A Figure 8-15. Teledyne’s 90004 TAS/Plus Air Data Computer (ADC) computes air data information from the pitot-static pneumatic system, aircraft temperature probe, and barometric correction device to help create a clear picture of flight characteristics.

does not enter a diaphragm. The ADC computes the received barometric pressure and sends a digital signal to the PFD to display the proper altitude readout. EFDs also show trend vectors, which show the pilot how the altitude and airspeed are progressing.

Trend Vectors Trend vectors are magenta lines that move up and down both the ASI and the altimeter. [Figures 8-16 and 8-17] The ADC computes the rate of change and displays the 6-second projection of where the aircraft will be. Pilots can utilize the trend vectors Figure 8-14. Chelton’s FlightLogic (top) and Avidyne’s Entegra to better control the aircraft’s attitude. By including the trend (bottom) are examples of panel displays that are configurable.

vectors in the instrument scan, pilots are able to precisely control airspeed and altitude. Additional information can be obtained Air Data Computer (ADC) by referencing the Instrument Flying Handbook or specific EFDs utilize the same type of instrument inputs as traditional avionics manufacturer’s training material.

analogue gauges; however, the processing system is different.

The pitot static inputs are received by an ADC. The ADC Airspeed trend vector computes the difference between the total pressure and the static pressure and generates the information necessary to 150 display the airspeed on the PFD. Outside air temperatures are also monitored and introduced into various components within the system, as well as being displayed on the PFD screen. [Figure 8-15] The ADC is a separate solid state device that, in addition to providing data to the PFD, is capable of providing data to the autopilot control system. In the event of system malfunction, the ADC can quickly be removed and replaced in order to decrease downtime and decrease maintenance turn-around times.

TAS 120 KT Altitude information is derived from the static pressure port just as an analogue system does; however, the static pressure Figure 8-16. Airspeed trend vector.

8-14 the bicycle wheels increase speed, they become more stable in Airspeed trend (increasing) their plane of rotation. This is why a bicycle is unstable and 4 200 maneuverable at low speeds and stable and less maneuverable 4 100 120 at higher speeds.

Altitude trend vector 4 110 4 000 By mounting this wheel, or gyroscope, on a set of gimbal 3 900 900 100 3 925 9 -375 80 05 -500 rings, the gyro is able to rotate freely in any direction. Thus, 3 90 3 100 1 800 if the gimbal rings are tilted, twisted, or otherwise moved, 3 700 80 4 000 ° 270 the gyro remains in the plane in which it was originally -250 70 3 900 3700 30 TAS 100 KT spinning. [Figure 8-18] 3 100 ° 4 000 VOR 1 3 -125 3500 Precession 3 900 4 100 3400 Precession is the tilting or turning of a gyro in response to a Turn rate trend vector deflective force. The reaction to this force does not occur at 3300 4 the point at which it was applied; rather, it occurs at a point 3 900 that is 90° later in the direction of rotation. This principle Figure 4-27. Supporting Instruments allows the gyro to determine a rate of turn by sensing the Figure 8-17. Altimeter trend vector.

amount of pressure created by a change in direction. The rate at which the gyro precesses is inversely proportional to the Gyroscopic Flight Instruments speed of the rotor and proportional to the deflective force.

Several flight instruments utilize the properties of a gyroscope Using the example of the bicycle, precession acts on the for their operation. The most common instruments containing wheels in order to allow the bicycle to turn. While riding gyroscopes are the turn coordinator, heading indicator, and at normal speed, it is not necessary to turn the handle bars the attitude indicator. To understand how these instruments in the direction of the desired turn. A rider simply leans in operate requires knowledge of the instrument power systems, the direction that he or she wishes to go. Since the wheels gyroscopic principles, and the operating principles of each are rotating in a clockwise direction when viewed from the instrument.

right side of the bicycle, if a rider leans to the left, a force is applied to the top of the wheel to the left. The force actually Gyroscopic Principles acts 90° in the direction of rotation, which has the effect of Any spinning object exhibits gyroscopic properties. A wheel applying a force to the front of the tire, causing the bicycle or rotor designed and mounted to utilize these properties is called a gyroscope. Two important design characteristics of an instrument gyro are great weight for its size, or high density, and rotation at high speed with low friction bearings.

There are two general types of mountings; the type used depends upon which property of the gyro is utilized. A freely or universally mounted gyroscope is free to rotate in any direction about its center of gravity. Such a wheel is said to have three planes of freedom. The wheel or rotor is free to rotate in any plane in relation to the base and is balanced so that, with the gyro wheel at rest, it remains in the position in which it is placed. Restricted or semi-rigidly mounted gyroscopes are those mounted so that one of the planes of freedom is held fixed in relation to the base.

There are two fundamental properties of gyroscopic action: rigidity in space and precession.

Rigidity in Space Figure 8-18. Regardless of the position of its base, a gyro tends to Rigidity in space refers to the principle that a gyroscope remain rigid in space, with its axis of rotation pointed in a constant remains in a fixed position in the plane in which it is spinning.

direction.

An example of rigidity in space is that of a bicycle wheel. As 8-15 to move to the left. There is a need to turn the handlebars at of pressure in the system (vacuum is measured in inches of low speeds because of the instability of the slowly turning mercury less than ambient pressure).

gyros and also to increase the rate of turn.

As shown in Figure 8-20, air is drawn into the vacuum Precession can also create some minor errors in some system by the engine-driven vacuum pump. It first goes instruments. [Figure 8-19] Precession can cause a freely through a filter, which prevents foreign matter from entering spinning gyro to become displaced from its intended plane the vacuum or pressure system. The air then moves through of rotation through bearing friction, etc. Certain instruments the attitude and heading indicators where it causes the gyros may require corrective realignment during flight, such as the to spin. A relief valve prevents the vacuum pressure, or heading indicator. suction, from exceeding prescribed limits. After that, the air is expelled overboard or used in other systems, such as for Sources of Power inflating pneumatic deicing boots.

In some aircraft, all the gyros are vacuum, pressure, or It is important to monitor vacuum pressure during flight, electrically operated. In other aircraft, vacuum or pressure systems provide the power for the heading and attitude because the attitude and heading indicators may not provide reliable information when suction pressure is low. The indicators, while the electrical system provides the power for the turn coordinator. Most aircraft have at least two sources vacuum, or suction, gauge is generally marked to indicate the normal range. Some aircraft are equipped with a warning of power to ensure at least one source of bank information is available if one power source fails. The vacuum or pressure light that illuminates when the vacuum pressure drops below the acceptable level.

system spins the gyro by drawing a stream of air against the rotor vanes to spin the rotor at high speed, much like the When the vacuum pressure drops below the normal operating operation of a waterwheel or turbine. The amount of vacuum or pressure required for instrument operation varies, but is range, the gyroscopic instruments may become unstable and inaccurate. Cross-checking the instruments routinely is a usually between 4.5 "Hg and 5.5 "Hg.

good habit to develop.

One source of vacuum for the gyros is a vane-type engine- Turn Indicators driven pump that is mounted on the accessory case of the engine. Pump capacity varies in different aircraft, depending Aircraft use two types of turn indicators: turn-and-slip on the number of gyros. indicators and turn coordinators. Because of the way the gyro is mounted, the turn-and-slip indicator shows only the rate of A typical vacuum system consists of an engine-driven turn in degrees per second. The turn coordinator is mounted vacuum pump, relief valve, air filter, gauge, and tubing at an angle, or canted, so it can initially show roll rate. When necessary to complete the connections. The gauge is mounted the roll stabilizes, it indicates rate of turn. Both instruments in the aircraft’s instrument panel and indicates the amount indicate turn direction and quality (coordination), and also serve as a backup source of bank information in the event an Plane of Rotation attitude indicator fails. Coordination is achieved by referring to the inclinometer, which consists of a liquid-filled curved tube with a ball inside. [Figure 8-21] Plane of Force FORCE Turn-and-Slip Indicator Plane of Precession The gyro in the turn-and-slip indicator rotates in the vertical plane corresponding to the aircraft’s longitudinal axis. A single gimbal limits the planes in which the gyro can tilt, and a spring works to maintain a center position. Because of precession, a yawing force causes the gyro to tilt left or right, as viewed from the pilot seat. The turn-and-slip indicator uses a pointer, called the turn needle, to show the direction and rate of turn. The turn-and-slip indicator is incapable of “tumbling” off its rotational axis because of the restraining springs. When extreme forces are applied to a gyro, the gyro is displaced from its normal plane of rotation, rendering its indications invalid. Certain instruments have specific pitch Figure 8-19. Precession of a gyroscope resulting from an applied and bank limits that induce a tumble of the gyro.

deflective force.

8-16 Vacuum relief valve Heading indicator Overboard vent line I2 I5 2I Vacuum pump 20 20 I0 I0 I0 I0 20 20 TEST STBY PWR SUCTION INCHES MERCURT 0 I0 Suction Attitude indicator gauge Vacuum air filter Figure 8-20. Typical vacuum system.

aircraft with the turn index. Figure 8-22 shows a picture of a Turn Coordinator turn coordinator. There are two marks on each side (left and The gimbal in the turn coordinator is canted; therefore, its right) of the face of the instrument. The first mark is used to gyro can sense both rate of roll and rate of turn. Since turn reference a wings level zero rate of turn. The second mark coordinators are more prevalent in training aircraft, this on the left and right side of the instrument serve to indicate discussion concentrates on that instrument. When rolling into a standard rate of turn. A standard-rate turn is defined as a or out of a turn, the miniature aircraft banks in the direction turn rate of 3° per second. The turn coordinator indicates only the aircraft is rolled. A rapid roll rate causes the miniature the rate and direction of turn; it does not display a specific aircraft to bank more steeply than a slow roll rate.

angle of bank.

The turn coordinator can be used to establish and maintain a standard-rate turn by aligning the wing of the miniature Horizontal gyro Gimbal rotation Gyro rotation Gimbal Gimbal rotation Gyro rotation Canted gyro Standard rate turn index Standard rate turn index Inclinometer Inclinometer Turn coordinator Turn-and-slip indicator Figure 8-21. Turn indicators rely on controlled precession for their operation.

8-17 to the center of the wind screen. When in coordinated flight, the string trails straight back over the top of the wind screen.

D.C. D.C.

ELEC. ELEC.

When the aircraft is either slipping or skidding, the yaw string moves to the right or left depending on the direction of slip or skid.

TURN COORDINATOR TURN COORDINATOR L R L R 2 MIN. 2 MIN.

Instrument Check NO PITCH NO PITCH INFORMATION INFORMATION During preflight, ensure that the inclinometer is full of fluid and has no air bubbles. The ball should also be resting at Slipping turn Skidding turn its lowest point. When taxiing, the turn coordinator should indicate a turn in the correct direction while the ball moves D.C.

ELEC.

opposite the direction of the turn.

Attitude Indicator TURN COORDINATOR The attitude indicator, with its miniature aircraft and horizon L R bar, displays a picture of the attitude of the aircraft. The 2 MIN.

NO PITCH INFORMATION relationship of the miniature aircraft to the horizon bar is the same as the relationship of the real aircraft to the actual Coordinated turn horizon. The instrument gives an instantaneous indication of even the smallest changes in attitude.

Figure 8-22. If inadequate right rudder is applied in a right turn, The gyro in the attitude indicator is mounted in a horizontal a slip results. Too much right rudder causes the aircraft to skid plane and depends upon rigidity in space for its operation.

through the turn. Centering the ball results in a coordinated turn.

The horizon bar represents the true horizon. This bar is fixed to the gyro and remains in a horizontal plane as the Inclinometer aircraft is pitched or banked about its lateral or longitudinal The inclinometer is used to depict aircraft yaw, which is axis, indicating the attitude of the aircraft relative to the true the side-to-side movement of the aircraft’s nose. During horizon. [Figure 8-23] coordinated, straight-and-level flight, the force of gravity causes the ball to rest in the lowest part of the tube, centered The gyro spins in the horizontal plane and resists deflection between the reference lines. Coordinated flight is maintained of the rotational path. Since the gyro relies on rigidity in by keeping the ball centered. If the ball is not centered, it can space, the aircraft actually rotates around the spinning gyro.

be centered by using the rudder.

Bank index To center the ball, apply rudder pressure on the side to Gimbal rotation which the ball is deflected. Use the simple rule, “step on the ball,” to remember which rudder pedal to press. If aileron and rudder are coordinated during a turn, the ball remains centered in the tube. If aerodynamic forces are unbalanced, 20 20 20 20 the ball moves away from the center of the tube. As shown 0 I I 0 I0 I0 in Figure 8-22, in a slip, the rate of turn is too slow for the I0 0 I I 0 I0 angle of bank, and the ball moves to the inside of the turn. In 20 a skid, the rate of turn is too great for the angle of bank, and TEST the ball moves to the outside of the turn. To correct for these STBY PWR conditions, and improve the quality of the turn, remember to “step on the ball.” Varying the angle of bank can also help Roll gimbal Horizon reference arm restore coordinated flight from a slip or skid. To correct for a slip, decrease bank and/or increase the rate of turn. To correct Gyro Pitch gimbal for a skid, increase the bank and/or decrease the rate of turn.

Figure 8-23. Attitude indicator.

Yaw String One additional tool that can be added to the aircraft is a yaw string. A yaw string is simply a string or piece of yarn attached 8-18 An adjustment knob is provided with which the pilot may the top of the instrument move in the same direction from move the miniature aircraft up or down to align the miniature that in which the aircraft is actually banked. Some other aircraft with the horizon bar to suit the pilot’s line of vision. models move in the opposite direction from that in which Normally, the miniature aircraft is adjusted so that the wings the aircraft is actually banked. This may confuse the pilot if overlap the horizon bar when the aircraft is in straight-and the indicator is used to determine the direction of bank. This level cruising flight. scale should be used only to control the degree of desired bank. The relationship of the miniature aircraft to the horizon The pitch and bank limits depend upon the make and model bar should be used for an indication of the direction of bank.

of the instrument. Limits in the banking plane are usually The attitude indicator is reliable and the most realistic flight from 100° to 110°, and the pitch limits are usually from 60° instrument on the instrument panel. Its indications are very to 70°. If either limit is exceeded, the instrument will tumble close approximations of the actual attitude of the aircraft.

or spill and will give incorrect indications until realigned. A Heading Indicator number of modern attitude indicators do not tumble.

The heading indicator is fundamentally a mechanical Every pilot should be able to interpret the banking scale instrument designed to facilitate the use of the magnetic illustrated in Figure 8-24. Most banking scale indicators on compass. Errors in the magnetic compass are numerous, 20 20 I0 I0 I0 I0 I0 20 I0 I0 I0 I0 I0 I0 20 I0 20 20 TEST STBY PWR TEST STBY PWR TEST STBY PWR Climbing left bank Straight climb Climbing right bank B Pointer 10° a n 20° k s c 30° a 20 20 l e I0 I0 45° I0 I0 I0 I0 I0 I0 20 20 60° I0 I0 TEST STBY PWR 90° TEST STBY PWR I0 I0 20 20 TEST STBY PWR Level left bank Level right bank Artificial horizon Adjustment knob 20 20 I0 I0 I0 I0 I0 I0 I0 I0 I0 I0 20 I0 I0 20 20 TEST STBY PWR TEST STBY PWR TEST STBY PWR Descending left bank Straight descent Descending right bank Figure 8-24. Attitude representation by the attitude indicator corresponds to the relation of the aircraft to the real horizon.

8-19 making straight flight and precision turns to headings difficult Attitude and Heading Reference System (AHRS) to accomplish, particularly in turbulent air. A heading Electronic flight displays have replaced free-spinning gyros indicator, however, is not affected by the forces that make with solid-state laser systems that are capable of flight at the magnetic compass difficult to interpret. [Figure 8-25] any attitude without tumbling. This capability is the result of the development of the Attitude and Heading Reference The operation of the heading indicator depends upon the System (AHRS).

principle of rigidity in space. The rotor turns in a vertical plane and fixed to the rotor is a compass card. Since the rotor The AHRS sends attitude information to the PFD in order remains rigid in space, the points on the card hold the same to generate the pitch and bank information of the attitude position in space relative to the vertical plane of the gyro. The indicator. The heading information is derived from a aircraft actually rotates around the rotating gyro, not the other magnetometer that senses the earth’s lines of magnetic flux.

way around. As the instrument case and the aircraft revolve This information is then processed and sent out to the PFD around the vertical axis of the gyro, the card provides clear to generate the heading display. [Figure 8-26] and accurate heading information.

The Flux Gate Compass System Because of precession caused by friction, the heading As mentioned earlier, the lines of flux in the Earth’s magnetic indicator creeps or drifts from its set position. Among field have two basic characteristics: a magnet aligns with other factors, the amount of drift depends largely upon the them, and an electrical current is induced, or generated, in condition of the instrument. If the bearings are worn, dirty, any wire crossed by them.

or improperly lubricated, the drift may be excessive. Another error in the heading indicator is caused by the fact that the The flux gate compass that drives slaved gyros uses the gyro is oriented in space, and the Earth rotates in space at a characteristic of current induction. The flux valve is a small, rate of 15° in 1 hour. Thus, discounting precession caused segmented ring, like the one in Figure 8-27, made of soft iron by friction, the heading indicator may indicate as much as that readily accepts lines of magnetic flux. An electrical coil 15° error per every hour of operation.

is wound around each of the three legs to accept the current induced in this ring by the Earth’s magnetic field. A coil Some heading indicators referred to as horizontal situation wound around the iron spacer in the center of the frame has indicators (HSI) receive a magnetic north reference from 400 Hz alternating current (AC) flowing through it. During a magnetic slaving transmitter and generally need no the times when this current reaches its peak, twice during adjustment. The magnetic slaving transmitter is called each cycle, there is so much magnetism produced by this a magnetometer.

coil that the frame cannot accept the lines of flux from the Earth’s field.

Compass card gear Main drive gear Gimbal rotation I2 I5 2I Adjustment gears Gimbal Gyro Adjustment knob Figure 8-25. A heading indicator displays headings based on a 360° Figure 8-26. Attitude and heading reference system (AHRS).

azimuth, with the final zero omitted. For example, “6” represents 060°, while “21” indicates 210°. The adjustment knob is used to align the heading indicator with the magnetic compass.

8-20 Remote Indicating Compass Remote indicating compasses were developed to compensate for the errors and limitations of the older type of heading indicators. The two panel-mounted components of a typical system are the pictorial navigation indicator and the slaving control and compensator unit. [Figure 8-29] The pictorial navigation indicator is commonly referred to as an HSI.

The slaving control and compensator unit has a push button that provides a means of selecting either the “slaved gyro” or “free gyro” mode. This unit also has a slaving meter and two manual heading-drive buttons. The slaving meter indicates the difference between the displayed heading and the magnetic heading. A right deflection indicates a clockwise error of the compass card; a left deflection indicates a counterclockwise error. Whenever the aircraft is in a turn and the card rotates, the slaving meter shows a full deflection to one side or the other. When the system is in “free gyro” mode, the compass card may be adjusted by depressing the appropriate heading-drive button.

Figure 8-27. The soft iron frame of the flux valve accepts the flux from A separate unit, the magnetic slaving transmitter, is mounted the Earth’s magnetic field each time the current in the center coil Figure 3-23. The soft iron frame of the flux valve accepts the remotely, usually in a wingtip to eliminate the possibility of reverses. This flux causes current to flow in the three pickup coils.

flux from the Earth’s magnetic field each time the current in the magnetic interference. It contains the flux valve, which is center coil reverse.This flux causes current to flow in the three the direction-sensing device of the system. A concentration picked coils.

As the current reverses between the peaks, it demagnetizes of lines of magnetic force, after being amplified, becomes the frame so it can accept the flux from the Earth’s field. As this flux cuts across the windings in the three coils, it causes current to flow in them. These three coils are connected in such a way that the current flowing in them changes as the heading of the aircraft changes. [Figure 8-28] The three coils are connected to three similar but smaller coils in a synchro inside the instrument case. The synchro rotates the dial of a radio magnetic indicator (RMI) or a HSI.

Figure 8-29. Pictorial navigation indicator (HSI, top), slaving meter (lower right), and slaving control compensator unit (lower left).

Figure 8-28. The current in each of the three pickup coils changes with the heading of the aircraft.

Figure 3-24. The current in each of the three pickup coils changes with the heading of the aircraft.

8-21 a signal relayed to the heading indicator unit, which is also or “spills” and no longer gives the correct indication until remotely mounted. This signal operates a torque motor in reset. After spilling, it may be reset with the caging knob.

the heading indicator unit that processes the gyro unit until Many of the modern instruments used are designed in such it is aligned with the transmitter signal. The magnetic slaving a manner so that they do not tumble.

transmitter is connected electrically to the HSI.

An additional precession error may occur due to a gyro not There are a number of designs of the remote indicating spinning fast enough to maintain its alignment. When the compass; therefore, only the basic features of the system are vacuum system stops producing adequate suction to maintain covered here. Instrument pilots must become familiar with the gyro speed, the heading indicator and the attitude indicator the characteristics of the equipment in their aircraft. gyros begin to slow down. As they slow, they become more susceptible to deflection from the plane of rotation. Some As instrument panels become more crowded and the pilot’s aircraft have warning lights to indicate that a low vacuum available scan time is reduced by a heavier flight deck situation has occurred. Other aircraft may have only a vacuum workload, instrument manufacturers have worked toward gauge that indicates the suction.

combining instruments. One good example of this is the RMI in Figure 8-30. The compass card is driven by signals Instrument Check from the flux valve, and the two pointers are driven by an As the gyro spools up, make sure there are no abnormal automatic direction finder (ADF) and a very high frequency sounds. While taxiing, the instrument should indicate turns in (VHF) omni-directional radio range (VOR).

the correct direction, and precession should be normal. At idle power settings, the gyroscopic instruments using the vacuum Heading indicators that do not have this automatic system might not be up to operating speeds and precession northseeking capability are called “free” gyros and require might occur more rapidly than during flight.

periodic adjustment. It is important to check the indications frequently (approximately every 15 minutes) and reset the Angle of Attack Indicators heading indicator to align it with the magnetic compass The purpose of an AOA indicator is to give the pilot better when required. Adjust the heading indicator to the magnetic situational awareness pertaining to the aerodynamic health compass heading when the aircraft is straight and level at a of the airfoil. This can also be referred to as stall margin constant speed to avoid compass errors.

awareness. More simply explained, it is the margin that exists between the current AOA that the airfoil is operating at, and The bank and pitch limits of the heading indicator vary the AOA at which the airfoil will stall (critical AOA).

with the particular design and make of instrument. On some heading indicators found in light aircraft, the limits are Speed by itself is not a reliable parameter to avoid a stall.

approximately 55° of pitch and 55° of bank. When either of An airplane can stall at any speed. Angle of attack is a better these attitude limits is exceeded, the instrument “tumbles” parameter to use to avoid a stall. For a given configuration, the airplane always stalls at the same AOA, referred to as the critical AOA. This critical AOA does not change with: • Weight • Bank Angle • Temperature • Density Altitude • Center of Gravity An AOA indicator can have several benefits when installed in General Aviation aircraft, not the least of which is increased situational awareness. Without an AOA indicator, the AOA is “invisible” to pilots. These devices measure several parameters simultaneously and determine the current AOA providing a visual image to the pilot of the current AOA along with representations of the proximity to the critical AOA.

Figure 8-30. Driven by signals from a flux valve, the compass card [Figure 8-31] These devices can give a visual representation in this RMI indicates the heading of the aircraft opposite the upper of the energy management state of the airplane. The energy center index mark. The green pointer is driven by the ADF.

8-22 Figure 8-31. Angle of attack indicators.

state of an airplane is the balance between airspeed, altitude, There are long and short graduation marks between the letters drag, and thrust and represents how efficiently the airfoil is and numbers, each long mark representing 10° and each short operating. mark representing 5°.

Compass Systems The float and card assembly has a hardened steel pivot in its center that rides inside a special, spring-loaded, hard glass The Earth is a huge magnet, spinning in space, surrounded jewel cup. The buoyancy of the float takes most of the weight by a magnetic field made up of invisible lines of flux. These off of the pivot, and the fluid damps the oscillation of the lines leave the surface at the magnetic North Pole and reenter float and card. This jewel-and-pivot type mounting allows the at the magnetic South Pole.

float freedom to rotate and tilt up to approximately 18° angle of bank. At steeper bank angles, the compass indications are Lines of magnetic flux have two important characteristics: erratic and unpredictable.

any magnet that is free to rotate will align with them, and an electrical current is induced into any conductor that cuts The compass housing is entirely full of compass fluid. To across them. Most direction indicators installed in aircraft prevent damage or leakage when the fluid expands and make use of one of these two characteristics.

contracts with temperature changes, the rear of the compass case is sealed with a flexible diaphragm, or with a metal Magnetic Compass bellows in some compasses.

One of the oldest and simplest instruments for indicating direction is the magnetic compass. It is also one of the basic The magnets align with the Earth’s magnetic field and the instruments required by Title 14 of the Code of Federal pilot reads the direction on the scale opposite the lubber Regulations (14 CFR) part 91 for both VFR and IFR flight.

line. Note that in Figure 8-32, the pilot views the compass A magnet is a piece of material, usually a metal containing iron, that attracts and holds lines of magnetic flux. Regardless of size, every magnet has two poles: north and south. When one magnet is placed in the field of another, the unlike poles attract each other, and like poles repel.

An aircraft magnetic compass, such as the one in Figure 8-32, has two small magnets attached to a metal float sealed inside a bowl of clear compass fluid similar to kerosene. A graduated scale, called a card, is wrapped around the float and viewed through a glass window with a lubber line across it. The card E-W N-S is marked with letters representing the cardinal directions, north, east, south, and west, and a number for each 30° between these letters. The final “0” is omitted from these Figure 8-32. A magnetic compass. The vertical line is called the directions. For example, 3 = 30°, 6 = 60°, and 33 = 330°.

lubber line.

8-23 card from its backside. When the pilot is flying north, as the the two poles are aligned, and there is no variation. East compass indicates, east is to the pilot’s right. On the card, of this line, the magnetic North Pole is to the west of the “33,” which represents 330° (west of north), is to the right of geographic North Pole and a correction must be applied to north. The reason for this apparent backward graduation is a compass indication to get a true direction.

that the card remains stationary, and the compass housing and the pilot rotate around it. Because of this setup, the magnetic Flying in the Washington, D.C., area, for example, the compass can be confusing to read. variation is 10° west. If a pilot wants to fly a true course of south (180°), the variation must be added to this, resulting in Magnetic Compass Induced Errors a magnetic course of 190° to fly. Flying in the Los Angeles, California area, the variation is 14° east. To fly a true course The magnetic compass is the simplest instrument in of 180° there, the pilot would have to subtract the variation the panel, but it is subject to a number of errors that must and fly a magnetic course of 166°. The variation error does be considered.

not change with the heading of the aircraft; it is the same anywhere along the isogonic line.

Variation The Earth rotates about its geographic axis; maps and charts Deviation are drawn using meridians of longitude that pass through the The magnets in a compass align with any magnetic field.

geographic poles. Directions measured from the geographic Some causes for magnetic fields in aircraft include flowing poles are called true directions. The magnetic North Pole to electrical current, magnetized parts, and conflict with the which the magnetic compass points is not collocated with Earth’s magnetic field. These aircraft magnetic fields create the geographic North Pole, but is some 1,300 miles away; a compass error called deviation.

directions measured from the magnetic poles are called magnetic directions. In aerial navigation, the difference Deviation, unlike variation, depends on the aircraft heading.

between true and magnetic directions is called variation. This Also unlike variation, the aircraft’s geographic location same angular difference in surveying and land navigation is does not affect deviation. While no one can reduce or called declination.

change variation error, an aviation maintenance technician (AMT) can provide the means to minimize deviation error Figure 8-33 shows the isogonic lines that identify the number by performing the maintenance task known as “swinging of degrees of variation in their area. The line that passes near the compass.” Chicago is called the agonic line. Anywhere along this line 180˚W 165 ˚ W 150 ˚ W 135 ˚ W 120 ˚ W 105 ˚ W 90 ˚ W 75 ˚ W 60 ˚ W 45 ˚ W 30 ˚ W 15 ˚ W 0 ˚ 15 ˚ E 30 ˚ E 45 ˚ E 60 ˚ E 75 ˚ E 90 ˚ E 105 ˚ E 120 ˚ E 135 ˚ E 150 ˚ E 165 ˚ E 180˚W -10 10 -40 70˚N 70˚N -10 -30 60 ˚ N 60 ˚ N -20 -10 45 ˚ N 45 ˚ N 30 ˚ N 30 ˚ N 15 ˚ N 15 ˚ N -10 -10 -20 0 ˚ 0 ˚ -10 15 ˚ S 15 ˚ S -20 -30 30 ˚ S 30 ˚ S Main field declination (D) Contour interval: 30 30 2 degrees 45 ˚ S 45 ˚ S -60 red contours positive (east) 40 40 20 blue negative (west) -70 pink (agonic) zero line.

60 -90 60 ˚ N 60 ˚ N Mercator Projection.

-100 -80 60 80 Position of dip poles -130 110 -120 80 -110 -50 -40 -30 -20 70˚N 70˚N 180˚W 165 ˚ W 150 ˚ W 135 ˚ W 120 ˚ W 105 ˚ W 90 ˚ W 75 ˚ W 60 ˚ W 45 ˚ W 30 ˚ W 15 ˚ W 0 ˚ 15 ˚ E 30 ˚ E 45 ˚ E 60 ˚ E 75 ˚ E 90 ˚ E 105 ˚ E 120 ˚ E 135 ˚ E 150 ˚ E 165 ˚ E 180˚W Figure 8-33. Isogonic lines are lines of equal variation.

8-24 To swing the compass, an AMT positions the aircraft on a series of known headings, usually at a compass rose. [Figure 8-34] A compass rose consists of a series of lines marked every 30° on an airport ramp, oriented to magnetic north. There is minimal magnetic interference at the compass rose. The pilot or the AMT, if authorized, can taxi the aircraft to the compass rose and maneuver the aircraft to the headings prescribed by the AMT.

Figure 8-35. A compass correction card shows the deviation As the aircraft is “swung” or aligned to each compass rose correction for any heading.

heading, the AMT adjusts the compensator assembly located on the top or bottom of the compass. The compensator Step 1: Determine the Magnetic Course assembly has two shafts whose ends have screwdriver slots True Course (180°) ± Variation (+10°) = Magnetic Course accessible from the front of the compass. Each shaft rotates (190°) one or two small compensating magnets. The end of one shaft is marked E-W, and its magnets affect the compass when the The magnetic course (190°) is steered if there is no deviation aircraft is pointed east or west. The other shaft is marked error to be applied. The compass card must now be considered N-S and its magnets affect the compass when the aircraft is for the compass course of 190°.

pointed north or south.

Step 2: Determine the Compass Course The adjustments position the compensating magnets to Magnetic Course (190°, from step 1) ± Deviation (–2°, from minimize the difference between the compass indication and correction card) = Compass Course (188°) the actual aircraft magnetic heading. The AMT records any remaining error on a compass correction card like the one NOTE: Intermediate magnetic courses between those listed in Figure 8-35 and places it in a holder near the compass.

on the compass card need to be interpreted. Therefore, to Only AMTs can adjust the compass or complete the compass steer a true course of 180°, the pilot would follow a compass correction card. Pilots determine and fly compass headings course of 188°.

using the deviation errors noted on the card. Pilots must also note the use of any equipment causing operational magnetic To find the true course that is being flown when the compass interference such as radios, deicing equipment, pitot heat, course is known: radar, or magnetic cargo.

Compass Course ± Deviation = Magnetic Course ± Variation= True Course The corrections for variation and deviation must be applied in the correct sequence as shown below, starting from the Dip Errors true course desired.

The Earth's magnetic field runs parallel to its surface only at the Magnetic Equator, which is the point halfway between the Magnetic North and South Poles. As you move away True north from the Magnetic Equator towards the magnetic poles, the 330 N angle created by the vertical pull of the Earth's magnetic field 030 in relation to the Earth’s surface increases gradually. This angle is known as the dip angle. The dip angle increases in a downward direction as you move towards the Magnetic W North Pole and increases in an upward direction as you move towards the Magnetic South Pole.

E 240 If the compass needle were mounted so that it could pivot freely in three dimensions, it would align itself with the S magnetic field, pointing up or down at the dip angle in the direction of local Magnetic North. Because the dip angle is Figure 8-34. Utilization of a compass rose aids compensation for of no navigational interest, the compass is made so that it can deviation errors.

8-25 rotate only in the horizontal plane. This is done by lowering Southerly Turning Errors the center of gravity below the pivot point and making the When turning in a southerly direction, the forces are such that assembly heavy enough that the vertical component of the the compass float assembly lags rather than leads. The result magnetic force is too weak to tilt it significantly out of the is a false southerly turn indication. The compass card, or float horizontal plane. The compass can then work effectively at assembly, should be allowed to pass the desired heading prior all latitudes without specific compensation for dip. However, to stopping the turn. As with the northerly error, this error close to the magnetic poles, the horizontal component of is amplified with the proximity to either magnetic pole. To the Earth’s field is too small to align the compass which correct this lagging error, the aircraft should be allowed to makes the compass unuseable for navigation. Because of pass the desired heading prior to stopping the turn. The same this constraint, the compass only indicates correctly if the rule of 15 degrees plus half of the latitude applies here (i.e., card is horizontal. Once tilted out of the horizontal plane, if the aircraft is being operated in a position near 30 degrees it will be affected by the vertical component of the Earth’s latitude, the turn should be stopped 15+15+30 degrees after field which leads to the following discussions on northerly passing the desired heading). [Figure 8-36B] and southerly turning errors.

Acceleration Error Northerly Turning Errors The magnetic dip and the forces of inertia cause magnetic The center of gravity of the float assembly is located lower compass errors when accelerating and decelerating on than the pivotal point. As the aircraft turns, the force that easterly and westerly headings. Because of the pendulous- results from the magnetic dip causes the float assembly to type mounting, the aft end of the compass card is tilted swing in the same direction that the float turns. The result is upward when accelerating and downward when decelerating a false northerly turn indication. Because of this lead of the during changes of airspeed. When accelerating on either compass card, or float assembly, a northerly turn should be an easterly or westerly heading, the error appears as a stopped prior to arrival at the desired heading. This compass turn indication toward north. When decelerating on either error is amplified with the proximity to either magnetic pole.

of these headings, the compass indicates a turn toward One rule of thumb to correct for this leading error is to stop south. A mnemonic, or memory jogger, for the effect of the turn 15 degrees plus half of the latitude (i.e., if the aircraft acceleration error is the word “ANDS” (Acceleration- is being operated in a position near 40 degrees latitude, the North/Deceleration-South) may help you to remember the turn should be stopped 15+20=35 degrees prior to the desired acceleration error. [Figure 8-37] Acceleration causes an heading). [Figure 8-36A] Left turn No error Right turn A DIP DIP DIP 30 t t N D D 33 N c c i i N e e f p p f 3 33 D f f R 30 e C e e e A A f f C p f f p i R e e i D D c c D t t B Left turn No error Right turn DIP DIP DIP D D t t i i 15 c c p p S 21 e e f f S D C e e 12 f f S 15 21 R 15 e A f f e A f f R p C e e p i i 12 D c c D D t t Figure 8-36. Northerly and southerly turning errors.

8-26 h t u o S NORTH N 3 33 6 30 E W GS 24 NAV S 21 OBS 15 View is from the pilot’s perspective, and the movable card is reset after each turn.

Figure 8-37. The effects of acceleration error.

Figure 3-21. The effects of acceleration error.

indication toward north; deceleration causes an indication toward south.

N Oscillation Error Oscillation is a combination of all of the errors previously E mentioned and results in fluctuation of the compass card in W relation to the actual heading direction of the aircraft. When setting the gyroscopic heading indicator to agree with the 24 magnetic compass, use the average indication between the S swings.

The Vertical Card Magnetic Compass The vertical card magnetic compass eliminates some of the errors and confusion encountered with the magnetic compass.

The dial of this compass is graduated with letters representing Figure 8-38. Vertical card magnetic compass.

the cardinal directions, numbers every 30°, and tick marks every 5°. The dial is rotated by a set of gears from the shaft- Eddy Current Damping mounted magnet, and the nose of the symbolic aircraft on In the case of a vertical card magnetic compass, flux from the instrument glass represents the lubber line for reading the the oscillating permanent magnet produces eddy currents in heading of the aircraft from the dial. [Figure 8-38] a damping disk or cup. The magnetic flux produced by the eddy currents opposes the flux from the permanent magnet Lags or Leads and decreases the oscillations.

When starting a turn from a northerly heading, the compass lags behind the turn. When starting a turn from a southerly heading, the compass leads the turn.

8-27 Outside Air Temperature (OAT) Gauge The outside air temperature (OAT) gauge is a simple and 40 20 60 effective device mounted so that the sensing element is exposed to the outside air. The sensing element consists 0 80 -20 of a bimetallic-type thermometer in which two dissimilar materials are welded together in a single strip and twisted -20 100 into a helix. One end is anchored into protective tube and the -40 other end is affixed to the pointer, which reads against the -40 120 C calibration on a circular face. OAT gauges are calibrated in -60 140 degrees °C, °F, or both. An accurate air temperature provides F the pilot with useful information about temperature lapse rate with altitude change. [Figure 8-39] Figure 8-39. Outside air temperature (OAT) gauge.

Chapter Summary Flight instruments enable an aircraft to be operated with maximum performance and enhanced safety, especially when flying long distances. Manufacturers provide the necessary flight instruments, but to use them effectively, pilots need to understand how they operate. As a pilot, it is important to become very familiar with the operational aspects of the pitot static system and associated instruments, the vacuum system and associated instruments, the gyroscopic instruments, and the magnetic compass.

8-28

Chapter 9

Flight Manuals and

Other Documents

Introduction Each aircraft comes with documentation and a set of manuals with which a pilot must be familiar in order to fly that aircraft.

This chapter covers airplane flight manuals (AFM), the pilot’s operating handbook (POH), and aircraft documents pertaining to ownership, airworthiness, maintenance, and operations with inoperative equipment. Knowledge of these required documents and manuals is essential for a pilot to conduct a safe flight.

Airplane Flight Manuals (AFM) Flight manuals and operating handbooks are concise reference books that provide specific information about a particular aircraft or subject. They contain basic facts, information, and/or instructions for the pilot about the operation of an aircraft, flying techniques, etc., and are intended to be kept on hand for ready reference.

9-1 The aircraft owner/information manual is a document Most manufacturers include a table of contents that identifies developed by the aircraft manufacturer and contains general the order of the entire manual by section number and title.

information about the make and model of the aircraft. Usually, each section also contains a table of contents for that The manual is not approved by the Federal Aviation section. Page numbers reflect the section and page within that Administration (FAA) and is not specific to an individual section (1-1, 1-2, 2-1, 3-1, etc.). If the manual is published aircraft. The manual provides general information about the in loose-leaf form, each section is usually marked with a operation of an aircraft, is not kept current, and cannot be divider tab indicating the section number, title, or both. The substituted for the AFM/POH. Emergency Procedures section may have a red tab for quick identification and reference.

An AFM is a document developed by the aircraft manufacturer General (Section 1) and approved by the FAA. This book contains the information and instructions required to operate an aircraft safely. A The General section provides the basic descriptive pilot must comply with this information which is specific information on the airframe and powerplant(s). Some to a particular make and model of aircraft, usually by serial manuals include a three-dimensional drawing of the aircraft number. An AFM contains the operating procedures and that provides dimensions of various components. Included limitations of that aircraft. Title 14 of the Code of Federal are such items as wingspan, maximum height, overall length, Regulations (14 CFR) part 91 requires that pilots comply wheelbase length, main landing gear track width, diameter with the operating limitations specified in the approved flight of the rotor system, maximum propeller diameter, propeller manuals, markings, and placards. ground clearance, minimum turning radius, and wing area.

This section serves as a quick reference and helps a pilot Originally, flight manuals followed whatever format and become familiar with the aircraft.

content the manufacturer felt was appropriate, but this changed with the acceptance of Specification No. 1 prepared The last segment of the General section contains definitions, by the General Aviation Manufacturers Association (GAMA).

abbreviations, explanations of symbology, and some of Specification No. 1 established a standardized format for all the terminology used in the POH. At the discretion of the general aviation airplane and helicopter flight manuals.

manufacturer, metric and other conversion tables may also be included.

The POH is a document developed by the aircraft manufacturer and contains FAA-approved AFM information. Limitations (Section 2) If “POH” is used in the main title, a statement must be The Limitations section contains only those limitations required included on the title page indicating that sections of the by regulation or that are necessary for the safe operation of document are FAA approved as the AFM.

the aircraft, powerplant, systems, and equipment. It includes operating limitations, instrument markings, color-coding, The POH for most light aircraft built after 1975 is also and basic placards. Some of the limitation areas are airspeed, designated as the FAA-approved flight manual. The typical powerplant, weight and loading distribution, and flight.

AFM/POH contains the following nine sections: General; Limitations; Emergency Procedures; Normal Procedures; Airspeed Performance; Weight and Balance/Equipment List; Systems Airspeed limitations are shown on the airspeed indicator Description; Handling, Service, and Maintenance; and (ASI) by color coding and on placards or graphs in the Supplements. Manufacturers also have the option of including aircraft. [Figure 9-1] A red line on the ASI shows the airspeed additional sections, such as one on Safety and Operational limit beyond which structural damage could occur. This is Tips or an alphabetical index at the end of the POH.

called the never-exceed speed (V ). A yellow arc indicates NE the speed range between maximum structural cruising speed Preliminary Pages (V ) and V . Operation of an aircraft in the yellow airspeed N0 NE While the AFM/POH may appear similar for the same make arc is for smooth air only and then only with caution. A green and model of aircraft, each manual is unique and contains arc depicts the normal operating speed range, with the upper specific information about a particular aircraft, such as the end at V and the lower end at stalling speed at maximum N0 equipment installed and weight and balance information.

weight with the landing gear and flaps retracted (V ). For S1 Manufacturers are required to include the serial number and airplanes, the flap operating range is depicted by the white registration on the title page to identify the aircraft to which arc, with the upper end at the maximum flap extended speed the manual belongs. If a manual does not indicate a specific (V ), and the lower end at the stalling speed with the landing FE aircraft registration and serial number, it is limited to general gear and flaps in the landing configuration (V ).

S0 study purposes only.

9-2 Maximum 245 II5 P I00 T P R E °F S 60 E I50 I M Normal operating range S I00 P S OIL Minimum Figure 9-3. Minimum, maximum, and normal operating range markings on oil gauge.

Figure 9-1. Single-engine air sp eed indicator.

a red radial line and the normal operating range with a green arc. [Figure 9-4] Some instruments may have a yellow arc In addition to the markings listed above, small multi-engine to indicate a caution area.

airplanes have a red radial line to indicate single-engine minimum controllable airspeed (V ). A blue radial line MC Weight and Loading Distribution is used to indicate single-engine best rate of climb speed at Weight and Loading Distribution contains the maximum maximum weight at sea level (V ). [Figure 9-2] YSE certificated weights, as well as the center of gravity (CG) range. The location of the reference datum used in balance Powerplant computations is included in this section. Weight and balance The Powerplant Limitations portion describes operating computations are not provided in this area, but rather in the limitations on an aircraft’s reciprocating or turbine engine(s). weight and balance section of the AFM/POH.

These include limitations for takeoff power, maximum continuous power, and maximum normal operating power, which is the maximum power the engine can produce without any restrictions and is depicted by a green arc. Other items 30 30 that can be included in this area are the minimum and 35 25 35 25 MANIFOLD maximum oil and fuel pressures, oil and fuel grades, and PRESSURE propeller operating limits. [Figure 9-3] 20 20 40 40 IN Hg All reciprocating-engine powered aircraft must have a ALg.

15 15 45 45 revolutions per minute (rpm) indicator for each engine.

Aircraft equipped with a constant-speed propeller or rotor 10 10 50 50 system use a manifold pressure gauge to monitor power output and a tachometer to monitor propeller or rotor speed.

Both instruments depict the maximum operating limit with IAS

20 20

I5 I5

25 25

RPM AIRSPEED

I0 I0

HUNDREDS KNOTS I I0

30 30

5 5

200 80

3 3 140

HOURS TAS AVOID

35 35

CONTINUOUS OPERATION BETWEEN 2250 140 AND 2350 RPM Figure 9-4. Manifold pressure gauge (top) and tachometer (bottom).

Figure 9-2. Multi-engine air sp eed indicator.

9-3 Flight Limits Manufacturers may include an optional subsection entitled Abnormal Procedures. This subsection describes Flight Limits list authorized maneuvers with appropriate recommended procedures for handling malfunctions that are entry speeds, flight load factor limits, and types of operation not considered emergencies.

limits. It also indicates those maneuvers that are prohibited, such as spins or acrobatic flight, as well as operational Normal Procedures (Section 4) limitations such as flight into known icing conditions.

This section begins with a list of the airspeeds for normal operations. The next area consists of several checklists that Placards may include preflight inspection, before starting procedures, Most aircraft display one or more placards that contain starting engine, before taxiing, taxiing, before takeoff, climb, information having a direct bearing on the safe operation of cruise, descent, before landing, balked landing, after landing, the aircraft. These placards are located in conspicuous places and post flight procedures. An Amplified Procedures area and are reproduced in the Limitations section or as directed by follows the checklists to provide more detailed information an Airworthiness Directive (AD). [Figure 9-5] Airworthiness about the various previously mentioned procedures.

Directives are explained in detail later in this chapter.

To avoid missing important steps, always use the appropriate Emergency Procedures (Section 3) checklists when available. Consistent adherence to approved Checklists describing the recommended procedures and checklists is a sign of a disciplined and competent pilot.

airspeeds for coping with various types of emergencies or critical situations are located in the Emergency Procedures Performance (Section 5) section. Some of the emergencies covered include: The Performance section contains all the information required engine failure, fire, and system failure. The procedures by the aircraft certification regulations and any additional for inflight engine restarting and ditching may also be performance information the manufacturer deems important included. Manufacturers may first show an emergency to pilot ability to safely operate the aircraft. Performance checklist in an abbreviated form with the order of items charts, tables, and graphs vary in style, but all contain the reflecting the sequence of action. Amplified checklists that same basic information. Examples of the performance provide additional information on the procedures follow information found in most flight manuals include a graph or the abbreviated checklist. To be prepared for emergency table for converting calibrated airspeed to true airspeed; stall situations, memorize the immediate action items and, after speeds in various configurations; and data for determining completion, refer to the appropriate checklist.

takeoff and climb performance, cruise performance, and landing performance. Figure 9-6 is an example of a typical performance graph. For more information on use of the charts, graphs, and tables, refer to Chapter 10, Aircraft Performance.

Weight and Balance/Equipment List (Section 6) The Weight and Balance/Equipment List section contains all the information required by the FAA to calculate the weight and balance of an aircraft. Manufacturers include sample weight and balance problems. Weight and balance is discussed in greater detail in Chapter 10, Weight and Balance.

Systems Description (Section 7) This section describes the aircraft systems in a manner appropriate to the pilot most likely to operate the aircraft.

For example, a manufacturer might assume an experienced pilot will be reading the information for an advanced aircraft.

For more information on aircraft systems, refer to Chapter 7, Aircraft Systems.

Figure 9-5. Placards are used to depict aircraft limitations.

9-4 Calibrated stall speed Gross weight: 2,170 pounds Angle of bank: 20° Indicated stall speed Flap position: 40° Stall speed, indicated: 44 knots EXAMPLE Stall speed (knots) 0° Flaps 0° Flaps 40° Flaps Maximum weight - 2,440 (pounds) 40° Flaps 2,400 2,200 2,000 1,800 1,600 0° 20° 40° 60° Gross weight (pounds) Angle of bank (degrees) Figure 9-6. Stall speed chart.

Handling, Service, and Maintenance (Section 8) The Handling, Service, and Maintenance section describes the maintenance and inspections recommended by the manufacturer (and the regulations). Additional maintenance or inspections may be required by the issuance of ADs applicable to the airframe, engine, propeller, or components.

This section also describes preventive maintenance that may be accomplished by certificated pilots, as well as the manufacturer’s recommended ground handling procedures. It includes considerations for hangaring, tie-down, and general storage procedures for the aircraft.

Supplements (Section 9) The Supplements section contains information necessary to safely and efficiently operate the aircraft when equipped with optional systems and equipment (not provided with the Figure 9-7. Supplements provide information on optional equipment.

standard aircraft). Some of this information may be supplied by the aircraft manufacturer or by the manufacturer of the optional equipment. The appropriate information is inserted into the flight manual at the time the equipment is installed.

Autopilots, navigation systems, and air-conditioning systems are examples of equipment described in this section.

[Figure 9-7] 9-5 Safety Tips (Section 10) • The aircraft’s registration is canceled upon written request of the certificate holder The Safety Tips section is an optional section containing a review of information that enhances the safe operation of the • The aircraft is totally destroyed or scrapped aircraft. For example, physiological factors, general weather • The ownership of the aircraft is transferred information, fuel conservation procedures, high altitude • The certificate holder loses United States citizenship operations, or cold weather operations might be discussed.

Aircraft Documents For additional information, see 14 CFR part 47, section 47.41.

When one of the events listed in 14 CFR part 47, section Certificate of Aircraft Registration 47.41 occurs, the previous owner must notify the FAA by Before an aircraft can be flown legally, it must be registered filling in the back of the Certificate of Aircraft Registration, with the FAA Aircraft Registry. The Certificate of Aircraft and mailing it to: Registration, which is issued to the owner as evidence of the registration, must be carried in the aircraft at all times.

FAA Aircraft Registration Branch, AFS-750 [Figure 9-8] P.O. Box 25504 Oklahoma City, OK 73125-0504 The Certificate of Aircraft Registration cannot be used for operations when: A dealer’s aircraft registration certificate is another form of • The aircraft is registered under the laws of a foreign registration certificate, but is valid only for required flight country tests by the manufacturer or in flights that are necessary for Figure 9-8. AC Form 8050-3, Certificate of Aircraft Registration.

9-6 the sale of the aircraft by the manufacturer or a dealer. The A Standard Airworthiness Certificate is issued for aircraft dealer must remove the certificate when the aircraft is sold. type certificated in the normal, utility, acrobatic, commuter, transport categories, and manned free balloons. Figure 9-9 Upon complying with 14 CFR part 47, section 47.31, the illustrates a Standard Airworthiness Certificate, and an pink copy of the application for an Aircraft Registration explanation of each item in the certificate follows.

Application, Aeronautical Center (AC) Form 8050-1, 1. Nationality and Registration Marks. The “N” provides authorization to operate an unregistered aircraft indicates the aircraft is registered in the United States.

for a period not to exceed 90 days. Since the aircraft is Registration marks consist of a series of up to five unregistered, it cannot be operated outside of the United numbers or numbers and letters. In this case, N2631A States until a permanent Certificate of Aircraft Registration is the registration number assigned to this aircraft.

is received and placed in the aircraft.

2. Manufacturer and Model . Indicates the manufacturer, make, and model of the aircraft.

The FAA does not issue any certificate of ownership or endorse any information with respect to ownership on a 3. Aircraft Serial Number . Indicates the manufacturer’s Certificate of Aircraft Registration.

serial number assigned to the aircraft, as noted on the aircraft data plate.

NOTE: For additional information concerning the Aircraft 4. Category . Indicates the category in which the aircraft Registration Application or the Aircraft Bill of Sale, contact must be operated. In this case, it must be operated the nearest FAA Flight Standards District Office (FSDO).

in accordance with the limitations specified for the “NORMAL” category.

Airworthiness Certificate 5. Authority and Basis for Issuance . Indicates the aircraft An Airworthiness Certificate is issued by a representative of conforms to its type certificate and is considered in the FAA after the aircraft has been inspected, is found to meet condition for safe operation at the time of inspection the requirements of 14 CFR part 21, and is in condition for safe and issuance of the certificate. Any exemptions from operation. The Airworthiness Certificate must be displayed in the applicable airworthiness standards are briefly the aircraft so it is legible to the passengers and crew whenever noted here and the exemption number given. The word it is operated. The Airworthiness Certificate must remain with “NONE” is entered if no exemption exists.

the aircraft unless it is sold to a foreign purchaser.

UNITED STATES OF AMERICA DEPARTMENT OF TRANSPORTATION-FEDERAL AVIATION ADMINISTRATION

STANDARD AIRWORTHINESS CERTIFICATE

1 NATIONALITY AND 2 MANUFACTURER AND MODEL 3 AIRCRAFT SERIAL 4 CATEGORY REGISTRATION MARKS NUMBER

N12345 Douglas DC-6A 43219 Transport

5 AUTHORITY AND BASIS FOR ISSUANCE This airworthiness certificate is issued pursuant to the Federal Aviation Act of 1958 and certifies that, as of the date of issuance, the aircraft to which issued has been inspected and found to conform to the type certificate therefor, to be in condition for safe operation, and has been shown to meet the requirements of the applicable comprehensive and detailed airworthiness code as provided by Annex 8 to the Convention on International Civil Aviation, except as noted herein.

Exceptions:

None

6 TERMS AND CONDITIONS Unless sooner surrendered, suspended, revoked, or a termination date is otherwise established by the Administrator, this airworthiness certificate is effective as long as the maintenance, preventative maintenance, and alterations are performed in accordance with Parts 21, 43, and 91 of the Federal Aviation Regulations, as appropriate, and the aircraft is registered in the United States.

DATE OF ISSUANCE FAA REPRESENTATIVE DESIGNATION NUMBER

01/20/00 NE-XX

E.R. White E.R. White

A ny iteration, reproduction, or misuse of this certificate may be punishable by a fine not exceeding $1,000 or imprisonment not exceeding 3 years or both.

THIS CERTIFICATE MUST BE DISPLAYED IN THE AIRCRAFT IN ACCORDANCE WITH APPLICABLE FEDERAL AVIATION REGULATIONS.

FAA Form 8100-2 (04-11) Supersedes Previous Edition Figure 9-9. FAA Form 8100-2, Standard Airworthiness Certificate.

9-7 6. Terms and Conditions . Indicates the Airworthiness Under 14 CFR, part 91, subpart E, all civil aircraft are Certificate is in effect indefinitely if the aircraft is required to be inspected at specific intervals to determine maintained in accordance with 14 CFR parts 21, 43, and the overall condition. The interval depends upon the type 91, and the aircraft is registered in the United States. of operations in which the aircraft is engaged. All aircraft need to be inspected at least once every 12 calendar months, Also included are the date the certificate was issued and the while inspection is required for others after every 100 hours signature and office identification of the FAA representative. of operation. Some aircraft are inspected in accordance with an inspection system set up to provide for total inspection A Standard Airworthiness Certificate remains in effect of the aircraft on the basis of calendar time, time in service, if the aircraft receives the required maintenance and is number of system operations, or any combination of these.

properly registered in the United States. Flight safety relies in part on the condition of the aircraft, which is determined All inspections should follow the current manufacturer’s by inspections performed by mechanics, approved repair maintenance manual, including the Instructions for stations, or manufacturers that meet specific requirements Continued Airworthiness concerning inspection intervals, of 14 CFR part 43. parts replacement, and life-limited items as applicable to the aircraft.

A Special Airworthiness Certificate is issued for all aircraft certificated in other than the Standard classifications, such Annual Inspection as Experimental, Restricted, Limited, Provisional, and Any reciprocating engine or single-engine turbojet/ Light-Sport Aircraft (LSA). LSA receive a pink special turbopropeller-powered small aircraft (weighing 12,500 airworthiness certificate; however, there are exceptions. pounds or less) flown for business or pleasure and not For example, the Piper Cub is in the LSA category, but it flown for compensation or hire is required to be inspected was certificated as a normal aircraft during its manufacture. at least annually. The inspection shall be performed by a When purchasing an aircraft classified as other than Standard, certificated airframe and powerplant (A&P) mechanic who it is recommended that the local FSDO be contacted for an holds an inspection authorization (IA) by the manufacturer explanation of the pertinent airworthiness requirements and of the aircraft or by a certificated and appropriately rated the limitations of such a certificate. repair station. The aircraft may not be operated unless the annual inspection has been performed within the preceding Aircraft Maintenance 12 calendar months. A period of 12 calendar months extends Maintenance is defined as the preservation, inspection, from any day of a month to the last day of the same month the overhaul, and repair of an aircraft, including the replacement following year. An aircraft overdue for an annual inspection of parts. Regular and proper maintenance ensures that may be operated under a Special Flight Permit issued by an aircraft meets an acceptable standard of airworthiness the FAA for the purpose of flying the aircraft to a location throughout its operational life. where the annual inspection can be performed. However, all applicable ADs that are due must be complied with before Although maintenance requirements vary for different the flight.

types of aircraft, experience shows that aircraft need some 100-Hour Inspection type of preventive maintenance every 25 hours of flying time or less and minor maintenance at least every 100 All aircraft under 12,500 pounds (except turbojet/ hours. This is influenced by the kind of operation, climatic turbopropeller-powered multi-engine airplanes and turbine conditions, storage facilities, age, and construction of the powered rotorcraft), used to carry passengers for hire, must aircraft. Manufacturers supply maintenance manuals, parts receive a 100-hour inspection within the preceding 100 hours catalogs, and other service information that should be used of time in service and must be approved for return to service.

in maintaining the aircraft. Additionally, an aircraft used for flight instruction for hire, when provided by the person giving the flight instruction, Aircraft Inspections must also have received a 100-hour inspection. This inspection must be performed by an FAA-certificated A&P mechanic, Under 14 CFR part 91, the primary responsibility for an appropriately rated FAA-certificated repair station, or maintaining an aircraft in an airworthy condition falls on the by the aircraft manufacturer. An annual inspection, or an owner or operator of the aircraft. Certain inspections must be inspection for the issuance of an Airworthiness Certificate, performed on the aircraft, and the owner must maintain the may be substituted for a required 100-hour inspection. The airworthiness of the aircraft during the time between required 100-hour limitation may be exceeded by no more than 10 inspections by having any defects corrected.

9-8 hours for the purpose of traveling to a location at which the An expiration date for replacing (or recharging) the battery required inspection can be performed. Any excess time used must be legibly marked on the outside of the transmitter for this purpose must be included in computing the next 100 and entered in the aircraft maintenance record. This does hours of time in service. not apply to batteries that are essentially unaffected during storage intervals, such as water-activated batteries.

Other Inspection Programs The annual and 100-hour inspection requirements do not Preflight Inspections apply to large (over 12,500 pounds) airplanes, turbojets, or The preflight inspection is a thorough and systematic means turbopropeller-powered multi-engine airplanes or to aircraft by which a pilot determines if an aircraft is airworthy and in for which the owner complies with a progressive inspection condition for safe operation. POHs and owner/information program. Details of these requirements may be determined manuals contain a section devoted to a systematic method by referencing 14 CFR, part 43, section 43.11 and 14 CFR of performing a preflight inspection.

part 91, subpart E, or by inquiring at a local FSDO.

Minimum Equipment Lists (MEL) and Altimeter System Inspection Operations With Inoperative Equipment Under 14 CFR, part 91, section 91.411, requires that the Under 14 CFR, all aircraft instruments and installed equipment altimeter, encoding altimeter, and related system must be are required to be operative prior to each departure. When the tested and inspected within the 24 months prior to operating in FAA adopted the minimum equipment list (MEL) concept for controlled airspace under instrument flight rules (IFR). This 14 CFR part 91 operations, it allowed aircraft to be operated applies to all aircraft being operated in controlled airspace.

with inoperative equipment determined to be nonessential for safe flight. At the same time, it allowed part 91 operators, Transponder Inspection without an MEL, to defer repairs on nonessential equipment Title 14 CFR, part 91, section 91.413, requires that before within the guidelines of part 91.

a transponder can be used under 14 CFR, part 91, section 91.215(a), it shall be tested and inspected within the 24 The FAA has two acceptable methods of deferring months prior to operation of the aircraft regardless of airspace maintenance on small rotorcraft, non-turbine powered restrictions.

airplanes, gliders, or lighter-than-air aircraft operated under part 91. They are the deferral provision of 14 CFR, part 91, Emergency Locator Transmitter section 91.213(d) and an FAA-approved MEL.

An emergency locator transmitter (ELT) is required by 14 CFR, part 91, section 91.207, and must be inspected within The deferral provision of 14 CFR, part 91, section 91.213(d) 12 calendar months after the last inspection for the following: is widely used by most pilot/operators. Its popularity is due to simplicity and minimal paperwork. When inoperative • Proper installation equipment is found during a preflight inspection or prior to • Battery corrosion departure, the decision should be to cancel the flight, obtain • Operation of the controls and crash sensor maintenance prior to flight, or to defer the item or equipment.

• The presence of a sufficient signal radiated from its Maintenance deferrals are not used for inflight discrepancies.

antenna The manufacturer’s AFM/POH procedures are to be used in those situations. The discussion that follows assumes that The ELT must be attached to the airplane in such a manner the pilot wishes to defer maintenance that would ordinarily that the probability of damage to the transmitter in the event be required prior to flight.

of crash impact is minimized. Fixed and deployable automatic type transmitters must be attached to the airplane as far aft Using the deferral provision of 14 CFR, part 91, section as practicable. Batteries used in the ELTs must be replaced 91.213(d), the pilot determines whether the inoperative (or recharged, if the batteries are rechargeable): equipment is required by type design, 14 CFR, or ADs. If • When the transmitter has been in use for more than 1 the inoperative item is not required, and the aircraft can be cumulative hour safely operated without it, the deferral may be made. The inoperative item shall be deactivated or removed and an • When 50 percent of the battery useful life or, for INOPERATIVE placard placed near the appropriate switch, rechargeable batteries, 50 percent of useful life of the control, or indicator. If deactivation or removal involves charge has expired 9-9 maintenance (removal always will), it must be accomplished confirming that daytime flight with inoperative position by certificated maintenance personnel and recorded in lights is acceptable in accordance with the provisions of the accordance with 14 CFR part 43.

MEL, the pilot would leave the position lights switch OFF, open the circuit breaker (or whatever action is called for in For example, if the position lights (installed equipment) the procedures document), and placard the position light were discovered to be inoperative prior to a daytime flight, switch as INOPERATIVE.

the pilot would follow the requirements of 14 CFR, part 91, section 91.213(d).

There are exceptions to the use of the MEL for deferral. For example, should a component fail that is not listed in the MEL The deactivation may be a process as simple as the pilot as deferrable (the tachometer, flaps, or stall warning device, positioning a circuit breaker to the OFF position or as for example), then repairs are required to be performed prior complex as rendering instruments or equipment totally to departure. If maintenance or parts are not readily available inoperable. Complex maintenance tasks require a certificated at that location, a special flight permit can be obtained from and appropriately rated maintenance person to perform the the nearest FSDO. This permit allows the aircraft to be deactivation. In all cases, the item or equipment must be flown to another location for maintenance. This allows an placarded INOPERATIVE.

aircraft that may not currently meet applicable airworthiness requirements, but is capable of safe flight, to be operated All small rotorcraft, non-turbine powered airplanes, gliders, under the restrictive special terms and conditions attached or lighter-than-air aircraft operated under 14 CFR part 91 to the special flight permit.

are eligible to use the maintenance deferral provisions of 14 CFR, part 91, section 91.213(d). However, once an operator Deferral of maintenance is not to be taken lightly, and due requests an MEL, and a Letter of Authorization (LOA) consideration should be given to the effect an inoperative is issued by the FAA, then the use of the MEL becomes component may have on the operation of an aircraft, mandatory for that aircraft. All maintenance deferrals must particularly if other items are inoperative. Further information be accomplished in accordance with the terms and conditions regarding MELs and operations with inoperative equipment of the MEL and the operator-generated procedures document.

can be found in AC 91-67, Minimum Equipment Requirements for General Aviation Operations Under FAR Part 91.

The use of an MEL for an aircraft operated under 14 CFR part 91 also allows for the deferral of inoperative Preventive Maintenance items or equipment. The primary guidance becomes the Preventive maintenance is regarded as simple or minor FAA-approved MEL issued to that specific operator and preservation operations and the replacement of small standard N-numbered aircraft.

parts, not involving complex assembly operations. Allowed items of preventative maintenance are listed and limited to The FAA has developed master minimum equipment lists the items of 14 CFR part 43, appendix A(c).

(MMELs) for aircraft in current use. Upon written request by an operator, the local FSDO may issue the appropriate make Maintenance Entries and model MMEL, along with an LOA, and the preamble.

All pilots who perform preventive maintenance must make The operator then develops operations and maintenance an entry in the maintenance record of the aircraft. The entry (O&M) procedures from the MMEL. This MMEL with O&M must include the following information: procedures now becomes the operator’s MEL. The MEL, 1. A description of the work, such as “changed oil (Shell LOA, preamble, and procedures document developed by the operator must be on board the aircraft during each operation. Aero-50) at 2,345 hours” The FAA considers an approved MEL to be a supplemental 2. The date of completion of the work performed type certificate (STC) issued to an aircraft by serial number 3. The pilot’s name, signature, certificate number, and and registration number. It, therefore, becomes the authority type of certificate held to operate that aircraft in a condition other than originally type certificated.

Examples of Preventive Maintenance The following examples of preventive maintenance are taken With an approved MEL, if the position lights were discovered from 14 CFR, part 43, Maintenance, Preventive Maintenance, inoperative prior to a daytime flight, the pilot would make Rebuilding, and Alternation, which should be consulted for a an entry in the maintenance record or discrepancy record more in-depth look at the preventive maintenance a pilot can provided for that purpose. The item would then either be perform on an aircraft. Remember, preventive maintenance repaired or deferred in accordance with the MEL. Upon 9-10 is limited to work that does not involve complex assembly • Cleaning or replacing fuel and oil strainers or filter operations including the following: elements; servicing batteries, cleaning balloon burner pilot and main nozzles in accordance with the balloon • Removal, installation, and repair of landing gear manufacturer’s instructions.

tires and shock cords; servicing landing gear shock struts by adding oil, air, or both; servicing gear wheel • The interchange of balloon baskets and burners on bearings; replacing defective safety wiring or cotter envelopes when the basket or burner is designated as keys; lubrication not requiring disassembly other than interchangeable in the balloon type certificate data removal of nonstructural items, such as cover plates, and the baskets and burners are specifically designed cowlings, and fairings; making simple fabric patches for quick removal and installation; adjustment not requiring rib stitching or the removal of structural of nonstructural standard fasteners incidental to parts or control surfaces. In the case of balloons, operations.

the making of small fabric repairs to envelopes • The installations of anti-misfueling devices to reduce (as defined in, and in accordance with, the balloon the diameter of fuel tank filler openings only if the manufacturer’s instructions) not requiring load tape specific device has been made a part of the aircraft type repair or replacement.

certificate data by the aircraft manufacturer, the aircraft • Replenishing hydraulic fluid in the hydraulic manufacturer has provided FAA-approved instructions reservoir; refinishing decorative coating of fuselage, for installation of the specific device, and installation balloon baskets, wings, tail group surfaces (excluding does not involve the disassembly of the existing tank balanced control surfaces), fairings, cowlings, filler opening; troubleshooting and repairing broken landing gear, cabin, or flight deck interior when circuits in landing light wiring circuits.

removal or disassembly of any primary structure • Removing and replacing self-contained, front or operating system is not required; applying instrument panel-mounted navigation and preservative or protective material to components communication devices that employ tray-mounted where no disassembly of any primary structure or connectors which connect the unit when the unit operating system is involved and where such coating is installed into the instrument panel (excluding is not prohibited or is not contrary to good practices; automatic flight control systems, transponders, and repairing upholstery and decorative furnishings of the microwave frequency distance measuring equipment cabin, flight deck, or balloon basket interior when the (DME)). The approved unit must be designed to be repair does not require disassembly of any primary readily and repeatedly removed and replaced, and structure or operating system or interfere with an pertinent instructions must be provided. Prior to the operating system or affect the primary structure of unit’s intended use, an operational check must be the aircraft; making small, simple repairs to fairings, performed in accordance with the applicable sections nonstructural cover plates, cowlings, and small of 14 CFR part 91 on checking, removing, and patches and reinforcements not changing the contour replacing magnetic chip detectors.

to interfere with proper air flow; replacing side • Inspection and maintenance tasks prescribed and windows where that work does not interfere with the specifically identified as preventive maintenance in structure or any operating system, such as controls, a primary category aircraft type certificate or STC electrical equipment, etc.

holder’s approved special inspection and preventive • Replacing safety belts, seats or seat parts with maintenance program when accomplished on a replacement parts approved for the aircraft, not primary category aircraft.

involving disassembly of any primary structure or • Updating self-contained, front instrument panel- operating system, bulbs, reflectors, and lenses of mounted air traffic control (ATC) navigational position and landing lights.

software databases (excluding those of automatic • Replacing wheels and skis where no weight-and flight control systems, transponders, and microwave balance computation is involved; replacing any frequency DME), only if no disassembly of the unit is cowling not requiring removal of the propeller or required and pertinent instructions are provided; prior disconnection of flight controls; replacing or cleaning to the unit’s intended use, an operational check must spark plugs and setting of spark plug gap clearance; be performed in accordance with applicable sections replacing any hose connection, except hydraulic of 14 CFR part 91.

connections; however, prefabricated fuel lines may be replaced.

9-11 Certificated pilots, excluding student pilots, sport pilots, and or Designated Airworthiness Representative (DAR).

recreational pilots, may perform preventive maintenance on [Figure 9-10] any aircraft that is owned or operated by them provided that the aircraft is not used in air carrier service and does not Airworthiness Directives (ADs) qualify under 14 CFR parts 121, 129, or 135. A pilot holding A primary safety function of the FAA is to require correction a sport pilot certificate may perform preventive maintenance of unsafe conditions found in an aircraft, aircraft engine, on an aircraft owned or operated by that pilot if that aircraft is propeller, or appliance when such conditions exist and are issued a special airworthiness certificate in the LSA category.

likely to exist or develop in other products of the same design.

(Sport pilots operating LSA should refer to 14 CFR part 65 The unsafe condition may exist because of a design defect, for maintenance privileges.) 14 CFR part 43, appendix A, maintenance, or other causes. Airworthiness Directives contains a list of the operations that are considered to be (ADs), under 14 CFR, part 39, define the authority and preventive maintenance.

responsibility of the Administrator for requiring the necessary corrective action. ADs are used to notify aircraft owners and Repairs and Alterations other interested persons of unsafe conditions and to specify Repairs and alterations are classified as either major or minor.

the conditions under which the product may continue to be 14 CFR part 43, appendix A, describes the alterations and operated. ADs are divided into two categories: repairs considered major. Major repairs or alterations shall 1. Those of an emergency nature requiring immediate be approved for return to service on FAA Form 337, Major compliance prior to further flight Repair and Alteration, by an appropriately rated certificated repair station, an FAA-certificated A&P mechanic holding an 2. Those of a less urgent nature requiring compliance IA, or a representative of the Administrator. Minor repairs and within a specified period of time minor alterations may be approved for return to service with a proper entry in the maintenance records by an FAA-certificated ADs are regulatory and shall be complied with unless a A&P mechanic or an appropriately certificated repair station.

specific exemption is granted. It is the responsibility of the aircraft owner or operator to ensure compliance with all For modifications of experimental aircraft, refer to the pertinent ADs, including those ADs that require recurrent operating limitations issued to that aircraft. Modifications or continuing action. For example, an AD may require a in accordance with FAA Order 8130.2, Airworthiness repetitive inspection each 50 hours of operation, meaning Certification of Aircraft and Related Products, may require the particular inspection shall be accomplished and recorded the notification of the issuing authority.

every 50 hours of time in service. Owners/operators are reminded that there is no provision to overfly the maximum Special Flight Permits hour requirement of an AD unless it is specifically written A special flight permit is a Special Airworthiness Certificate into the AD. To help determine if an AD applies to an authorizing operation of an aircraft that does not currently amateur-built aircraft, contact the local FSDO.

meet applicable airworthiness requirements but is safe for a specific flight. Before the permit is issued, an FAA 14 CFR, part 91, section 91.417 requires a record to be inspector may personally inspect the aircraft or require it to maintained that shows the current status of applicable be inspected by an FAA-certificated A&P mechanic or an ADs, including the method of compliance; the AD number appropriately certificated repair station to determine its safety and revision date, if recurring; next due date and time; the for the intended flight. The inspection shall be recorded in signature; type of certificate; and certificate number of the the aircraft records.

repair station or mechanic who performed the work. For ready reference, many aircraft owners have a chronological listing The special flight permit is issued to allow the aircraft to be of the pertinent ADs in the back of their aircraft, engine, and flown to a base where repairs, alterations, or maintenance propeller maintenance records.

can be performed; for delivering or exporting the aircraft; or for evacuating an aircraft from an area of impending danger.

All ADs and the AD Biweekly are free on the Internet A special flight permit may be issued to allow the operation at http://rgl.faa.gov and are available through e-mail.

of an overweight aircraft for flight beyond its normal range Individuals can enroll for the e-mail service at the website over water or land areas where adequate landing facilities above. Paper copies of the Summary of Airworthiness or fuel is not available.

Directives and the AD Biweekly may be purchased from the Superintendent of Documents. The Summary contains If a special flight permit is needed, assistance and the all the valid ADs previously published and is divided into necessary forms may be obtained from the local FSDO 9-12 UNITED STATES OF AMERICA DEPARTMENT OF TRANSPORTATION - FEDERAL AVIATION ADMINISTRATION

SPECIAL AIRWORTHINESS CERTIFICATE

CATEGORY/DESIGNATION Special Flight Permit

A

PURPOSE Production Flight Testing or Customer Demonstration MANU- NAME The Boeing Company

B

FACTURER ADDRESS P.O. Box 767, Renton WA 13567 FROM N/A FLIGHT

C

TO N/A N- N/A SERIAL NO. N/A

D

BUILDER N/A MODEL N/A EXPIRY 01/31/2001 DATE OF ISSUANCE 01/31/2001 OPERATING LIMITATIONS DATED 01/31/2001 ARE PART OF THIS CERTIFICATE SIGNATURE OF FAA REPRESENTATIVE

E

DESIGNATION OR OFFICE NO.

Sam T. Smith NM-XX Sam T. Smith Any alteration, reproduction or misuse of this certificate may be punishable by a fine not exceeding $1,000 or imprisonment not exceeding 3 years, or both. THIS CERTIFICATE MUST BE DISPLAYED IN THE AIRCRAFT IN ACCORDANCE WITH APPLICABLE TITLE 14, CODE OF FEDERAL REGULATIONS (CFR).

FAA Form 8130-7 (07/04) SEE REVERSE SIDE Figure 9-10. FAA Form 8130-7, Special Airworthiness Certificate.

two areas. The small aircraft and helicopter books contain • Having a current Federal Communications Commission all ADs applicable to small aircraft (12,500 pounds or less (FCC) radio station license if equipped with radios, maximum certificated takeoff weight) and ADs applicable including emergency locator transmitter (ELT), if to all helicopters. The large aircraft books contain all ADs operated outside of the United States.

applicable to large aircraft.

Chapter Summary For current information on how to order paper copies of AD Knowledge of an aircraft’s AFM/POH and documents, books and the AD Biweekly, visit the FAA online regulatory such as ADs, provide pilots with ready access to pertinent and guidance library at: http://rgl.faa.gov .

information needed to safely fly a particular aircraft. By understanding the operations, limitations, and performance Aircraft Owner/Operator Responsibilities characteristics of the aircraft, the pilot can make educated The registered owner/operator of an aircraft is responsible for: flight decisions. By learning what preventive maintenance is allowed on the aircraft, a pilot can maintain his or her • Having a current Airworthiness Certificate and a aircraft in an airworthy condition. The goal of every pilot is Certificate of Aircraft Registration in the aircraft.

a safe flight. Flight manuals and aircraft documentation are • Maintaining the aircraft in an airworthy condition, essential tools used to reach that goal.

including compliance with all applicable ADs and assuring that maintenance is properly recorded.

• Keeping abreast of current regulations concerning the operation and maintenance of the aircraft.

• Notifying the FAA Aircraft Registry immediately of any change of permanent mailing address, of the sale or export of the aircraft, or of the loss of the eligibility to register an aircraft. (Refer to 14 CFR, part 47, section 47.41.)

9-13 9-14

Chapter 10

Weight and Balance

Introduction Compliance with the weight and balance limits of any aircraft is critical to flight safety. Operating above the maximum weight limitation compromises the structural integrity of an aircraft and adversely affects its performance. Operation with the center of gravity (CG) outside the approved limits results in control difficulty.

Weight Control As discussed in Chapter 5, Aerodynamics of Flight, weight is the force with which gravity attracts a body toward the center of the Earth. It is a product of the mass of a body and the acceleration acting on the body. Weight is a major factor in aircraft construction and operation and demands respect from all pilots.

The force of gravity continuously attempts to pull an aircraft down toward Earth. The force of lift is the only force that counteracts weight and sustains an aircraft in flight. The amount of lift produced by an airfoil is limited by the airfoil design, angle of attack (AOA), airspeed, and air density. To assure that the lift generated is sufficient to counteract weight, loading an aircraft beyond the manufacturer’s recommended weight must be avoided. If the weight is greater than the lift generated, the aircraft may be incapable of flight.

10-1 Effects of Weight change that takes place. As fuel is used, an aircraft becomes lighter and performance is improved.

Any item aboard an aircraft that increases the total weight is undesirable for performance. Manufacturers attempt to make Changes of fixed equipment have a major effect upon the an aircraft as light as possible without sacrificing strength weight of an aircraft. The installation of extra radios or or safety.

instruments, as well as repairs or modifications, may also affect the weight of an aircraft.

The pilot should always be aware of the consequences of overloading. An overloaded aircraft may not be able to leave Balance, Stability, and Center of Gravity the ground, or if it does become airborne, it may exhibit unexpected and unusually poor flight characteristics. If not Balance refers to the location of the CG of an aircraft, and is properly loaded, the initial indication of poor performance important to stability and safety in flight. The CG is a point usually takes place during takeoff.

at which the aircraft would balance if it were suspended at that point.

Excessive weight reduces the flight performance in almost every respect. For example, the most important performance The primary concern in balancing an aircraft is the fore deficiencies of an overloaded aircraft are: and aft location of the CG along the longitudinal axis. The CG is not necessarily a fixed point; its location depends on • Higher takeoff speed the distribution of weight in the aircraft. As variable load • Longer takeoff run items are shifted or expended, there is a resultant shift in • Reduced rate and angle of climb CG location. The distance between the forward and back limits for the position of the center for gravity or CG range • Lower maximum altitude is certified for an aircraft by the manufacturer. The pilot • Shorter range should realize that if the CG is displaced too far forward • Reduced cruising speed on the longitudinal axis, a nose-heavy condition will result. Conversely, if the CG is displaced too far aft on the • Reduced maneuverability longitudinal axis, a tail heavy condition results. It is possible • Higher stalling speed that the pilot could not control the aircraft if the CG location produced an unstable condition. [Figure 10-1] • Higher approach and landing speed • Longer landing roll Location of the CG with reference to the lateral axis is also • Excessive weight on the nose wheel or tail wheel important. For each item of weight existing to the left of The pilot must be knowledgeable about the effect of weight Empty Full on the performance of the particular aircraft being flown.

Preflight planning should include a check of performance charts to determine if the aircraft’s weight may contribute to hazardous flight operations. Excessive weight in itself reduces the safety margins available to the pilot and becomes even more hazardous when other performance-reducing Lateral unbalance will cause wing heaviness.

factors are combined with excess weight. The pilot must also consider the consequences of an overweight aircraft if Excess baggage an emergency condition arises. If an engine fails on takeoff or airframe ice forms at low altitude, it is usually too late to reduce an aircraft’s weight to keep it in the air.

Weight Changes The operating weight of an aircraft can be changed by simply altering the fuel load. Gasoline has considerable weight—6 pounds per gallon. Thirty gallons of fuel may Longitudinal unbalance will cause weigh more than one passenger. If a pilot lowers airplane either nose or tail heaviness.

weight by reducing fuel, the resulting decrease in the range of the airplane must be taken into consideration during flight Figure 10-1. Lateral and longitudinal unbalance.

planning. During flight, fuel burn is normally the only weight 10-2 the fuselage centerline, there is an equal weight existing at The forward CG limit is often established at a location that a corresponding location on the right. This may be upset is determined by the landing characteristics of an aircraft.

by unbalanced lateral loading. The position of the lateral During landing, one of the most critical phases of flight, CG is not computed in all aircraft, but the pilot must be exceeding the forward CG limit may result in excessive loads aware that adverse effects arise as a result of a laterally on the nosewheel, a tendency to nose over on tailwheel type unbalanced condition. In an airplane, lateral unbalance occurs airplanes, decreased performance, higher stalling speeds, and if the fuel load is mismanaged by supplying the engine(s) higher control forces.

unevenly from tanks on one side of the airplane. The pilot can compensate for the resulting wing-heavy condition by Control adjusting the trim or by holding a constant control pressure.

In extreme cases, a CG location that is beyond the forward This action places the aircraft controls in an out-of-streamline limit may result in nose heaviness, making it difficult or condition, increases drag, and results in decreased operating impossible to flare for landing. Manufacturers purposely efficiency. Since lateral balance is addressed when needed in place the forward CG limit as far rearward as possible to the aircraft flight manual (AFM) and longitudinal balance is aid pilots in avoiding damage when landing. In addition to more critical, further reference to balance in this handbook decreased static and dynamic longitudinal stability, other means longitudinal location of the CG.

undesirable effects caused by a CG location aft of the allowable range may include extreme control difficulty, Flying an aircraft that is out of balance can produce increased violent stall characteristics, and very light control forces pilot fatigue with obvious effects on the safety and efficiency which make it easy to overstress an aircraft inadvertently.

of flight. The pilot’s natural correction for longitudinal unbalance is a change of trim to remove the excessive control A restricted forward CG limit is also specified to assure pressure. Excessive trim, however, has the effect of reducing that sufficient elevator/control deflection is available at not only aerodynamic efficiency but also primary control minimum airspeed. When structural limitations do not limit travel distance in the direction the trim is applied.

the forward CG position, it is located at the position where full-up elevator/control deflection is required to obtain a high Effects of Adverse Balance AOA for landing.

Adverse balance conditions affect flight characteristics in much the same manner as those mentioned for an excess The aft CG limit is the most rearward position at which the weight condition. It is vital to comply with weight and CG can be located for the most critical maneuver or operation.

balance limits established for all aircraft. Operating above As the CG moves aft, a less stable condition occurs, which the maximum weight limitation compromises the structural decreases the ability of the aircraft to right itself after integrity of the aircraft and can adversely affect performance.

maneuvering or turbulence.

Stability and control are also affected by improper balance.

For some aircraft, both fore and aft CG limits may be Stability specified to vary as gross weight changes. They may also Loading in a nose-heavy condition causes problems in be changed for certain operations, such as acrobatic flight, controlling and raising the nose, especially during takeoff retraction of the landing gear, or the installation of special and landing. Loading in a tail heavy condition has a serious loads and devices that change the flight characteristics.

effect upon longitudinal stability, and reduces the capability to recover from stalls and spins. Tail heavy loading also The actual location of the CG can be altered by many variable produces very light control forces, another undesirable factors and is usually controlled by the pilot. Placement of characteristic. This makes it easy for the pilot to inadvertently baggage and cargo items determines the CG location. The overstress an aircraft.

assignment of seats to passengers can also be used as a means of obtaining a favorable balance. If an aircraft is tail heavy, Stability and Center of Gravity it is only logical to place heavy passengers in forward seats.

Fuel burn can also affect the CG based on the location of the Limits for the location of the CG are established by the manufacturer. These are the fore and aft limits beyond fuel tanks. For example, most small aircraft carry fuel in the wings very near the CG and burning off fuel has little effect which the CG should not be located for flight. These limits are published for each aircraft in the Type Certificate Data on the loaded CG.

Sheet (TCDS), or aircraft specification and the AFM or pilot’s operating handbook (POH). If the CG is not within the allowable limits after loading, it will be necessary to relocate some items before flight is attempted.

10-3 Management of Weight and Balance Control Before any flight, the pilot should determine the weight and balance condition of the aircraft. Simple and orderly Title 14 of the Code of Federal Regulations (14 CFR) part 23, procedures based on sound principles have been devised section 23.23 requires establishment of the ranges of weights by the manufacturer for the determination of loading and CGs within which an aircraft may be operated safely. The conditions. The pilot uses these procedures and exercises manufacturer provides this information, which is included in good judgment when determining weight and balance. In the approved AFM, TCDS, or aircraft specifications.

many modern aircraft, it is not possible to fill all seats, baggage compartments, and fuel tanks, and still remain within While there are no specified requirements for a pilot operating the approved weight and balance limits. If the maximum under 14 CFR part 91 to conduct weight and balance passenger load is carried, the pilot must often reduce the fuel calculations prior to each flight, 14 CFR part 91, section load or reduce the amount of baggage.

91.9 requires the pilot in command (PIC) to comply with the operating limits in the approved AFM. These limits include 14 CFR part 125 requires aircraft with 20 or more seats the weight and balance of the aircraft. To enable pilots to or maximum payload capacity of 6,000 pounds or more make weight and balance computations, charts and graphs to be weighed every 36 calendar months. Multi-engine are provided in the approved AFM.

aircraft operated under 14 CFR part 135 are also required to be weighed every 36 months. Aircraft operated under 14 Weight and balance control should be a matter of concern to CFR part 135 are exempt from the 36 month requirement all pilots. The pilot controls loading and fuel management if operated under a weight and balance system approved in (the two variable factors that can change both total weight the operations specifications of the certificate holder. For and CG location) of a particular aircraft. The aircraft owner additional information on approved weight and balance or operator should make certain that up-to-date information control programs for operations under parts 121 and 135, is available for pilot use, and should ensure that appropriate reference the current edition of AC 120-27, Aircraft Weight entries are made in the records when repairs or modifications and Balance Control. AC 43.13-l, Acceptable Methods, have been accomplished. The removal or addition of Techniques and Practices—Aircraft Inspection and Repair equipment results in changes to the CG.

also requires that the aircraft mechanic ensure that the weight and balance data in the aircraft records is current and accurate Weight changes must be accounted for and the proper after a 100-hour or annual inspection.

notations made in weight and balance records. The equipment list must be updated, if appropriate. Without such Terms and Definitions information, the pilot has no foundation upon which to base The pilot should be familiar with the appropriate terms the necessary calculations and decisions.

regarding weight and balance. The following list of terms and their definitions is standardized, and knowledge of these Standard parts with negligible weight or the addition of minor terms aids the pilot to better understand weight and balance items of equipment such as nuts, bolts, washers, rivets, and calculations of any aircraft. Terms defined by the General similar standard parts of negligible weight on fixed-wing Aviation Manufacturers Association (GAMA) as industry aircraft do not require a weight and balance check. The standard are marked in the titles with GAMA.

following criteria for negligible weight change is outlined in Advisory Circular (AC) 43.13-1 (as revised), Methods • Arm (moment arm)—the horizontal distance in inches Techniques and Practices—Aircraft Inspection and Repair: from the reference datum line to the CG of an item.

The algebraic sign is plus (+) if measured aft of the • One pound or less for an aircraft whose weight empty datum and minus (–) if measured forward of the datum.

is less than 5,000 pounds • Basic empty weight (GAMA)—the standard empty • Two pounds or less for aircraft with an empty weight weight plus the weight of optional and special of more than 5,000 pounds to 50,000 pounds equipment that have been installed.

• Five pounds or less for aircraft with an empty weight • Center of gravity (CG)—the point about which an of more than 50,000 pounds aircraft would balance if it were possible to suspend it at that point. It is the mass center of the aircraft or the Negligible CG change is any change of less than 0.05 percent theoretical point at which the entire weight of the aircraft Mean Aerodynamic Chord (MAC) for fixed-wing aircraft is assumed to be concentrated. It may be expressed in or 0.2 percent for rotary wing aircraft. MAC is the average inches from the reference datum or in percent of MAC.

distance from the leading edge to the trailing edge of the The CG is a three-dimensional point with longitudinal, wing. Exceeding these limits would require a weight and lateral, and vertical positioning in the aircraft.

balance check.

10-4 • CG limits—the specified forward and aft points within • Moment index (or index)—a moment divided by a which the CG must be located during flight. These constant such as 100, 1,000, or 10,000. The purpose limits are indicated on pertinent aircraft specifications. of using a moment index is to simplify weight and balance computations of aircraft where heavy items • CG range—the distance between the forward and aft and long arms result in large, unmanageable numbers.

CG limits indicated on pertinent aircraft specifications.

• Payload (GAMA)—the weight of occupants, cargo, • Datum (reference datum)—an imaginary vertical and baggage.

plane or line from which all measurements of arm are taken. The datum is established by the manufacturer. • Standard empty weight (GAMA)—aircraft weight Once the datum has been selected, all moment arms that consists of the airframe, engines, and all items of and the location of CG range are measured from this operating equipment that have fixed locations and are point. permanently installed in the aircraft, including fixed ballast, hydraulic fluid, unusable fuel, and full engine • Delta—a Greek letter expressed by the symbol r to oil.

indicate a change of values. As an example, r CG indicates a change (or movement) of the CG. • Standard weights—established weights for numerous items involved in weight and balance computations.

• Floor load limit—the maximum weight the floor These weights should not be used if actual weights can sustain per square inch/foot as provided by the are available. Some of the standard weights are: manufacturer.

Gasoline.................................................. 6 lb/US gal • Fuel load—the expendable part of the load of the aircraft. It includes only usable fuel, not fuel required Jet A, Jet A-1....................................... 6.8 lb/US gal to fill the lines or that which remains trapped in the Jet B......................................................6.5 lb/US gal tank sumps.

Oil.........................................................7.5 lb/US gal • Licensed empty weight—the empty weight that Water ................................................. 8.35 lb/US gal consists of the airframe, engine(s), unusable fuel, and undrainable oil plus standard and optional equipment • Station—a location in the aircraft that is identified by as specified in the equipment list. Some manufacturers a number designating its distance in inches from the used this term prior to GAMA standardization.

datum. The datum is, therefore, identified as station zero. An item located at station +50 would have an • Maximum landing weight—the greatest weight that arm of 50 inches.

an aircraft is normally allowed to have at landing.

• Useful load—the weight of the pilot, copilot, • Maximum ramp weight—the total weight of a loaded passengers, baggage, usable fuel, and drainable oil.

aircraft including all fuel. It is greater than the takeoff It is the basic empty weight subtracted from the weight due to the fuel that will be burned during the maximum allowable gross weight. This term applies taxi and run-up operations. Ramp weight may also be to general aviation (GA) aircraft only.

referred to as taxi weight.

• Maximum takeoff weight—the maximum allowable Principles of Weight and Balance Computations weight for takeoff.

It is imperative that all pilots understand the basic principles • Maximum weight—the maximum authorized weight of weight and balance determination. The following methods of the aircraft and all of its equipment as specified in of computation can be applied to any object or vehicle for the TCDS for the aircraft.

which weight and balance information is essential.

• Maximum zero fuel weight (GAMA)—the maximum By determining the weight of the empty aircraft and adding weight, exclusive of usable fuel.

the weight of everything loaded on the aircraft, a total weight • Mean aerodynamic chord (MAC)—the average can be determined—a simple concept. A greater problem, distance from the leading edge to the trailing edge of particularly if the basic principles of weight and balance are the wing.

not understood, is distributing this weight in such a manner that the entire mass of the loaded aircraft is balanced around • Moment—the product of the weight of an item multiplied by its arm. Moments are expressed in a point (CG) that must be located within specified limits.

pound-inches (in-lb). Total moment is the weight of the airplane multiplied by the distance between the The point at which an aircraft balances can be determined by locating the CG, which is, as stated in the definitions of terms, datum and the CG.

10-5 the imaginary point at which all the weight is concentrated.

To provide the necessary balance between longitudinal Datum stability and elevator control, the CG is usually located 100" slightly forward of the center of lift. This loading condition causes a nose-down tendency in flight, which is desirable during flight at a high AOA and slow speeds.

lb As mentioned earlier, a safe zone within which the balance point (CG) must fall is called the CG range. The extremities Fulcrum of the range are called the forward CG limits and aft CG Moment = 5,000 in-lb limits. These limits are usually specified in inches, along the Wt x Arm = Moment longitudinal axis of the airplane, measured from a reference (lb) x (in) = (in-lb) Note: The datum is assumed to be 50 x 100 = 5,000 point called a datum reference. The datum is an arbitrary located at the fulcrum.

point, established by aircraft designers that may vary in location between different aircraft. [Figure 10-2] Figure 10-3. Determining moment.

The distance from the datum to any component part or any in Figure 10-4) , if a 100-pound weight is placed at a point object loaded on the aircraft is called the arm. When the (station) 25 inches from the datum, and another 50-pound object or component is located aft of the datum, it is measured weight is placed at a point (station) 50 inches from the datum, in positive inches; if located forward of the datum, it is the sum of the product of the two weights and their distances measured as negative inches or minus inches. The location total a moment of 5,000 in-lb, which will balance the board.

of the object or part is often referred to as the station. If the weight of any object or component is multiplied by the Weight and Balance Restrictions distance from the datum (arm), the product is the moment.

An aircraft’s weight and balance restrictions should be The moment is the measurement of the gravitational force closely followed. The loading conditions and empty weight that causes a tendency of the weight to rotate about a point of a particular aircraft may differ from that found in the or axis and is expressed in inch-pounds (in-lb).

AFM/POH because modifications or equipment changes may have been made. Sample loading problems in the To illustrate, assume a weight of 50 pounds is placed on AFM/POH are intended for guidance only; therefore, each the board at a station or point 100 inches from the datum.

aircraft must be treated separately. Although an aircraft is The downward force of the weight can be determined by certified for a specified maximum gross takeoff weight, it multiplying 50 pounds by 100 inches, which produces a may not safely take off at this weight under all conditions.

moment of 5,000 in-lb. [Figure 10-3] Conditions that affect takeoff and climb performance, such as high elevations, high temperatures, and high humidity (high To establish a balance, a total of 5,000 in-lb must be applied density altitudes), may require a reduction in weight before to the other end of the board. Any combination of weight flight is attempted. Other factors to consider when computing and distance which, when multiplied, produces a 5,000 in- lb moment will balance the board. For example (illustrated Datum 50" 100" CG range 25" Aft limit Fwd limit Datum 50 50 lb lb lb ( + ) ( – ) Arm Arm Fulcrum 2,500 2,500 5,000 Moment = 700 in-lb in-lb in-lb in-lb ( + ) Arm 70" 100 x 25 = 2,500 Wt x Arm = Moment 10 lb 50 x 50 = 2,500 (lb) x (in) = (in-lb) Total = 5,000 Sta 0 Sta 70 Figure 10-4. Establishing a balance.

Figure 10-2. Weight and balance.

10-6 weight and balance distribution prior to takeoff are runway Item Weight Arm Moment length, runway surface, runway slope, surface wind, and the Aircraft Empty Weight 2,100 78.3 164,430 presence of obstacles. These factors may require a reduction Front Seat Occupants 340 85.0 28,900 in or redistribution of weight prior to flight.

Rear Seat Occupants 350 121.0 42,350 Fuel 450 75.0 33,750 Baggage Area 1 80 150.0 12,000 Some aircraft are designed so that it is difficult to load them in a manner that places the CG out of limits. These are Total 3,320 281,430 usually small aircraft with the seats, fuel, and baggage areas 281,430 ÷ 3,320 = 84.8 located near the CG limit. Pilots must be aware that while within CG limits these aircraft can be overloaded in weight.

Figure 10-5. Example of weight and balance computations.

Other aircraft can be loaded in such a manner that they will be out of CG limits even though the useful load has not been 84.8 is within the 78–86 inch range; therefore, the aircraft is exceeded. Because of the effects of an out-of-balance or loaded within limits.

overweight condition, a pilot should always be sure that an aircraft is properly loaded.

Graph Method Another method for determining the loaded weight and CG is Determining Loaded Weight and CG the use of graphs provided by the manufacturers. To simplify There are various methods for determining the loaded weight calculations, the moment may sometimes be divided by 100, and CG of an aircraft. There is the computational method as 1,000, or 10,000. [Figures 10-6, 10-7, and 10-8] well as methods that utilize graphs and tables provided by Front seat occupants....................................340 pounds the aircraft manufacturer.

Rear seat occupants ......................................300 pounds Computational Method Fuel.................................................................40 gallons The following is an example of the computational method Baggage area 1 ...............................................20 pounds involving the application of basic math functions.

Aircraft Allowances: The same steps should be followed in the graph method as were used in the computational method except the graphs Maximum gross weight......................3,400 pounds provided will calculate the moments and allow the pilot to CG range.............................................78–86 inches determine if the aircraft is loaded within limits. To determine Given: the moment using the loading graph, find the weight and draw a line straight across until it intercepts the item for which the Weight of front seat occupants.............340 pounds moment is to be calculated. Then draw a line straight down Weight of rear seat occupants..............350 pounds to determine the moment. (The red line on the loading graph Fuel...........................................................75 gallons in Figure 10-7 represents the moment for the pilot and front passenger. All other moments were determined the same Weight of baggage in area 1....................80 pounds 1. List the weight of the aircraft, occupants, fuel, and Moment Sample Loading Problem Weight (lb) baggage. Remember that aviation gas (AVGAS) (in-lb/1,000) weighs 6 pounds per gallon and is used in this 1. Basic empty weight (Use data pertaining to aircraft as it is presently equipped) example.

includes unusable fuel and full oil 1,467 57.3 2. Enter the moment for each item listed. Remember 2. Usable fuel (At 6 lb/gal) Standard tanks (40 gal maximum) 240 11.5 “weight x arm = moment.” Long range tanks (50 gal maximum) Integral tanks (62 gal maximum) 3. Find the total weight and total moment.

Integral reduced fuel (42 gal) 4. To determine the CG, divide the total moment by the 3. Pilot and front passenger (Station 34 to 46) total weight. 340 12.7 4. Rear passengers 300 21.8 5. Baggage area 1 or passenger on child’s NOTE: The weight and balance records for a particular seat (Station 82 to 108, 120 lb maximum) 20 1.9 aircraft provide the empty weight and moment, as well as the 6. Baggage area 2 information on the arm distance. [Figure 10-5] (Station 108 to 142, 50 lb maximum) 7. Weight and moment 2,367 105.2 The total loaded weight of 3,320 pounds does not exceed Figure 10-6. Weight and balance data.

the maximum gross weight of 3,400 pounds, and the CG of 10-7 Load Moment/1,000 (kilogram-millimeters) 0 50 100 150 200 250 300 350 400 62 gal***(234.7 liters) 340 60 gal (227.1 liters) 150 Rear passengers 50 gal**(189.3 liters) 42 gal reduced***(159 liters) 40 gal*(189.3 liters) 100 Fuel (6 lb/gal; 0.72 kg/liter) 30 gal (113.6 liters) Pilot & front passenger Load Weight (kilograms) Load Weight (pounds) 20 gal (75.7 liters) Maximum Usable Fuel Baggage area 1 or * Standard tanks passenger on child’s seat ** Long range tanks 10 gal (37.9 liters) *** Internal tanks Baggage area 2 0 0 5 10 15 20 25 30 12.7 Load Moment/1,000 (inch-pounds) Figure 10-7. Loading graph.

Loaded Aircraft Moment/1,000 (kilogram-millimeters) 600 700 800 900 1,000 1,100 1,200 1,300 1,100 2,400 2,367 1,050 2,300 Normal 1,000 2,200 category 2,100 2,000 1,900 1,800 Utility category Loaded Aircraft Weight (pounds) 800 Loaded Airplane Weight (kilograms) 1,700 1,600 1,500 45 50 55 60 65 70 75 80 85 90 95 100 105 110 105.2 Loaded Aircraft Moment/1,000 (inch-pounds) Figure 10-8. CG moment envelope.

10-8 way.) Once this has been done for each item, total the weight Table Method and moments and draw a line for both weight and moment The table method applies the same principles as the on the CG envelope graph. If the lines intersect within the computational and graph methods. The information envelope, the aircraft is loaded within limits. In this sample and limitations are contained in tables provided by the loading problem, the aircraft is loaded within limits.

manufacturer. Figure 10-9 is an example of a table and a Occupants Maximum Minimum Usable Fuel Moment Moment Weight Front Seat Rear Seats 100 100 Arm 85 Arm 121 Main Wing Tanks Arm 75 2,057 2,400 1,848 Moment Moment Weight Weight 2,065 2,410 1,856 Moment 100 100 Weight Gallons 2,074 2,420 1,863 120 145 120 102 2,083 2,430 1,871 5 30 22 130 157 2,091 130 110 2,440 1,879 10 60 45 140 169 140 119 2,100 2,450 1,887 FUEL TANK 15 90 68 150 150 128 182 2,108 2,460 1,894 20 120 90 160 194 2,117 160 136 2,470 1,092 25 150 112 170 206 170 144 2,125 2,480 1,911 30 180 135 180 218 2,134 2,490 1,921 180 153 35 210 158 190 230 190 162 40 240 180 200 200 170 242 2,143 2,500 1,932 44 264 198 2,151 2,510 1,942 2,160 2,520 1,953 2,168 2,530 1,963 2,176 2,540 1,974 2,184 2,550 1,984 2,192 2,560 1,995 2,200 2,570 2,005 2,208 2,580 2,016 2,216 2,590 2,026 BAGGAGE AREA OIL SEATING AREA 2,224 2,600 2,037 2,232 2,610 2,048 2,239 2,620 2,058 2,247 2,630 2,069 Maximum Minimum 2,255 2,640 2,080 Baggage or 5th Weight Moment Moment *Oil 2,263 2,650 2,090 Seat Occupant 100 100 Moment 2,271 2,660 2,101 Weight Quarts Arm 140 1,800 2,100 1,617 2,279 2,670 2,112 1,808 2,110 1,625 2,287 Moment 2,680 2,123 10 19 5 Weight 1,817 2,120 1,632 2,295 2,690 2,133 FUEL TANK 1,825 2,130 1,640 *Included in basic empty weight 1,834 2,140 1,648 2,303 2,700 2,144 1,843 2,150 1,656 2,311 2,710 2,155 30 Empty Weight ~ 2,015 1,851 2,160 1,663 2,319 2,720 2,166 MOM/ 100 ~ 1,554 1,860 2,170 1,671 2,326 2,730 2,177 1,868 2,180 1,679 2,334 2,740 2,188 1,877 2,190 1,686 2,342 2,750 2,199 Moment Limits vs Weight 2,350 2,760 2,210 Moment limits are based on the following weight and 80 1,885 2,200 1,694 2,358 2,770 2,221 center of gravity limit data (landing gear down).

1,894 2,210 1,702 2,366 2,780 2,232 Forward Weight AFT 1,903 2,220 1,709 2,374 2,790 2,243 CG Limit Condition CG Limit 1,911 2,230 1,717 1,920 2,240 2,950 lb (takeoff 82.1 84.7 1,725 2,381 2,800 2,254 or landing) 1,928 2,250 1,733 2,389 2,810 2,265 196 2,525 lb 77.5 85.7 1,937 2,260 1,740 2,397 2,820 2,276 2,475 lb or less 77.0 85.7 1,945 2,270 2,405 1,748 2,830 2,287 1,954 2,280 1,756 2,413 2,840 2,298 1,963 2,290 1,763 2,421 2,850 2,309 Sample Loading Problem Weight Moment 1,971 2,300 1,771 2,426 2,860 2,320 Basic empty weight 2,015 1,554 1,980 2,310 1,779 2,436 2,870 2,332 1,988 2,320 1,786 2,444 2,880 2,343 Fuel main tanks (44 gal) 264 198 210 1,997 2,330 1,794 2,452 2,890 2,354 *Front seat passengers 300 254 220 2,005 2,340 1,802 3,460 2,900 2,365 *Rear seat passengers 190 230 2,014 2,350 1,810 2,468 2,910 2,377 240 2,023 2,360 1,817 2,475 2,920 Baggage 30 42 2,388 250 2,031 2,370 1,825 2,483 2,930 2,399 260 2,040 2,380 1,833 2,491 2,940 2,411 Total 2,799 2,278/100 270 2,048 2,390 1,840 2,499 2,950 2,422 * Interpolate or, as in this case, add appropriate numbers.

Figure 10-9. Loading schedule placard.

10-9 weight and balance calculation based on that table. In this Item Weight Arm Moment problem, the total weight of 2,799 pounds and moment of Basic empty weight 3,230 292,315.0 CG 90.5 2,278/100 are within the limits of the table.

Front seat occupants 335 29,815.0 89.0 rd th 3 & 4 seat occupants 350 44,100.0 126.0 forward facing Computations With a Negative Arm th th 5 & 6 seat occupants 200 31,400.0 157.0 Figure 10-10 is a sample of weight and balance computation Nose baggage 100 1,000.0 10.0 using an aircraft with a negative arm. It is important to Aft baggage 25 4,575.0 183.0 Zero fuel weight max 4,400 pounds remember that a positive times a negative equals a negative, 4,240 403,205.0 CG 95.1 Subtotal and a negative would be subtracted from the total moments.

822 92,886.0 113.0 Fuel Ramp weight max 5,224 pounds 5,062 496,091.0 CG 98.0 Subtotal ramp weight Computations With Zero Fuel Weight * Less fuel for start, Figure 10-11 is a sample of weight and balance computation taxi, and takeoff −24 −2,712.0 113.0 using an aircraft with a zero fuel weight. In this example, Subtotal 5,038 493,379.0 CG 97.9 takeoff weight the total weight of the aircraft less fuel is 4,240 pounds, Less fuel to destination −450 −50,850.0 113.0 which is under the zero fuel weight of 4,400 pounds. If the Max landing weight 4,940 pounds 4,588 442,529.0 CG 96.5 total weight of the aircraft without fuel had exceeded 4,400 Actual landing weight pounds, passengers or cargo would have needed to be reduced *Fuel for start, taxi, and takeoff is normally 24 pounds.

to bring the weight at or below the max zero fuel weight.

Figure 10-11. Sample weight and balance using an aircraft with a published zero fuel weight.

Shifting, Adding, and Removing Weight A pilot must be able to solve any problems accurately that aircraft have forward and aft baggage compartments, weight involve the shift, addition, or removal of weight. For example, may be shifted from one to the other to change the CG. If the pilot may load the aircraft within the allowable takeoff starting with a known aircraft weight, CG, and total moments, weight limit, then find that the CG limit has been exceeded.

calculate the new CG (after the weight shift) by dividing the The most satisfactory solution to this problem is to shift new total moments by the total aircraft weight.

baggage, passengers, or both. The pilot should be able to determine the minimum load shift needed to make the aircraft To determine the new total moments, find out how many safe for flight. Pilots should be able to determine if shifting a moments are gained or lost when the weight is shifted.

load to a new location will correct an out-of-limit condition.

Assume that 100 pounds has been shifted from station 30 to There are some standardized calculations that can help make station 150. This movement increases the total moments of these determinations.

the aircraft by 12,000 in-lb.

Weight Shifting Moment when When weight is shifted from one location to another, the at station 150 = 100 lb x 150 in = 15,000 in-lb total weight of the aircraft is unchanged. The total moments, however, do change in relation and proportion to the Moment when direction and distance the weight is moved. When weight is at station 30 = 100 lb x 30 in = 3,000 in-lb moved forward, the total moments decrease; when weight is moved aft, total moments increase. The moment change Moment change = [15,000 – 3,000] = 12,000 in-lb is proportional to the amount of weight moved. Since many By adding the moment change to the original moment (or subtracting if the weight has been moved forward instead of Item Weight Arm Moment aft), the new total moments are obtained. Then determine the Licensed empty weight 1,011.9 68.6 69,393.0 new CG by dividing the new moments by the total weight: Oil (6 quarts) 11.0 −31.0 −341.0 Fuel (18 gallons) 108.0 84.0 9,072.0 Fuel, auxiliary (18 gallons) 108.0 84.0 9,072.0 Total moments = Pilot 170.0 81.0 13,770.0 616,000 in-lb + 12,000 in-lb = 628,000 in-lb Passenger 170.0 81.0 13,770.0 Baggage 70.0 105.0 7,350.0 628,000 in-lb CG = = 78.5 in 8,000 lb Total 1,648.9 122,086.0 CG 74.0 The shift has caused the CG to shift to station 78.5.

Figure 10-10. Sample weight and balance using a negative.

10-10 Example Example Given: Weight shifted ∆CG (change of CG) = Aircraft total weight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6,860 lb Total weight Distance weight is shifted CG station. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80.0 in 100 ∆CG = 8,000 120 Determine the location of the CG if 140 pounds of baggage is added to station 150.

∆CG 1.5 in = The change of CG is added to (or subtracted from when appropriate) Solution: the original CG to determine the new CG: Added weight ∆CG 77 + 1.5 = 78.5 inches aft of datum = New total weight Distance between weight and old CG The shifting weight proportion formula can also be used to determine ∆CG 140 lb = how much weight must be shifted to achieve a particular shift of the CG.

150 in − 80 in 6,860 lb + 140 lb The following problem illustrates a solution of this type.

140 lb ∆CG = 7,000 lb 70 in Example 1.4 in aft = CG Given: Add ∆CG to old CG Aircraft total weight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7,800 lb New CG = 80 in + 1.4 in = 81.4 in CG station. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81.5 in Aft CG limit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80.5 in Determine how much cargo must be shifted from the aft cargo compart- Example ment at station 150 to the forward cargo compartment at station 30 to move the CG to exactly the aft limit.

Given: Aircraft total weight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6,100 lb Solution: CG station. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80.0 in Weight to be shifted CG = Total weight Distance weight is shifted Determine the location of the CG if 100 pounds is removed from station 150.

Weight to be shifted 1.0 in = 7,800 lb 120 in Solution: 65 lb = Weight removed ∆CG Weight to be shifted = New total weight Distance between weight and old CG ∆CG 100 lb = A simpler solution may be obtained by using a computer 150 in − 80 in 6,100 lb − 100 lb or calculator and a proportional formula. This can be done 100 lb ∆CG = because the CG will shift a distance that is proportional to 6,000 lb 70 in the distance the weight is shifted.

1.2 in forward = CG Subtract ∆CG from old CG Weight Addition or Removal New CG = 80 in − 1.2 in = 78.8 in In many instances, the weight and balance of the aircraft will be changed by the addition or removal of weight. When this In the previous examples, the r CG is either added or happens, a new CG must be calculated and checked against subtracted from the old CG. Deciding which to accomplish is the limitations to see if the location is acceptable. This type best handled by mentally calculating which way the CG will of weight and balance problem is commonly encountered shift for the particular weight change. If the CG is shifting when the aircraft burns fuel in flight, thereby reducing the aft, the r CG is added to the old CG; if the CG is shifting weight located at the fuel tanks. Most small aircraft are forward, the r CG is subtracted from the old CG.

designed with the fuel tanks positioned close to the CG; therefore, the consumption of fuel does not affect the CG to Chapter Summary any great extent.

Operating an aircraft within the weight and balance limits is critical to flight safety. Pilots must ensure that the CG is The addition or removal of cargo presents a CG change and remains within approved limits throughout all phases of problem that must be calculated before flight. The problem a flight. For additional information on weight, balance, CG, may always be solved by calculations involving total and aircraft stability refer to the FAA handbook appropriate moments. A typical problem may involve the calculation to the specific aircraft category.

of a new CG for an aircraft which, when loaded and ready for flight, receives some additional cargo or passengers just before departure time.

10-11 10-12

Chapter 11

Aircraft

Performance

Introduction This chapter discusses the factors that affect aircraft performance, which include the aircraft weight, atmospheric conditions, runway environment, and the fundamental physical laws governing the forces acting on an aircraft.

Importance of Performance Data The performance or operational information section of the Aircraft Flight Manual/Pilot’s Operating Handbook (AFM/ POH) contains the operating data for the aircraft; that is, the data pertaining to takeoff, climb, range, endurance, descent, and landing. The use of this data in flying operations is mandatory for safe and efficient operation. Considerable knowledge and familiarity of the aircraft can be gained by studying this material.

11-1 It must be emphasized that the manufacturers’ information exerted by the weight of the atmosphere is approximately 14.7 and data furnished in the AFM/POH is not standardized. pounds per square inch (psi). The density of air has significant Some provide the data in tabular form, while others use effects on the aircraft’s performance. As air becomes less graphs. In addition, the performance data may be presented dense, it reduces: on the basis of standard atmospheric conditions, pressure • Power, because the engine takes in less air altitude, or density altitude. The performance information in • Thrust, because the propeller is less efficient in thin air the AFM/POH has little or no value unless the user recognizes those variations and makes the necessary adjustments.

• Lift, because the thin air exerts less force on the airfoils To be able to make practical use of the aircraft’s capabilities The pressure of the atmosphere may vary with time but more and limitations, it is essential to understand the significance importantly, it varies with altitude and temperature. Due to of the operational data. The pilot must be cognizant of the the changing atmospheric pressure, a standard reference basis for the performance data, as well as the meanings of was developed. The standard atmosphere at sea level has the various terms used in expressing performance capabilities a surface temperature of 59 degrees Fahrenheit (°F) or 15 and limitations.

degrees Celsius (°C) and a surface pressure of 29.92 inches of mercury ("Hg) or 1013.2 millibars (mb). [Figure 11-1] Since the characteristics of the atmosphere have a major effect on performance, it is necessary to review two dominant A standard temperature lapse rate is one in which the factors—pressure and temperature.

temperature decreases at the rate of approximately 3.5 °F or 2 °C per thousand feet up to 36,000 feet. Above this point, Structure of the Atmosphere the temperature is considered constant up to 80,000 feet. A standard pressure lapse rate is one in which pressure decreases The atmosphere is an envelope of air that surrounds the at a rate of approximately 1 "Hg per 1,000 feet of altitude gain Earth and rests upon its surface. It is as much a part of the to 10,000 feet. [Figure 11-2] The International Civil Aviation Earth as is land and water. However, air differs from land Organization (ICAO) has established this as a worldwide and water in that it is a mixture of gases. It has mass, weight, standard, and it is often referred to as International Standard and indefinite shape.

Atmosphere (ISA) or ICAO Standard Atmosphere. Any temperature or pressure that differs from the standard lapse Air, like any other fluid, is able to flow and change its shape rates is considered nonstandard temperature and pressure.

when subjected to even minute pressures because of the Adjustments for nonstandard temperatures and pressures are lack of strong molecular cohesion. For example, gas will provided on the manufacturer’s performance charts.

completely fill any container into which it is placed, expanding or contracting to adjust its shape to the limits of the container.

The atmosphere is composed of 78 percent nitrogen, 21 Inches of Millibars Standard Standard percent oxygen, and 1 percent other gases, such as argon Mercury Sea Level Sea Level or helium. Most of the oxygen is contained below 35,000 30 1016 Pressure Pressure feet altitude.

29.92" Hg 1013 mb 25 847 20 677 Atmospheric Pressure 15 508 Though there are various kinds of pressure, pilots are mainly 10 339 concerned with atmospheric pressure. It is one of the basic factors in weather changes, helps to lift the aircraft, and 5 170 A t m o s p h e r i c P r e s s u r e actuates some of the most important flight instruments in the 0 0 aircraft. These instruments often include the altimeter, the airspeed indicator (ASI), the vertical speed indicator (VSI), and the manifold pressure gauge.

Though air is very light, it has mass and is affected by the attraction of gravity. Therefore, like any other substance, it has weight; because it has weight, it has force. Since it is a fluid substance, this force is exerted equally in all directions, and its effect on bodies within the air is called pressure.

Figure 11-1. Standard sea level pressure.

Under standard conditions at sea level, the average pressure 11-2 2. By applying a correction factor to the indicated Temperature Pressure Altitude (ft) altitude according to the reported “altimeter setting,” ( " Hg) (°C) (°F) [Figure 11-3] 0 29.92 15.0 59.0 1,000 28.86 13.0 55.4 3. By using a flight computer 2,000 27.82 11.0 51.9 3,000 26.82 9.1 48.3 Density Altitude 4,000 25.84 7.1 44.7 The more appropriate term for correlating aerodynamic 5,000 24.89 5.1 41.2 6,000 23.98 3.1 37.6 performance in the nonstandard atmosphere is density 7,000 23.09 1.1 34.0 altitude—the altitude in the standard atmosphere 8,000 22.22 −0.9 30.5 corresponding to a particular value of air density.

9,000 21.38 −2.8 26.9 10,000 20.57 −4.8 23.3 Density altitude is pressure altitude corrected for nonstandard 11,000 19.79 −6.8 19.8 temperature. As the density of the air increases (lower 12,000 19.02 −8.8 16.2 density altitude), aircraft performance increases. Conversely, 13,000 18.29 −10.8 12.6 14,000 17.57 −12.7 9.1 Method for Determining 15,000 16.88 −14.7 5.5 Alternate Method for Determining Pressure Altitude 16,000 16.21 −16.7 1.9 Pressure Altitude Altimeter Altitude 17,000 15.56 −18.7 −1.6 setting correction 18,000 14.94 −20.7 −5.2 28.0 1,824 19,000 14.33 −22.6 −8.8 28.1 1,727 20,000 13.74 −24.6 −12.3 28.2 1,630 28.3 1,533 Figure 11-2. Properties of standard atmosphere.

28.4 1,436 28.5 1,340 Since all aircraft performance is compared and evaluated 28.6 1,244 28.7 1,148 using the standard atmosphere, all aircraft instruments 28.8 1,053 are calibrated for the standard atmosphere. Thus, certain 28.9 957 corrections must apply to the instrumentation, as well as the To field 29.0 863 elevation aircraft performance, if the actual operating conditions do Add 29.1 768 not fit the standard atmosphere. In order to account properly 29.2 673 for the nonstandard atmosphere, certain related terms must 29.3 579 be defined.

29.4 485 29.5 392 29.6 298 Pressure Altitude 29.7 205 Pressure altitude is the height above the standard datum 29.8 112 plane (SDP). The aircraft altimeter is essentially a sensitive 29.9 20 To get barometer calibrated to indicate altitude in the standard 29.92 0 pressure altitude 30.0 −73 atmosphere. If the altimeter is set for 29.92 "Hg SDP, the 30.1 −165 altitude indicated is the pressure altitude—the altitude in the 30.2 −257 standard atmosphere corresponding to the sensed pressure.

30.3 −348 Field elevation is sea level 30.4 −440 The SDP is a theoretical level at which the pressure of the From field 30.5 −531 elevation atmosphere is 29.92 "Hg and the weight of air is 14.7 psi. As 30.6 −622 Subtract atmospheric pressure changes, the SDP may be below, at, or 30.7 −712 above sea level. Pressure altitude is important as a basis for 30.8 −803 30.9 −893 determining aircraft performance, as well as for assigning 31.0 −983 flight levels to aircraft operating at above 18,000 feet.

Figure 11-3. Field elevation versus pressure. The aircraft is located The pressure altitude can be determined by any of the three on a field that happens to be at sea level. Set the altimeter to the following methods: current altimeter setting (29.7). The difference of 205 feet is added 1. By setting the barometric scale of the altimeter to to the elevation or a PA of 205 feet.

29.92 "Hg and reading the indicated altitude, 11-3 as air density decreases (higher density altitude), aircraft flight level. Density altitude can also be determined by referring performance decreases. A decrease in air density means a to the table and chart in Figures 11-3 and 11-4 respectively.

high density altitude; an increase in air density means a lower density altitude. Density altitude is used in calculating aircraft Effects of Pressure on Density performance. Under standard atmospheric condition, air at Since air is a gas, it can be compressed or expanded. When each level in the atmosphere has a specific density; under air is compressed, a greater amount of air can occupy a standard conditions, pressure altitude and density altitude given volume. Conversely, when pressure on a given volume identify the same level. Density altitude, then, is the vertical of air is decreased, the air expands and occupies a greater distance above sea level in the standard atmosphere at which space. That is, the original column of air at a lower pressure a given density is to be found.

Density altitude is computed using pressure altitude and 15,000 temperature. Since aircraft performance data at any level is 14,000 based upon air density under standard day conditions, such 14,000 performance data apply to air density levels that may not be 13,000 identical to altimeter indications. Under conditions higher 13,000 or lower than standard, these levels cannot be determined directly from the altimeter. 12,000 12,000 Density altitude is determined by first finding pressure 11,000 altitude and then correcting this altitude for nonstandard 11,000 temperature variations. Since density varies directly with 10,000 Pressure altitude (feet) pressure, and inversely with temperature, a given pressure Standard temperature 10,000 altitude may exist for a wide range of temperature by allowing 9,000 the density to vary. However, a known density occurs for 9,000 any one temperature and pressure altitude. The density of the 8,000 air, of course, has a pronounced effect on aircraft and engine 8,000 performance. Regardless of the actual altitude at which the aircraft is operating, it will perform as though it were 7,000 operating at an altitude equal to the existing density altitude. 7,000 6,000 For example, when set at 29.92 "Hg, the altimeter may 6,000 indicate a pressure altitude of 5,000 feet. According to the 5,000 AFM/POH, the ground run on takeoff may require a distance Density altitude (feet) 5,000 of 790 feet under standard temperature conditions. However, 4,000 if the temperature is 20 °C above standard, the expansion of 4,000 air raises the density level. Using temperature correction data from tables or graphs, or by deriving the density altitude with 3,000 3,000 a computer, it may be found that the density level is above 7,000 feet, and the ground run may be closer to 1,000 feet.

2,000 2,000 Air density is affected by changes in altitude, temperature, 1,000 and humidity. High density altitude refers to thin air while 1,000 low density altitude refers to dense air. The conditions that Sea level result in a high density altitude are high elevations, low -2,000 -1,000 Sea level atmospheric pressures, high temperatures, high humidity, or -20° -10° 0° 10° 20° 30° 40° C some combination of these factors. Lower elevations, high F 0° 10° 20° 30° 40° 50° 60° 70° 80° 90° 100° atmospheric pressure, low temperatures, and low humidity are more indicative of low density altitude. Outside air temperature (OAT) Using a flight computer, density altitude can be computed by Figure 11-4. Density altitude chart.

inputting the pressure altitude and outside air temperature at 11-4 contains a smaller mass of air. In other words, the density is consideration. Expect a decrease in overall performance in decreased. In fact, density is directly proportional to pressure. high humidity conditions.

If the pressure is doubled, the density is doubled, and if the pressure is lowered, so is the density. This statement is true Performance only at a constant temperature.

Performance is a term used to describe the ability of an aircraft to accomplish certain things that make it useful for Effects of Temperature on Density certain purposes. For example, the ability of an aircraft to land Increasing the temperature of a substance decreases its and take off in a very short distance is an important factor density. Conversely, decreasing the temperature increases to the pilot who operates in and out of short, unimproved the density. Thus, the density of air varies inversely with airfields. The ability to carry heavy loads, fly at high altitudes temperature. This statement is true only at a constant pressure.

at fast speeds, and/or travel long distances is essential for the performance of airline and executive type aircraft.

In the atmosphere, both temperature and pressure decrease with altitude and have conflicting effects upon density.

The primary factors most affected by performance are the However, the fairly rapid drop in pressure as altitude is takeoff and landing distance, rate of climb, ceiling, payload, increased usually has the dominant effect. Hence, pilots can range, speed, maneuverability, stability, and fuel economy.

expect the density to decrease with altitude.

Some of these factors are often directly opposed: for example, high speed versus short landing distance, long range versus Effects of Humidity (Moisture) on Density great payload, and high rate of climb versus fuel economy.

The preceding paragraphs are based on the presupposition of It is the preeminence of one or more of these factors that perfectly dry air. In reality, it is never completely dry. The dictates differences between aircraft and explains the high small amount of water vapor suspended in the atmosphere degree of specialization found in modern aircraft.

may be negligible under certain conditions, but in other conditions humidity may become an important factor in the The various items of aircraft performance result from the performance of an aircraft. Water vapor is lighter than air; combination of aircraft and powerplant characteristics. The consequently, moist air is lighter than dry air. Therefore, as the aerodynamic characteristics of the aircraft generally define water content of the air increases, the air becomes less dense, the power and thrust requirements at various conditions of increasing density altitude and decreasing performance. It is flight, while powerplant characteristics generally define the lightest or least dense when, in a given set of conditions, it power and thrust available at various conditions of flight.

contains the maximum amount of water vapor.

The matching of the aerodynamic configuration with the powerplant is accomplished by the manufacturer to provide Humidity, also called relative humidity, refers to the amount maximum performance at the specific design condition (e.g., of water vapor contained in the atmosphere and is expressed range, endurance, and climb).

as a percentage of the maximum amount of water vapor the air can hold. This amount varies with the temperature; Straight-and-Level Flight warm air can hold more water vapor, while colder air can All of the principal components of flight performance involve hold less. Perfectly dry air that contains no water vapor has steady-state flight conditions and equilibrium of the aircraft.

a relative humidity of zero percent, while saturated air that For the aircraft to remain in steady, level flight, equilibrium cannot hold any more water vapor has a relative humidity must be obtained by a lift equal to the aircraft weight and a of 100 percent. Humidity alone is usually not considered an powerplant thrust equal to the aircraft drag. Thus, the aircraft essential factor in calculating density altitude and aircraft drag defines the thrust required to maintain steady, level performance; however, it does contribute.

flight. As presented in Chapter 4, Aerodynamics of Flight, all parts of an aircraft contribute to the drag, either induced The higher the temperature, the greater amount of water (from lifting surfaces) or parasite drag.

vapor that the air can hold. When comparing two separate air masses, the first warm and moist (both qualities making air While parasite drag predominates at high speed, induced drag lighter) and the second cold and dry (both qualities making predominates at low speed. [Figure 11-5] For example, if it heavier), the first must be less dense than the second.

an aircraft in a steady flight condition at 100 knots is then Pressure, temperature, and humidity have a great influence accelerated to 200 knots, the parasite drag becomes four on aircraft performance because of their effect upon density.

times as great, but the power required to overcome that There is no rule-of-thumb or chart used to compute the effects drag is eight times the original value. Conversely, when the of humidity on density altitude, but it must be taken into 11-5 energy comes in two forms: (1) Kinetic Energy (KE), the energy of speed; (2) Potential Energy (PE), the stored energy Total drag of position.

Aircraft motion (KE) is described by its velocity (airspeed).

L/D MAX Parasite drag Aircraft position (PE) is described by its height (altitude).

Drag Both KE and PE are directly proportional to the object’s Stall mass. KE is directly proportional to the square of the object’s Induced drag velocity (airspeed). PE is directly proportional to the object’s height (altitude). The formulas below summarize these energy relationships: Speed m = object mass Figure 11-5. Drag versus speed. 2 KE = ½ × m × v v = object velocity aircraft is operated in steady, level flight at twice as great a m = object mass speed, the induced drag is one-fourth the original value, and PE = m × g × h g = gravity field strength the power required to overcome that drag is only one-half h = object height the original value.

We sometimes use the terms “power” and “thrust” When an aircraft is in steady, level flight, the condition of interchangeably when discussing climb performance. This equilibrium must prevail. The unaccelerated condition of erroneously implies the terms are synonymous. It is important flight is achieved with the aircraft trimmed for lift equal to distinguish between these terms. Thrust is a force or to weight and the powerplant set for a thrust to equal the pressure exerted on an object. Thrust is measured in pounds aircraft drag.

(lb) or newtons (N). Power, however, is a measurement of the rate of performing work or transferring energy (KE and The maximum level flight speed for the aircraft is obtained PE). Power is typically measured in horsepower (hp) or when the power or thrust required equals the maximum power kilowatts (kw). We can think of power as the motion (KE or thrust available from the powerplant. [Figure 11-6] The and PE) a force (thrust) creates when exerted on an object minimum level flight airspeed is not usually defined by thrust over a period of time.

or power requirement since conditions of stall or stability and control problems generally predominate.

Positive climb performance occurs when an aircraft gains PE by increasing altitude. Two basic factors, or a combination Climb Performance of the two factors, contribute to positive climb performance If an aircraft is to move, fly, and perform, work must act in most aircraft: upon it. Work involves force moving the aircraft. The aircraft 1. The aircraft climbs (gains PE) using excess power acquires mechanical energy when it moves. Mechanical above that required to maintain level flight, or 2. The aircraft climbs by converting airspeed (KE) to altitude (PE).

a v a i l a b u m l e i m p x o a M w e r As an example of factor 1 above, an aircraft with an engine High cruise speed capable of producing 200 horsepower (at a given altitude) is using only 130 horsepower to maintain level flight at that altitude. This leaves 70 horsepower available to climb. The Low cruise speed pilot holds airspeed constant and increases power to perform Min. speed Power required the climb.

As an example of factor 2, an aircraft is flying level at 120 Maximum level flight speed knots. The pilot leaves the engine power setting constant but applies other control inputs to perform a climb. The climb, Speed sometimes called a zoom climb, converts the airspeed (KE) Figure 11-6. Power versus speed.

11-6 to altitude (PE); the airspeed decreases to something less so as to achieve maximum altitude increase with minimum than 120 knots as the altitude increases. horizontal travel over the ground. A good use of maximum AOC is when taking off from a short airfield surrounded by There are two primary reasons to evaluate climb performance. high obstacles, such as trees or power lines. The objective is First, aircraft must climb over obstacles to avoid hitting to gain sufficient altitude to clear the obstacle while traveling them. Second, climbing to higher altitudes can provide the least horizontal distance over the surface.

better weather, fuel economy, and other benefits. Maximum Angle of Climb (AOC), obtained at V , may provide climb One method to climb (have positive AOC performance) is X performance to ensure an aircraft will clear obstacles. to have excess thrust available. Essentially, the greater the Maximum Rate of Climb (ROC), obtained at V , provides force that pushes the aircraft upward, the steeper it can climb.

Y climb performance to achieve the greatest altitude gain over Maximum AOC occurs at the airspeed and angle of attack time. Maximum ROC may not be sufficient to avoid obstacles (AOA) combination which allows the maximum excess in some situations, while maximum AOC may be sufficient thrust. The airspeed and AOA combination where excess to avoid the same obstacles. [Figure 11-7] thrust exists varies amongst aircraft types. As an example, Figure 11-8 provides a comparison between jet and propeller airplanes as to where maximum excess thrust (for maximum Angle of Climb (AOC) AOC) occurs. In a jet, maximum excess thrust normally AOC is a comparison of altitude gained relative to distance occurs at the airspeed where the thrust required is at a traveled. AOC is the inclination (angle) of the flight path. For minimum (approximately L/D ). In a propeller airplane, maximum AOC performance, a pilot flies the aircraft at V MAX X maximum excess thrust normally occurs at an airspeed below L/D and frequently just above stall speed.

MAX Rate of Climb (ROC) ROC is a comparison of altitude gained relative to the time needed to reach that altitude. ROC is simply the vertical component of the aircraft’s flight path velocity vector. For maximum ROC performance, a pilot flies the aircraft at V Y Altitude so as to achieve a maximum gain in altitude over a given period of time.

Max ROC Max AOC Maximum ROC expedites a climb to an assigned altitude.

This gains the greatest vertical distance over a period of time. For example, in a maximum AOC profile, a certain Distance aircraft takes 30 seconds to reach 1,000 feet AGL, but covers only 3,000 feet over the ground. By comparison, Figure 11-7. Maximum angle of climb (AOC) versus maximum rate using its maximum ROC profile, the same aircraft climbs of climb (ROC).

LEGEND T thrust E excess (Full PCL) T thrust A (Full Throttle) T T A A available T thrust R T required T E E T AOC angle of R T Thrust Thrust Max AOC (jet) R climb TAS true airspeed L/D lift to drag MAX L/D L/D MAX MAX ratio maximum Max AOC (prop) PCL power Velocity (TAS) Velocity (TAS) control lever Figure 11-8. Comparison of maximum AOC between jet and propeller airplanes.

11-7 to 1,500 feet in 30 seconds but covers 6,000 feet across the to minimize the weight, since it has such a marked effect on ground. Note that both ROC and AOC maximum climb the factors pertaining to performance.

profiles use the aircraft’s maximum throttle setting. Any differences between max ROC and max AOC lie primarily A change in an aircraft’s weight produces a twofold effect in the velocity (airspeed) and AOA combination the aircraft on climb performance. First, a change in weight changes the manual specifies. [Figure 11-7] drag and the power required. This alters the reserve power available, which in turn, affects both the climb angle and ROC performance depends upon excess power. Since the climb rate. Secondly, an increase in weight reduces the climbing is work and power is the rate of performing work, maximum ROC, but the aircraft must be operated at a higher a pilot can increase the climb rate by using any power not climb speed to achieve the smaller peak climb rate.

used to maintain level flight. Maximum ROC occurs at an airspeed and AOA combination that produces the maximum An increase in altitude also increases the power required excess power. Therefore, maximum ROC for a typical jet and decreases the power available. Therefore, the climb airplane occurs at an airspeed greater than L/D and at an performance of an aircraft diminishes with altitude. The MAX AOA less than L/D AOA. In contrast, maximum ROC for speeds for maximum ROC, maximum AOC, and maximum MAX a typical propeller airplane occurs at an airspeed and AOA and minimum level flight airspeeds vary with altitude. As combination closer to L/D . [Figure 11-9] altitude is increased, these various speeds finally converge MAX at the absolute ceiling of the aircraft. At the absolute ceiling, Climb Performance Factors there is no excess of power and only one speed allows steady, level flight. Consequently, the absolute ceiling of an aircraft Since weight, altitude and configuration changes affect produces zero ROC. The service ceiling is the altitude at excess thrust and power, they also affect climb performance.

which the aircraft is unable to climb at a rate greater than 100 Climb performance is directly dependent upon the ability to feet per minute (fpm). Usually, these specific performance produce either excess thrust or excess power. Earlier in the reference points are provided for the aircraft at a specific book it was shown that an increase in weight, an increase in design configuration. [Figure 11-10] altitude, lowering the landing gear, or lowering the flaps all decrease both excess thrust and excess power for all aircraft.

The terms “power loading,” “wing loading,” “blade loading,” Therefore, maximum AOC and maximum ROC performance and “disk loading” are commonly used in reference to decreases under any of these conditions.

performance. Power loading is expressed in pounds per horsepower and is obtained by dividing the total weight Weight has a very pronounced effect on aircraft performance.

of the aircraft by the rated horsepower of the engine. It If weight is added to an aircraft, it must fly at a higher AOA is a significant factor in an aircraft’s takeoff and climb to maintain a given altitude and speed. This increases the capabilities. Wing loading is expressed in pounds per square induced drag of the wings, as well as the parasite drag of the foot and is obtained by dividing the total weight of an airplane aircraft. Increased drag means that additional thrust is needed in pounds by the wing area (including ailerons) in square feet.

to overcome it, which in turn means that less reserve thrust is It is the airplane’s wing loading that determines the landing available for climbing. Aircraft designers go to great lengths LEGEND P power E excess P power A available (Full PCL) P power (Full Throttle) R required P A ROC rate of Power Power P P P climb A R E P TAS true E P R airspeed L/D lift to drag MAX ratio Max ROC (jet) L/D maximum MAX Max ROC (prop) L/D MAX PCL power control lever Velocity (TAS) Velocity (TAS) Figure 11-9. Comparison of maximum ROC between jet and propeller airplanes.

11-8 A common element for each of these operating problems is the specific range; that is, nautical miles (NM) of flying distance versus the amount of fuel consumed. Range must 24,000 be clearly distinguished from the item of endurance. Range 22,000 involves consideration of flying distance, while endurance 20,000 involves consideration of flying time. Thus, it is appropriate Absolute ceiling 18,000 to define a separate term, specific endurance.

Service ceiling 16,000 14,000 flight hours specific endurance = pounds of fuel 12,000 Best angle Best rate 10,000 of climb (V of climb (V x) y) or Standard altitude (feet) 8,000 6,000 flight hours/hour specific endurance = 4,000 pounds of fuel/hour 2,000 Sea level or 70 80 90 100 110 120 Indicated airspeed (knots) specific endurance = fuel flow Figure 11-10. Absolute and service ceiling.

Fuel flow can be defined in either pounds or gallons. If speed. Blade loading is expressed in pounds per square foot maximum endurance is desired, the flight condition must and is obtained by dividing the total weight of a helicopter by provide a minimum fuel flow. In Figure 11-11 at point A, the area of the rotor blades. Blade loading is not to be confused the airspeed is low and fuel flow is high. This would occur with disk loading, which is the total weight of a helicopter during ground operations or when taking off and climbing.

divided by the area of the disk swept by the rotor blades.

As airspeed is increased, power requirements decrease due to aerodynamic factors, and fuel flow decreases to point B.

Range Performance This is the point of maximum endurance. Beyond this point, The ability of an aircraft to convert fuel energy into flying increases in airspeed come at a cost. Airspeed increases distance is one of the most important items of aircraft require additional power and fuel flow increases with performance. In flying operations, the problem of efficient additional power.

range operation of an aircraft appears in two general forms: 1. To extract the maximum flying distance from a given Cruise flight operations for maximum range should be fuel load conducted so that the aircraft obtains maximum specific range throughout the flight. The specific range can be defined by 2. To fly a specified distance with a minimum the following relationship.

expenditure of fuel e d u t i t l a t A Reference line Maximum endurance at minimum power required Applicable for a particular A Weight Altitude Fuel flow/power required (HP) Configuration Maximum range at L/D MAX B Speed Figure 11-11. Airspeed for maximum endurance.

11-9 NM recommended long-range cruise condition. By this procedure, specific range = pounds of fuel the aircraft is capable of its maximum design-operating radius or can achieve flight distances less than the maximum with or a maximum of fuel reserve at the destination.

NM/hour A propeller-driven aircraft combines the propeller with the specific range = pounds of fuel/hour reciprocating engine for propulsive power. Fuel flow is determined mainly by the shaft power put into the propeller or rather than thrust. Thus, the fuel flow can be related directly to the power required to maintain the aircraft in steady, level knots flight, and on performance charts power can be substituted specific range = fuel flow for fuel flow. This fact allows for the determination of range through analysis of power required versus speed.

If maximum specific range is desired, the flight condition must provide a maximum of speed per fuel flow. While The maximum endurance condition would be obtained at the the peak value of specific range would provide maximum point of minimum power required since this would require the range operation, long-range cruise operation is generally lowest fuel flow to keep the airplane in steady, level flight.

recommended at a slightly higher airspeed. Most long-range Maximum range condition would occur where the ratio of cruise operations are conducted at the flight condition that speed to power required is greatest. [Figure 11-11] provides 99 percent of the absolute maximum specific range.

The advantage of such operation is that one percent of range The maximum range condition is obtained at maximum lift/ is traded for three to five percent higher cruise speed. Since drag ratio (L/D ), and it is important to note that for a given MAX the higher cruise speed has a great number of advantages, the aircraft configuration, the L/D occurs at a particular AOA MAX small sacrifice of range is a fair bargain. The values of specific and lift coefficient and is unaffected by weight or altitude. A range versus speed are affected by three principal variables: variation in weight alters the values of airspeed and power required to obtain the L/D . [Figure 11-12] Different MAX 1. Aircraft gross weight theories exist on how to achieve max range when there is a 2. Altitude headwind or tailwind present. Many say that speeding up in a headwind or slowing down in a tail wind helps to achieve 3. The external aerodynamic configuration of the aircraft.

max range. While this theory may be true in a lot of cases, it is not always true as there are different variables to every These are the source of range and endurance operating data situation. Each aircraft configuration is different, and there included in the performance section of the AFM/POH.

is not a rule of thumb that encompasses all of them as to how to achieve the max range.

Cruise control of an aircraft implies that the aircraft is operated to maintain the recommended long-range cruise condition throughout the flight. Since fuel is consumed during t cruise, the gross weight of the aircraft varies and optimum h g i e L / airspeed, altitude, and power setting can also vary. Cruise w D M A X r e t h h g g control means the control of the optimum airspeed, altitude, i i H e t w h and power setting to maintain the 99 percent maximum c i g i s e a B w specific range condition. At the beginning of cruise flight, the r e w o relatively high initial weight of the aircraft requires specific L values of airspeed, altitude, and power setting to produce the Power required recommended cruise condition. As fuel is consumed and the C o n s ta n t al ti tu d e aircraft’s gross weight decreases, the optimum airspeed and power setting may decrease, or the optimum altitude may increase. In addition, the optimum specific range increases.

Therefore, the pilot must provide the proper cruise control Speed procedure to ensure that optimum conditions are maintained.

Figure 11-12. Effect of weight.

Total range is dependent on both fuel available and specific range. When range and economy of operation are the principal goals, the pilot must ensure that the aircraft is operated at the 11-10 The variations of speed and power required must be specific fuel consumption for values of brake horsepower monitored by the pilot as part of the cruise control procedure below the maximum cruise power rating of the engine that to maintain the L/D . When the aircraft’s fuel weight is a is the lean range of engine operation. Thus, an increase in MAX small part of the gross weight and the aircraft’s range is small, altitude produces a decrease in specific range only when the the cruise control procedure can be simplified to essentially increased power requirement exceeds the maximum cruise maintaining a constant speed and power setting throughout power rating of the engine. One advantage of supercharging the time of cruise flight. However, a long-range aircraft has a is that the cruise power may be maintained at high altitude, fuel weight that is a considerable part of the gross weight, and and the aircraft may achieve the range at high altitude with cruise control procedures must employ scheduled airspeed the corresponding increase in TAS. The principal differences and power changes to maintain optimum range conditions. in the high altitude cruise and low altitude cruise are the TAS and climb fuel requirements.

The effect of altitude on the range of a propeller-driven Region of Reversed Command aircraft is illustrated in Figure 11-13. A flight conducted at high altitude has a greater true airspeed (TAS), and the power The aerodynamic properties of an aircraft generally determine required is proportionately greater than when conducted at the power requirements at various conditions of flight, while sea level. The drag of the aircraft at altitude is the same as the the powerplant capabilities generally determine the power drag at sea level, but the higher TAS causes a proportionately available at various conditions of flight. When an aircraft greater power required.

is in steady, level flight, a condition of equilibrium must prevail. An unaccelerated condition of flight is achieved NOTE: The straight line that is tangent to the sea level power when lift equals weight, and the powerplant is set for thrust curve is also tangent to the altitude power curve. equal to drag. The power required to achieve equilibrium in constant-altitude flight at various airspeeds is depicted on a The effect of altitude on specific range can also be appreciated power required curve. The power required curve illustrates from the previous relationships. If a change in altitude causes the fact that at low airspeeds near the stall or minimum identical changes in speed and power required, the proportion controllable airspeed, the power setting required for steady, of speed to power required would be unchanged. The fact level flight is quite high.

implies that the specific range of a propeller-driven aircraft would be unaffected by altitude. Actually, this is true to the Flight in the region of normal command means that while extent that specific fuel consumption and propeller efficiency holding a constant altitude, a higher airspeed requires a higher are the principal factors that could cause a variation of power setting and a lower airspeed requires a lower power specific range with altitude. If compressibility effects are setting. The majority of aircraft flying (climb, cruise, and negligible, any variation of specific range with altitude is maneuvers) is conducted in the region of normal command.

strictly a function of engine/propeller performance.

Flight in the region of reversed command means flight in An aircraft equipped with a reciprocating engine experiences which a higher airspeed requires a lower power setting very little, if any, variation of specific range up to its and a lower airspeed requires a higher power setting to absolute altitude. There is negligible variation of brake hold altitude. It does not imply that a decrease in power produces lower airspeed. The region of reversed command is encountered in the low speed phases of flight. Flight speeds below the speed for maximum endurance (lowest point e d u on the power curve) require higher power settings with a t l i t l e v a t e decrease in airspeed. Since the need to increase the required l A a e power setting with decreased speed is contrary to the normal S command of flight, the regime of flight speeds between the speed for minimum required power setting and the stall speed (or minimum control speed) is termed the region of reversed Power required command. In the region of reversed command, a decrease in airspeed must be accompanied by an increased power setting Constant weight in order to maintain steady flight.

L/D MAX Figure 11-14 shows the maximum power available as a Speed curved line. Lower power settings, such as cruise power, would also appear in a similar curve. The lowest point on Figure 11-13. Effect of altitude on range.

11-11 Takeoff and landing performance is a condition of accelerated and decelerated motion. For instance, during takeoff an aircraft starts at zero speed and accelerates to M a x i m u m p o w e r a v a i l a the takeoff speed to become airborne. During landing, the b l e aircraft touches down at the landing speed and decelerates Region of d to zero speed. The important factors of takeoff or landing e Excess power reversed r i u command q performance are: e r r e w • The takeoff or landing speed is generally a function o P Power setting of the stall speed or minimum flying speed.

• The rate of acceleration/deceleration during the takeoff or landing roll. The speed (acceleration and Best endurance speed deceleration) experienced by any object varies directly with the imbalance of force and inversely with the Speed mass of the object. An airplane on the runway moving at 75 knots has four times the energy it has traveling Figure 11-14. Power required curve.

at 37 knots. Thus, an airplane requires four times as much distance to stop as required at half the speed.

the power required curve represents the speed at which the • The takeoff or landing roll distance is a function of lowest brake horsepower sustains level flight. This is termed both acceleration/deceleration and speed.

the best endurance airspeed.

Runway Surface and Gradient An airplane performing a low airspeed, high pitch attitude Runway conditions affect takeoff and landing performance.

power approach for a short-field landing is an example Typically, performance chart information assumes paved, of operating in the region of reversed command. If an level, smooth, and dry runway surfaces. Since no two unacceptably high sink rate should develop, it may be runways are alike, the runway surface differs from one possible for the pilot to reduce or stop the descent by applying runway to another, as does the runway gradient or slope.

power. But without further use of power, the airplane would [Figure 11-15] probably stall or be incapable of flaring for the landing.

Merely lowering the nose of the airplane to regain flying Runway surfaces vary widely from one airport to another.

speed in this situation, without the use of power, would The runway surface encountered may be concrete, asphalt, result in a rapid sink rate and corresponding loss of altitude.

gravel, dirt, or grass. The runway surface for a specific airport is noted in the Chart Supplement U.S. (formerly If during a soft-field takeoff and climb, for example, the pilot Airport/Facility Directory). Any surface that is not hard attempts to climb out of ground effect without first attaining and smooth increases the ground roll during takeoff. This normal climb pitch attitude and airspeed, the airplane may is due to the inability of the tires to roll smoothly along the inadvertently enter the region of reversed command at a runway. Tires can sink into soft, grassy, or muddy runways.

dangerously low altitude. Even with full power, the airplane Potholes or other ruts in the pavement can be the cause of may be incapable of climbing or even maintaining altitude.

poor tire movement along the runway. Obstructions such The pilot’s only recourse in this situation is to lower the pitch as mud, snow, or standing water reduce the airplane’s attitude in order to increase airspeed, which inevitably results acceleration down the runway. Although muddy and wet in a loss of altitude.

surface conditions can reduce friction between the runway and the tires, they can also act as obstructions and reduce Airplane pilots must give particular attention to precise the landing distance. [Figure 11-16] Braking effectiveness control of airspeed when operating in the low flight speeds is another consideration when dealing with various runway of the region of reversed command.

types. The condition of the surface affects the braking ability of the aircraft.

Takeoff and Landing Performance The majority of pilot-caused aircraft accidents occur during The amount of power that is applied to the brakes without the takeoff and landing phase of flight. Because of this fact, skidding the tires is referred to as braking effectiveness.

the pilot must be familiar with all the variables that influence Ensure that runways are adequate in length for takeoff the takeoff and landing performance of an aircraft and must acceleration and landing deceleration when less than ideal strive for exacting, professional procedures of operation surface conditions are being reported.

during these phases of flight.

11-12 Figure 11-15. Takeoff distance chart.

The gradient or slope of the runway is the amount of change Water on the Runway and Dynamic Hydroplaning in runway height over the length of the runway. The gradient Water on the runways reduces the friction between the tires is expressed as a percentage, such as a 3 percent gradient. This and the ground and can reduce braking effectiveness. The means that for every 100 feet of runway length, the runway ability to brake can be completely lost when the tires are height changes by 3 feet. A positive gradient indicates the hydroplaning because a layer of water separates the tires from runway height increases, and a negative gradient indicates the the runway surface. This is also true of braking effectiveness runway decreases in height. An upsloping runway impedes when runways are covered in ice.

acceleration and results in a longer ground run during takeoff.

However, landing on an upsloping runway typically reduces When the runway is wet, the pilot may be confronted with the landing roll. A downsloping runway aids in acceleration dynamic hydroplaning. Dynamic hydroplaning is a condition on takeoff resulting in shorter takeoff distances. The opposite in which the aircraft tires ride on a thin sheet of water rather is true when landing, as landing on a downsloping runway than on the runway’s surface. Because hydroplaning wheels increases landing distances. Runway slope information is are not touching the runway, braking and directional control contained in the Chart Supplement U.S. (formerly Airport/ are almost nil. To help minimize dynamic hydroplaning, Facility Directory). [Figure 11-17] some runways are grooved to help drain off water; most runways are not.

Figure 11-16. An aircraft’s performance during takeoff depends greatly on the runway surface.

11-13 Runway surface Airport name Runway slope and direction of slope Runway Figure 11-17. Chart Supplement U.S. (formerly Airport/Facility Directory) information.

Tire pressure is a factor in dynamic hydroplaning. Using well before landing and be prepared for hydroplaning. Opt for the simple formula in Figure 11-18, a pilot can calculate a suitable runway most aligned with the wind. Mechanical the minimum speed, in knots, at which hydroplaning begins. braking may be ineffective, so aerodynamic braking should In plain language, the minimum hydroplaning speed is be used to its fullest advantage.

determined by multiplying the square root of the main gear tire pressure in psi by nine. For example, if the main gear tire Takeoff Performance pressure is at 36 psi, the aircraft would begin hydroplaning The minimum takeoff distance is of primary interest in at 54 knots.

the operation of any aircraft because it defines the runway requirements. The minimum takeoff distance is obtained by Landing at higher than recommended touchdown speeds taking off at some minimum safe speed that allows sufficient exposes the aircraft to a greater potential for hydroplaning. margin above stall and provides satisfactory control and And once hydroplaning starts, it can continue well below the initial ROC. Generally, the lift-off speed is some fixed minimum initial hydroplaning speed. percentage of the stall speed or minimum control speed for the aircraft in the takeoff configuration. As such, the lift-off is On wet runways, directional control can be maximized accomplished at some particular value of lift coefficient and by landing into the wind. Abrupt control inputs should be AOA. Depending on the aircraft characteristics, the lift-off avoided. When the runway is wet, anticipate braking problems speed is anywhere from 1.05 to 1.25 times the stall speed or minimum control speed.

Minimum dynamic hydroplaning speed (rounded off) = To obtain minimum takeoff distance at the specific lift-off speed, the forces that act on the aircraft must provide the maximum acceleration during the takeoff roll. The various forces acting on the aircraft may or may not be under the control of the pilot, and various procedures may be necessary 9 x Tire pressure (in psi) in certain aircraft to maintain takeoff acceleration at the highest value.

The powerplant thrust is the principal force to provide the acceleration and, for minimum takeoff distance, the output 36 = 6 thrust should be at a maximum. Lift and drag are produced 9 x 6 = 54 knots as soon as the aircraft has speed, and the values of lift and drag depend on the AOA and dynamic pressure.

Figure 11-18. Tire pressure.

11-14 As discussed in Chapter 6, engine pressure ratio (EPR) is the ratio, the increase in takeoff distance would be approximately ratio between exhaust pressure (jet blast) and inlet (static) 25 to 30 percent. Such a powerful effect requires proper pressure on a turbo jet or turbo fan engine. An EPR gauge consideration of gross weight in predicting takeoff distance.

tells the pilot how much power the engines are generating.

The higher the EPR, the higher the engine thrust. EPR is The effect of wind on takeoff distance is large, and proper used to avoid over-boosting an engine and to set takeoff and consideration must also be provided when predicting takeoff go around power if needed. This information is important to distance. The effect of a headwind is to allow the aircraft to know before taking off as it helps determine the performance reach the lift-off speed at a lower groundspeed, while the of the aircraft. effect of a tailwind is to require the aircraft to achieve a greater groundspeed to attain the lift-off speed.

In addition to the important factors of proper procedures, many other variables affect the takeoff performance of an A headwind that is 10 percent of the takeoff airspeed reduces aircraft. Any item that alters the takeoff speed or acceleration the takeoff distance approximately 19 percent. However, a rate during the takeoff roll affects the takeoff distance. tailwind that is 10 percent of the takeoff airspeed increases the takeoff distance approximately 21 percent. In the case For example, the effect of gross weight on takeoff distance where the headwind speed is 50 percent of the takeoff speed, is significant, and proper consideration of this item must be the takeoff distance would be approximately 25 percent of made in predicting the aircraft’s takeoff distance. Increased the zero wind takeoff distance (75 percent reduction).

gross weight can be considered to produce a threefold effect on takeoff performance: The effect of wind on landing distance is identical to its effect on takeoff distance. Figure 11-19 illustrates the general 1. Higher lift-off speed effect of wind by the percent change in takeoff or landing 2. Greater mass to accelerate distance as a function of the ratio of wind velocity to takeoff or landing speed.

3. Increased retarding force (drag and ground friction) The effect of proper takeoff speed is especially important If the gross weight increases, a greater speed is necessary to when runway lengths and takeoff distances are critical. The produce the greater lift necessary to get the aircraft airborne takeoff speeds specified in the AFM/POH are generally at the takeoff lift coefficient. As an example of the effect of the minimum safe speeds at which the aircraft can become a change in gross weight, a 21 percent increase in takeoff airborne. Any attempt to take off below the recommended weight requires a 10 percent increase in lift-off speed to speed means that the aircraft could stall, be difficult to support the greater weight.

control, or have a very low initial ROC. In some cases, an A change in gross weight changes the net accelerating force and changes the mass that is being accelerated. If the aircraft has a relatively high thrust-to-weight ratio, the change in the net accelerating force is slight and the principal effect on Percent increase acceleration is due to the change in mass.

in takeoff or Reference line landing distance For example, a 10 percent increase in takeoff gross weight would cause: Ratio of wind velocity to takeoff • A 5 percent increase in takeoff velocity or landing speed • At least a 9 percent decrease in rate of acceleration 10 Tailwind 30 % 20 % 10 % • At least a 21 percent increase in takeoff distance 10 % 20 % 30 % Headwind Ratio of wind With ISA conditions, increasing the takeoff weight of the velocity to takeoff or landing speed average Cessna 182 from 2,400 pounds to 2,700 pounds (11 percent increase) results in an increased takeoff distance from 440 feet to 575 feet (23 percent increase).

Percent decrease in takeoff or landing distance For the aircraft with a high thrust-to-weight ratio, the increase 60 in takeoff distance might be approximately 21 to 22 percent, Figure 11-19. Effect of wind on takeoff and landing.

but for the aircraft with a relatively low thrust-to-weight 11-15 excessive AOA may not allow the aircraft to climb out of In the prediction of takeoff distance from the AFM/POH ground effect. On the other hand, an excessive airspeed at data, the following primary considerations must be given: takeoff may improve the initial ROC and “feel” of the aircraft • Pressure altitude and temperature—to define the effect but produces an undesirable increase in takeoff distance.

of density altitude on distance Assuming that the acceleration is essentially unaffected, the • Gross weight—a large effect on distance takeoff distance varies with the square of the takeoff velocity.

• Wind—a large effect due to the wind or wind Thus, ten percent excess airspeed would increase the takeoff component along the runway distance 21 percent. In most critical takeoff conditions, such • Runway slope and condition—the effect of an incline an increase in takeoff distance would be prohibitive, and the and retarding effect of factors such as snow or ice pilot must adhere to the recommended takeoff speeds.

Landing Performance The effect of pressure altitude and ambient temperature In many cases, the landing distance of an aircraft defines the is to define the density altitude and its effect on takeoff runway requirements for flight operations. The minimum performance. While subsequent corrections are appropriate landing distance is obtained by landing at some minimum safe for the effect of temperature on certain items of powerplant speed, that allows sufficient margin above stall and provides performance, density altitude defines specific effects on satisfactory control and capability for a go-around. Generally, takeoff performance. An increase in density altitude can the landing speed is some fixed percentage of the stall speed produce a twofold effect on takeoff performance: or minimum control speed for the aircraft in the landing 1. Greater takeoff speed configuration. As such, the landing is accomplished at some particular value of lift coefficient and AOA. The exact values 2. Decreased thrust and reduced net accelerating force depend on the aircraft characteristics but, once defined, the values are independent of weight, altitude, and wind.

If an aircraft of given weight and configuration is operated at greater heights above standard sea level, the aircraft requires To obtain minimum landing distance at the specified landing the same dynamic pressure to become airborne at the takeoff speed, the forces that act on the aircraft must provide lift coefficient. Thus, the aircraft at altitude takes off at the maximum deceleration during the landing roll. The forces same indicated airspeed (IAS) as at sea level, but because of acting on the aircraft during the landing roll may require the reduced air density, the TAS is greater.

various procedures to maintain landing deceleration at the peak value.

The effect of density altitude on powerplant thrust depends much on the type of powerplant. An increase in altitude A distinction should be made between the procedures for above standard sea level brings an immediate decrease in minimum landing distance and an ordinary landing roll power output for the unsupercharged reciprocating engine.

with considerable excess runway available. Minimum However, an increase in altitude above standard sea level does landing distance is obtained by creating a continuous peak not cause a decrease in power output for the supercharged deceleration of the aircraft; that is, extensive use of the brakes reciprocating engine until the altitude exceeds the critical for maximum deceleration. On the other hand, an ordinary operating altitude. For those powerplants that experience landing roll with considerable excess runway may allow a decay in thrust with an increase in altitude, the effect extensive use of aerodynamic drag to minimize wear and tear on the net accelerating force and acceleration rate can be on the tires and brakes. If aerodynamic drag is sufficient to approximated by assuming a direct variation with density.

cause deceleration, it can be used in deference to the brakes Actually, this assumed variation would closely approximate in the early stages of the landing roll (i.e., brakes and tires the effect on aircraft with high thrust-to-weight ratios.

suffer from continuous hard use, but aircraft aerodynamic drag is free and does not wear out with use). The use of Proper accounting of pressure altitude and temperature is aerodynamic drag is applicable only for deceleration to 60 mandatory for accurate prediction of takeoff roll distance.

or 70 percent of the touchdown speed. At speeds less than The most critical conditions of takeoff performance are the 60 to 70 percent of the touchdown speed, aerodynamic drag result of some combination of high gross weight, altitude, is so slight as to be of little use, and braking must be utilized temperature, and unfavorable wind. In all cases, the pilot to produce continued deceleration. Since the objective during must make an accurate prediction of takeoff distance from the landing roll is to decelerate, the powerplant thrust should the performance data of the AFM/POH, regardless of the be the smallest possible positive value (or largest possible runway available, and strive for a polished, professional negative value in the case of thrust reversers).

takeoff procedure.

11-16 In addition to the important factors of proper procedures, approximately three and one-half percent for each 1,000 feet many other variables affect the landing performance. Any of altitude. Proper accounting of density altitude is necessary item that alters the landing speed or deceleration rate during to accurately predict landing distance.

the landing roll affects the landing distance.

The effect of proper landing speed is important when runway The effect of gross weight on landing distance is one of the lengths and landing distances are critical. The landing speeds principal items determining the landing distance. One effect specified in the AFM/POH are generally the minimum safe of an increased gross weight is that a greater speed is required speeds at which the aircraft can be landed. Any attempt to to support the aircraft at the landing AOA and lift coefficient. land at below the specified speed may mean that the aircraft For an example of the effect of a change in gross weight, a may stall, be difficult to control, or develop high rates of 21 percent increase in landing weight requires a ten percent descent. On the other hand, an excessive speed at landing may increase in landing speed to support the greater weight. improve the controllability slightly (especially in crosswinds) but causes an undesirable increase in landing distance.

When minimum landing distances are considered, braking friction forces predominate during the landing roll and, for A ten percent excess landing speed causes at least a 21 the majority of aircraft configurations, braking friction is the percent increase in landing distance. The excess speed main source of deceleration. places a greater working load on the brakes because of the additional kinetic energy to be dissipated. Also, the additional The minimum landing distance varies in direct proportion speed causes increased drag and lift in the normal ground to the gross weight. For example, a ten percent increase in attitude, and the increased lift reduces the normal force on gross weight at landing would cause a: the braking surfaces. The deceleration during this range of speed immediately after touchdown may suffer, and it is more • Five percent increase in landing velocity probable for a tire to be blown out from braking at this point.

• Ten percent increase in landing distance The most critical conditions of landing performance are A contingency of this is the relationship between weight and combinations of high gross weight, high density altitude, braking friction force.

and unfavorable wind. These conditions produce the greatest required landing distances and critical levels of energy The effect of wind on landing distance is large and deserves dissipation on the brakes. In all cases, it is necessary to proper consideration when predicting landing distance. Since make an accurate prediction of minimum landing distance to the aircraft lands at a particular airspeed independent of the compare with the available runway. A polished, professional wind, the principal effect of wind on landing distance is landing procedure is necessary because the landing phase of the change in the groundspeed at which the aircraft touches flight accounts for more pilot-caused aircraft accidents than down. The effect of wind on deceleration during the landing any other single phase of flight.

is identical to the effect on acceleration during the takeoff.

In the prediction of minimum landing distance from the The effect of pressure altitude and ambient temperature is to AFM/POH data, the following considerations must be given: define density altitude and its effect on landing performance.

• Pressure altitude and temperature—to define the effect An increase in density altitude increases the landing speed of density altitude but does not alter the net retarding force. Thus, the aircraft at altitude lands at the same IAS as at sea level but, because • Gross weight—which defines the CAS for landing of the reduced density, the TAS is greater. Since the aircraft • Wind—a large effect due to wind or wind component lands at altitude with the same weight and dynamic pressure, along the runway the drag and braking friction throughout the landing roll have • Runway slope and condition—relatively small the same values as at sea level. As long as the condition is correction for ordinary values of runway slope, but a within the capability of the brakes, the net retarding force significant effect of snow, ice, or soft ground is unchanged, and the deceleration is the same as with the landing at sea level. Since an increase in altitude does not A tail wind of ten knots increases the landing distance by alter deceleration, the effect of density altitude on landing about 21 percent. An increase of landing speed by ten percent distance is due to the greater TAS.

increases the landing distance by 20 percent. Hydroplaning makes braking ineffective until a decrease of speed that can The minimum landing distance at 5,000 feet is 16 percent be determined by using Figure 11-18 .

greater than the minimum landing distance at sea level. The approximate increase in landing distance with altitude is 11-17 For instance, a pilot is downwind for runway 18, and the Performance Speeds tower asks if runway 27 could be accepted. There is a light True airspeed (TAS)—the speed of the aircraft in relation to rain and the winds are out of the east at ten knots. The pilot the air mass in which it is flying.

accepts because he or she is approaching the extended centerline of runway 27. The turn is tight and the pilot must Indicated airspeed (IAS)—the speed of the aircraft as descend (dive) to get to runway 27. After becoming aligned observed on the ASI. It is the airspeed without correction for with the runway and at 50 feet AGL, the pilot is already 1,000 indicator, position (or installation), or compressibility errors.

feet down the 3,500 feet runway. The airspeed is still high by about ten percent (should be at 70 knots and is at about Calibrated airspeed (CAS)—the ASI reading corrected for 80 knots). The wind of ten knots is blowing from behind.

position (or installation) and instrument errors. (CAS is equal to TAS at sea level in standard atmosphere.) The color First, the airspeed being high by about ten percent (80 knots coding for various design speeds marked on ASIs may be versus 70 knots), as presented in the performance chapter, IAS or CAS.

results in a 20 percent increase in the landing distance.

In performance planning, the pilot determined that at 70 Equivalent airspeed (EAS)—the ASI reading corrected knots the distance would be 1,600 feet. However, now it for position (or installation), for instrument error, and for is increased by 20 percent and the required distance is now adiabatic compressible flow for the particular altitude. (EAS 1,920 feet.

is equal to CAS at sea level in standard atmosphere.)

The newly revised landing distance of 1,920 feet is also V —the calibrated power-off stalling speed or the minimum S0 affected by the wind. In looking at Figure 11-19 , the affect steady flight speed at which the aircraft is controllable in the of the wind is an additional 20 percent for every ten miles landing configuration.

per hour (mph) in wind. This is computed not on the original estimate but on the estimate based upon the increased V —the calibrated power-off stalling speed or the minimum S1 airspeed. Now the landing distance is increased by another steady flight speed at which the aircraft is controllable in a 320 feet for a total requirement of 2,240 feet to land the specified configuration.

airplane after reaching 50 feet AGL.

V —the speed at which the aircraft obtains the maximum Y That is the original estimate of 1,600 under planned conditions increase in altitude per unit of time. This best ROC speed plus the additional 640 feet for excess speed and the tailwind.

normally decreases slightly with altitude.

Given the pilot overshot the threshhold by 1,000 feet, the total length required is 3,240 on a 3,500 foot runway; 260 V —the speed at which the aircraft obtains the highest X feet to spare. But this is in a perfect environment. Most pilots altitude in a given horizontal distance. This best AOC speed become fearful as the end of the runway is facing them just normally increases slightly with altitude.

ahead. A typical pilot reaction is to brake—and brake hard.

Because the aircraft does not have antilock braking features V —the maximum speed at which the aircraft can be safely LE like a car, the brakes lock, and the aircraft hydroplanes on flown with the landing gear extended. This is a problem the wet surface of the runway until decreasing to a speed of involving stability and controllability.

about 54 knots (the square root of the tire pressure ( √ 36) × 9). Braking is ineffective when hydroplaning.

V —the maximum speed at which the landing gear can LO be safely extended or retracted. This is a problem involving The 260 feet that a pilot might feel is left over has long since the air loads imposed on the operating mechanism during evaporated as the aircraft hydroplaned the first 300–500 feet extension or retraction of the gear.

when the brakes locked. This is an example of a true story, but one which only changes from year to year because of new V —the highest speed permissible with the wing flaps in a FE participants and aircraft with different N-numbers.

prescribed extended position. This is because of the air loads imposed on the structure of the flaps.

In this example, the pilot actually made many bad decisions.

Bad decisions, when combined, have a synergy greater V —the calibrated design maneuvering airspeed. This is A than the individual errors. Therefore, the corrective the maximum speed at which the limit load can be imposed actions become larger and larger until correction is almost (either by gusts or full deflection of the control surfaces) impossible. Aeronautical decision-making is discussed more without causing structural damage. Operating at or below fully in Chapter 2, Aeronautical Decision-Making (ADM).

11-18 maneuvering speed does not provide structural protection Each aircraft performs differently and, therefore, has different against multiple full control inputs in one axis or full control performance numbers. Compute the performance of the inputs in more than one axis at the same time. aircraft prior to every flight, as every flight is different. (See appendix for examples of performance charts for a Cessna V —the maximum speed for normal operation or the Model 172R and Challenger 605.)

N0 maximum structural cruising speed. This is the speed at which exceeding the limit load factor may cause permanent Every chart is based on certain conditions and contains deformation of the aircraft structure. notes on how to adapt the information for flight conditions.

It is important to read every chart and understand how to V —the speed that should never be exceeded. If flight is use it. Read the instructions provided by the manufacturer.

NE attempted above this speed, structural damage or structural For an explanation on how to use the charts, refer to the failure may result. example provided by the manufacturer for that specific chart.

[Figure 11-20] Performance Charts The information manufacturers furnish is not standardized.

Performance charts allow a pilot to predict the takeoff, climb, Information may be contained in a table format and cruise, and landing performance of an aircraft. These charts, other information may be contained in a graph format.

provided by the manufacturer, are included in the AFM/POH.

Sometimes combined graphs incorporate two or more graphs Information the manufacturer provides on these charts has into one chart to compensate for multiple conditions of been gathered from test flights conducted in a new aircraft, flight. Combined graphs allow the pilot to predict aircraft under normal operating conditions while using average performance for variations in density altitude, weight, piloting skills, and with the aircraft and engine in good and winds all on one chart. Because of the vast amount of working order. Engineers record the flight data and create information that can be extracted from this type of chart, it performance charts based on the behavior of the aircraft is important to be very accurate in reading the chart. A small during the test flights. By using these performance charts, error in the beginning can lead to a large error at the end.

a pilot can determine the runway length needed to take off and land, the amount of fuel to be used during flight, and the The remainder of this section covers performance information time required to arrive at the destination. It is important to for aircraft in general and discusses what information the remember that the data from the charts will not be accurate charts contain and how to extract information from the charts if the aircraft is not in good working order or when operating by direct reading and interpolation methods. Every chart under adverse conditions. Always consider the necessity to contains a wealth of information that should be used when compensate for the performance numbers if the aircraft is not flight planning. Examples of the table, graph, and combined in good working order or piloting skills are below average.

graph formats for all aspects of flight are discussed.

, , , Figure 11-20. Conditions notes chart.

11-19 Interpolation and read the approximate density altitude. The approximate density altitude in thousands of feet is 7,700 feet.

Not all of the information on the charts is easily extracted.

Some charts require interpolation to find the information for Takeoff Charts specific flight conditions. Interpolating information means Takeoff charts are typically provided in several forms and that by taking the known information, a pilot can compute allow a pilot to compute the takeoff distance of the aircraft intermediate information. However, pilots sometimes round with no flaps or with a specific flap configuration. A pilot can off values from charts to a more conservative figure.

also compute distances for a no flap takeoff over a 50 foot obstacle scenario, as well as with flaps over a 50 foot obstacle.

Using values that reflect slightly more adverse conditions The takeoff distance chart provides for various aircraft provides a reasonable estimate of performance information weights, altitudes, temperatures, winds, and obstacle heights.

and gives a slight margin of safety. The following illustration is an example of interpolating information from a takeoff Sample Problem 2 distance chart. [Figure 11-21] Pressure Altitude...............................................2,000 feet Density Altitude Charts OAT..........................................................................22 °C Use a density altitude chart to figure the density altitude at the Takeoff Weight.............................................2,600 pounds departing airport. Using Figure 11-22 , determine the density altitude based on the given information.

Headwind...............................................................6 knots Obstacle Height.......................................50 foot obstacle Sample Problem 1 Airport Elevation...............................................5,883 feet Refer to Figure 11-23 . This chart is an example of a combined OAT...........................................................................70 °F takeoff distance graph. It takes into consideration pressure altitude, temperature, weight, wind, and obstacles all on one Altimeter...........................................................30 .10 "Hg chart. First, find the correct temperature on the bottom left side of the graph. Follow the line from 22 °C straight up until First, compute the pressure altitude conversion. Find 30.10 it intersects the 2,000 foot altitude line. From that point, draw under the altimeter heading. Read across to the second a line straight across to the first dark reference line. Continue column. It reads “–165.” Therefore, it is necessary to subtract to draw the line from the reference point in a diagonal 165 from the airport elevation giving a pressure altitude of direction following the surrounding lines until it intersects 5,718 feet. Next, locate the outside air temperature on the the corresponding weight line. From the intersection of 2,600 scale along the bottom of the graph. From 70°, draw a line up pounds, draw a line straight across until it reaches the second to the 5,718 feet pressure altitude line, which is about two- reference line. Once again, follow the lines in a diagonal thirds of the way up between the 5,000 and 6,000 foot lines.

manner until it reaches the six knot headwind mark. Follow Draw a line straight across to the far left side of the graph Flaps 10° TAKEOFF DISTANCE ns Full throttle prior to brake release itio MAXIMUM WEIGHT 2,400 LB Paved level runway Zero wind Cond Takeoff 0 °C 10 °C 20 °C 30 °C 40 °C speed KIAS Weight Press ALT Total feet Grnd Total feet Grnd Grnd Total feet Grnd Total feet Grnd Total feet (lb) Lift AT (ft) to clear roll to clear roll roll to clear roll to clear roll to clear off 50 ft 50 ft OBS (ft) 50 ft OBS (ft) (ft) 50 ft OBS (ft) 50 ft OBS (ft) 50 ft OBS 2,400 51 56 S.L. 795 1,460 860 1,570 925 1,685 1,810 1,945 1,065 1,000 875 1,605 940 1,725 1,015 1,860 2,000 2,155 1,170 1,090 2,000 960 1,770 1,035 1,910 1,115 2,060 2,220 2,395 1,290 1,200 3,000 1,055 1,960 1,140 2,120 1,230 2,295 2,480 2,685 1,425 1,325 4,000 1,165 2,185 1,260 2,365 1,355 2,570 2,790 3,030 1,575 1,465 5,000 1,285 2,445 1,390 2,660 1,500 2,895 3,160 3,455 1,745 1,620 6,000 1,425 2,755 1,540 3,015 1,665 3,300 3,620 3,990 1,940 1,800 7,000 1,580 3,140 1,710 3,450 1,850 3,805 4,220 - - - - - - 2,000 8,000 1,755 3,615 1,905 4,015 2,060 4,480 - - - - - - - - - - - To find the takeoff distance for a pressure altitude of 2,500 feet at 20 °C, average the ground roll for 2,000 feet and 3,000 feet.

1,115 + 1,230 = 1,173 feet Figure 11-21. Interpolating charts.

11-20 Sample Problem 3 Pressure Altitude...............................................3,000 feet 14,000 OAT.........................................................................30 °C ("Hg) 13,000 Takeoff Weight............................................2,400 pounds Altimeter setting 13 Pressure altitude conversion factor Headwind............................................................18 knots 12,000 28.0 1,824 28.1 1,727 Refer to Figure 11-24 . This chart is an example of a takeoff 11,000 28.2 1,630 distance table for short-field takeoffs. For this table, first find 28.3 1,533 the takeoff weight. Once at 2,400 pounds, begin reading from 10,000 28.4 1,436 left to right across the table. The takeoff speed is in the second Pressure altitude (feet) Standard temperature 28.5 1,340 column and, in the third column under pressure altitude, find the pressure altitude of 3,000 feet. Carefully follow that line 28.6 1,244 9,000 to the right until it is under the correct temperature column 9 28.7 1,148 of 30 °C. The ground roll total reads 1,325 feet and the total 28.8 1,053 8,000 required to clear a 50 foot obstacle is 2,480 feet. At this point, 28.9 957 there is an 18 knot headwind. According to the notes section 29.0 863 7,000 under point number two, decrease the distances by ten percent 29.1 768 for each 9 knots of headwind. With an 18 knot headwind, it 29.2 673 6,000 is necessary to decrease the distance by 20 percent. Multiply 29.3 579 1,325 feet by 20 percent (1,325 × .20 = 265), subtract the 29.4 485 5,000 product from the total distance (1,325 – 265 = 1,060). Repeat 29.5 392 Approximate density altitude (thousand feet) this process for the total distance over a 50 foot obstacle. The 29.6 298 ground roll distance is 1,060 feet and the total distance over 4,000 29.7 205 a 50 foot obstacle is 1,984 feet.

29.8 112 3,000 29.9 20 Climb and Cruise Charts 29.92 0 Climb and cruise chart information is based on actual flight 30.0 −73 2,000 tests conducted in an aircraft of the same type. This information 30.1 −165 is extremely useful when planning a cross-country flight to 30.2 −257 1,000 predict the performance and fuel consumption of the aircraft.

Sea level 30.3 −348 1 Manufacturers produce several different charts for climb and 30.4 −440 cruise performance. These charts include everything from 30.5 −531 –1,000 fuel, time, and distance to climb to best power setting during S.L.

C -18 -12° -7° -1° 4° 10° 16° 21° 27° 32° 38° 30.6 −622 cruise to cruise range performance.

30.7 −712 F 0° 10° 20° 30° 40° 50° 60° 70° 80° 90° 100° 30.8 −803 The first chart to check for climb performance is a fuel, Outside air temperature time, and distance-to-climb chart. This chart gives the fuel amount used during the climb, the time it takes to accomplish Figure 11-22. Density altitude chart.

the climb, and the ground distance that is covered during the climb. To use this chart, obtain the information for straight across to the third reference line and from here, draw the departing airport and for the cruise altitude. Using a line in two directions. First, draw a line straight across to Figure 11-25, calculate the fuel, time, and distance to climb figure the ground roll distance. Next, follow the diagonal lines based on the information provided.

again until they reach the corresponding obstacle height. In this case, it is a 50 foot obstacle. Therefore, draw the diagonal Sample Problem 4 line to the far edge of the chart. This results in a 700 foot Departing Airport Pressure Altitude.................6,000 feet ground roll distance and a total distance of 1,400 feet over a 50 foot obstacle. To find the corresponding takeoff speeds Departing Airport OAT............................................25 °C at lift-off and over the 50 foot obstacle, refer to the table on Cruise Pressure Altitude..................................10,000 feet the top of the chart. In this case, the lift-off speed at 2,600 pounds would be 63 knots and over the 50 foot obstacle Cruise OAT..............................................................10 °C would be 68 knots.

11-21 6,000 Takeoff speed Associated conditions Weight Lift-off 50 ft pounds Power Full throttle 2,600 rpm kts MPH kts MPH 5,000 Mixture Lean to appropriate fuel Guide lines not 2,950 66 76 72 83 pressure applicable for 2,800 64 74 70 81 Flaps Up Intermediate 2,600 63 72 68 78 Landing Retract after positive 4,000 Reference line Reference line Reference line 70 66 76 gear climb established 2,400 61 Tailwind 2,200 58 67 63 73 Cowl Open Obstacle heights flaps 3,000 Headwind 2,000 Pressure altitude - feet ISA 10,000 8,000 1,000 6,000 4,000 2,000 S.L.

C -40° -30° -20° -10° 0° 10° 20° 30° 40° 50° 2,800 2,600 2,400 2,200 0 10 20 30 0 50 Outside air temperature Weight Wind component Obstacle (pounds) (knots) height (feet) F -40° -20° 0° 20° 40° 60° 80° 100° 120° Figure 11-23. Takeoff distance graph.

Flaps 10° TAKEOFF DISTANCE Full throttle prior to brake release MAXIMUM WEIGHT 2,400 LB Paved level runway Zero wind SHORT FIELD Conditions 1. Prior to takeoff from fields above 3,000 feet elevation, the mixture should be leaned to give maximum rpm in a full throttle, static runup.

2. Decrease distances 10% for each 9 knots headwind. For operation with tailwind up to 10 knots, increase distances by 10% for each 2 knots.

3. For operation on a dry, grass runway, increase distances by 15% of the “ground roll” figure.

Notes Takeoff 0 °C 10 °C 20 °C 30 °C 40 °C speed KIAS Press Weight ALT Total feet Total feet Total feet Total feet Total feet Grnd Grnd Grnd Grnd Grnd (lb) (ft) to clear to clear to clear to clear Lift AT to clear roll roll roll roll roll 50 ft OBS 50 ft OBS 50 ft OBS 50 ft OBS off 50 ft 50 ft OBS (ft) (ft) (ft) (ft) (ft) 2,400 S.L. 795 1,460 860 1,570 995 1,810 1,065 1,945 51 56 925 1,685 1,000 875 1,605 940 1,725 1,090 2,000 1,170 2,155 1,015 1,860 960 1,770 1,035 2,000 1,910 1,200 2,220 1,290 2,395 1,115 2,060 1,055 1,960 1,140 3,000 2,120 1,325 2,480 1,425 2,685 1,230 2,295 1,165 2,185 1,260 4,000 2,365 1,465 2,790 1,575 3,030 1,355 2,570 1,285 2,445 5,000 1,390 2,660 1,620 3,160 1,745 3,455 1,500 2,895 1,425 2,755 6,000 1,540 3,015 1,800 3,620 1,940 3,990 1,665 3,300 1,580 3,140 7,000 1,710 3,450 2,000 4,220 - - - - - - 1,850 3,805 1,755 8,000 3,615 1,905 4,015 - - - - - - - - - - - 2,060 4,480 2,200 650 S.L. 1,195 700 1,280 805 1,470 865 1,575 49 54 750 1,375 1,000 710 1,310 765 1,405 885 1,615 950 1,735 825 1,510 2,000 780 1,440 840 1,545 975 1,785 1,045 1,915 905 1,660 3,000 855 1,585 925 1,705 1,070 1,975 1,150 2,130 995 1,835 4,000 945 1,750 1,020 1,890 1,180 2,200 1,270 2,375 1,100 2,040 5,000 1,040 1,945 1,125 2,105 1,305 2,465 1,405 2,665 1,210 2,275 6,000 1,150 2,170 1,240 2,355 1,445 2,775 1,555 3,020 1,340 2,555 7,000 1,270 2,440 1,375 2,655 1,605 3,155 1,730 3,450 1,485 2,890 8,000 1,410 2,760 1,525 3,015 1,785 3,630 1,925 4,005 1,650 3,305 2,000 S.L. 525 970 565 1,035 650 1,185 695 1,265 46 51 605 1,110 1,000 570 1,060 615 1,135 710 1,295 765 1,385 665 1,215 2,000 625 1,160 675 1,240 780 1,425 840 1,525 725 1,330 3,000 690 1,270 740 1,365 860 1,570 920 1,685 800 1,465 4,000 755 1,400 815 1,500 945 1,735 1,015 1,865 880 1,615 5,000 830 1,545 900 1,660 2,145 1,925 1,120 2,070 970 1,790 6,000 920 1,710 990 1,845 2,405 2,145 1,235 2,315 1,070 1,990 7,000 1,015 1,900 1,095 2,055 2,715 2,405 1,370 2,605 1,180 2,225 8,000 1,125 2,125 1,215 2,305 1,410 2,715 1,520 2,950 1,310 2,500 Figure 11-24. Takeoff distance short field charts.

11-22 t s e 20,000 f e e - s l i L T s e t m A r e l u n u s s a r e n P o c i i l t 18,000 l m u a a - n g - e e - c 16,000 m l i n e T a t u s i F D 14,000 Cruise 12,000 Associated conditions 10,000 Maximum continuous power* 3,600 lb gross weight 8,000 Flaps up 6,000 90 KIAS No wind 4,000 * 2,700 rpm & 36 in M.P. (3-blade prop) 2,000 2,575 rpm & 36 in M.P. (2-blade prop) Departure Sea level -40° -30° -20° -10° 0° 10° 20° 30° 40°C 0 10 20 30 40 50 Outside air temperature Fuel, time and distance to climb Figure 11-25. Fuel, time, and distance climb chart.

First, find the information for the departing airport. Find the To begin, find the given weight of 3,400 in the first column of OAT for the departing airport along the bottom, left side of the the chart. Move across to the pressure altitude column to find graph. Follow the line from 25 °C straight up until it intersects the sea level altitude numbers. At sea level, the numbers read the line corresponding to the pressure altitude of 6,000 feet. zero. Next, read the line that corresponds with the cruising Continue this line straight across until it intersects all three altitude of 8,000 feet. Normally, a pilot would subtract these lines for fuel, time, and distance. Draw a line straight down from the intersection of altitude and fuel, altitude and time, and Flaps up Gear up a third line at altitude and distance. It should read three and 2,500 rpm NORMAL CLIMB 30 "Hg one-half gallons of fuel, 6 minutes of time, and nine NM. Next, 120 PPH fuel flow 110 KIAS Cowl flaps open repeat the steps to find the information for the cruise altitude.

Conditions Standard temperature It should read six gallons of fuel, 10.5 minutes of time, and 1. Add 16 pounds of fuel for engine start, taxi, and takeoff allowance.

15 NM. Take each set of numbers for fuel, time, and distance 2. Increase time, fuel, and distance by 10% for each 7 °C above standard temperature.

and subtract them from one another (6.0 – 3.5 = 2.5 gallons of Notes 3. Distances shown are based on zero wind.

fuel). It takes two and one-half gallons of fuel and 4 minutes From sea level of time to climb to 10,000 feet. During that climb, the distance Press Rate of Weight ALT climb covered is six NM. Remember, according to the notes at the Distance (pounds) Time Fuel used (feet) fpm (nautical (minutes) (pounds) top of the chart, these numbers do not take into account wind, miles) and it is assumed maximum continuous power is being used.

4,000 S.L. 605 0 0 0 4,000 570 7 14 13 8,000 530 14 28 27 12,000 485 22 44 43 The next example is a fuel, time, and distance-to-climb table.

16,000 430 31 62 63 For this table, use the same basic criteria as for the previous 20,000 365 41 82 87 chart. However, it is necessary to figure the information in a 3,700 S.L. 700 0 0 0 4,000 665 6 12 11 different manner. Refer to Figure 11-26 to work the following 8,000 625 12 24 23 12,000 580 19 37 37 sample problem.

16,000 525 26 52 53 20,000 460 34 68 72 Sample Problem 5 S.L. 810 0 0 0 4,000 775 5 10 9 3,400 8,000 735 10 21 20 Departing Airport Pressure Altitude..................Sea level 12,000 690 16 32 31 16,000 635 22 44 45 Departing Airport OAT............................................22 °C 20,000 565 29 57 61 Cruise Pressure Altitude....................................8,000 feet Figure 11-26. Fuel time distance climb.

Takeoff Weight.............................................3,400 pounds 11-23 two sets of numbers from one another, but given the fact that Gross weight—2,300 lb.

the numbers read zero at sea level, it is known that the time Standard conditions Zero wind to climb from sea level to 8,000 feet is 10 minutes. It is also Lean mixture Conditions known that 21 pounds of fuel is used and 20 NM is covered Maximum cruise is normally limited to 75% power.

during the climb. However, the temperature is 22 °C, which is Notes 7° above the standard temperature of 15 °C. The notes section 38 gal 48 gal of this chart indicate that the findings must be increased by ten ALT GAL/ % TAS (no reserve) (no reserve) RPM Hour BHP MPH percent for each 7° above standard. Multiply the findings by Endr. Range Endr. Range hours miles hours miles ten percent or .10 (10 × .10 = 1, 1 + 10 = 11 minutes). After 2,500 9.7 3.9 525 4.9 660 86 134 2,700 8.6 4.4 570 5.6 720 79 129 2,600 accounting for the additional ten percent, the findings should 7.8 4.9 600 6.2 760 72 123 2,500 read 11 minutes, 23.1 pounds of fuel, and 22 NM. Notice that 7.2 5.3 620 6.7 780 65 117 2,400 6.7 5.7 630 7.2 795 58 111 2,300 the fuel is reported in pounds of fuel, not gallons. Aviation 6.3 6.1 625 7.7 790 52 103 2,200 fuel weighs six pounds per gallon, so 23.1 pounds of fuel is 5,000 9.0 4.2 565 5.3 710 82 134 2,700 8.1 4.7 600 5.9 760 75 128 2,600 equal to 3.85 gallons of fuel (23.1 ÷ 6 = 3.85).

7.4 5.1 625 6.4 790 68 122 2,500 6.9 5.5 635 6.9 805 61 116 2,400 6.5 5.9 635 7.4 805 55 108 2,300 The next example is a cruise and range performance chart.

6.0 6.3 630 7.9 795 49 100 2,200 This type of table is designed to give TAS, fuel consumption, 7,500 8.4 4.5 600 5.7 755 78 133 2,700 7.7 4.9 625 6.2 790 71 127 2,600 endurance in hours, and range in miles at specific cruise 7.1 5.3 645 6.7 810 64 121 2,500 6.7 5.7 645 7.2 820 58 113 2,400 configurations. Use Figure 11-27 to determine the cruise and 6.2 6.1 640 7.7 810 52 105 2,300 range performance under the given conditions.

10,000 7.6 5.0 640 6.3 810 70 129 2,650 7.3 5.2 650 6.5 820 67 125 2,600 6.9 5.5 655 7.0 830 61 118 2,500 Sample Problem 6 6.4 5.9 650 7.5 825 55 110 2,400 6.0 6.3 635 8.0 800 49 100 2,300 Pressure Altitude...............................................5,000 feet Figure 11-27. Cruise and range performance.

RPM..................................................................2,400 rpm Fuel Carrying Capacity..................38 gallons, no reserve Another type of cruise chart is a best power mixture range graph. This graph gives the best range based on power Find 5,000 feet pressure altitude in the first column on the setting and altitude. Using Figure 11-29, find the range at left side of the table. Next, find the correct rpm of 2,400 65 percent power with and without a reserve based on the in the second column. Follow that line straight across and provided conditions.

read the TAS of 116 mph and a fuel burn rate of 6.9 gallons per hour. As per the example, the aircraft is equipped with Sample Problem 8 a fuel carrying capacity of 38 gallons. Under this column, OAT....................................................................Standard read that the endurance in hours is 5.5 hours and the range in miles is 635 miles.

Pressure Altitude...............................................5,000 feet Cruise power setting tables are useful when planning cross- First, move up the left side of the graph to 5,000 feet and country flights. The table gives the correct cruise power standard temperature. Follow the line straight across the settings, as well as the fuel flow and airspeed performance graph until it intersects the 65 percent line under both the numbers at that altitude and airspeed.

reserve and no reserve categories. Draw a line straight down from both intersections to the bottom of the graph. At 65 Sample Problem 7 percent power with a reserve, the range is approximately 522 miles. At 65 percent power with no reserve, the range Pressure Altitude at Cruise................................6,000 feet should be 581 miles.

OAT..................................................36 °F above standard The last cruise chart referenced is a cruise performance graph.

Refer to Figure 11-28 for this sample problem. First, locate This graph is designed to tell the TAS performance of the the pressure altitude of 6,000 feet on the far left side of the airplane depending on the altitude, temperature, and power table. Follow that line across to the far right side of the table setting. Using Figure 11-30, find the TAS performance based under the 20 °C (or 36 °F) column. At 6,000 feet, the rpm on the given information.

setting of 2,450 will maintain 65 percent continuous power at 21.0 "Hg with a fuel flow rate of 11.5 gallons per hour and airspeed of 161 knots.

11-24 CRUISE POWER SETTING 65% MAXIMUM CONTINUOUS POWER (OR FULL THROTTLE) 2,800 POUNDS ISA –20° (–36 °F) Standard day (ISA) ISA +20° (+36 °F) Fuel Fuel Fuel Engine Man. Engine Man. Engine Man.

IOAT TAS flow per IOAT TAS flow per IOAT TAS flow per Press speed press speed press speed press engine engine engine ALT °F °C PSI GPH kts MPH RPM "HG °F °C PSI GPH kts MPH RPM "HG °F °C PSI GPH kts MPH RPM "HG 27 –3 S.L. 2,450 20.7 6.6 11.5 147 169 2,450 2,450 6.6 6.6 11.5 11.5 63 17 21.2 150 173 99 37 21.8 153 176 19 –7 2,000 2,450 20.4 6.6 11.5 149 171 2,450 2,450 6.6 6.6 11.5 11.5 55 13 21.0 153 176 91 33 21.5 156 180 12 –11 4,000 2,450 20.1 6.6 11.5 152 175 2,450 2,450 6.6 6.6 11.5 11.5 48 9 20.7 156 180 84 29 21.3 159 183 5 –15 6,000 2,450 19.8 6.6 11.5 155 178 2,450 2,450 6.6 6.6 11.5 11.5 41 5 20.4 158 182 79 26 21.0 161 185 –2 –19 8,000 2,450 19.5 6.6 11.5 157 181 2,450 2,450 6.6 6.6 11.5 11.5 36 2 20.2 161 185 72 22 20.8 164 189 –8 –22 10,000 2,450 19.2 6.6 11.5 160 184 2,450 2,450 6.6 6.5 11.5 11.4 28 –2 19.9 163 188 64 18 20.3 166 191 –15 –26 12,000 2,450 18.8 6.4 11.3 162 186 2,450 2,450 6.1 5.9 10.9 10.6 21 –6 18.8 163 188 57 14 18.8 163 188 –22 –30 14,000 2,450 17.4 5.8 10.5 159 183 2,450 2,450 5.6 5.4 10.1 9.8 14 –10 17.4 160 184 50 10 17.4 160 184 –29 –34 16,000 2,450 16.1 5.3 9.7 156 180 2,450 2,450 5.1 4.9 9.4 9.1 7 –14 16.1 156 180 43 6 16.1 155 178 1. Full throttle manifold pressure settings are approximate.

2. Shaded area represents operation with full throttle.

Notes Figure 11-28. Cruise power setting.

Sample Problem 9 65 percent, best power line. This is the solid line, that represents best economy. Draw a line straight down from OAT.........................................................................16 °C this intersection to the bottom of the graph. The TAS at 65 Pressure Altitude...............................................6,000 feet percent best power is 140 knots. However, it is necessary to subtract 8 knots from the speed since there are no wheel Power Setting................................65 percent, best power fairings. This note is listed under the title and conditions.

Wheel Fairings..............................................Not installed The TAS is 132 knots.

Begin by finding the correct OAT on the bottom left side of Crosswind and Headwind Component Chart the graph. Move up that line until it intersects the pressure Every aircraft is tested according to Federal Aviation altitude of 6,000 feet. Draw a line straight across to the Administration (FAA) regulations prior to certification. The aircraft is tested by a pilot with average piloting skills in 14 -13° 45 minutes reserve at 55% 90° crosswinds with a velocity up to 0.2 V or two-tenths No reserve S0 power best economy mixture 12 -9° of the aircraft’s stalling speed with power off, gear down, and flaps down. This means that if the stalling speed of the 10 -5° Power 65% Power 65% Power 55% Power 55% aircraft is 45 knots, it must be capable of landing in a 9-knot, 90° crosswind. The maximum demonstrated crosswind 8 -1° component is published in the AFM/POH. The crosswind and Power 75% Power 75% headwind component chart allows for figuring the headwind 6 3° and crosswind component for any given wind direction and velocity.

Range may be reduced 4 7° by up to 7% if wheel fairings are not installed Notes 11° Sample Problem 10 S.L. 15° 450 500 550 600 500 550 600 650 Wind........................................................140° at 25 knots Range (nautical miles) (Includes distance to climb and descend) Refer to Figure 11-31 to solve this problem. First, determine Associated conditions Add 0.6 NM for each how many degrees difference there is between the runway degree Celsius above Mixture Leaned per section 4 standard temperature and the wind direction. It is known that runway 17 means Weight 2,300 lb.

and subtract 1 NM for each degree Celsius Wings No Notes a direction of 170°; from that subtract the wind direction below standard Fuel 48 gal usable temperature.

of 140°. This gives a 30° angular difference or wind angle.

Wheel Fairings installed Standard Temperature °C Pressure ALT (1,000 feet) Cruise Mid cruise Next, locate the 30° mark and draw a line from there until it intersects the correct wind velocity of 25 knots. From Figure 11-29. Best power mixture range.

11-25 Subtract 8 knots if wheel fairings are not installed.

Notes S 20,000 ta nd Best power 18,000 a r p d te Power 75% Best economy Power 55% Power 65% p o 16,000 pro t) r e m pe de rat 14,000 re ALT (fe u ade p Associated conditions bla l - u Press b r e 12,000 – Weight 3,600 lb. gross weight .

Flaps Up P. – 3- 10,000 . M.P M.

Best power Mixture leaned to 100° N .

I 8,000 N I rich of peak EGT 36 6,000 t Best economy Mixture leaned to peak EGT m at p 4,000 m a 1,650° Max allowable EGT p 75 r Wheel Fairings installed 2,000 5 00 r , Sea level , –40° –30° –20° –10° 0° 10° 20° 30° 40° 100 120 140 160 180 200 Outside air temperature (°C) True airspeed (knots) Figure 11-30. Cruise performance graph.

there, draw a line straight down and a line straight across. usual, read the associated conditions and notes in order to The headwind component is 22 knots and the crosswind ascertain the basis of the chart information. Remember, when component is 13 knots. This information is important when calculating landing distance that the landing weight is not the taking off and landing so that, first of all, the appropriate same as the takeoff weight. The weight must be recalculated runway can be picked if more than one exists at a particular to compensate for the fuel that was used during the flight.

airport, but also so that the aircraft is not pushed beyond its tested limits. Sample Problem 11 Pressure Altitude...............................................1,250 feet Landing Charts Temperature.........................................................Standard Landing performance is affected by variables similar to those affecting takeoff performance. It is necessary to compensate Refer to Figure 10-32 . This example makes use of a landing for differences in density altitude, weight of the airplane, and distance table. Notice that the altitude of 1,250 feet is not headwinds. Like takeoff performance charts, landing distance on this table. It is, therefore, necessary to interpolate to find information is available as normal landing information, the correct landing distance. The pressure altitude of 1,250 as well as landing distance over a 50 foot obstacle. As is halfway between sea level and 2,500 feet. First, find the column for sea level and the column for 2,500 feet. Take the 0° 10° total distance of 1,075 for sea level and the total distance of 20° 1,135 for 2,500 and add them together. Divide the total by 30° 60 two to obtain the distance for 1,250 feet. The distance is 1,105 W i 40° n d feet total landing distance to clear a 50 foot obstacle. Repeat v e l o c i t y 50 this process to obtain the ground roll distance for the pressure 50° altitude. The ground roll should be 457.5 feet.

60° Sample Problem 12 OAT.......................................................................... 57 °F 70° Headwind component Pressure Altitude.............................................. 4,000 feet 80° Landing Weight...........................................2,400 pounds Headwind.............................................................. 6 knots 90° Obstacle Height..................................................... 50 feet 10 20 30 40 50 60 70 Crosswind component Using the given conditions and Figure 11-33, determine the landing distance for the aircraft. This graph is an example of Figure 10-31. Crosswind component chart.

11-26 LANDING DISTANCE Flaps lowered to 40° Power off Hard surface runway Zero wind Conditions At sea level & 59 °F At 2,500 ft & 50 °F At 5,000 ft & 41 °F At 7,500 ft & 32 °F Gross Approach speed weight IAS, MPH Total to clear Total to clear Total to clear Total to clear lb Ground roll Ground roll Ground roll Ground roll 50 ft OBS 50 ft OBS 50 ft OBS 50 ft OBS 1,600 60 445 1,075 470 1,135 495 1,195 520 1,255 1. Decrease the distances shown by 10% for each 4 knots of headwind.

2. Increase the distance by 10% for each 60 °F temperature increase above standard.

Note 3. For operation on a dry, grass runway, increase distances (both “ground roll” and “total to clear 50 ft obstacle”) by 20% of the “total to clear 50 ft obstacle” figure.

Figure 11-32. Landing distance table.

a combined landing distance graph and allows compensation Stall Speed Performance Charts for temperature, weight, headwinds, tailwinds, and varying Stall speed performance charts are designed to give an obstacle height. Begin by finding the correct OAT on the understanding of the speed at which the aircraft stalls in scale on the left side of the chart. Move up in a straight a given configuration. This type of chart typically takes line to the correct pressure altitude of 4,000 feet. From this into account the angle of bank, the position of the gear and intersection, move straight across to the first dark reference flaps, and the throttle position. Use Figure 11-34 and the line. Follow the lines in the same diagonal fashion until the accompanying conditions to find the speed at which the correct landing weight is reached. At 2,400 pounds, continue airplane stalls.

in a straight line across to the second dark reference line.

Once again, draw a line in a diagonal manner to the correct Sample Problem 13 wind component and then straight across to the third dark Power........................................................................ OFF reference line. From this point, draw a line in two separate Flaps....................................................................... Down directions: one straight across to figure the ground roll and one in a diagonal manner to the correct obstacle height. This Gear........................................................................ Down should be 975 feet for the total ground roll and 1,500 feet for Angle of Bank............................................................. 45° the total distance over a 50 foot obstacle.

First, locate the correct flap and gear configuration. The bottom half of the chart should be used since the gear and 3,500 Speed Associated conditions Weight at 50 feet 3,000 (pounds) Power Retarded to maintain kts MPH 900 feet/on final approach Guide lines not Obstacle heights 2,950 70 Flaps Down applicable for Intermediate 2,800 68 78 Landing gear Down 2,500 2,600 65 75 Runway Paved, level, dry surface Reference line Reference line Reference line 2,400 63 72 Approach speed IAS as tabulated 2,200 60 69 Braking Maximum Tailwind 2,000 1,500 Headwind Pressure altitude (feet) 10,000 8,000 6,000 4,000 1,000 2,000 ISA S.L.

C –40° –30° –20° –10° 0° 10° 20° 30° 40° 50° 2,800 2,600 2,400 2,200 0 10 20 30 0 50 Outside air temperature Weight Wind component Obstacle (pounds) (knots) height (feet) F –40° –20° 0° 20° 40° 60° 80° 100° 120° Figure 11-33. Landing distance graph.

11-27 Angle of bank Air Carrier Obstacle Clearance Gross weight Level 30° 45° 60° Requirements 2,750 lb Gear and flaps up For information on air carrier obstacle clearance MPH 62 67 74 88 On knots 54 58 64 76 requirements consult the Instrument Procedures Handbook, MPH 75 81 89 106 Power Off FAA-H-8083-16 (as revised).

knots 65 70 77 92 Gear and flaps down MPH 54 58 64 76 Chapter Summary On knots 47 50 56 66 MPH 66 71 78 93 Performance characteristics and capabilities vary greatly Off Power knots 57 62 68 81 among aircraft. As transport aircraft become more capable and more complex, most operators find themselves having Figure 11-34. Stall speed table.

to rely increasingly on computerized flight mission planning systems. These systems may be on board or used during flaps are down. Next, choose the row corresponding to a the planning phase of the flight. Moreover, aircraft weight, power-off situation. Now, find the correct angle of bank atmospheric conditions, and external environmental factors column, which is 45°. The stall speed is 78 mph, and the can significantly affect aircraft performance. It is essential stall speed in knots would be 68 knots.

that a pilot become intimately familiar with the mission planning programs, performance characteristics, and Performance charts provide valuable information to the pilot.

capabilities of the aircraft being flown, as well as all of the By using these charts, a pilot can predict the performance of onboard computerized systems in today’s complex aircraft.

the aircraft under most flying conditions, providing a better The primary source of this information is the AFM/POH.

plan for every flight. The Code of Federal Regulations (CFR) requires that a pilot be familiar with all information available prior to any flight. Pilots should use the information to their advantage as it can only contribute to safety in flight.

Transport Category Aircraft Performance Transport category aircraft are certificated under Title 14 of the CFR (14 CFR) part 25. For additional information concerning transport category airplanes, consult the Airplane Flying Handbook, FAA-H-8083-3 (as revised).

Transport category helicopters are certificated under 14 CFR part 29.

11-28

Chapter 12

Weather Theory

Introduction Weather is an important factor that influences aircraft performance and flying safety. It is the state of the atmosphere at a given time and place with respect to variables, such as temperature (heat or cold), moisture (wetness or dryness), wind velocity (calm or storm), visibility (clearness or cloudiness), and barometric pressure (high or low). The term “weather” can also apply to adverse or destructive atmospheric conditions, such as high winds.

This chapter explains basic weather theory and offers pilots background knowledge of weather principles. It is designed to help them gain a good understanding of how weather affects daily flying activities. Understanding the theories behind weather helps a pilot make sound weather decisions based on the reports and forecasts obtained from a Flight Service Station (FSS) weather specialist and other aviation weather services.

Be it a local flight or a long cross-country flight, decisions based on weather can dramatically affect the safety of the flight.

12-1 Atmosphere The atmosphere is a blanket of air made up of a mixture of 1% gases that surrounds the Earth and reaches almost 350 miles from the surface of the Earth. This mixture is in constant

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motion. If the atmosphere were visible, it might look like

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an ocean with swirls and eddies, rising and falling air, and waves that travel for great distances.

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7 og Life on Earth is supported by the atmosphere, solar energy,

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energy from the sun, recycles water and other chemicals, and works with the electrical and magnetic forces to provide a moderate climate. The atmosphere also protects life on Earth from high energy radiation and the frigid vacuum of space.

Figure 12-1. Composition of the atmosphere.

Composition of the Atmosphere In any given volume of air, nitrogen accounts for 78 percent atmosphere have been identified using thermal characteristics of the gases that comprise the atmosphere, while oxygen (temperature changes), chemical composition, movement, makes up 21 percent. Argon, carbon dioxide, and traces and density. [Figure 12-2] of other gases make up the remaining one percent. This volume of air also contains some water vapor, varying from The first layer, known as the troposphere, extends from 6 zero to about five percent by volume. This small amount of to 20 kilometers (km) (4 to 12 miles) over the northern and water vapor is responsible for major changes in the weather.

southern poles and up to 48,000 feet (14.5 km) over the [Figure 12-1] equatorial regions. The vast majority of weather, clouds, storms, and temperature variances occur within this first The envelope of gases surrounding the Earth changes layer of the atmosphere. Inside the troposphere, the average from the ground up. Four distinct layers or spheres of the temperature decreases at a rate of about 2 °Celsius (C) every e r e e t f e h 0 0 0 p 0 , 2 8 s o m r e h T e e t r f e 0 0 e , 0 h 6 0 p s o s e M t e e e r f e 0 0 , 0 h 0 p s o t a r t S e r e h p s o p o r T Figure 12-2. Layers of the atmosphere.

12-2 1,000 feet of altitude gain, and the pressure decreases at a rate of about one inch per 1,000 feet of altitude gain.

At the top of the troposphere is a boundary known as the tropopause, which traps moisture and the associated weather in the troposphere. The altitude of the tropopause varies with latitude and with the season of the year; therefore, it takes on an elliptical shape as opposed to round. Location of the tropopause is important because it is commonly associated with the location of the jet stream and possible clear air turbulence.

Above the tropopause are three more atmospheric levels. The first is the stratosphere, which extends from the tropopause to a height of about 160,000 feet (50 km). Little weather exists in this layer and the air remains stable, although certain types of clouds occasionally extend in it. Above the stratosphere are the mesosphere and thermosphere, which have little Figure 12-3. Circulation pattern in a static environment.

influence over weather.

Atmospheric Circulation Atmospheric Pressure As noted earlier, the atmosphere is in constant motion. The unequal heating of the Earth’s surface not only modifies Certain factors combine to set the atmosphere in motion, but a air density and creates circulation patterns; it also causes major factor is the uneven heating of the Earth’s surface. This changes in air pressure or the force exerted by the weight heating upsets the equilibrium of the atmosphere, creating of air molecules. Although air molecules are invisible, they changes in air movement and atmospheric pressure. The still have weight and take up space.

movement of air around the surface of the Earth is called atmospheric circulation. Imagine a sealed column of air that has a footprint of one square inch and is 350 miles high. It would take 14.7 pounds Heating of the Earth’s surface is accomplished by several of effort to lift that column. This represents the air’s weight; processes, but in the simple convection-only model used for if the column is shortened, the pressure exerted at the bottom this discussion, the Earth is warmed by energy radiating from (and its weight) would be less.

the sun. The process causes a circular motion that results when warm air rises and is replaced by cooler air. The weight of the shortened column of air at 18,000 feet is approximately 7.4 pounds; almost 50 percent that at sea level.

Warm air rises because heat causes air molecules to spread For instance, if a bathroom scale (calibrated for sea level) apart. As the air expands, it becomes less dense and lighter were raised to 18,000 feet, the column of air weighing 14.7 than the surrounding air. As air cools, the molecules pack pounds at sea level would be 18,000 feet shorter and would together more closely, becoming denser and heavier than weigh approximately 7.3 pounds (50 percent) less than at warm air. As a result, cool, heavy air tends to sink and replace sea level. [Figure 12-4] warmer, rising air.

The actual pressure at a given place and time differs with Because the Earth has a curved surface that rotates on a tilted altitude, temperature, and density of the air. These conditions axis while orbiting the sun, the equatorial regions of the Earth also affect aircraft performance, especially with regard to receive a greater amount of heat from the sun than the polar takeoff, rate of climb, and landings.

regions. The amount of solar energy that heats the Earth depends on the time of year and the latitude of the specific Coriolis Force region. All of these factors affect the length of time and the In general atmospheric circulation theory, areas of low angle at which sunlight strikes the surface.

pressure exist over the equatorial regions and areas of high pressure exist over the polar regions due to a difference in Solar heating causes higher temperatures in equatorial areas, temperature. The resulting low pressure allows the high- which causes the air to be less dense and rise. As the warm pressure air at the poles to flow along the planet’s surface air flows toward the poles, it cools, becoming denser and toward the equator. While this pattern of air circulation is sinks back toward the surface. [Figure 12-3] 12-3 1 Square Inch 1 Square Inch 1 Square Inch 1 Square Inch 7.4 lb

18,000 feet

18,000 feet

14.7 lb Sea level Figure 12-5. Three-cell circulation pattern due to the rotation of the Earth.

Figure 12-4. Atmosphere weights.

the surface. Then, it flows southward along the surface back toward the equator. Coriolis force bends the flow to the right, thus creating the northeasterly trade winds that prevail from correct in theory, the circulation of air is modified by several 30° latitude to the equator. Similar forces create circulation forces, the most important of which is the rotation of the Earth.

cells that encircle the Earth between 30° and 60° latitude and between 60° and the poles. This circulation pattern results in The force created by the rotation of the Earth is known as the prevailing upper level westerly winds in the conterminous the Coriolis force. This force is not perceptible to humans as United States.

they walk around because humans move slowly and travel relatively short distances compared to the size and rotation Circulation patterns are further complicated by seasonal rate of the Earth. However, the Coriolis force significantly changes, differences between the surfaces of continents and affects motion over large distances, such as an air mass or oceans, and other factors such as frictional forces caused body of water.

by the topography of the Earth’s surface that modify the movement of the air in the atmosphere. For example, within The Coriolis force deflects air to the right in the Northern 2,000 feet of the ground, the friction between the surface and Hemisphere, causing it to follow a curved path instead of a the atmosphere slows the moving air. The wind is diverted straight line. The amount of deflection differs depending on from its path because of the frictional force. Thus, the wind the latitude. It is greatest at the poles and diminishes to zero direction at the surface varies somewhat from the wind at the equator. The magnitude of Coriolis force also differs direction just a few thousand feet above the Earth.

with the speed of the moving body—the greater the speed, the greater the deviation. In the Northern Hemisphere, the Measurement of Atmosphere Pressure rotation of the Earth deflects moving air to the right and changes the general circulation pattern of the air.

Atmospheric pressure historically was measured in inches of mercury ("Hg) by a mercurial barometer. [Figure 12-6] The The Coriolis force causes the general flow to break up into barometer measures the height of a column of mercury inside a three distinct cells in each hemisphere. [Figure 12-5] In glass tube. A section of the mercury is exposed to the pressure the Northern Hemisphere, the warm air at the equator rises of the atmosphere, which exerts a force on the mercury. An upward from the surface, travels northward, and is deflected increase in pressure forces the mercury to rise inside the tube.

eastward by the rotation of the Earth. By the time it has When the pressure drops, mercury drains out of the tube traveled one-third of the distance from the equator to the decreasing the height of the column. This type of barometer is North Pole, it is no longer moving northward, but eastward.

typically used in a laboratory or weather observation station, This air cools and sinks in a belt-like area at about 30° is not easily transported, and difficult to read.

latitude, creating an area of high pressure as it sinks toward 12-4 the linkage mechanism of an aneroid barometer, it is not as At sea level in a standard accurate as a mercurial barometer.

atmosphere, the weight of the atmosphere To provide a common reference, the International Standard (14.7 lb/in ) supports a column of mercury Atmosphere (ISA) has been established. These standard 29.92 inches high.

conditions are the basis for certain flight instruments and most aircraft performance data. Standard sea level pressure is defined as 29.92 "Hg and a standard temperature of 59 °F (15 °C). Atmospheric pressure is also reported in millibars (mb), with 1 "Hg equal to approximately 34 mb. Standard sea (760 mm) level pressure is 1,013.2 mb. Typical mb pressure readings " range from 950.0 to 1,040.0 mb. Surface charts, high and low pressure centers, and hurricane data are reported using mb.

Atmospheric pressure Height of mercury 29.92 Since weather stations are located around the globe, all local barometric pressure readings are converted to a sea level pressure to provide a standard for records and reports. To achieve this, each station converts its barometric pressure by adding approximately 1 "Hg for every 1,000 feet of elevation.

For example, a station at 5,000 feet above sea level, with a reading of 24.92 "Hg, reports a sea level pressure reading of Sea level 29.92 "Hg. [Figure 12-8] Using common sea level pressure 29.92 " Hg = 1,013.2 mb (hPa) = 14.7 lb/in readings helps ensure aircraft altimeters are set correctly, based on the current pressure readings.

Figure 12-6. Although mercurial barometers are no longer used in the U. S., they are still a good historical reference for where the By tracking barometric pressure trends across a large area, altimeter setting came from (inches of mercury).

weather forecasters can more accurately predict movement of pressure systems and the associated weather. For example, An aneroid barometer is the standard instrument used tracking a pattern of rising pressure at a single weather station to measure pressure; it is easier to read and transport.

generally indicates the approach of fair weather. Conversely, [Figure 12-7] The aneroid barometer contains a closed vessel decreasing or rapidly falling pressure usually indicates called an aneroid cell that contracts or expands with changes approaching bad weather and, possibly, severe storms.

in pressure. The aneroid cell attaches to a pressure indicator with a mechanical linkage to provide pressure readings. The Altitude and Atmospheric Pressure pressure sensing part of an aircraft altimeter is essentially As altitude increases, atmospheric pressure decreases. On an aneroid barometer. It is important to note that due to average, with every 1,000 feet of increase in altitude, the atmospheric pressure decreases 1 "Hg. As pressure decreases, the air becomes less dense or thinner. This is the equivalent of Higher being at a higher altitude and is referred to as density altitude.

As pressure decreases, density altitude increases and has a pronounced effect on aircraft performance.

Differences in air density caused by changes in temperature Atmospheric pressure result in a change in pressure. This, in turn, creates motion in the atmosphere, both vertically and horizontally, in the form Lower of currents and wind. The atmosphere is almost constantly in S l l e a l d c e e d a n e r o i motion as it strives to reach equilibrium. These never-ending S l l e a l d c e e d a n e r o i air movements set up chain reactions that cause a continuing S l l e a c e l e d a n e r o i d variety in the weather.

Figure 12-7. Aneroid barometer.

12-5 Station Pressure Denver 24.92 " Hg Standard Atmosphere Station Pressure New Orleans 29.92 " Hg New Orleans 29.92 "Hg Denver 29.92 "Hg Figure 12-8. Station pressure is converted to and reported in sea level pressure.

is longer. An aircraft that requires 745 feet of ground run at Altitude and Flight sea level requires more than double that at a pressure altitude Altitude affects every aspect of flight from aircraft of 8,000 feet. [Figure 12-9] . It is also true that at higher performance to human performance. At higher altitudes, altitudes, due to the decreased density of the air, aircraft with a decreased atmospheric pressure, takeoff and landing engines and propellers are less efficient. This leads to reduced distances are increased, while climb rates decrease.

rates of climb and a greater ground run for obstacle clearance.

When an aircraft takes off, lift is created by the flow of air Altitude and the Human Body around the wings. If the air is thin, more speed is required As discussed earlier, nitrogen and other trace gases make to obtain enough lift for takeoff; therefore, the ground run up 79 percent of the atmosphere, while the remaining 21 TAKEOFF DISTANCE Pressure Altitude: Sea level MAXIMUM WEIGHT 2,400 LB 0 °C Pressure altitude Ground Total feet (feet) roll to clear (feet) 50 foot obstacle S.L. 745 1,320 1,000 815 1,445 2,000 895 1,585 3,000 980 1,740 745 feet 1,075 1,920 4,000 5,000 1,185 2,125 6,000 1,305 2,360 7,000 1,440 2,635 1,590 2,960 8,000 Pressure Altitude: 8,000 feet 1,590 feet Figure 12-9. Takeoff distances increase with increased altitude.

12-6 percent is life sustaining atmospheric oxygen. At sea level, atmospheric pressure is great enough to support normal growth, activity, and life. By 18,000 feet, the partial pressure of oxygen is reduced and adversely affects the normal activities and functions of the human body.

The reactions of the average person become impaired at an altitude of about 10,000 feet, but for some people impairment can occur at an altitude as low as 5,000 feet. The physiological reactions to hypoxia or oxygen deprivation are insidious and affect people in different ways. These symptoms range from mild disorientation to total incapacitation, depending on body tolerance and altitude. Supplemental oxygen or cabin pressurization systems help pilots fly at higher altitudes and overcome the effects of oxygen deprivation.

Wind and Currents Air flows from areas of high pressure into areas of low Figure 12-10. Circulation pattern about areas of high and low pressure because air always seeks out lower pressure. The pressure.

combination of atmospheric pressure differences, Coriolis force, friction, and temperature differences of the air near is a better understanding of what type of weather to expect the earth cause two kinds of atmospheric motion: convective in a given area along a route of flight based on the prevailing currents (upward and downward motion) and wind areas of highs and lows.

(horizontal motion). Currents and winds are important as they affect takeoff, landing, and cruise flight operations. Most While the theory of circulation and wind patterns is accurate for importantly, currents and winds or atmospheric circulation large scale atmospheric circulation, it does not take into account cause weather changes.

changes to the circulation on a local scale. Local conditions, geological features, and other anomalies can change the wind Wind Patterns direction and speed close to the Earth’s surface.

In the Northern Hemisphere, the flow of air from areas of high to low pressure is deflected to the right and produces Convective Currents a clockwise circulation around an area of high pressure.

Plowed ground, rocks, sand, and barren land absorb solar This is known as anticyclonic circulation. The opposite energy quickly and can therefore give off a large amount is true of low-pressure areas; the air flows toward a low of heat; whereas, water, trees, and other areas of vegetation and is deflected to create a counterclockwise or cyclonic tend to more slowly absorb heat and give off heat. The circulation. [Figure 12-10] resulting uneven heating of the air creates small areas of local circulation called convective currents.

High-pressure systems are generally areas of dry, descending air. Good weather is typically associated with high-pressure Convective currents cause the bumpy, turbulent air sometimes systems for this reason. Conversely, air flows into a low- experienced when flying at lower altitudes during warmer pressure area to replace rising air. This air usually brings weather. On a low-altitude flight over varying surfaces, increasing cloudiness and precipitation. Thus, bad weather updrafts are likely to occur over pavement or barren places, is commonly associated with areas of low pressure.

and downdrafts often occur over water or expansive areas of vegetation like a group of trees. Typically, these turbulent A good understanding of high- and low-pressure wind patterns conditions can be avoided by flying at higher altitudes, even can be of great help when planning a flight because a pilot can above cumulus cloud layers. [Figure 12-12] take advantage of beneficial tailwinds. [Figure 12-11] When planning a flight from west to east, favorable winds would Convective currents are particularly noticeable in areas with a be encountered along the northern side of a high-pressure land mass directly adjacent to a large body of water, such as an system or the southern side of a low-pressure system. On ocean, large lake, or other appreciable area of water. During the return flight, the most favorable winds would be along the day, land heats faster than water, so the air over the land the southern side of the same high-pressure system or the becomes warmer and less dense. It rises and is replaced by northern side of a low-pressure system. An added advantage 12-7 Figure 12-11. Favorable winds near a high pressure system.

Figure 12-12. Convective turbulence avoidance.

cooler, denser air flowing in from over the water. This causes Effect of Obstructions on Wind an onshore wind called a sea breeze. Conversely, at night land Another atmospheric hazard exists that can create problems cools faster than water, as does the corresponding air. In this for pilots. Obstructions on the ground affect the flow of case, the warmer air over the water rises and is replaced by wind and can be an unseen danger. Ground topography and the cooler, denser air from the land, creating an offshore wind large buildings can break up the flow of the wind and create called a land breeze. This reverses the local wind circulation wind gusts that change rapidly in direction and speed. These pattern. Convective currents can occur anywhere there is an obstructions range from man-made structures, like hangars, uneven heating of the Earth’s surface. [Figure 12-13] to large natural obstructions, such as mountains, bluffs, or canyons. It is especially important to be vigilant when flying Convective currents close to the ground can affect a pilot’s in or out of airports that have large buildings or natural ability to control the aircraft. For example, on final approach, obstructions located near the runway. [Figure 12-15] the rising air from terrain devoid of vegetation sometimes produces a ballooning effect that can cause a pilot to overshoot The intensity of the turbulence associated with ground the intended landing spot. On the other hand, an approach over obstructions depends on the size of the obstacle and the a large body of water or an area of thick vegetation tends to primary velocity of the wind. This can affect the takeoff and create a sinking effect that can cause an unwary pilot to land landing performance of any aircraft and can present a very short of the intended landing spot. [Figure 12-14] serious hazard. During the landing phase of flight, an aircraft 12-8 Return flow Cool Warm Sea breeze Return flow Warm Cool Land breeze Figure 12-13. Sea breeze and land breeze wind circulation patterns.

C o o l s i n k i n g a i r W a r m r i s i n g a i r Intended Flight path Figure 12-14. Currents generated by varying surface conditions.

12-9

W

I

N

D

Figure 12-15. Turbulence caused by manmade obstructions.

may “drop in” due to the turbulent air and be too low to clear a similar manner. As the air flows down the leeward side of obstacles during the approach. the mountain, the air follows the contour of the terrain and is increasingly turbulent. This tends to push an aircraft into This same condition is even more noticeable when flying in the side of a mountain. The stronger the wind, the greater the mountainous regions. [Figure 12-16] While the wind flows downward pressure and turbulence become.

smoothly up the windward side of the mountain and the upward currents help to carry an aircraft over the peak of Due to the effect terrain has on the wind in valleys or canyons, the mountain, the wind on the leeward side does not act in downdrafts can be severe. Before conducting a flight in or WIND Figure 12-16. Turbulence in mountainous regions.

12-10 near mountainous terrain, it is helpful for a pilot unfamiliar and headwind losses of 30–90 knots, seriously degrading with a mountainous area to get a checkout with a mountain performance. It can also produce strong turbulence and qualified flight instructor. hazardous wind direction changes. Consider Figure 12-17 : During an inadvertent takeoff into a microburst, the plane Low-Level Wind Shear may first experience a performance-increasing headwind (1), followed by performance-decreasing downdrafts (2), Wind shear is a sudden, drastic change in wind speed and/or direction over a very small area. Wind shear can subject an followed by a rapidly increasing tailwind (3). This can result in terrain impact or flight dangerously close to the ground (4).

aircraft to violent updrafts and downdrafts, as well as abrupt changes to the horizontal movement of the aircraft. While An encounter during approach involves the same sequence of wind changes and could force the plane to the ground wind shear can occur at any altitude, low-level wind shear is especially hazardous due to the proximity of an aircraft to the short of the runway.

ground. Low-level wind shear is commonly associated with passing frontal systems, thunderstorms, temperature inversions, The FAA has made a substantial investment in microburst accident prevention. The totally redesigned LLWAS-NE, the and strong upper level winds (greater than 25 knots).

TDWR, and the ASR-9 WSP are skillful microburst alerting systems installed at major airports. These three systems were Wind shear is dangerous to an aircraft. It can rapidly change the performance of the aircraft and disrupt the normal flight extensively evaluated over a 3-year period. Each was seen to issue very few false alerts and to detect microbursts well attitude. For example, a tailwind quickly changing to a headwind causes an increase in airspeed and performance. above the 90 percent detection requirement established by Congress. Many flights involve airports that lack microburst Conversely, a headwind changing to a tailwind causes a decrease in airspeed and performance. In either case, a pilot alert equipment, so the FAA has also prepared wind shear training material: Advisory Circular (AC) 00-54, FAA must be prepared to react immediately to these changes to maintain control of the aircraft. Pilot Wind Shear Guide. Included is information on how to recognize the risk of a microburst encounter, how to avoid an The most severe type of low-level wind shear, a microburst, encounter, and the best flight strategy for successful escape should an encounter occur.

is associated with convective precipitation into dry air at cloud base. Microburst activity may be indicated by an It is important to remember that wind shear can affect any intense rain shaft at the surface but virga at cloud base and a ring of blowing dust is often the only visible clue. flight and any pilot at any altitude. While wind shear may be reported, it often remains undetected and is a silent danger A typical microburst has a horizontal diameter of 1–2 miles and a nominal depth of 1,000 feet. The lifespan of a to aviation. Always be alert to the possibility of wind shear, especially when flying in and around thunderstorms and microburst is about 5–15 minutes during which time it can produce downdrafts of up to 6,000 feet per minute (fpm) frontal systems.

Strong downdraft Intended Path d n i w i l t a I g n i n I c r e a s n c r e a s i n d g n i h e a d w Outflow Outflow Figure 12-17. Effects of a microburst wind.

12-11 Wind and Pressure Representation on Surface Weather Maps Surface weather maps provide information about fronts, areas p e t e s a .

n s of high and low pressure, and surface winds and pressures d a i n e w m g s n r r s o a a r b t for each station. This type of weather map allows pilots to o b I s s o s d i n d a e t see the locations of fronts and pressure systems, but more c n a e i p d s a y r l g importantly, it depicts the wind and pressure at the surface e s e r o l u C s s for each location. For more information on surface analysis e s r r a b p s o I and weather depiction charts, see Chapter 13, Aviation Weather Services.

Wind conditions are reported by an arrow attached to the 1016 s r a e station location circle. [Figure 12-18] The station circle b o r i s u s d s e c e a r p p s represents the head of the arrow, with the arrow pointing l y y e w l i d W o e l l i v a t h s a l a e r n in the direction from which the wind is blowing. Winds e a m d n a t n e i d a .

r are described by the direction from which they blow, thus g s d n i w t h l i g a northwest wind means that the wind is blowing from the northwest toward the southeast. The speed of the wind is

L

depicted by barbs or pennants placed on the wind line. Each barb represents a speed of ten knots, while half a barb is equal Figure 12-19. Isobars reveal the pressure gradient of an area of to five knots, and a pennant is equal to 50 knots.

high- or low-pressure areas.

The pressure for each station is recorded on the weather chart and is shown in mb. Isobars are lines drawn on the chart to wind direction is modified by the friction and wind speed depict lines of equal pressure. These lines result in a pattern decreases due to friction with the surface. At levels 2,000 to that reveals the pressure gradient or change in pressure over 3,000 feet above the surface, however, the speed is greater distance. [Figure 12-19] Isobars are similar to contour lines and the direction becomes more parallel to the isobars.

on a topographic map that indicate terrain altitudes and slope steepness. For example, isobars that are closely spaced Generally, the wind 2,000 feet above ground level (AGL) is indicate a steep pressure gradient and strong winds prevail.

20° to 40° to the right of surface winds, and the wind speed is Shallow gradients, on the other hand, are represented by greater. The change of wind direction is greatest over rough isobars that are spaced far apart and are indicative of light terrain and least over flat surfaces, such as open water. In the winds. Isobars help identify low- and high-pressure systems, absence of winds aloft information, this rule of thumb allows as well as the location of ridges and troughs. A high is an for a rough estimate of the wind conditions a few thousand area of high pressure surrounded by lower pressure; a low feet above the surface.

is an area of low pressure surrounded by higher pressure. A ridge is an elongated area of high pressure, and a trough is Atmospheric Stability an elongated area of low pressure.

The stability of the atmosphere depends on its ability to resist vertical motion. A stable atmosphere makes vertical Isobars furnish valuable information about winds in the first movement difficult, and small vertical disturbances dampen few thousand feet above the surface. Close to the ground, out and disappear. In an unstable atmosphere, small vertical air movements tend to become larger, resulting in turbulent airflow NW/5 kts SW/20 kts Calm and convective activity. Instability can lead to significant turbulence, extensive vertical clouds, and severe weather.

Rising air expands and cools due to the decrease in air pressure as altitude increases. The opposite is true of N/50 kts W/105 kts E/35 kts descending air; as atmospheric pressure increases, the temperature of descending air increases as it is compressed.

Adiabatic heating and adiabatic cooling are terms used to describe this temperature change.

Figure 12-18. Depiction of winds on a surface weather chart.

12-12 The adiabatic process takes place in all upward and Moisture and Temperature downward moving air. When air rises into an area of lower The atmosphere, by nature, contains moisture in the form pressure, it expands to a larger volume. As the molecules of water vapor. The amount of moisture present in the of air expand, the temperature of the air lowers. As a result, atmosphere is dependent upon the temperature of the air.

when a parcel of air rises, pressure decreases, volume Every 20 °F increase in temperature doubles the amount of increases, and temperature decreases. When air descends, moisture the air can hold. Conversely, a decrease of 20 °F the opposite is true. The rate at which temperature decreases cuts the capacity in half.

with an increase in altitude is referred to as its lapse rate.

As air ascends through the atmosphere, the average rate of Water is present in the atmosphere in three states: liquid, temperature change is 2 °C (3.5 °F) per 1,000 feet.

solid, and gaseous. All three forms can readily change to another, and all are present within the temperature ranges of Since water vapor is lighter than air, moisture decreases air the atmosphere. As water changes from one state to another, density, causing it to rise. Conversely, as moisture decreases, an exchange of heat takes place. These changes occur through air becomes denser and tends to sink. Since moist air cools the processes of evaporation, sublimation, condensation, at a slower rate, it is generally less stable than dry air since deposition, melting, or freezing. However, water vapor the moist air must rise higher before its temperature cools is added into the atmosphere only by the processes of to that of the surrounding air. The dry adiabatic lapse rate evaporation and sublimation.

(unsaturated air) is 3 °C (5.4 °F) per 1,000 feet. The moist adiabatic lapse rate varies from 1.1 °C to 2.8 °C (2 °F to Evaporation is the changing of liquid water to water vapor.

5 °F) per 1,000 feet.

As water vapor forms, it absorbs heat from the nearest available source. This heat exchange is known as the latent The combination of moisture and temperature determine the heat of evaporation. A good example is the evaporation of stability of the air and the resulting weather. Cool, dry air human perspiration. The net effect is a cooling sensation is very stable and resists vertical movement, which leads to as heat is extracted from the body. Similarly, sublimation good and generally clear weather. The greatest instability is the changing of ice directly to water vapor, completely occurs when the air is moist and warm, as it is in the tropical bypassing the liquid stage. Though dry ice is not made of regions in the summer. Typically, thunderstorms appear on water, but rather carbon dioxide, it demonstrates the principle a daily basis in these regions due to the instability of the of sublimation when a solid turns directly into vapor.

surrounding air.

Relative Humidity Inversion Humidity refers to the amount of water vapor present in the As air rises and expands in the atmosphere, the temperature atmosphere at a given time. Relative humidity is the actual decreases. There is an atmospheric anomaly that can occur; amount of moisture in the air compared to the total amount of however, that changes this typical pattern of atmospheric moisture the air could hold at that temperature. For example, behavior. When the temperature of the air rises with altitude, a if the current relative humidity is 65 percent, the air is temperature inversion exists. Inversion layers are commonly holding 65 percent of the total amount of moisture that it is shallow layers of smooth, stable air close to the ground. The capable of holding at that temperature and pressure. While temperature of the air increases with altitude to a certain much of the western United States rarely sees days of high point, which is the top of the inversion. The air at the top humidity, relative humidity readings of 75 to 90 percent are of the layer acts as a lid, keeping weather and pollutants not uncommon in the southern United States during warmer trapped below. If the relative humidity of the air is high, it months. [Figure 12-20] can contribute to the formation of clouds, fog, haze, or smoke resulting in diminished visibility in the inversion layer.

Temperature/Dew Point Relationship The relationship between dew point and temperature defines Surface-based temperature inversions occur on clear, cool the concept of relative humidity. The dew point, given in nights when the air close to the ground is cooled by the degrees, is the temperature at which the air can hold no lowering temperature of the ground. The air within a few more moisture. When the temperature of the air is reduced hundred feet of the surface becomes cooler than the air above to the dew point, the air is completely saturated and moisture it. Frontal inversions occur when warm air spreads over a begins to condense out of the air in the form of fog, dew, layer of cooler air, or cooler air is forced under a layer of frost, clouds, rain, or snow.

warmer air.

12-13 At sea level pressure, air can hold 9 g H O/cubic meter of air at 10 °C 17 g H O/cubic meter of air at 20 °C 30 g H O/cubic meter of air at 30 °C If the temperature is lowered to 10 °C, the air can hold only 9 g of water vapor, and 8 g of water will condense as water droplets. The relative humidity will still be at 100%.

If the same cubic meter of air warms to 30 °C, the 17 g of water vapor will produce a relative humidity of 56%.

(17 g is 56% of the 30 g the air could hold at this temperature.)

A cubic meter of air with 17g of water vapor at 20 °C is at saturation or 100% relative humidity. Any further cooling will cause condensation (fog, clouds, dew) to form. Thus, 20 °C is the dew point for this situation.

Figure 12-20. Relationship between relative humidity, temperature, and dewpoint.

As moist, unstable air rises, clouds often form at the altitude Explanation: where temperature and dew point reach the same value. When With an outside air temperature (OAT) of 85 °F at the surface lifted, unsaturated air cools at a rate of 5.4 °F per 1,000 feet and dew point at the surface of 71 °F, the spread is 14°. Divide and the dew point temperature decreases at a rate of 1 °F per the temperature dew point spread by the convergence rate of 1,000 feet. This results in a convergence of temperature and 4.4 °F, and multiply by 1,000 to determine the approximate dew point at a rate of 4.4 °F. Apply the convergence rate height of the cloud base.

to the reported temperature and dew point to determine the height of the cloud base.

Methods by Which Air Reaches the Saturation Point If air reaches the saturation point while temperature and Given: dew point are close together, it is highly likely that fog, low Temperature (T) = 85 °F clouds, and precipitation will form. There are four methods by which air can reach the saturation point. First, when warm Dew point (DP) = 71 °F air moves over a cold surface, the air temperature drops and Convergence Rate (CR) = 4.4° reaches the saturation point. Second, the saturation point may be reached when cold air and warm air mix. Third, when air T – DP = Temperature Dew Point Spread (TDS) cools at night through contact with the cooler ground, air TDS ÷ CR = X reaches its saturation point. The fourth method occurs when X × 1,000 feet = height of cloud base AGL air is lifted or is forced upward in the atmosphere.

Example: As air rises, it uses heat energy to expand. As a result, the rising 85 °F – 71 °F = 14 °F air loses heat rapidly. Unsaturated air loses heat at a rate of 14 °F ÷ 4.4 °F = 3.18 3.0 °C (5.4 °F) for every 1,000 feet of altitude gain. No matter what causes the air to reach its saturation point, saturated air 3.18 × 1,000 = 3,180 feet AGL brings clouds, rain, and other critical weather situations.

The height of the cloud base is 3,180 feet AGL.

12-14 Dew and Frost allow the fog to form and intensify; above a speed of 15 knots, the fog usually lifts and forms low stratus clouds. Advection On cool, clear, calm nights, the temperature of the ground fog is common in coastal areas where sea breezes can blow and objects on the surface can cause temperatures of the the air over cooler landmasses.

surrounding air to drop below the dew point. When this occurs, the moisture in the air condenses and deposits itself on Upslope fog occurs when moist, stable air is forced up sloping the ground, buildings, and other objects like cars and aircraft.

land features like a mountain range. This type of fog also This moisture is known as dew and sometimes can be seen requires wind for formation and continued existence. Upslope on grass and other objects in the morning. If the temperature and advection fog, unlike radiation fog, may not burn off with is below freezing, the moisture is deposited in the form of the morning sun but instead can persist for days. They can frost. While dew poses no threat to an aircraft, frost poses a also extend to greater heights than radiation fog.

definite flight safety hazard. Frost disrupts the flow of air over the wing and can drastically reduce the production of lift. It Steam fog, or sea smoke, forms when cold, dry air moves over also increases drag, which when combined with lowered lift warm water. As the water evaporates, it rises and resembles production, can adversely affect the ability to take off. An smoke. This type of fog is common over bodies of water aircraft must be thoroughly cleaned and free of frost prior during the coldest times of the year. Low-level turbulence to beginning a flight.

and icing are commonly associated with steam fog.

Fog Ice fog occurs in cold weather when the temperature is Fog is a cloud that is on the surface. It typically occurs when much below freezing and water vapor forms directly into ice the temperature of air near the ground is cooled to the air’s crystals. Conditions favorable for its formation are the same dew point. At this point, water vapor in the air condenses and as for radiation fog except for cold temperature, usually –25 becomes visible in the form of fog. Fog is classified according °F or colder. It occurs mostly in the arctic regions but is not to the manner in which it forms and is dependent upon the unknown in middle latitudes during the cold season.

current temperature and the amount of water vapor in the air.

Clouds On clear nights, with relatively little to no wind present, Clouds are visible indicators and are often indicative of radiation fog may develop. [Figure 12-21] Usually, it forms future weather. For clouds to form, there must be adequate in low-lying areas like mountain valleys. This type of fog water vapor and condensation nuclei, as well as a method by occurs when the ground cools rapidly due to terrestrial which the air can be cooled. When the air cools and reaches radiation, and the surrounding air temperature reaches its its saturation point, the invisible water vapor changes into dew point. As the sun rises and the temperature increases, a visible state. Through the processes of deposition (also radiation fog lifts and eventually burns off. Any increase in referred to as sublimation) and condensation, moisture wind also speeds the dissipation of radiation fog. If radiation condenses or sublimates onto miniscule particles of matter fog is less than 20 feet thick, it is known as ground fog.

like dust, salt, and smoke known as condensation nuclei. The nuclei are important because they provide a means for the When a layer of warm, moist air moves over a cold surface, moisture to change from one state to another.

advection fog is likely to occur. Unlike radiation fog, wind is required to form advection fog. Winds of up to 15 knots Cloud type is determined by its height, shape, and characteristics. They are classified according to the height of their bases as low, middle, or high clouds, as well as clouds with vertical development. [Figure 12-22] Low clouds are those that form near the Earth’s surface and extend up to about 6,500 feet AGL. They are made primarily of water droplets but can include supercooled water droplets that induce hazardous aircraft icing. Typical low clouds are stratus, stratocumulus, and nimbostratus. Fog is also classified as a type of low cloud formation. Clouds in this family create low ceilings, hamper visibility, and can change rapidly. Because of this, they influence flight planning and can make visual flight rules (VFR) flight impossible.

Figure 12-21. Radiation fog.

12-15 Cirrocumulus Cirrostratus Cumulonimbus High clouds Cirrus 20,000 AGL Altocumulus Altostratus Clouds with vertical development Middle clouds 6,500 AGL Stratocumulus Towering Cumulus Nimbostratus Stratus Low clouds Figure 12-22. Basic cloud types.

Middle clouds form around 6,500 feet AGL and extend up to and usually produce hazardous weather phenomena, such 20,000 feet AGL. They are composed of water, ice crystals, as lightning, hail, tornadoes, gusty winds, and wind shear.

and supercooled water droplets. Typical middle-level clouds These extensive vertical clouds can be obscured by other include altostratus and altocumulus. These types of clouds cloud formations and are not always visible from the ground may be encountered on cross-country flights at higher or while in flight. When this happens, these clouds are said altitudes. Altostratus clouds can produce turbulence and may to be embedded, hence the term, embedded thunderstorms.

contain moderate icing. Altocumulus clouds, which usually form when altostratus clouds are breaking apart, also may To pilots, the cumulonimbus cloud is perhaps the most contain light turbulence and icing. dangerous cloud type. It appears individually or in groups and is known as either an air mass or orographic thunderstorm.

High clouds form above 20,000 feet AGL and usually form Heating of the air near the Earth’s surface creates an air mass only in stable air. They are made up of ice crystals and pose thunderstorm; the upslope motion of air in the mountainous no real threat of turbulence or aircraft icing. Typical high regions causes orographic thunderstorms. Cumulonimbus level clouds are cirrus, cirrostratus, and cirrocumulus. clouds that form in a continuous line are nonfrontal bands of thunderstorms or squall lines.

Clouds with extensive vertical development are cumulus clouds that build vertically into towering cumulus or Since rising air currents cause cumulonimbus clouds, they cumulonimbus clouds. The bases of these clouds form in are extremely turbulent and pose a significant hazard to flight the low to middle cloud base region but can extend into high safety. For example, if an aircraft enters a thunderstorm, altitude cloud levels. Towering cumulus clouds indicate areas the aircraft could experience updrafts and downdrafts that of instability in the atmosphere, and the air around and inside exceed 3,000 fpm. In addition, thunderstorms can produce them is turbulent. These types of clouds often develop into large hailstones, damaging lightning, tornadoes, and large cumulonimbus clouds or thunderstorms. Cumulonimbus quantities of water, all of which are potentially hazardous clouds contain large amounts of moisture and unstable air to aircraft.

12-16 Cloud classification can be further broken down into specific Drizzle is classified as very small water droplets, smaller cloud types according to the outward appearance and cloud than 0.02 inches in diameter. Drizzle usually accompanies composition. Knowing these terms can help a pilot identify fog or low stratus clouds. Water droplets of larger size are visible clouds. referred to as rain. Rain that falls through the atmosphere but evaporates prior to striking the ground is known as virga.

The following is a list of cloud classifications: Freezing rain and freezing drizzle occur when the temperature of the surface is below freezing; the rain freezes on contact • Cumulus—heaped or piled clouds with the cooler surface.

• Stratus—formed in layers If rain falls through a temperature inversion, it may freeze • Cirrus—ringlets, fibrous clouds, also high level clouds as it passes through the underlying cold air and fall to the above 20,000 feet ground in the form of ice pellets. Ice pellets are an indication • Castellanus—common base with separate vertical of a temperature inversion and that freezing rain exists at a development, castle-like higher altitude. In the case of hail, freezing water droplets are • Lenticularus—lens-shaped, formed over mountains carried up and down by drafts inside cumulonimbus clouds, in strong winds growing larger in size as they come in contact with more moisture. Once the updrafts can no longer hold the freezing • Nimbus—rain-bearing clouds water, it falls to the Earth in the form of hail. Hail can be • Fracto—ragged or broken pea sized, or it can grow as large as five inches in diameter, • Alto—middle level clouds existing at 5,000 to 20,000 larger than a softball.

feet Snow is precipitation in the form of ice crystals that falls Ceiling at a steady rate or in snow showers that begin, change in For aviation purposes, a ceiling is the lowest layer of clouds intensity, and end rapidly. Snow also varies in size, from very reported as being broken or overcast, or the vertical visibility small grains to large flakes. Snow grains are the equivalent into an obscuration like fog or haze. Clouds are reported of drizzle in size.

as broken when five-eighths to seven-eighths of the sky is covered with clouds. Overcast means the entire sky is covered Precipitation in any form poses a threat to safety of flight.

with clouds. Current ceiling information is reported by the Often, precipitation is accompanied by low ceilings and aviation routine weather report (METAR) and automated reduced visibility. Aircraft that have ice, snow, or frost on weather stations of various types.

their surfaces must be carefully cleaned prior to beginning a flight because of the possible airflow disruption and Visibility loss of lift. Rain can contribute to water in the fuel tanks.

Closely related to cloud cover and reported ceilings is Precipitation can create hazards on the runway surface itself, visibility information. Visibility refers to the greatest making takeoffs and landings difficult, if not impossible, horizontal distance at which prominent objects can be due to snow, ice, or pooling water and very slick surfaces.

viewed with the naked eye. Current visibility is also reported in METAR and other aviation weather reports, as well as Air Masses by automated weather systems. Visibility information, as Air masses are classified according to the regions where predicted by meteorologists, is available for a pilot during a they originate. They are large bodies of air that take on the preflight weather briefing.

characteristics of the surrounding area or source region. A source region is typically an area in which the air remains Precipitation relatively stagnant for a period of days or longer. During Precipitation refers to any type of water particles that this time of stagnation, the air mass takes on the temperature form in the atmosphere and fall to the ground. It has a and moisture characteristics of the source region. Areas of profound impact on flight safety. Depending on the form of stagnation can be found in polar regions, tropical oceans, and precipitation, it can reduce visibility, create icing situations, dry deserts. Air masses are generally identified as polar or and affect landing and takeoff performance of an aircraft.

tropical based on temperature characteristics and maritime or continental based on moisture content.

Precipitation occurs because water or ice particles in clouds grow in size until the atmosphere can no longer support A continental polar air mass forms over a polar region and them. It can occur in several forms as it falls toward the brings cool, dry air with it. Maritime tropical air masses form Earth, including drizzle, rain, ice pellets, hail, snow, and ice.

12-17 over warm tropical waters like the Caribbean Sea and bring There are four types of fronts that are named according to the warm, moist air. As the air mass moves from its source region temperature of the advancing air relative to the temperature and passes over land or water, the air mass is subjected to of the air it is replacing: [Figure 12-24] the varying conditions of the land or water which modify the • Warm nature of the air mass. [Figure 12-23] • Cold An air mass passing over a warmer surface is warmed from • Stationary below, and convective currents form, causing the air to rise.

• Occluded This creates an unstable air mass with good surface visibility.

Moist, unstable air causes cumulus clouds, showers, and Any discussion of frontal systems must be tempered with turbulence to form.

the knowledge that no two fronts are the same. However, generalized weather conditions are associated with a specific Conversely, an air mass passing over a colder surface does not type of front that helps identify the front.

form convective currents but instead creates a stable air mass with poor surface visibility. The poor surface visibility is due Warm Front to the fact that smoke, dust, and other particles cannot rise A warm front occurs when a warm mass of air advances and out of the air mass and are instead trapped near the surface.

replaces a body of colder air. Warm fronts move slowly, A stable air mass can produce low stratus clouds and fog.

typically 10 to 25 miles per hour (mph). The slope of the advancing front slides over the top of the cooler air and Fronts gradually pushes it out of the area. Warm fronts contain As an air mass moves across bodies of water and land, it warm air that often has very high humidity. As the warm eventually comes in contact with another air mass with air is lifted, the temperature drops and condensation occurs.

different characteristics. The boundary layer between two types of air masses is known as a front. An approaching Generally, prior to the passage of a warm front, cirriform front of any type always means changes to the weather or stratiform clouds, along with fog, can be expected to are imminent.

form along the frontal boundary. In the summer months, cumulonimbus clouds (thunderstorms) are likely to develop.

Standard air mass abbreviations: arctic (A), continental polar (cP), A maritime polar (mP), continental tropical (cT), and maritime tropical (mT).

cP mP mP mT mT cT mT Figure 12-23. North American air mass source regions.

12-18 steadily from the inflow of relatively warmer air. For the most Symbols for surface fronts and other significant lines part, the dew point remains steady and the pressure levels off.

shown on the surface analysis chart After the passage of a warm front, stratocumulus clouds Warm front (red)* predominate and rain showers are possible. The visibility Cold front (blue)* eventually improves, but hazy conditions may exist for a short period after passage. The wind blows from the south- Stationary front (red/blue)* southwest. With warming temperatures, the dew point rises and then levels off. There is generally a slight rise in Occluded front (purple)* barometric pressure, followed by a decrease of barometric * Note: Fronts may be black and white or color depending on their pressure.

source. Also, fronts shown in color code do not necessarily show frontal symbols.

Flight Toward an Approaching Warm Front Figure 12-24. Common chart symbology to depict weather front By studying a typical warm front, much can be learned location.

about the general patterns and atmospheric conditions that exist when a warm front is encountered in flight.

Light to moderate precipitation is probable, usually in the Figure 12-25 depicts a warm front advancing eastward from form of rain, sleet, snow, or drizzle, accentuated by poor St. Louis, Missouri, toward Pittsburgh, Pennsylvania during visibility. The wind blows from the south-southeast, and the a flight from Pittsburgh to St. Louis.

outside temperature is cool or cold with an increasing dew point. Finally, as the warm front approaches, the barometric At the time of departure from Pittsburgh, the weather is good pressure continues to fall until the front passes completely.

VFR with a scattered layer of cirrus clouds at 15,000 feet.

As the flight progresses westward to Columbus and closer During the passage of a warm front, stratiform clouds are to the oncoming warm front, the clouds deepen and become visible and drizzle may be falling. The visibility is generally increasingly stratiform in appearance with a ceiling of 6,000 poor, but improves with variable winds. The temperature rises feet. The visibility decreases to six miles in haze with a falling CIRRUS CIRROSTRATUS ALTOSTRATUS

WARM AIR

NIMBOSTRATUS

COLD AIR

Indianapolis Columbus Pittsburgh St. Louis 200 miles 400 miles 600 miles 999 1002 1005 1008 1011 1014 METAR KSTL 1950Z 21018KT 1SM –RA 0VC010 18/18 A2960 40 METAR KIND 1950Z 16012KT 3SM RA 65 3 125 166 53 020 1 59 26 18 6 10 20 BKN020 15/15 A2973 65 34 St. Louis 10 Columbus 1002 Pittsburgh Indianapolis METAR KCMH 1950Z 13018KT 6SM HZ 0VC060 14/10 A2990 METAR KPIT 1950Z 13012KT 10SM SCT150 12/01 A3002 1008 1011 1014 1017 Figure 12-25. Warm front cross-section with surface weather chart depiction and associated METAR.

12-19 barometric pressure. Approaching Indianapolis, the weather Fast-Moving Cold Front deteriorates to broken clouds at 2,000 feet with three miles Fast-moving cold fronts are pushed by intense pressure visibility and rain. With the temperature and dew point the systems far behind the actual front. The friction between same, fog is likely to develop. At St. Louis, the sky is overcast the ground and the cold front retards the movement of the with low clouds and drizzle and the visibility is one mile.

front and creates a steeper frontal surface. This results in a Beyond Indianapolis, the ceiling and visibility are too low very narrow band of weather, concentrated along the leading to continue VFR. Therefore, it would be wise to remain in edge of the front. If the warm air being overtaken by the Indianapolis until the warm front passes, which may take cold front is relatively stable, overcast skies and rain may up to two days.

occur for some distance behind the front. If the warm air is unstable, scattered thunderstorms and rain showers may Cold Front form. A continuous line of thunderstorms, or squall line, A cold front occurs when a mass of cold, dense, and stable may form along or ahead of the front. Squall lines present air advances and replaces a body of warmer air.

a serious hazard to pilots as squall-type thunderstorms are intense and move quickly. Behind a fast-moving cold front, Cold fronts move more rapidly than warm fronts, progressing the skies usually clear rapidly, and the front leaves behind at a rate of 25 to 30 mph. However, extreme cold fronts gusty, turbulent winds and colder temperatures.

have been recorded moving at speeds of up to 60 mph.

A typical cold front moves in a manner opposite that of a Flight Toward an Approaching Cold Front warm front. It is so dense, it stays close to the ground and Like warm fronts, not all cold fronts are the same. Examining acts like a snowplow, sliding under the warmer air and a flight toward an approaching cold front, pilots can get a forcing the less dense air aloft. The rapidly ascending air better understanding of the type of conditions that can be causes the temperature to decrease suddenly, forcing the encountered in flight. Figure 12-26 depicts a flight from creation of clouds. The type of clouds that form depends Pittsburgh, Pennsylvania, toward St. Louis, Missouri.

on the stability of the warmer air mass. A cold front in the Northern Hemisphere is normally oriented in a northeast to At the time of departure from Pittsburgh, the weather is VFR southwest manner and can be several hundred miles long, with three miles visibility in smoke and a scattered layer of encompassing a large area of land.

clouds at 3,500 feet. As the flight progresses westward to Columbus and closer to the oncoming cold front, the clouds Prior to the passage of a typical cold front, cirriform or show signs of vertical development with a broken layer at towering cumulus clouds are present, and cumulonimbus 2,500 feet. The visibility is six miles in haze with a falling clouds may develop. Rain showers may also develop due barometric pressure. Approaching Indianapolis, the weather to the rapid development of clouds. A high dew point and has deteriorated to overcast clouds at 1,000 feet and three falling barometric pressure are indicative of imminent cold miles visibility with thunderstorms and heavy rain showers.

front passage.

At St. Louis, the weather gets better with scattered clouds at 1,000 feet and a ten mile visibility.

As the cold front passes, towering cumulus or cumulonimbus clouds continue to dominate the sky. Depending on the A pilot using sound judgment based on the knowledge of intensity of the cold front, heavy rain showers form and may frontal conditions will likely remain in Indianapolis until the be accompanied by lightning, thunder, and/or hail. More front has passed. Trying to fly below a line of thunderstorms severe cold fronts can also produce tornadoes. During cold or a squall line is hazardous, and flight over the top of or front passage, the visibility is poor with winds variable and around the storm is not an option. Thunderstorms can extend gusty, and the temperature and dew point drop rapidly. A up to well over the capability of small airplanes and can quickly falling barometric pressure bottoms out during frontal extend in a line for 300 to 500 miles.

passage, then begins a gradual increase.

Comparison of Cold and Warm Fronts After frontal passage, the towering cumulus and Warm fronts and cold fronts are very different in nature as are cumulonimbus clouds begin to dissipate to cumulus clouds the hazards associated with each front. They vary in speed, with a corresponding decrease in the precipitation. Good composition, weather phenomenon, and prediction. Cold fronts, visibility eventually prevails with the winds from the west- which move at 20 to 35 mph, travel faster than warm fronts, northwest. Temperatures remain cooler and the barometric which move at only 10 to 25 mph. Cold fronts also possess a pressure continues to rise.

12-20

C

O

L

D

A

WARM AIR

I

R

CUMULONIMBUS Indianapolis Columbus Pittsburgh St. Louis 200 miles 400 miles 600 miles 1008 1005 1008 METAR KSTL 1950Z 30018KT 10SM SCT010 08/02 A2979 METAR KIND 1950Z 20024KT 3SM +TSRA 4 102 46 77 066 71 75 122 10 8 42 6 3 12 10 33 73 OVC010 24/23 A2974 Indianapolis Columbus Pittsburgh METAR KCMH 1950Z 20012KT 6SM HZ St. Louis BKN025 25/24 A2983 METAR KPIT 1950Z 20012KT 3SM FU SCT035 24/22 A2989 1011 1011 1014 Figure 12-26. Cold front cross-section with surface weather chart depiction and associated METAR.

steeper frontal slope. Violent weather activity is associated with Stationary Front cold fronts, and the weather usually occurs along the frontal When the forces of two air masses are relatively equal, the boundary, not in advance. However, squall lines can form boundary or front that separates them remains stationary and during the summer months as far as 200 miles in advance of influences the local weather for days. This front is called a a strong cold front. Whereas warm fronts bring low ceilings, stationary front. The weather associated with a stationary poor visibility, and rain, cold fronts bring sudden storms, gusty front is typically a mixture that can be found in both warm winds, turbulence, and sometimes hail or tornadoes.

and cold fronts.

Cold fronts are fast approaching with little or no warning, Occluded Front and they bring about a complete weather change in just a An occluded front occurs when a fast-moving cold front few hours. The weather clears rapidly after passage and drier catches up with a slow-moving warm front. As the occluded air with unlimited visibilities prevail. Warm fronts, on the front approaches, warm front weather prevails but is other hand, provide advance warning of their approach and immediately followed by cold front weather. There are two can take days to pass through a region.

types of occluded fronts that can occur, and the temperatures of the colliding frontal systems play a large part in defining Wind Shifts the type of front and the resulting weather. A cold front Wind around a high-pressure system rotates clockwise, while occlusion occurs when a fast moving cold front is colder low-pressure winds rotate counter-clockwise. When two than the air ahead of the slow moving warm front. When high pressure systems are adjacent, the winds are almost in this occurs, the cold air replaces the cool air and forces the direct opposition to each other at the point of contact. Fronts warm front aloft into the atmosphere. Typically, the cold are the boundaries between two areas of high pressure, and front occlusion creates a mixture of weather found in both therefore, wind shifts are continually occurring within a front.

warm and cold fronts, providing the air is relatively stable.

Shifting wind direction is most pronounced in conjunction A warm front occlusion occurs when the air ahead of the with cold fronts.

12-21 warm front is colder than the air of the cold front. When this and instability are present, the clouds continue to increase is the case, the cold front rides up and over the warm front. If in vertical height. Continuous, strong updrafts prohibit the air forced aloft by the warm front occlusion is unstable, moisture from falling. Within approximately 15 minutes, the weather is more severe than the weather found in a cold the thunderstorm reaches the mature stage, which is the most front occlusion. Embedded thunderstorms, rain, and fog are violent time period of the thunderstorm’s life cycle. At this likely to occur. point, drops of moisture, whether rain or ice, are too heavy for the cloud to support and begin falling in the form of rain Figure 12-27 depicts a cross-section of a typical cold or hail. This creates a downward motion of the air. Warm, front occlusion. The warm front slopes over the prevailing rising air; cool, precipitation-induced descending air; and cooler air and produces the warm front type weather. Prior violent turbulence all exist within and near the cloud. Below to the passage of the typical occluded front, cirriform and the cloud, the down-rushing air increases surface winds and stratiform clouds prevail, light to heavy precipitation falls, decreases the temperature. Once the vertical motion near the visibility is poor, dew point is steady, and barometric pressure top of the cloud slows down, the top of the cloud spreads drops. During the passage of the front, nimbostratus and out and takes on an anvil-like shape. At this point, the storm cumulonimbus clouds predominate, and towering cumulus enters the dissipating stage. This is when the downdrafts clouds may also form. Light to heavy precipitation falls, spread out and replace the updrafts needed to sustain the visibility is poor, winds are variable, and the barometric storm. [Figure 12-28] pressure levels off. After the passage of the front, nimbostratus and altostratus clouds are visible, precipitation decreases, and It is impossible to fly over thunderstorms in light aircraft.

visibility improves. Severe thunderstorms can punch through the tropopause and reach staggering heights of 50,000 to 60,000 feet depending Thunderstorms on latitude. Flying under thunderstorms can subject aircraft to rain, hail, damaging lightning, and violent turbulence.

A thunderstorm makes its way through three distinct stages A good rule of thumb is to circumnavigate thunderstorms before dissipating. It begins with the cumulus stage, in identified as severe or giving an extreme radar echo by at which lifting action of the air begins. If sufficient moisture CIRRUS

WARM AIR

CIRROSTRATUS CUMULONIMBUS ALTOSTRATUS NIMBOSTRATUS

C

OL

D A

C OL D A I R

I

R

Indianapolis Columbus Pittsburgh St. Louis 200 miles 400 miles 600 miles 1020 1017 1014 1011 1006 1005 1002 999 999 1002 1005 1006 METAR KSTL 1950Z 31023G40KT 8SM SCT035 05/M03 A2976 METAR KIND 1950Z 29028G45KT 1/2SM TSRAGR VV005 18/16 A2970 52 47 200 42 8 076 66 2 7 20 1 8 32 2 51 40 METAR KCMH 1950Z 16017KT 2SM BR Indianapolis OVC080 11/10 A2970 St. Louis Columbus Pittsburgh METAR KPIT 1950Z 13012KT 75SM BKN130 08/04 A3012 1011 1014 1017 1020 1023 Figure 12-27. Occluded front cross-section with a weather chart depiction and associated METAR.

12-22 Cumulus Stage (3–5 mile height) Mature Stage (5–10 mile height) Dissipating Stage (5–7 mile height) 40,000 ft.

Equilibrium level 30,000 ft.

20,000 ft.

0 °C 32 °F 10,000 ft.

5,000 ft.

Figure 12-28. Life cycle of a thunderstorm.

least 20 nautical miles (NM) since hail may fall for miles Squall Line outside of the clouds. If flying around a thunderstorm is not A squall line is a narrow band of active thunderstorms. Often an option, stay on the ground until it passes.

it develops on or ahead of a cold front in moist, unstable air, but it may develop in unstable air far removed from For a thunderstorm to form, the air must have sufficient water any front. The line may be too long to detour easily and too vapor, an unstable lapse rate, and an initial lifting action to wide and severe to penetrate. It often contains steady-state start the storm process. Some storms occur at random in thunderstorms and presents the single most intense weather unstable air, last for only an hour or two, and produce only hazard to aircraft. It usually forms rapidly, generally reaching moderate wind gusts and rainfall. These are known as air maximum intensity during the late afternoon and the first mass thunderstorms and are generally a result of surface few hours of darkness.

heating. Steady-state thunderstorms are associated with weather systems. Fronts, converging winds, and troughs Tornadoes aloft force upward motion spawning these storms that often The most violent thunderstorms draw air into their cloud form into squall lines. In the mature stage, updrafts become bases with great vigor. If the incoming air has any initial stronger and last much longer than in air mass storms, hence rotating motion, it often forms an extremely concentrated the name steady state. [Figure 12-29] vortex from the surface well into the cloud. Meteorologists have estimated that wind in such a vortex can exceed 200 Knowledge of thunderstorms and the hazards associated with knots with pressure inside the vortex quite low. The strong them is critical to the safety of flight.

winds gather dust and debris and the low pressure generates a funnel-shaped cloud extending downward from the Hazards cumulonimbus base. If the cloud does not reach the surface, All thunderstorms have conditions that are a hazard to aviation.

it is a funnel cloud; if it touches a land surface, it is a tornado; These hazards occur in numerous combinations. While not and if it touches water, it is a “waterspout.” every thunderstorm contains all hazards, it is not possible to visually determine which hazards a thunderstorm contains.

12-23 Turbulence Anvil Storm movement Roll cloud Wind shear turbulence Wind shear turbulance First gust Dust Figure 12-29. Movement and turbulence of a maturing thunderstorm.

Tornadoes occur with both isolated and squall line of an approaching storm. Advisory Circular (AC) 00-54, Pilot thunderstorms. Reports for forecasts of tornadoes indicate Windshear Guide, explains gust front hazards associated with that atmospheric conditions are favorable for violent thunderstorms. Figure 2 in the AC shows a cross section of a turbulence. An aircraft entering a tornado vortex is almost mature stage thunderstorm with a gust front area where very certain to suffer loss of control and structural damage. Since serious turbulence may be encountered.

the vortex extends well into the cloud, any pilot inadvertently caught on instruments in a severe thunderstorm could Icing encounter a hidden vortex.

Updrafts in a thunderstorm support abundant liquid water with relatively large droplet sizes. When carried above Families of tornadoes have been observed as appendages of the freezing level, the water becomes supercooled. When the main cloud extending several miles outward from the area temperature in the upward current cools to about –15 °C, of lightning and precipitation. Thus, any cloud connected to much of the remaining water vapor sublimates as ice crystals.

a severe thunderstorm carries a threat of violence.

Above this level, at lower temperatures, the amount of supercooled water decreases.

Turbulence Potentially hazardous turbulence is present in all Supercooled water freezes on impact with an aircraft. Clear thunderstorms, and a severe thunderstorm can destroy an icing can occur at any altitude above the freezing level, but at aircraft. Strongest turbulence within the cloud occurs with high levels, icing from smaller droplets may be rime or mixed shear between updrafts and downdrafts. Outside the cloud, rime and clear ice. The abundance of large, supercooled shear turbulence has been encountered several thousand feet water droplets makes clear icing very rapid between 0 °C and above and 20 miles laterally from a severe storm. A low-level –15 °C and encounters can be frequent in a cluster of cells.

turbulent area is the shear zone associated with the gust front. Thunderstorm icing can be extremely hazardous.

Often, a “roll cloud” on the leading edge of a storm marks the top of the eddies in this shear, and it signifies an extremely Thunderstorms are not the only area where pilots could turbulent zone. Gust fronts often move far ahead (up to 15 encounter icing conditions. Pilots should be alert for icing miles) of associated precipitation. The gust front causes a anytime the temperature approaches 0 °C and visible moisture rapid, and sometimes drastic, change in surface wind ahead is present.

12-24 Hail Engine Water Ingestion Hail competes with turbulence as the greatest thunderstorm Turbine engines have a limit on the amount of water they hazard to aircraft. Supercooled drops above the freezing level can ingest. Updrafts are present in many thunderstorms, begin to freeze. Once a drop has frozen, other drops latch on particularly those in the developing stages. If the updraft and freeze to it, so the hailstone grows—sometimes into a velocity in the thunderstorm approaches or exceeds the huge ice ball. Large hail occurs with severe thunderstorms terminal velocity of the falling raindrops, very high with strong updrafts that have built to great heights. concentrations of water may occur. It is possible that these Eventually, the hailstones fall, possibly some distance from concentrations can be in excess of the quantity of water the storm core. Hail may be encountered in clear air several turbine engines are designed to ingest. Therefore, severe miles from thunderstorm clouds. thunderstorms may contain areas of high water concentration, which could result in flameout and/or structural failure of As hailstones fall through air whose temperature is above 0 one or more engines.

°C, they begin to melt and precipitation may reach the ground as either hail or rain. Rain at the surface does not mean the Chapter Summary absence of hail aloft. Possible hail should be anticipated Knowledge of the atmosphere and the forces acting within with any thunderstorm, especially beneath the anvil of a it to create weather is essential to understand how weather large cumulonimbus. Hailstones larger than one-half inch affects a flight. By understanding basic weather theories, a in diameter can significantly damage an aircraft in a few pilot can make sound decisions during flight planning after seconds.

receiving weather briefings. For additional information on the topics discussed in this chapter, see the following publications Ceiling and Visibility as amended: AC 00-6, Aviation Weather For Pilots and Flight Generally, visibility is near zero within a thunderstorm Operations Personnel; AC 00-24, Thunderstorms; AC 00-45, cloud. Ceiling and visibility also may be restricted in Aviation Weather Services; AC 91-74, Pilot Guide: Flight in precipitation and dust between the cloud base and the ground.

Icing Conditions; and chapter 7, section 2 of the Aeronautical The restrictions create the same problem as all ceiling and Information Manual (AIM).

visibility restrictions; but the hazards are multiplied when associated with the other thunderstorm hazards of turbulence, hail, and lightning.

Effect on Altimeters Pressure usually falls rapidly with the approach of a thunderstorm, rises sharply with the onset of the first gust and arrival of the cold downdraft and heavy rain showers, and then falls back to normal as the storm moves on. This cycle of pressure change may occur in 15 minutes. If the pilot does not receive a corrected altimeter setting, the altimeter may be more than 100 feet in error.

Lightning A lightning strike can puncture the skin of an aircraft and damage communications and electronic navigational equipment. Although lightning has been suspected of igniting fuel vapors and causing an explosion, serious accidents due to lightning strikes are rare. Nearby lightning can blind the pilot, rendering him or her momentarily unable to navigate either by instrument or by visual reference. Nearby lightning can also induce permanent errors in the magnetic compass.

Lightning discharges, even distant ones, can disrupt radio communications on low and medium frequencies. Though lightning intensity and frequency have no simple relationship to other storm parameters, severe storms, as a rule, have a high frequency of lightning.

12-25 12-26

Chapter 13

Aviation Weather Services

Introduction In aviation, weather service is a combined effort of the National Weather Service (NWS), Federal Aviation Administration (FAA), Department of Defense (DOD), other aviation groups, and individuals. Because of the increasing need for worldwide weather services, foreign weather organizations also provide vital input.

While weather forecasts are not 100 percent accurate, meteorologists, through careful scientific study and computer modeling, have the ability to predict weather patterns, trends, and characteristics with increasing accuracy. Through a complex system of weather services, government agencies, and independent weather observers, pilots and other aviation professionals receive the benefit of this vast knowledge base in the form of up-to-date weather reports and forecasts.

These reports and forecasts enable pilots to make informed decisions regarding weather and flight safety before and during a flight.

13-1 radiosonde observations, pilot weather reports (PIREPs), Observations Aircraft Meteorological Data Relay (AMDAR) and the The data gathered from surface and upper altitude Meteorological Data Collection and Reporting System observations form the basis of all weather forecasts, (MDCRS). A radiosonde is a small cubic instrumentation advisories, and briefings. There are four types of weather package that is suspended below a six foot hydrogen- or observations: surface, upper air, radar, and satellite.

helium-filled balloon. Once released, the balloon rises at a rate of approximately 1,000 feet per minute (fpm). As it ascends, Surface Aviation Weather Observations the instrumentation gathers various pieces of data, such as air Surface aviation weather observations (METARs) are a temperature, moisture, and pressure, as well as wind speed compilation of elements of the current weather at individual and direction. Once the information is gathered, it is relayed ground stations across the United States. The network is to ground stations via a 300 milliwatt radio transmitter.

made up of government and privately contracted facilities that provide continuous up-to-date weather information.

The balloon flight can last as long as 2 hours or more and Automated weather sources, such as the Automated Weather can ascend to altitudes as high as 115,000 feet and drift as Observing Systems (AWOS), Automated Surface Observing far as 125 miles. The temperatures and pressures experienced Systems (ASOS), as well as other automated facilities, also during the flight can be as low as -130 °F and pressures as play a major role in the gathering of surface observations.

low as a few thousandths of what is experienced at sea level.

Surface observations provide local weather conditions Since the pressure decreases as the balloon rises in the and other relevant information for a specific airport. This atmosphere, the balloon expands until it reaches the limits information includes the type of report, station identifier, of its elasticity. This point is reached when the diameter has date and time, modifier (as required), wind, visibility, increased to over 20 feet. At this point, the balloon pops and runway visual range (RVR), weather phenomena, sky the radiosonde falls back to Earth. The descent is slowed by condition, temperature/dew point, altimeter reading, and means of a parachute. The parachute aids in protecting people applicable remarks. The information gathered for the surface and objects on the ground. Each year over 75,000 balloons observation may be from a person, an automated station, or are launched. Of that number, 20 percent are recovered and an automated station that is updated or enhanced by a weather returned for reconditioning. Return instructions are printed observer. In any form, the surface observation provides on the side of each radiosonde.

valuable information about individual airports around the country. Although the reports cover only a small radius, the Pilots also provide vital information regarding upper air pilot can generate a good picture of the weather over a wide weather observations and remain the only real-time source area when many reporting stations are viewed together.

of information regarding turbulence, icing, and cloud heights. This information is gathered and filed by pilots Air Route Traffic Control Center (ARTCC) in flight. Together, PIREPs and radiosonde observations The Air Route Traffic Control Center (ARTCC) facilities provide information on upper air conditions important for are responsible for maintaining separation between flights flight planning. Many domestic and international airlines conducted under instrument flight rules (IFR) in the en have equipped their aircraft with instrumentation that route structure. Center radars (Air Route Surveillance Radar automatically transmits in flight weather observations (ARSR)) acquire and track transponder returns using the same through the DataLink system.

basic technology as terminal radars. Earlier center radars displayed weather as an area of slashes (light precipitation) The Aircraft Meteorological Data Relay (AMDAR) is and Hs (moderate rainfall). Because the controller could not an international program utilizing commercial aircraft to detect higher levels of precipitation, pilots had to be wary provide automated weather observations. The AMDAR of areas showing moderate rainfall. Newer radar displays program provides approximately 220,000-230,000 aircraft show weather as three shades of blue. Controllers can select observations per day on a worldwide basis utilizing aircraft the level of weather to be displayed. Weather displays of onboard sensors and probes that measure wind, temperature, higher levels of intensity make it difficult for controllers to humidity/water vapor, turbulence and icing data. AMDAR see aircraft data blocks, so pilots should not expect air traffic vertical profiles and en route observations provide significant control (ATC) to keep weather displayed continuously.

benefits to the aviation community by enhancing aircraft safety and operating efficiency through improved weather Upper Air Observations analysis and forecasting. The AMDAR program also Observations of upper air weather are more challenging contributes to improved short and medium term numerical than surface observations. There are several methods by weather forecasts for a wide range of services including which upper air weather phenomena can be observed: 13-2 severe weather, defense, marine, public weather and environmental monitoring. The information is down linked either via Very High Frequency (VHF) communications through the Aircraft Communications Addressing and Reporting System (ACARS) or via satellite link through the Aircraft to Satellite Data Acquisition and Relay (ASDAR).

The Meteorological Data Collection and Reporting System (MDCRS) is an automated airborne weather observation program that is used in the U.S. This program collects and disseminates real-time upper-air weather observations from participating airlines. The weather elements are down linked via ACARS and are managed by Aeronautical Radio, Inc.

(ARINC) who then forwards them in Binary Universal Form for the Representation of Meteorological Data (BUFR) format to the NWS and in raw data form to the Earth Science Research Laboratory (ESRL) and the participating airline.

More than 1,500 aircraft report wind and temperature data with some of these same aircraft also providing turbulence and humidity/water vapor information. In conjunction with Figure 13-1. Example of a weather radar scope.

avionics manufacturers, each participating airline programs their equipment to provide certain levels of meteorological data. The monitoring and collection of climb, en route, and descent data is accomplished through the aircraft’s Flight Data Acquisition and Monitoring System (FDAMS) and is then transmitted via ACARS. When aircraft are out of ACARS range, reports can be relayed through ASDAR. However, in most cases, the reports are buffered until the aircraft comes within ACARS range, at which point they are downloaded.

Radar Observations There are four types of radars which provide information about precipitation and wind.

1. The WSR-88D NEXRAD radar, commonly called Doppler radar, provides in-depth observations that inform surrounding communities of impending weather. Doppler radar has two operational modes: clear air and precipitation. In clear air mode, the radar is in its most sensitive operational mode because a Figure 13-2. WSR-88D Weather Radar Echo Intensity Legend.

slow antenna rotation allows the radar to sample the atmosphere longer. Images are updated about every Weather Radar Echo Intensity Reflectivity (dBZ) Ranges 10 minutes in this mode.

Light <30 dBZ Precipitation targets provide stronger return signals; Moderate 30–40 dBZ Heavy >40–50 therefore, the radar is operated in the Precipitation Extreme 50+ dBZ mode when precipitation is present. A faster antenna rotation in this mode allows images to update at Figure 13-3. WSR-88D Weather Radar Precipitation Intensity a faster rate, approximately every 4 to 6 minutes.

Terminology.

Intensity values in both modes are measured in dBZ (decibels of Z) and are depicted in color on the radar image. [Figure 13-1] Intensities are correlated to intensity terminology (phraseology) for ATC purposes. [Figures 13-2 and 13-3] 13-3 2. FAA terminal Doppler weather radar (TDWR), recordings of meteorological and aeronautical information.

installed at some major airports around the country, TIBS provides area and route briefings, airspace procedures, also aids in providing severe weather alerts and and special announcements. The recordings are automatically warnings to ATC. Terminal radar ensures pilots updated as changes occur. It is designed to be a preliminary are aware of wind shear, gust fronts, and heavy briefing tool and is not intended to replace a standard briefing precipitation, all of which are dangerous to arriving from a FSS specialist. The TIBS service can only be accessed and departing aircraft. by a touchtone phone. The phone numbers for the TIBS service are listed in the Chart Supplement U.S. (formerly 3. The third type of radar commonly used in the detection Airport/Facility Directory).

of precipitation is the FAA airport surveillance radar.

This radar is used primarily to detect aircraft, but it Hazardous Inflight Weather Advisory Service also detects the location and intensity of precipitation, (HIWAS) which is used to route aircraft traffic around severe Hazardous Inflight Weather Advisory Service (HIWAS), weather in an airport environment.

available in the 48 conterminous states, is an automated 4. Airborne radar is equipment carried by aircraft to continuous broadcast of hazardous weather information locate weather disturbances. The airborne radars over selected VOR navigational aids (NAVAIDs). The generally operate in the C or X bands (around 6 broadcasts include advisories such as AIRMETS, SIGMETS, GHz or around 10 GHz, respectively) permitting convective SIGMETS, and urgent PIREPs. The broadcasts both penetration of heavy precipitation, required for are automatically updated as changes occur. Pilots should determining the extent of thunderstorms, and sufficient contact a FSS or EFAS for additional information. VORs that reflection from less intense precipitation.

have HIWAS capability are depicted on aeronautical charts with an “H” in the upper right corner of the identification Satellite box. [Figure 13-4] Advancement in satellite technologies has recently allowed for commercial use to include weather uplinks. Through the Transcribed Weather Broadcast (TWEB) (Alaska use of satellite subscription services, individuals are now able Only) to receive satellite transmitted signals that provide near real- A continuous automated broadcast of meteorological and time weather information for the North American continent.

aeronautical data over selected low or medium frequency (L/ MF) and very high frequency (VHF) omnidirectional range (VOR) NAVAID facilities. The broadcasts are automatically Service Outlets updated as changes occur. The broadcast contains adverse Service outlets are government, government contract, or conditions, surface weather observations, PIREPS, and private facilities that provide aviation weather services. Several a density altitude statement (if applicable). Recordings different government agencies, including the FAA, National may also include a synopsis, winds aloft forecast, en route Oceanic and Atmospheric Administration (NOAA), and the and terminal forecast data, and radar reports. At selected NWS work in conjunction with private aviation companies locations, telephone access to the TWEB has been provided to provide different means of accessing weather information.

(TEL-TWEB). Telephone numbers for this service are found Flight Service Station (FSS) The FSS is the primary source for preflight weather information. A preflight weather briefing from an FSS can be obtained 24 hours a day by calling 1-800-WX BRIEF from anywhere in the United States and Puerto Rico. Telephone numbers for FSS can be found in the Chart Supplement U.S.

(formerly Airport/Facility Directory) or in the United States Government section of the telephone book.

The FSS also provides inflight weather briefing services and weather advisories to flights within the FSS area of responsibility.

Telephone Information Briefing Service (TIBS) Symbol indicates HIWAS The Telephone Information Briefing Service (TIBS), provided by FSS, is a system of automated telephone Figure 13-4. HIWAS availability is shown on sectional chart.

13-4 in the Alaska Chart Supplement U.S. (formerly Airport/ 5. En route forecast—a summary of the weather forecast Facility Directory). These broadcasts are made available for the proposed route of flight.

primarily for preflight and inflight planning, and as such, 6. Destination forecast—a summary of the expected should not be considered as a substitute for specialist- weather for the destination airport at the estimated provided preflight briefings.

time of arrival (ETA).

7. Forecast winds and temperatures aloft—a forecast of Weather Briefings the winds at specific altitudes for the route of flight.

Prior to every flight, pilots should gather all information The forecast temperature information aloft is provided vital to the nature of the flight. This includes an appropriate only upon request.

weather briefing obtained from a specialist at a FSS.

8. Notices to Airmen (NOTAM)—information pertinent to the route of flight that has not been published in the For weather specialists to provide an appropriate weather NOTAM publication. Published NOTAM information briefing, they need to know which of the three types of is provided during the briefing only when requested.

briefings is needed—standard, abbreviated, or outlook. Other helpful information is whether the flight is visual flight rules 9. ATC delays—an advisory of any known ATC delays (VFR) or IFR, aircraft identification and type, departure that may affect the flight.

point, estimated time of departure (ETD), flight altitude, route 10. Other information—at the end of the standard briefing, of flight, destination, and estimated time en route (ETE).

the FSS specialist provides the radio frequencies needed to open a flight plan and to contact EFAS. Any This information is recorded in the flight plan system and a additional information requested is also provided at note is made regarding the type of weather briefing provided.

this time.

If necessary, it can be referenced later to file or amend a flight plan. It is also used when an aircraft is overdue or is Abbreviated Briefing reported missing.

An abbreviated briefing is a shortened version of the standard briefing. It should be requested when a departure has been Standard Briefing delayed or when weather information is needed to update A standard briefing provides the most complete information the previous briefing. When this is the case, the weather and a more complete weather picture. This type of briefing specialist needs to know the time and source of the previous should be obtained prior to the departure of any flight and briefing so the necessary weather information is not omitted should be used during flight planning. A standard briefing inadvertently. It is always a good idea for the pilot to update provides the following information in sequential order if it the weather information whenever he/she has additional time.

is applicable to the route of flight.

1. Adverse conditions—this includes information about Outlook Briefing adverse conditions that may influence a decision to An outlook briefing should be requested when a planned cancel or alter the route of flight. Adverse conditions departure is 6 hours or more away. It provides initial forecast include significant weather, such as thunderstorms or information that is limited in scope due to the time frame aircraft icing, or other important items such as airport of the planned flight. This type of briefing is a good source closings.

of flight planning information that can influence decisions regarding route of flight, altitude, and ultimately the go/no-go 2. VFR flight not recommended—if the weather for decision. A prudent pilot requests a follow-up briefing prior the route of flight is below VFR minimums, or if to departure since an outlook briefing generally only contains it is doubtful the flight could be made under VFR information based on weather trends and existing weather in conditions due to the forecast weather, the briefer may geographical areas at or near the departure airport. A standard state “VFR flight not recommended.” It is the pilot’s briefing near the time of departure ensures that the pilot has decision whether or not to continue the flight under the latest information available prior to his/her flight.

VFR, but this advisory should be weighed carefully.

3. Synopsis—an overview of the larger weather picture.

Aviation Weather Reports Fronts and major weather systems that affect the Aviation weather reports are designed to give accurate general area are provided.

depictions of current weather conditions. Each report 4. Current conditions—the current ceilings, visibility, provides current information that is updated at different times.

winds, and temperatures. If the departure time is more Some typical reports are METARs and PIREPs.

than 2 hours away, current conditions are not included in the briefing.

13-5 Aviation Routine Weather Report (METAR) 4. Modifier—denotes that the METAR/SPECI came from an automated source or that the report was corrected. If A METAR is an observation of current surface weather the notation “AUTO” is listed in the METAR/SPECI, reported in a standard international format. While the the report came from an automated source. It also lists METAR code has been adopted worldwide, each country is “AO1” (for no precipitation discriminator) or “AO2” allowed to make modifications to the code. Normally, these (with precipitation discriminator) in the “Remarks” differences are minor but necessary to accommodate local section to indicate the type of precipitation sensors procedures or particular units of measure. This discussion of employed at the automated station.

METAR covers elements used in the United States.

When the modifier “COR” is used, it identifies a METARs are issued on a regularly scheduled basis unless corrected report sent out to replace an earlier report significant weather changes have occurred. A special that contained an error (for example: METAR KGGG METAR (SPECI) can be issued at any time between routine 161753Z COR).

METAR reports.

5. Wind—reported with five digits (14021KT) unless the speed is greater than 99 knots, in which case the Example: wind is reported with six digits. The first three digits METAR KGGG 161753Z AUTO 14021G26KT 3/4SM indicate the direction the true wind is blowing from in +TSRA BR BKN008 OVC012CB 18/17 A2970 RMK tens of degrees. If the wind is variable, it is reported PRESFR as “VRB.” The last two digits indicate the speed of the wind in knots unless the wind is greater than 99 A typical METAR report contains the following information knots, in which case it is indicated by three digits. If in sequential order: the winds are gusting, the letter “G” follows the wind 1. Type of report—there are two types of METAR speed (G26KT). After the letter “G,” the peak gust reports. The first is the routine METAR report that is recorded is provided. If the wind direction varies more transmitted on a regular time interval. The second is than 60° and the wind speed is greater than six knots, the aviation selected SPECI. This is a special report a separate group of numbers, separated by a “V,” will that can be given at any time to update the METAR for indicate the extremes of the wind directions.

rapidly changing weather conditions, aircraft mishaps, 6. Visibility—the prevailing visibility (¾ SM) is reported or other critical information.

in statute miles as denoted by the letters “SM.” It is 2. Station identifier—a four-letter code as established by reported in both miles and fractions of miles. At times, the International Civil Aviation Organization (ICAO).

runway visual range (RVR) is reported following the In the 48 contiguous states, a unique three-letter prevailing visibility. RVR is the distance a pilot can identifier is preceded by the letter “K.” For example, see down the runway in a moving aircraft. When RVR Gregg County Airport in Longview, Texas, is is reported, it is shown with an R, then the runway identified by the letters “KGGG,” K being the country number followed by a slant, then the visual range designation and GGG being the airport identifier.

in feet. For example, when the RVR is reported as In other regions of the world, including Alaska and R17L/1400FT, it translates to a visual range of 1,400 Hawaii, the first two letters of the four-letter ICAO feet on runway 17 left.

identifier indicate the region, country, or state. Alaska 7. Weather—can be broken down into two different identifiers always begin with the letters “PA” and categories: qualifiers and weather phenomenon Hawaii identifiers always begin with the letters “PH.” (+TSRA BR). First, the qualifiers of intensity, Station identifiers can be found by calling the FSS, a proximity, and the descriptor of the weather are given.

NWS office, or by searching various websites such The intensity may be light (–), moderate ( ), or heavy as DUATS and NOAA's Aviation Weather Aviation (+). Proximity only depicts weather phenomena that Digital Data Services (ADDS).

are in the airport vicinity. The notation “VC” indicates 3. Date and time of report—depicted in a six-digit group a specific weather phenomenon is in the vicinity (161753Z). The first two digits are the date. The last of five to ten miles from the airport. Descriptors four digits are the time of the METAR/SPECI, which are used to describe certain types of precipitation is always given in coordinated universal time (UTC).

and obscurations. Weather phenomena may be A “Z” is appended to the end of the time to denote reported as being precipitation, obscurations, and the time is given in Zulu time (UTC) as opposed to other phenomena, such as squalls or funnel clouds.

local time.

13-6 Descriptions of weather phenomena as they begin or Contraction Sky Cover end and hailstone size are also listed in the “Remarks” SKC, CLR, FEW Less than ∕ 8 sections of the report. [Figure 13-5] 1 2 (Clear) ∕ 8 – ∕ 8 (Few) FEW ³∕ 8 – ∕ 8 (Scattered) SCT 8. Sky condition—always reported in the sequence of 5 7 ∕ 8 – ∕ 8 (Broken) BKN amount, height, and type or indefinite ceiling/height ∕ 8 or (Overcast) OVC (vertical visibility) (BKN008 OVC012CB, VV003).

The heights of the cloud bases are reported with a Figure 13-6. Reportable contractions for sky condition.

three-digit number in hundreds of feet AGL. Clouds above 12,000 feet are not detected or reported by an 12. Remarks—the remarks section always begins with the automated station. The types of clouds, specifically letters “RMK.” Comments may or may not appear in towering cumulus (TCU) or cumulonimbus (CB) this section of the METAR. The information contained clouds, are reported with their height. Contractions in this section may include wind data, variable are used to describe the amount of cloud coverage and visibility, beginning and ending times of particular obscuring phenomena. The amount of sky coverage is phenomenon, pressure information, and various other reported in eighths of the sky from horizon to horizon.

information deemed necessary. An example of a [Figure 13-6] remark regarding weather phenomenon that does not 9. Temperature and dew point—the air temperature and fit in any other category would be: OCNL LTGICCG.

dew point are always given in degrees Celsius (C) or This translates as occasional lightning in the clouds (18/17). Temperatures below 0 °C are preceded by and from cloud to ground. Automated stations also use the letter “M” to indicate minus.

the remarks section to indicate the equipment needs maintenance.

10. Altimeter setting—reported as inches of mercury ("Hg) in a four-digit number group (A2970). It is Example: always preceded by the letter “A.” Rising or falling METAR KGGG 161753Z AUTO 14021G26KT 3/4SM pressure may also be denoted in the “Remarks” +TSRA BR BKN008 OVC012CB 18/17 A2970 RMK sections as “PRESRR” or “PRESFR,” respectively.

PRESFR 11. Zulu time—a term used in aviation for UTC, which places the entire world on one time standard.

Qualifier Weather Phenomena Intensity or Proximity 1 Precipitation 3 Obscuration 4 Other 5 Descriptor 2 – Light MI Shallow DZ Drizzle BR Mist PO Dust/sand whirls Moderate (no qualifier) BC Patches RA Rain FG Fog SQ Squalls + Heavy DR Low drifting SN Snow FU Smoke FC Funnel cloud VC in the vicinity BL Blowing SG Snow grains DU Dust +FC Tornado or waterspout SH Showers IC Ice crystals (diamond dust) SA Sand SS Sandstorm TS Thunderstorms PL Ice pellets HZ Haze DS Dust storm FZ Freezing GR Hail PY Spray PR Partial GS Small hail or snow pellets VA Volcanic ash UP *Unknown precipitation The weather groups are constructed by considering columns 1–5 in this table in sequence: intensity, followed by descriptor, followed by weather phenomena (e.g., heavy rain showers(s) is coded as +SHRA).

* Automated stations only Figure 13-5. Descriptors and weather phenomena used in a typical METAR.

13-7 Explanation: one weather phenomenon encountered. A PIREP is normally Routine METAR for Gregg County Airport for the 16th transmitted as an individual report but may be appended to day of the month at 1753Z automated source. Winds are a surface report. Pilot reports are easily decoded, and most 140 at 21 knots gusting to 26. Visibility is ¾ statute mile. contractions used in the reports are self-explanatory.

Thunderstorms with heavy rain and mist. Ceiling is broken at 800 feet, overcast at 1,200 feet with cumulonimbus clouds. Example: Temperature 18 °C and dew point 17 °C. Barometric pressure UA/OV GGG 090025/TM 1450/FL 060/TP C182/SK is 29.70 "Hg and falling rapidly. 080 OVC/WX FV04SM RA/TA 05/WV 270030KT/TB LGT/RM HVY RAIN Pilot Weather Reports (PIREPs) PIREPs provide valuable information regarding the Explanation: Type: .................................Routine pilot report conditions as they actually exist in the air, which cannot be gathered from any other source. Pilots can confirm the height Location: .......................... 25 NM out on the 090° radial, Gregg County VOR of bases and tops of clouds, locations of wind shear and turbulence, and the location of inflight icing. If the ceiling is Time: ................................ 1450 Zulu Altitude or Flight Level: 6,000 feet below 5,000 feet, or visibility is at or below five miles, ATC facilities are required to solicit PIREPs from pilots in the area. Aircraft Type: ...................Cessna 182 Sky Cover: ........................8,000 overcast When unexpected weather conditions are encountered, pilots are encouraged to make a report to a FSS or ATC. When a Visibility/Weather: ...........4 miles in rain Temperature: .....................5 °Celsius pilot weather report is filed, the ATC facility or FSS adds it to the distribution system to brief other pilots and provide Wind: ................................270° at 30 knots Turbulence: .......................Light inflight advisories.

Icing: ................................ None reported Remarks: .......................... Rain is heavy PIREPs are easy to file and a standard reporting form outlines the manner in which they should be filed. Figure 13-7 shows the elements of a PIREP form. Item numbers 1 through 5 are required information when making a report, as well as at least Encoding Pilot Weather Reports (PIREPS) 1 XXX 3-letter station identifier Nearest weather reporting location to the reported phenomenon 2 UA Routine PIREP, UUA-Urgent PIREP.

3 /OV Location Use 3-letter NAVAID idents only.

a. Fix: /OV ABC, /OV ABC 090025.

b. Fix: /OV ABC 045020-DEF, /OV ABC-DEF-GHI 4 /TM Time 4 digits in UTC: /TM 0915.

5 /FL Altitude/flight level 3 digits for hundreds of feet. If not known, use UNKN: /FL095, /FL310, /FLUNKN.

6 /TP Type aircraft 4 digits maximum. If not known, use UNKN: /TP L329, /TP B727, /TP UNKN.

7 /SK Sky cover/cloud layers Describe as follows: a. Height of cloud base in hundreds of feet. If unknown, use UNKN.

b. Cloud cover symbol.

c. Height of cloud tops in hundreds of feet.

8 /WX Weather Flight visibility reported first: Use standard weather symbols: /WX FV02SM RA HZ, /WX FV01SM TSRA.

9 /TA Air temperature in celsius (C) If below zero, prefix with a hyphen: /TA 15, /TA M06.

10 /WV Wind Direction in degrees magnetic north and speed in six digits: /WV270045KT, WV 280110KT.

11 /TB Turbulence Use standard contractions for intensity and type (use CAT or CHOP when appropriate). Include altitude only if different from /FL, /TB EXTRM, /TB LGT-MOD BLO 090.

12 /IC Icing Describe using standard intensity and type contractions. Include altitude only if different than /FL: /IC LGT-MOD RIME, /IC SEV CLR 028-045.

13 /RM Remarks Use free form to clarify the report and type hazardous elements first: /RM LLWS -15KT SFC-030 DURC RY22 JFK.

Figure 13-7. PIREP encoding and decoding.

13-8 7. Forecast significant weather—weather phenomena Aviation Forecasts are coded in the TAF reports in the same format as Observed weather condition reports are often used in the the METAR.

creation of forecasts for the same area. A variety of different forecast products are produced and designed to be used in the 8. Forecast sky condition—given in the same format as preflight planning stage. The printed forecasts that pilots need the METAR. Only cumulonimbus (CB) clouds are to be familiar with are the terminal aerodrome forecast (TAF), forecast in this portion of the TAF report as opposed aviation area forecast (FA), inflight weather advisories to CBs and towering cumulus in the METAR.

(SIGMET, AIRMET), and the winds and temperatures aloft 9. Forecast change group—for any significant weather forecast (FB).

change forecast to occur during the TAF time period, the expected conditions and time period are included Terminal Aerodrome Forecasts (TAF) in this group. This information may be shown as from A TAF is a report established for the five statute mile (FM), and temporary (TEMPO). “FM” is used when a radius around an airport. TAF reports are usually given for rapid and significant change, usually within an hour, is larger airports. Each TAF is valid for a 24 or 30-hour time expected. “TEMPO” is used for temporary fluctuations period and is updated four times a day at 0000Z, 0600Z, of weather, expected to last less than 1 hour.

1200Z, and 1800Z. The TAF utilizes the same descriptors 10. PROB30—a given percentage that describes the and abbreviations as used in the METAR report. The TAF probability of thunderstorms and precipitation includes the following information in sequential order: occurring in the coming hours. This forecast is not 1. Type of report—a TAF can be either a routine forecast used for the first 6 hours of the 24-hour forecast.

(TAF) or an amended forecast (TAF AMD).

2. ICAO station identifier—the station identifier is the Example: same as that used in a METAR.

TAF KPIR 111130Z 1112/1212 3. Date and time of origin—time and date (081125Z) TEMPO 1112/1114 5SM BR of TAF origination is given in the six-number code FM1500 16015G25KT P6SM SCT040 BKN250 with the first two being the date, the last four being FM120000 14012KT P6SM BKN080 OVC150 PROB30 the time. Time is always given in UTC as denoted by 1200/1204 3SM TSRA BKN030CB the Z following the time block.

FM120400 1408KT P6SM SCT040 OVC080 4. Valid period dates and times—The TAF valid period TEMPO 1204/1208 3SM TSRA OVC030CB (0812/0912) follows the date/time of forecast origin group. Scheduled 24 and 30 hour TAFs are issued Explanation: four times per day, at 0000, 0600, 1200, and 1800Z.

Routine TAF for Pierre, South Dakota…on the 11th day of The first two digits (08) are the day of the month for the month, at 1130Z…valid for 24 hours from 1200Z on the the start of the TAF. The next two digits (12) are the 11th to 1200Z on the 12th…wind from 150° at 12 knots… starting hour (UTC). 09 is the day of the month for visibility greater than 6 SM…broken clouds at 9,000 feet… the end of the TAF, and the last two digits (12) are temporarily, between 1200Z and 1400Z, visibility 5 SM in the ending hour (UTC) of the valid period. A forecast mist…from 1500Z winds from 160° at 15 knots, gusting period that begins at midnight UTC is annotated as 00.

to 25 knots visibility greater than 6 SM…clouds scattered If the end time of a valid period is at midnight UTC, at 4,000 feet and broken at 25,000 feet…from 0000Z wind it is annotated as 24. For example, a 00Z TAF issued from 140° at 12 knots…visibility greater than 6 SM…clouds on the 9th of the month and valid for 24 hours would broken at 8,000 feet, overcast at 15,000 feet…between 0000Z have a valid period of 0900/0924.

and 0400Z, there is 30 percent probability of visibility 3 5. Forecast wind—the wind direction and speed forecast SM…thunderstorm with moderate rain showers…clouds are coded in a five-digit number group. An example broken at 3,000 feet with cumulonimbus clouds…from would be 15011KT. The first three digits indicate the 0400Z…winds from 140° at 8 knots…visibility greater than direction of the wind in reference to true north. The 6 miles…clouds at 4,000 scattered and overcast at 8,000… last two digits state the windspeed in knots appended temporarily between 0400Z and 0800Z…visibility 3 miles… with “KT.” Like the METAR, winds greater than 99 thunderstorms with moderate rain showers…clouds overcast knots are given in three digits. at 3,000 feet with cumulonimbus clouds…end of report (=).

6. Forecast visibility—given in statute miles and may be in whole numbers or fractions. If the forecast is greater than six miles, it is coded as “P6SM.” 13-9 Area Forecasts (FA) and implies there may be occurrences of severe or greater turbulence, severe icing, low-level wind shear, and IFR The FA gives a picture of clouds, general weather conditions, conditions. The final line of the precautionary statement alerts and visual meteorological conditions (VMC) expected over the user that heights, for the most part, are MSL. Those that a large area encompassing several states. There are six areas are not MSL will state AGL or CIG.

for which area forecasts are published in the contiguous 48 states. Area forecasts are issued three times a day and are 3. Synopsis—gives a brief summary identifying the valid for 18 hours. This type of forecast gives information location and movement of pressure systems, fronts, vital to en route operations, as well as forecast information and circulation patterns.

for smaller airports that do not have terminal forecasts.

Example: Area forecasts are typically disseminated in four sections and SYNOPSIS…LOW PRES TROF 10Z OK/TX PNHDL AREA include the following information: FCST MOV EWD INTO CNTRL-SWRN OK BY 04Z.

WRMFNT 10Z CNTRL OK-SRN AR-NRN MS FCST LIFT 1. Header—gives the location identifier of the source of NWD INTO NERN OK-NRN AR EXTRM NRN MS BY 04Z.

the FA, the date and time of issuance, the valid forecast time, and the area of coverage.

Explanation: As of 1000Z, there is a low pressure trough over the Oklahoma Example: and Texas panhandle area, which is forecast to move eastward DFWC FA 120945 into central to southwestern Oklahoma by 0400Z. A warm SYNOPSIS AND VFR CLDS/WX front located over central Oklahoma, southern Arkansas, and SYNOPSIS VALID UNTIL 130400 northern Mississippi at 1000Z is forecast to lift northwestward CLDS/WX VALID UNTIL 122200…OTLK VALID into northeastern Oklahoma, northern Arkansas, and extreme 122200-130400 northern Mississippi by 0400Z.

OK TX AR LA MS AL AND CSTL WTRS 4. VFR Clouds and Weather—This section lists expected Explanation: sky conditions, visibility, and weather for the next 12 The area forecast shows information given by Dallas Fort hours and an outlook for the following 6 hours.

Worth, for the region of Oklahoma, Texas, Arkansas, Louisiana, Mississippi, and Alabama, as well as a portion Example: of the Gulf coastal waters. It was issued on the 12th day S CNTRL AND SERN TX of the month at 0945. The synopsis is valid from the time AGL SCT-BKN010. TOPS 030. VIS 3-5SM BR. 14-16Z of issuance until 0400 hours on the 13th. VFR clouds and BECMG AGL SCT030. 19Z AGL SCT050.

weather information on this area forecast are valid until 2200 OTLK…VFR hours on the 12th and the outlook is valid from 2200Z on the OK 12th to 0400Z on the 13th.

PNDLAND NW…AGL SCT030 SCT-BKN100.

TOPS FL200.

2. Precautionary statements—IFR conditions, mountain 15Z AGL SCT040 SCT100. AFT 20Z SCT TSRA DVLPG..

obscurations, and thunderstorm hazards are described FEW POSS SEV. CB TOPS FL450.

in this section. Statements made here regarding height OTLK…VFR are given in MSL, and if given otherwise, AGL or ceiling (CIG) is noted.

Explanation: In south central and southeastern Texas, there is a scattered Example: to broken layer of clouds from 1,000 feet AGL with tops at SEE AIRMET SIERRA FOR IFR CONDS AND MTN 3,000 feet, visibility is 3 to 5 SM in mist. Between 1400Z and OBSCN.

1600Z, the cloud bases are expected to increase to 3,000 feet TS IMPLY SEV OR GTR TURB SEV ICE LLWS AND AGL. After 1900Z, the cloud bases are expected to continue IFR CONDS.

to increase to 5,000 feet AGL and the outlook is VFR.

NON MSL HGTS DENOTED BYAGL OR CIG.

In northwestern Oklahoma and panhandle, the clouds are Explanation: scattered at 3,000 feet with another scattered to broken layer The area forecast covers VFR clouds and weather, so the at 10,000 feet AGL, with the tops at 20,000 feet. At 1500 precautionary statement warns that AIRMET Sierra should Z, the lowest cloud base is expected to increase to 4,000 be referenced for IFR conditions and mountain obscuration.

feet AGL with a scattered layer at 10,000 feet AGL. After The code TS indicates the possibility of thunderstorms 13-10 2000Z, the forecast calls for scattered thunderstorms with rain phenomena considered potentially hazardous to light aircraft developing and a few becoming severe; the CB clouds have and aircraft with limited operational capabilities.

tops at flight level (FL) 450 or 45,000 feet MSL.

An AIRMET includes forecast of moderate icing, moderate It should be noted that when information is given in the area turbulence, sustained surface winds of 30 knots or forecast, locations may be given by states, regions, or specific greater, widespread areas of ceilings less than 1,000 feet geological features such as mountain ranges. Figure 13-8 and/or visibilities less than three miles, and extensive shows an area forecast chart with six regions of forecast, mountain obscurement.

states, regional areas, and common geographical features.

Each AIRMET bulletin has a fixed alphanumeric designator, Inflight Weather Advisories numbered sequentially for easy identification, beginning with the first issuance of the day. Sierra is the AIRMET code used Inflight weather advisories, which are provided to en route aircraft, are forecasts that detail potentially hazardous to denote IFR and mountain obscuration; Tango is used to denote turbulence, strong surface winds, and low-level wind weather. These advisories are also available to pilots prior to departure for flight planning purposes. An inflight shear; and Zulu is used to denote icing and freezing levels.

weather advisory is issued in the form of either an AIRMET, SIGMET, or convective SIGMET. Example: BOSS WA 211945 AIRMET SIERRA UPDT 3 FOR IFR AND MTN OBSCN AIRMET VALID UNTIL 220200 AIRMETs (WAs) are examples of inflight weather advisories AIRMET IFT…ME NH VT MA CT RI NY NJ AND CSTL that are issued every 6 hours with intermediate updates WTRS FROM CAR TO YSJ TO 150E ACK TO EWR TO issued as needed for a particular area forecast region. The YOW TO CAR OCNL CIG BLW 010/VIS BLW 3SM information contained in an AIRMET is of operational PCPN/BR. CONDS CONT BYD 02Z THRU 08Z interest to all aircraft, but the weather section concerns Strait of Juan De Fuca CHI BOS Chicago Boston SLC Salt Lake City Mtns Olympic Mtns NE WA Puget NW NE Sound East Columbia Fort Peck Reservoir Slopes of Interior Souris WRN Upper MI River Valley Basin Valley Cont Dvd Cascade Mtns Coast and ME of Cascades Costal Valley n i o SE WA Champlain t c e Valley S Columbia Gorge ERN Upper MI l Flathead Valley Arrowhead ND a t SW Upper Blue s Bitterroot Range Lake Superior Cntrl SWRN Mississippi Shoreline a Mtns Upper o Missouri MT Valley Mtns Mtns C Dame Green Wallowa MI Adirondack Mtns Slope Red River Valley Reservoir Central Northeast Lakes Mackinac Area Mtns Costal Range VT Mtns of NE Lakes White Mtns E of Cont Dvd Region Mtns Yellowstone N of Catskills MN NE OR North of Willamette Valley (Sawtooth) Region East Slopes NH The MA Park Black NW NE Mohawk OR Big Horn Wind River Mtns Thumb Cascade Mtns Big Horn Mtns r Big Bend Hills Valley e o E Cntrl Cape Cod High Plateau i v i Basin R Reservoir Lower Great O r e n t a Catskill MI e ID Door Peninsula Lakes Basin k WI NY NE WY n Mtns S y n L F NRN Highlands Teton Mtns n Extrm a l e Wind River e James a r SD La k l Saginaw e a y k a SE West of Black R i V e e e CT v e r Basin h River n SW SE Valley Extrm s C WY e i n Catskills Rosebud Pine L c Lee L a Hills i Grand NW l e s P Hudson Valley RI Shasta Laramie Mtns Lake NE Siskiyous N Country Ridge Area w l NE CA C Valley a i s Erie N t P a Nebraska Lake Mich Shoreline NRN a s Sand Hills s Western l NE a n e NW Cntrl a PA t d pan o SW t C Irish Hills Nevada e C Eastern R l a N e i v Handle e r i NW NRN Great Basin WY e r Central Nebraska Extrm a E SE IA r k NE r a NJ Nevada So Central V NW L ke a Near Lake Mi N Extrm S Sierra Salt ll Plateau Green River e SE Central y NE NW N Third Allegheny SW Lake Mtns NE Iowa Cntrl Mtns P SRN WY E NE l a SE Valley t t e NV SW W Lake Tahoe North Park R NW NE Cntrl NW i v MD OH e r Cntrl Coastal Mtns and Valleys s i n Sacramento Uinta Basin B a IL Great r UT Southern Cntrl e SWRN Coastal IN v Basin Blue River Valley SE i Eastern NW S Waters Wasatch Mtns Colorado So Platte Valley Lower NE R Shore Republican SRN A Third NE l o NW Extrm West Central Mtns Central SE n g o SW i MO WV Sierra Valley N s O h NE SW Valleys S Cntrl n Mtns Palmer Lake Ridge Kansas River Valley Cntrl i DC Mtns SW a t Valley or Divide CO NE SE Marais des Cygnes Basin SW SE n VA San Juan u o SE Eastern Plains High Plains San Joaquin Near Ohio River Death Lake Mtns San Luis Northern M CA Extreme Cntrl East Flint KS Lake Powell SW n Mead Lake of the n i NE Valley Valley SRN Coastal Lower Arkansas Valley i a a Four Ozarks Area Southern l Hills IL h SE P Areas c Antelope Grand Canyon Mojave Corners SW Missouri a l West l Coastal Mtns and Valleys Area SE a a Valley Lakes Area t Desert p Lake s Coastal Range Santa e Boot p d Panhandle East a i Middle A Northwest Mojave SRN Valley i v Heel o West NC Barbara D Little l C SE Deserts t a Northeast Ozarks Channel Coastal Plain Colorado n e West TN Mogollon Rim Valley i n Mtns t Panhandle OK NW Mtns Santa Monica Coacnella River n NE o NE C of Bay Sangre De Cristo and Piedmont NW SC Mtns White AR SC Northwest Imperial Southwest n Mtns Hills i Northern Mtns Eastern Southeast Valleys AZ a of Central Texas l Gulf of New Mexico P Alabama East l Colorado Santa Catalina a Cntrl t West NM s MS SW SE Gilariver Valley a Cntrl Mtns o Eastern AL Chiricahua C Extrm Sacremento NW Plains NE SE North Central Rio Grande Valley North GA Mtns Coastal SE Lower Mississippi Valley Waters P West of Extrm Southern SW Northeast e TX MIA Georgia c Pecos East of Miami o s Central R SFO Mobile i FL W 85 v Pecos e Area Extrm r South North LA Southwest San Francisco Apalachee Southeast Delta Area South Central Big Bend Bay Area North Plain Upper Coastal Lower Central Rio FL Grande Plain Valley South Mid Coastal Extrm m Coastal Waters–from Coastal Bend a South e DFW r t coast outward to the Lower Upper S f Coastal Keys l flight information u Dallas/Fort Worth Plain G region border Lower Keys Florida Straits Figure 13-8. Area forecast region map.

13-11 AIRMET MTN OBSCN…ME NH VT MA NY PA Washington, for a defined area from Seattle to Portland to FROM CAR TO MLT TO CON TO SLT TO SYR TO CAR Eugene to Seattle. It calls for occasional severe clear air MTNS OCNLY OBSCD BY CLDS/PCPN/BR. CONDS turbulence between FL280 and FL350 due to the location of CONT BYD 02Z THRU 08Z the jet stream. These conditions will begin after 0200Z and continue beyond the forecast scope of this SIGMET of 0530Z.

Explanation: AIRMET SIERRA was issued for the Boston area at 1945Z Convective Significant Meteorological Information on the 21st day of the month. SIERRA contains information (WST) on IFR and/or mountain obscurations. This is the third A Convective SIGMET (WST) is an inflight weather updated issuance of this Boston AIRMET series as indicated advisory issued for hazardous convective weather that affects by “SIERRA UPDT 3” and is valid until 0200Z on the the safety of every flight. Convective SIGMETs are issued 22nd. The affected states within the BOS area are: Maine, for severe thunderstorms with surface winds greater than 50 New Hampshire, Vermont, Massachusetts, New York, and knots, hail at the surface greater than or equal to ¾ inch in Pennsylvania. Within an area bounded by: Caribou, ME; diameter, or tornadoes. They are also issued to advise pilots to Saint Johns, New Brunswick; to 150 nautical miles east of embedded thunderstorms, lines of thunderstorms, or of Nantucket, MA; to Newark, NJ; to Ottawa, Ontario; thunderstorms with heavy or greater precipitation that affect to Caribou, ME. The effected states within Caribou, ME 40 percent or more of a 3,000 square mile or greater region.

to Millinocket, ME to Concord, NH to Slate Run, PA to Syracuse, NY to Caribou, ME will experience ceilings Convective SIGMETs are issued for each area of the below 1,000 feet/visibility below 3 SM, precipitation/mist.

contiguous 48 states but not Alaska or Hawaii. Convective Conditions will continue beyond 0200Z through 0800Z.

SIGMETs are issued for the eastern (E), western (W), and central (C) United States. Each report is issued at 55 minutes SIGMET past the hour, but special Convective SIGMETs can be SIGMETs (WSs) are inflight advisories concerning non- issued during the interim for any reason. Each forecast is convective weather that is potentially hazardous to all valid for 2 hours. They are numbered sequentially each day aircraft. They report weather forecasts that include severe from 1–99, beginning at 00Z time. If no hazardous weather icing not associated with thunderstorms, severe or extreme exists, the convective SIGMET is still issued; however, it turbulence or clear air turbulence (CAT) not associated with states “CONVECTIVE SIGMET…NONE.” thunderstorms, dust storms or sandstorms that lower surface or inflight visibilities to below three miles, and volcanic ash.

Example: SIGMETs are unscheduled forecasts that are valid for 4 hours MKCC WST 221855 unless the SIGMET relates to a hurricane, in which case it CONVECTIVE SIGMET 20C is valid for 6 hours.

VALID UNTIL 2055Z ND SD A SIGMET is issued under an alphabetic identifier, from FROM 90W MOT-GFK-ABR-90W MOT November through Yankee. The first issuance of a SIGMET INTSFYG AREA SEV TS MOVG FROM 24045KT. TOPS is designated as an Urgent Weather SIGMET (UWS).

ABV FL450. WIND GUSTS TO 60KTS RPRTD.

Reissued SIGMETs for the same weather phenomenon are TORNADOES…HAIL TO 2 IN… WIND GUSTS TO sequentially numbered until the weather phenomenon ends.

65KTS POSS ND PTN Example: SFOR WS 100130 Explanation: SIGMET ROME02 VALID UNTIL 100530 Convective SIGMET was issued for the central portion of OR WA the United States on the 22nd at 1855Z. This is the 20th FROM SEA TO PDT TO EUG TO SEA Convective SIGMET issued on the 22nd for the central OCNL SEV CAT BTN FL280 AND FL350 EXPCD United States as indicated by “20C” and is valid until 2055Z.

DUE TO JTSTR.

The affected states are North and South Dakota, from 90 CONDS BGNG AFT 0200Z CONTG BYD 0530Z .

nautical miles west of Minot, ND; to Grand Forks, ND; to Aberdeen, SD; to 90 nautical miles west of Minot, ND. An Explanation: intensifying area of severe thunderstorms moving from 240 This is SIGMET Romeo 2, the second issuance for this degrees at 45 knots (to the northeast). Thunderstorm tops will weather phenomenon. It is valid until the 10th day of the be above FL 450. Wind gusts up to 60 knots were reported.

month at 0530Z time. This SIGMET is for Oregon and 13-12 Also reported were tornadoes, hail to 2 inches in diameter, and altitude is 6,000 feet for the forecast winds. In this case, wind gusts to 65 knots possible in the North Dakota portion. “2714” means the wind is forecast to be from 270° at a speed of 14 knots.

Winds and Temperature Aloft Forecast (FB) A six-digit group includes the forecast temperature aloft.

Winds and temperatures aloft forecasts (FB) provide wind The elevation at Denver (DEN) is 5,431 feet, so the lowest and temperature forecasts for specific locations throughout reportable altitude is 9,000 feet for the winds and temperature the United States, including network locations in Hawaii forecast. In this case, “2321-04” indicates the wind is forecast to and Alaska. The forecasts are made twice a day based on the be from 230° at a speed of 21 knots with a temperature of –4 °C.

radiosonde upper air observations taken at 0000Z and 1200Z.

Weather Charts Altitudes through 12,000 feet are classified as true altitudes, while altitudes 18,000 feet and above are classified as Weather charts are graphic charts that depict current or altitudes and are termed flight levels. Wind direction is forecast weather. They provide an overall picture of the always in reference to true north, and wind speed is given in United States and should be used in the beginning stages of knots. The temperature is given in degrees Celsius. No winds flight planning. Typically, weather charts show the movement are forecast when a given level is within 1,500 feet of the of major weather systems and fronts. Surface analysis, station elevation. Similarly, temperatures are not forecast for weather depiction, and significant weather prognostic charts any station within 2,500 feet of the station elevation.

are sources of current weather information. Significant weather prognostic charts provide an overall forecast weather If the wind speed is forecast to be greater than 99 knots but picture.

less than 199 knots, the computer adds 50 to the direction and subtracts 100 from the speed. To decode this type of data Surface Analysis Chart group, the reverse must be accomplished. For example, when The surface analysis chart depicts an analysis of the current the data appears as “731960,” subtract 50 from the 73 and surface weather. [Figure 13-10] This chart is transmitted add 100 to the 19, and the wind would be 230° at 119 knots every 3 hours and covers the contiguous 48 states and with a temperature of –60 °C. If the wind speed is forecast to adjacent areas. A surface analysis chart shows the areas of be 200 knots or greater, the wind group is coded as 99 knots.

high and low pressure, fronts, temperatures, dew points, wind For example, when the data appears as “7799,” subtract 50 directions and speeds, local weather, and visual obstructions.

from 77 and add 100 to 99, and the wind is 270° at 199 knots Surface weather observations for reporting points across or greater. When the forecast wind speed is calm, or less than the United States are also depicted on this chart. Each of 5 knots, the data group is coded “9900,” which means light these reporting points is illustrated by a station model.

and variable. [Figure 13-9] [Figure 13-11] A station model includes: • Sky cover—the station model depicts total sky cover Explanation of Figure 13-9: and is shown as clear, scattered, broken, overcast, or The heading indicates that this FB was transmitted on the obscured/partially obscured.

15th of the month at 1640Z and is based on the 1200Z upper • Sea level pressure—given in three digits to the nearest air data. The valid time is 1800Z on the same day and should be used for the period between 1400Z and 2100Z. The tenth of a millibar (mb). For 1,000 mbs or greater, prefix a 10 to the three digits. For less than 1,000 mbs, heading also indicates that the temperatures above FL240 are negative. Therefore, the minus sign will be omitted for prefix a 9 to the three digits.

all forecast temperatures above FL240.

• Pressure change/tendency—pressure change in tenths of mb over the past 3 hours. This is depicted directly A four-digit data group shows the wind direction in reference below the sea level pressure.

to true north and the wind speed in knots. The elevation at • Dew point—given in degrees Fahrenheit.

Amarillo, Texas (AMA) is 3,605 feet, so the lowest reportable • Present weather—over 100 different standard weather symbols are used to describe the current weather.

FB KWBC 151640 DATA BASED ON 151200Z • Temperature—given in degrees Fahrenheit.

VALID 151800Z FOR USE 1400-2100Z TEMPS NEGATIVE ABV 24000 • Wind—true direction of wind is given by the wind FB 3000 6000 9000 12000 18000 24000 30000 pointer line, indicating the direction from which the AMA 2714 2725+00 2625-04 2531-15 2542-27 265842 wind is blowing. A short barb is equal to 5 knots of DEN 2321-04 2532-08 2434-19 2441-31 235347 wind, a long barb is equal to 10 knots of wind, and a Figure 13-9. Winds and temperature aloft forecast.

pennant is equal to 50 knots.

13-13 Figure 13-10. Surface analysis chart.

Wind speed Total sky cover Wind direction Sea level pressure Temperature Pressure change in past 3 hours Present weather 28 / Pressure tendency Dew point

**

1. Total sky cover: Overcast 2. Temperature/dew point: 34 °F/32 °F 3. Wind: From the northwest at 20 knots (relative to true north) Examples of Wind Speed and Direction Plots NE/5 kts SW/10 kts Calm W/50 kts S/60 kts N/15 kts 4. Present weather: Continuous light snow 5. Sea level pressure: 1014.7 millibars (mb) Note: Pressure is always shown in 3 digits to the nearest tenth of a millibar.

For 1,000 mb or greater, prefix a “10” to the 3 digits For less than 1,000 mb, prefix a “9” to the 3 digits 6. Pressure change in past 3 hours: Increased steadily or unsteadily by 2.8 mb Figure 13-11. Sample station model and weather chart symbols.

13-14 Weather Depiction Chart ceiling height, weather, and obstructions to visibility, but does not include winds or pressure readings like the surface A weather depiction chart details surface conditions as analysis chart. A bracket ( ] ) symbol to the right of the station derived from METAR and other surface observations. The indicates the observation was made by an automated station.

weather depiction chart is prepared and transmitted by computer every 3 hours beginning at 0100Z time and is valid Significant Weather Prognostic Charts data for the forecast period. It is designed to be used for flight planning by giving an overall picture of the weather across Significant weather prognostic charts are available for low- level significant weather from the surface to FL 240 (24,000 the United States. [Figure 13-12] feet), also referred to as the 400 mb level and high-level significant weather from FL 250 to FL 630 (25,000 to 63,000 The weather depiction chart also provides a graphic display of IFR, VFR, and marginal VFR (MVFR) weather. Areas of feet). The primary concern of this discussion is the low-level significant weather prognostic chart.

IFR conditions (ceilings less than 1,000 feet and visibility less than three miles) are shown by a hatched area outlined The low-level chart is is a forecast of aviation weather by a smooth line. MVFR regions (ceilings 1,000 to 3,000 feet, visibility 3 to 5 miles) are shown by a nonhatched area hazards, primarily intended to be used as a guidance product for briefing the VFR pilot. The forecast domain covers the 48 outlined by a smooth line. Areas of VFR (no ceiling or ceiling greater than 3,000 feet and visibility greater than five miles) contiguous states, southern Canada and the coastal waters for altitudes below 24,000 ft. Low altitude Significant Weather are not outlined. Also plotted are fronts, troughs, and squall lines from the previous hours surface analysis chart. charts are issued four times daily and are valid at fixed times: 0000, 0600, 1200, and 1800 UTC. Each chart is divided on Weather depiction charts show a modified station model the left and right into 12 and 24 hour forecast intervals (based on the current NAM model available).

that provides sky conditions in the form of total sky cover, Figure 13-12. Weather depiction chart.

13-15 Effective September 1, 2015, the four-panel Low Level of a precipitation area, but the specific character of that area SFC-240 chart was replaced with a two-panel chart. The new (snow, rain, hail, VIRGA, etc.) cannot be determined. For two-panel chart will be the same as the top two panels in the this reason, ATC refers to all weather areas displayed on ATC former four-panel chart, depicting the freezing level and areas radar scopes as “precipitation.” of IFR, MVFR, and moderate or greater turbulence. The bottom two panels of the chart have been removed. In lieu of these ARTCC facilities normally use a Weather and Radar bottom two panels, an enhanced surface chart that includes Processor (WARP) to display a mosaic of data obtained fronts, pressure, precipitation type, precipitation intensity, and from multiple NEXRAD sites. There is a time delay between weather type, is displayed. The green precipitation polygons actual conditions and those displayed to the controller.

will be replaced by shaded precipitation areas using the The precipitation data on the ARTCC controller’s display National Digital Forecast Database (NDFD) weather grid. could be up to 6 minutes old. The WARP processor is only used in ARTCC facilities. All ATC facilities using radar Figure 13-13 depicts the new two-panel significant weather weather processors with the ability to determine precipitation prognostic chart, as well as the symbols typically used to intensity, describe the intensity to pilots as: depict precipitation. The two panels depict freezing levels, • Light turbulence, and low cloud ceilings and/or restrictions to • Moderate visibility (shown as contoured areas of MVFR and IFR conditions). These charts enable the pilot to pictorially • Heavy evaluate existing and potential weather hazards they may • Extreme encounter. Pilots can balance weather phenomena with their aircraft capability and skill set resulting in aeronautical When the WARP is not available, a second system, the decision-making appropriate to the flight. Prognostic charts narrowband Air Route Surveillance Radar (ARSR) can are an excellent source of information for preflight planning; display two distinct levels of precipitation intensity that however, this chart should be viewed in light of current is described to pilots as “MODERATE and “HEAVY TO conditions and specific local area forecasts.

EXTREME.” The 36- and 48-hour significant weather prognostic chart is ATC facilities that cannot display the intensity levels of an extension of the 12- and 24-hour forecast. This chart is precipitation due to equipment limitations describe the issued twice a day. It typically contains forecast positions and location of the precipitation area by geographic position or characteristics of pressure patterns, fronts, and precipitation.

position relative to the aircraft. Since the intensity level is not An example of a 36- and 48-hour surface prognostic chart is available, the controller states “INTENSITY UNKNOWN.” shown in Figure 13-14 .

ATC radar is not able to detect turbulence. Generally, ATC Radar Weather Displays turbulence can be expected to occur as the rate of rainfall or Although ATC systems cannot always detect the presence intensity of precipitation increases. Turbulence associated or absence of clouds, they can often determine the intensity with greater rates of precipitation is normally more severe than Figure 13-13. Significant weather prognostic chart.

13-16 Figure 13-14. 36- (top) and 48-hour (bottom) surface prognostic chart.

13-17 any associated with lesser rates of precipitation. Turbulence • Graphical cloud tops (CLD TOPS) should be expected to occur near convective activity, even • Graphical lightning strikes (LTNG) in clear air. Thunderstorms are a form of convective activity • Graphical storm cell movement (CELL MOV) that imply severe or greater turbulence. Operation within 20 miles of thunderstorms should be approached with great • NEXRAD radar coverage (information displayed with caution, as the severity of turbulence can be much greater than the NEXRAD data) the precipitation intensity might indicate.

• SIGMETs/AIRMETs (SIG/AIR) • Surface analysis to include city forecasts (SFC) Weather Avoidance Assistance To the extent possible, controllers will issue pertinent • County warnings (COUNTY) information on weather and assist pilots in avoiding such • Freezing levels (FRZ LVL) areas when requested. Pilots should respond to a weather • Hurricane track (CYCLONE) advisory by either acknowledging the advisory or by acknowledging the advisory and requesting an alternative • Temporary flight restrictions (TFR) course of action as follows: Pilots must be familiar with any EFD or MFD used and the • Request to deviate off course by stating the number data link weather products available on the display.

of miles and the direction of the requested deviation.

• Request a new route to avoid the affected area.

Weather Products Age and Expiration • Request a change of altitude.

The information displayed using a data link weather link is near real time but should not be thought of as instantaneous, • Request radar vectors around the affected areas.

up-to-date information. Each type of weather display is stamped with the age information on the MFD. The time is The controller’s primary function is to provide safe separation referenced from Zulu when the information was assembled at between aircraft. Any additional service, such as weather the ground station. The age should not be assumed to be the avoidance assistance, can only be provided to the extent time when the FIS received the information from the data link.

that it does not detract from the primary function. It’s also worth noting that the separation workload is generally greater Two types of weather are displayed on the screen: “current” than normal when weather disrupts the usual flow of traffic.

weather and forecast data. Current information is displayed ATC radar limitations and frequency congestion may also by an age while the forecast data has a data stamp in the form be a factor in limiting the controller’s capability to provide of “__ / __ __ : __.” [Figure 13-16] additional service.

The Next Generation Weather Radar System Electronic Flight Displays (EFD) /Multi- (NEXRAD) Function Display (MFD) Weather The NEXRAD system is comprised of a series of 159 Weather Many aircraft manufacturers now include data link weather Surveillance Radar–1988 Doppler (WSR-88D) sites situated services with new electronic flight display (EFD) systems.

throughout the United States, as well as selected overseas EFDs give a pilot access to many of the data link weather sites. The NEXRAD system is a joint venture between the services available.

United States Department of Commerce (DOC), the United States DOD, as well as the United States Department of Products available to a pilot on the display pictured in Transportation (DOT). The individual agencies that have Figure 13-15 are listed as follows. The letters in parentheses control over the system are the NWS, Air Force Weather indicate the soft key to press in order to access the data.

Agency (AFWA) and the FAA. [Figure 13-17] • Graphical NEXRAD data (NEXRAD) NEXRAD data for up to a 2,000 mile range can be displayed.

• Graphical METAR data (METAR) It is important to realize that the radar image is not real time • Textual METAR data and can be up to 5 minutes old. The NTSB has reported on 2 fatal accidents where in-cockpit NEXRAD mosaic imagery • Textual terminal aerodrome forecasts (TAF) was available to pilots operating near quickly-developing and • City forecast data fast-moving convective weather. In one of these accidents, • Graphical wind data (WIND) the images were from 6 to 8 minutes old. In some cases, NEXRAD data can age significantly by the time the mosaic • Graphical echo tops (ECHO T,,,OPS) image is created. In some extreme latency cases, the actual 13-18 Figure 13-15. Information page.

age of the oldest NEXRAD data in the mosaic can exceed does not show the age of the actual weather conditions, the age indication in the cockpit by 15 to 20 minutes. Even but rather the age of the mosaic image. The actual weather small-time differences between the age indicator and actual conditions could be up to 15 to 20 minutes OLDER than conditions can be important for safety of flight, especially the age indicated on the display. You should consider this when considering fast-moving weather hazards, quickly developing weather scenarios, and/or fast-moving aircraft.

At no time should the images be used as storm penetrating

NORTH UP

radar nor to navigate through a line of storms. The images display should only be used as a reference.

NEXRAD

NEXRAD radar is mutually exclusive of Topographic

RAIN

(TOPO), TERRAIN and STORMSCOPE. When NEXRAD is turned on, TOPO, TERRAIN, and STORMSCOPE are

H L

turned off because the colors used to display intensities are

E I

very similar.

MIX

A G

Lightning information is available to assist when NEXRAD V H

is enabled. This presents a more comprehensive picture of

Y T

SNOW

the weather in the surrounding area.

In addition to utilizing the soft keys to activate the NEXRAD display, the pilot also has the option of setting the desired

SIGMET

range. It is possible to zoom in on a specific area of the

__/__ __:__

display in order to gain a more detailed picture of the radar display. [Figure 13-18]

AIRMET

What Can Pilots Do? __/__ __:__

Remember that the in-cockpit NEXRAD display depicts Figure 13-16. List of weather products and the expiration times of each.

where the weather WAS, not where it IS. The age indicator 13-19 Figure 13-17. NEXRAD radar display.

Figure 13-18. NEXRAD radar display (500 mile range). The individual color gradients can be easily discerned and interpreted via the legend in the upper right corner of the screen. Additional information can be gained by pressing the LEGEND soft key, which displays the legend page.

13-20 potential delay when using in-cockpit NEXRAD capabilities, square indicates the strongest display return within that 1.24 as the movement and/or intensification of weather could mile square area.

adversely affect safety of flight.

AIRMET/SIGMET Display • Understand that the common perception of a “5-minute AIRMET/SIGMET information is available for the displayed latency” with radar data is not always correct.

viewing range on the MFD. Some displays are capable of • Get your preflight weather briefing! Having in-cockpit displaying weather information for a 2,000 mile range.

weather capabilities does not circumvent the need for AIRMETS/SIGMETS are displayed by dashed lines on the a complete weather briefing before takeoff.

map. [Figure 13-19] • Use all appropriate sources of weather information to The legend box denotes the various colors used to depict the make in-flight decisions.

AIRMETs, such as icing, turbulence, IFR weather, mountain • Let your fellow pilots know about the limitations of obscuration, and surface winds. [Figure 13-20] The great in-cockpit NEXRAD.

advantage of the graphically displayed AIRMET/SIGMET boundary box is the pilot can see the extent of the area that NEXRAD Abnormalities the advisory covers. The pilot does not need to manually plot Although NEXRAD is a compilation of stations across the points to determine the full extent of the coverage area.

the country, there can be abnormalities associated with the system. Some of the abnormalities are listed below.

Graphical METARs • Ground clutter METARs can be displayed on the MFD. Each reporting station that has a METAR/TAF available is depicted by a flag • Strobes and spurious radar data from the center of the airport symbol. Each flag is color coded • Sun strobes, when the radar antenna points directly at to depict the type of weather that is currently reported at that the sun station. A legend is available to assist users in determining what each flag color represents. [Figure 13-21] • Interference from buildings or mountains that may cause shadows The graphical METAR display shows all available reporting • Military aircraft that deploy metallic dust and may stations within the set viewing range. By setting the range reflect the radar signature knob up to a 2,000 mile range, pilots can pan around the display map to check the current conditions of various NEXRAD Limitations airports along the route of flight.

In addition to the abnormalities listed, the NEXRAD system does have some specific limitations.

By understanding what each colored flag indicates, a pilot can quickly determine where weather patterns display marginal Base Reflectivity weather, IFR, or areas of VFR. These flags make it easy to The NEXRAD base reflectivity does not provide adequate determine weather at a specific airport should the need arise information from which to determine cloud layers or type to divert from the intended airport of landing.

of precipitation with respect to hail versus rain. Therefore, a pilot may mistake rain for hail.

Data Link Weather Pilots now have the capability of receiving continuously In addition, the base reflectivity is sampled at the minimum updated weather across the entire country at any altitude.

antenna elevation angle. With this minimum angle, an No longer are pilots restricted by radio range or geographic individual site cannot depict high altitude storms directly isolations, such as mountains or valleys.

over the station. This leaves an area of null coverage if an adjacent site does not also cover the affected area.

In addition, pilots no longer have to request specific information from weather briefing personnel directly. When Resolution Display the weather becomes questionable, radio congestion often The resolution of the displayed data poses additional concerns increases, delaying the timely exchange of valuable inflight when the range is decreased. The minimum resolution for weather updates for a pilot’s specific route of flight. Flight NEXRAD returns is 1.24 miles. This means that when the Service Station (FSS) personnel can communicate with only display range is zoomed in to approximately ten miles, the one pilot at a time, which leaves other pilots waiting and individual square return boxes are more prevalent. Each flying in uncertain weather conditions. Data link weather 13-21 Figure 13-19. The AIRMET information box instructs the pilot to press the ENTER button soft key (ENT) to gain additional information on the selected area of weather. Once the ENTER soft key (ENT) is depressed, the specific textual information is displayed on the right side of the screen.

Figure 13-20. SIGMET/AIRMET legend display.

13-22 Figure 13-21. Graphical METAR legend display.

provides the pilot with a powerful resource for enhanced • Significant Meteorological Conditions (SIGMET) and situational awareness at any time. Due to continuous data link Convective SIGMET broadcasts, pilots can obtain a weather briefing by looking at • Status of Special Use Airspace (SUA) a display screen. Pilots have a choice between FAA-certified • Temporary Flight Restrictions (TFRs) devices or portable receivers as a source of weather data.

• Winds and Temperatures Aloft.

Data Link Weather Products • Pilot Reports (PIREPS) Flight Information Service- Broadcast (FIS-B) • TIS-B service status Flight Information Service–Broadcast (FIS-B) is a ground broadcast service provided through the Automatic Dependent The weather products provided by FIS-B are for information Surveillance–Broadcast (ADS-B) Services network over only. Therefore, these products do not meet the safety and the 978 MHz UAT data link. The FAA FIS-B system regulatory requirements of official weather products. The provides pilots and flight crews of properly-equipped aircraft weather products displayed on FIS-B should not be used with a flightdeck display of certain aviation weather and as primary weather products (i.e., aviation weather to meet aeronautical information which are listed below.

operational and safety requirements). Each aircraft system is • Aviation Routine Weather Reports (METARs) different and some of the data that is rendered can be up to • Special Aviation Reports (SPECIs) 20 or 30 minutes old and not current. Pilots should consult the individual equipment manuals for specific delay times.

• Terminal Area Forecasts (TAFs) and their amendments • NEXRAD (regional and CONUS) precipitation maps • Notice to Airmen (NOTAM) Distant and Flight Data Center • Airmen’s Meteorological Conditions (AIRMET) 13-23 creating a distraction. Pilots may need to adjust the Pilot Responsibility amount of information based on numerous factors It is important for pilots to understand the realization that the including, but not limited to, the phase of flight, single derived safety benefits of data link depends heavily upon the pilot operation, autopilot availability, class of airspace, pilot’s understanding of the specific system’s capabilities and and the weather conditions encountered.

limitations which are listed below.

• Product latency—be aware of the time stamp or “valid Chapter Summary until” time on the particular data link information While no weather forecast is guaranteed to be 100 percent displayed in the flightdeck. For example, since initial accurate, pilots have access to a myriad of weather information processing and transmission of NEXRAD data can on which to base flight decisions. Weather products available take several minutes, pilots must assume that data for preflight planning to en route information received over link weather information will always be a minimum the radio or via data link provide the pilot with the most of seven to eight minutes older than shown on the time accurate and up-to-date information available. Each report stamp and only use data link weather radar images for provides a piece of the weather puzzle. Pilots must use several broad strategic avoidance of adverse weather.

reports to get an overall picture and gain an understanding • Product update cycles—be aware of when and how of the weather that affects the safe completion of a flight.

often a product is updated as well as the Data Link Service Providers (DLSP) update rate for particular products.

• Indication of system failure—be aware of partial or total system failure indications.

• Coverage areas/service volume—coverage limitations are associated with the type of data link network being used. For example, ground-based systems that require a line-of-sight may have relatively limited coverage below 5,000 feet AGL. Satellite-based data link weather systems can have limitations stemming from whether the network is in geosynchronous orbit or low earth orbit. Also, NWS NEXRAD coverage has gaps, especially in the western states.

• Content/format—since service providers often refine or enhance data link products for flightdeck display, pilots must be familiar with the content, format, and meaning of symbols and displays (i.e., the legend) in the specific system.

• Data integrity/limitations to use—reliability of information depicted. Be aware of any applicable disclaimer provided by the service provider.

• Use of equipment/avionics display—pilots remain responsible for the proper use of an electronic flight bag (EFB) or installed avionics. Pilots should be cognizant that, per the FAA Practical Test Standards, they may be evaluated on the use and interpretation of an EFB or installed avionics on the aircraft.

• Overload of Information—most DLSPs offer numerous products with information that can be layered on top of each other. Pilots need to be aware that too much information can have a negative effect on their cognitive work load. Pilots need to manage the amount of information to a level that offers the most pertinent information to that specific flight without 13-24

Chapter 14

Airport

Operations

Introduction Each time a pilot operates an aircraft, the flight normally begins and ends at an airport. An airport may be a small sod field or a large complex utilized by air carriers. This chapter examines airport operations, identifies features of an airport complex, and provides information on operating on or in the vicinity of an airport.

Airport Categories The definition for airports refers to any area of land or water used or intended for landing or takeoff of aircraft. This includes, within the five categories of airports listed below, special types of facilities including seaplane bases, heliports, and facilities to accommodate tilt rotor aircraft. An airport includes an area used or intended for airport buildings, facilities, as well as rights of way together with the buildings and facilities.

14-1 The law defines airports by categories of airport activities, Towered Airport including commercial service, primary, cargo service, A towered airport has an operating control tower. Air traffic reliever, and general aviation airports, as shown below: control (ATC) is responsible for providing the safe, orderly, and expeditious flow of air traffic at airports where the • Commercial Service Airports—publicly owned type of operations and/or volume of traffic requires such a airports that have at least 2,500 passenger boardings service. Pilots operating from a towered airport are required each calendar year and receive scheduled passenger to maintain two-way radio communication with ATC and to service. Passenger boardings refer to revenue passenger acknowledge and comply with their instructions. Pilots must boardings on an aircraft in service in air commerce advise ATC if they cannot comply with the instructions issued whether or not in scheduled service. The definition and request amended instructions. A pilot may deviate from also includes passengers who continue on an aircraft an air traffic instruction in an emergency, but must advise in international flight that stops at an airport in any of ATC of the deviation as soon as possible.

the 50 States for a non-traffic purpose, such as refueling or aircraft maintenance rather than passenger activity.

Nontowered Airport Passenger boardings at airports that receive scheduled passenger service are also referred to as Enplanements.

A nontowered airport does not have an operating control tower. Two-way radio communications are not required, • Cargo Service Airports—airports that, in addition to any although it is a good operating practice for pilots to transmit other air transportation services that may be available, their intentions on the specified frequency for the benefit are served by aircraft providing air transportation of of other traffic in the area. The key to communicating at an only cargo with a total annual landed weight of more airport without an operating control tower is selection of the than 100 million pounds. “Landed weight” means the correct common frequency. The acronym CTAF, which stands weight of aircraft transporting only cargo in intrastate, for Common Traffic Advisory Frequency, is synonymous interstate, and foreign air transportation. An airport with this program. A CTAF is a frequency designated for may be both a commercial service and a cargo service the purpose of carrying out airport advisory practices while airport.

operating to or from an airport without an operating control • Reliever Airports—airports designated by the FAA tower. The CTAF may be a Universal Integrated Community to relieve congestion at Commercial Service Airports (UNICOM), MULTICOM, Flight Service Station (FSS), or and to provide improved general aviation access to the tower frequency and is identified in appropriate aeronautical overall community. These may be publicly or privately- publications. UNICOM is a nongovernment air/ground radio owned.

communication station that may provide airport information • General Aviation Airports — the remaining airports at public use airports where there is no tower or FSS. On pilot request, UNICOM stations may provide pilots with weather are commonly described as General Aviation Airports.

This airport type is the largest single group of airports information, wind direction, the recommended runway, or other necessary information. If the UNICOM frequency in the U.S. system. The category also includes privately owned, public use airports that enplane 2500 or more is designated as the CTAF, it is identified in appropriate aeronautical publications. Figure 14-1 lists recommended passengers annually and receive scheduled airline service. communication procedures. More information regarding radio communications is provided later in this chapter.

Types of Airports Nontowered airport traffic patterns are always entered at There are two types of airports—towered and nontowered.

pattern altitude. How you enter the pattern depends upon the These types can be further subdivided to: direction of arrival. The preferred method for entering from • Civil Airports—airports that are open to the general the downwind side of the pattern is to approach the pattern public.

on a course 45 degrees to the downwind leg and join the pattern at midfield.

• Military/Federal Government airports—airports operated by the military, National Aeronautics and There are several ways to enter the pattern if you’re coming Space Administration (NASA), or other agencies of from the upwind leg side of the airport. One method of entry the Federal Government.

from the opposite side of the pattern is to announce your • Private Airports—airports designated for private or intentions and cross over midfield at least 500 feet above restricted use only, not open to the general public.

14-2 Communication/Broadcast Procedures Facility at Airport Frequency Use Practice Instrument Outbound Inbound Approach UNICOM Before taxiing and Communicate with UNICOM 10 miles out.

(no tower or FSS) before taxiing on the Entering downwind, station on published CTAF runway for departure.

frequency (122.7, 122.8, 122.725, base, and final.

122.975, or 123.0). If unable to Leaving the runway.

contact UNICOM station, use self- announce procedures on CTAF.

No tower, FSS, Before taxiing and Self-announce on MULTICOM 10 miles out. Departing final or UNICOM before taxiing on the frequency 122.9. Entering downwind, approach fix (name) runway for departure. base, and final. or on final approach Leaving the runway. segment inbound.

No tower in Before taxiing and Communicate with FSS on CTAF 10 miles out. Approach operation, FSS open before taxiing on the frequency. Entering downwind, completed/terminated.

runway for departure. base, and final.

Leaving the runway.

FSS closed Before taxiing and Self-announce on CTAF. 10 miles out.

(no tower) before taxiing on the Entering downwind, runway for departure. base, and final.

Leaving the runway.

Tower or FSS Before taxiing and Self-announce on CTAF. 10 miles out.

not in operation before taxiing on the Entering downwind, runway for departure. base, and final.

Leaving the runway.

Figure 14-1. Recommended communication procedures.

pattern altitude (normally 1,500 feet AGL.) However, if large or pilot with information, such as communication frequencies, turbine aircraft operate at your airport, it is best to remain 2,000 services available, closed runways, or airport construction.

feet AGL so you are not in conflict with their traffic pattern. Three common sources of information are: When well clear of the pattern—approximately 2 miles–scan • Aeronautical Charts carefully for traffic, descend to pattern altitude, then turn right • Chart Supplement U.S. (formerly Airport/Facility to enter at 45° to the downwind leg at midfield. [Figure 14-2] Directory) An alternate method is to enter on a midfield crosswind at • Notices to Airmen (NOTAMs) pattern altitude, carefully scan for traffic, announce your • Automated Terminal Information Service (ATIS) intentions, and then turn downwind. [Figure 14-3] This technique should not be used if the pattern is busy. Always Aeronautical Charts remember to give way to aircraft on the preferred 45° entry Aeronautical charts provide specific information on airports.

and to aircraft already established on downwind.

Chapter 16, “Navigation,” contains an excerpt from an aeronautical chart and an aeronautical chart legend, which In either case, it is vital to announce your intentions, and provides guidance on interpreting the information on the chart.

remember to scan outside. Before joining the downwind leg, adjust your course or speed to blend into the traffic.

Chart Supplement U.S. (formerly Airport/Facility Adjust power on the downwind leg, or sooner, to fit into Directory) the flow of traffic. Avoid flying too fast or too slow. Speeds The Chart Supplement U.S. (formerly Airport/Facility recommended by the airplane manufacturer should be used.

Directory) provides the most comprehensive information on They will generally fall between 70 to 80 knots for fixed-gear a given airport. It contains information on airports, heliports, singles and 80 to 90 knots for high-performance retractable.

and seaplane bases that are open to the public. The Chart Supplement U.S. is published in seven books, which are Sources for Airport Data organized by regions and are revised every 56 days. The When a pilot flies into a different airport, it is important to Chart Supplement U.S. is also available digitally at www.

review the current data for that airport. This data provides the 14-3 Pattern altitude Pattern altitude +500 feet Fly clear of traffic pattern (approx. 2 mi.)

Yield to downwind traffic and enter Yield to the preferred midfield 45° and downwind downwind traffic, then turn at 45° downwind Descend to pattern altitude, then turn Figure 14-2. Preferred Entry-Crossing Midfield. Figure 14-3. Alternate Midfield Entry.

faa.gov/air_traffic/flight_info/aeronav. Figure 14-4 contains an excerpt from a directory. For a complete listing of information provided in a Chart Supplement U.S.

and how the information may be decoded, refer to the “Legend Sample” located in the front of each Chart Supplement U.S.

In addition to airport information, each Chart Supplement U.S. contains information such as special notices, Federal Aviation Administration (FAA) and National Weather Service (NWS) telephone numbers, preferred instrument flight rules (IFR) routing, visual flight rules (VFR) waypoints, a listing of very high frequency (VHF) omnidirectional range (VOR) receiver checkpoints, aeronautical chart bulletins, land and hold short operations (LAHSO) for selected airports, airport diagrams for selected towered airports, en route flight advisory service (EFAS) outlets, parachute jumping areas, and facility telephone numbers. It is beneficial to review a Chart Supplement U.S. to become familiar with the information it contains.

Notices to Airmen (NOTAM) Time-critical aeronautical information, which is of a temporary nature or not sufficiently known in advance to permit Figure 14-4. Chart Supplement U.S. (formerly Airport/Facility publication, on aeronautical charts or in other operational Directory excerpt.

14-4 publications receives immediate dissemination by the “Aeronautical Lighting and Other Airport Visual Aids,” of NOTAM system. The NOTAM information could affect your the Aeronautical Information Manual (AIM).

decision to make the flight. It includes such information as taxiway and runway closures, construction, communications, Runway Markings and Signs changes in status of navigational aids, and other information Runway markings vary depending on the type of operations essential to planned en route, terminal, or landing operations.

conducted at the airport. A basic VFR runway may only Exercise good judgment and common sense by carefully have centerline markings and runway numbers. Refer to regarding the information readily available in NOTAMs.

Appendix C of this publication for an example of the most common runway markings that are found at airports.

Prior to any flight, pilots should check for any NOTAMs that could affect their intended flight. For more information on Since aircraft are affected by the wind during takeoffs and NOTAMs, refer back to Chapter 1, “Pilot and Aeronautical landings, runways are laid out according to the local prevailing Information” section. winds. Runway numbers are in reference to magnetic north.

Certain airports have two or even three runways laid out in the Automated Terminal Information Service (ATIS) same direction. These are referred to as parallel runways and The Automated Terminal Information Service (ATIS) is a are distinguished by a letter added to the runway number (e.g., recording of the local weather conditions and other pertinent runway 36L (left), 36C (center), and 36R (right)).

non-control information broadcast on a local frequency in a looped format. It is normally updated once per hour but is Relocated Runway Threshold updated more often when changing local conditions warrant.

It is sometimes necessary, due to construction or runway Important information is broadcast on ATIS including maintenance, to close only a portion of a runway. When weather, runways in use, specific ATC procedures, and any a portion of a runway is closed, the runway threshold is airport construction activity that could affect taxi planning.

relocated as necessary. It is referred to as a relocated threshold and methods for identifying the relocated threshold vary. A When the ATIS is recorded, it is given a code. This code is common way for the relocated threshold to be marked is changed with every ATIS update. For example, ATIS Alpha a ten foot wide white bar across the width of the runway.

is replaced by ATIS Bravo. The next hour, ATIS Charlie is [Figure 14-5A and B] recorded, followed by ATIS Delta and progresses down the alphabet.

When the threshold is relocated, the closed portion of the runway is not available for use by aircraft for takeoff or Prior to calling ATC, tune to the ATIS frequency and listen to landing, but it is available for taxi. When a threshold is the recorded broadcast. The broadcast ends with a statement relocated, it closes not only a set portion of the approach containing the ATIS code. For example, “Advise on initial end of a runway, but also shortens the length of the opposite contact, you have information Bravo.” Upon contacting the direction runway. Yellow arrow heads are placed across the tower controller, state information Bravo was received. This width of the runway just prior to the threshold bar.

allows the tower controller to verify the pilot has the current local weather and airport information without having to Displaced Threshold state it all to each pilot who calls. This also clears the tower A displaced threshold is a threshold located at a point on frequency from being overtaken by the constant relay of the runway other than the designated beginning of the the same information, which would result without an ATIS runway. Displacement of a threshold reduces the length broadcast. The use of ATIS broadcasts at departure and arrival of runway available for landings. The portion of runway airports is not only a sound practice but a wise decision.

behind a displaced threshold is available for takeoffs in either direction, or landings from the opposite direction. A ten feet Airport Markings and Signs wide white threshold bar is located across the width of the There are markings and signs used at airports that provide runway at the displaced threshold, and white arrows are directions and assist pilots in airport operations. It is important located along the centerline in the area between the beginning for you to know the meanings of the signs, markings, and lights of the runway and displaced threshold. White arrow heads that are used on airports as surface navigational aids. All airport are located across the width of the runway just prior to the markings are painted on the surface, whereas some signs are threshold bar. [Figure 14-6A and B] vertical and some are painted on the surface. An overview of the most common signs and markings are described on the following pages. Additional information may be found in Chapter 2, 14-5 A B Figure 14-5. (A) Relocated runway threshold drawing. (B) Relocated threshold for Runway 36 at Joplin Regional Airport (JLN).

Runway Safety Area Runway Safety Area Boundary Sign The runway safety area (RSA) is a defined surface Some taxiway stubs also have a runway safety area boundary surrounding the runway prepared, or suitable, for reducing sign that faces the runway and is visible to you only when the risk of damage to airplanes in the event of an undershoot, exiting the runway. This sign has a yellow background with overshoot, or excursion from the runway. The dimensions black markings and is typically used at towered airports of the RSA vary and can be determined by using the where a controller commonly requests you to report clear of criteria contained within AC 150/5300-13, Airport Design, a runway. This sign is intended to provide you with another Chapter 3. Figure 3-1 in AC 150/5300-13 depicts the RSA. visual cue that is used as a guide to determine when you are Additionally, it provides greater accessibility for firefighting clear of the runway safety boundary area. The sign shown in and rescue equipment in emergency situations. Figure 14-8 is what you would see when exiting the runway at Taxiway Kilo. You are out of the runway safety area boundary The RSA is typically graded and mowed. The lateral when the entire aircraft passes the sign and the accompanying boundaries are usually identified by the presence of the surface painted marking.

runway holding position signs and markings on the adjoining taxiway stubs. Aircraft should not enter the RSA without Runway Holding Position Sign making sure of adequate separation from other aircraft during Noncompliance with a runway holding position sign may operations at uncontrolled airports. [Figure 14-7] result in the FAA filing a Pilot Deviation against you. A 14-6 A B

×

×

Figure 14-6. (A) Displaced runway threshold drawing. (B) Displaced threshold for Runway 17 at Albuquerque International Airport (ABQ).

runway holding position sign is an airport version of a stop sign. [Figure 14-9] It may be seen as a sign and/or its characters painted on the airport pavement. The sign has white characters outlined in black on a red background. It is always collocated with the surface painted holding position markings and is located where taxiways intersect runways.

On taxiways that intersect the threshold of the takeoff runway, only the designation of the runway may appear on the sign.

If a taxiway intersects a runway somewhere other than at the threshold, the sign has the designation of the intersecting runway. The runway numbers on the sign are arranged to correspond to the relative location of the respective runway Figure 14-8. Runway safety area boundary sign and marking located thresholds. Figure 14-10 shows “18-36” to indicate the on Taxiway Kilo.

threshold for Runway 18 is to the left and the threshold for 9 C Typical Runway Safety Area 27 B 9 A Figure 14-9. Runway holding position sign at takeoff end of Runway Figure 14-7. Runway Safety Area. 14 with collocated Taxiway Alpha location sign.

14-7 Runway Holding Position Marking Noncompliance with a runway holding position marking may result in the FAA filing a Pilot Deviation against you.

Runway holding position markings consist of four yellow lines, two solid and two dashed, that are painted on the surface and extend across the width of the taxiway to indicate where the aircraft should stop when approaching a runway. These markings are painted across the entire taxiway pavement, are in alignment, and are collocated with the holding position sign as described above.

Figure 14-10. Runway holding position sign at a location other As you approach the runway, two solid yellow lines and two than the takeoff end of Runway 18-36 with collocated Taxiway dashed lines will be visible. Prior to reaching the solid lines, it Alpha location sign.

is imperative to stop and ensure that no portion of the aircraft intersects the first solid yellow line. Do not cross the double Runway 36 is to the right. The sign also indicates that you solid lines until a clearance from ATC has been received.

are located on Taxiway Alpha.

[Figure 14-13] When the tower is closed or when operating at a nontowered airport, you may taxi onto or across the runway If the runway holding position sign is located on a taxiway only when the runway is clear and there are no aircraft on final at the intersection of two runways, the designations for approach. You should use extreme caution when crossing or both runways are shown on the sign along with arrows taxiing onto the runway and always look both ways.

showing the approximate alignment of each runway.

[Figure 14-11A and B] In addition to showing the When exiting the runway, the same markings will be seen approximate runway alignment, the arrows indicate the except the aircraft will be approaching the double dashed direction(s) to the threshold of the runway whose designation lines. [Figure 14-14] In order to be clear of the runway, the is immediately next to each corresponding arrow.

entire aircraft must cross both the dashed and solid lines.

An ATC clearance is not needed to cross this marking when This type of taxiway and runway/runway intersection exiting the runway.

geometry can be very confusing and create navigational challenges. Extreme caution must be exercised when taxiing Runway Distance Remaining Signs onto or crossing this type of intersection. Figure 14-11A and Runway distance remaining signs have a black background B shows a depiction of a taxiway, runway/runway intersection with a white number and may be installed along one or both and is also designated as a “ hot spot ” on the airport diagram.

sides of the runway. [Figure 14-15] The number on the In the example, Taxiway Bravo intersects with two runways, signs indicates the distance, in thousands of feet, of landing 31-13 and 35-17, which cross each other.

runway remaining. The last sign, which has the numeral “1,” is located at least 950 feet from the runway end.

Surface painted runway holding position signs may also be used to aid you in determining the holding position. These Runway Designation Marking markings consist of white characters on a red background Runway numbers and letters are determined from the and are painted on the left side of the taxiway centerline.

approach direction. The runway number is the whole number Figure 14-12 shows a surface painted runway holding nearest one-tenth the magnetic azimuth of the centerline of the position sign that is the holding point for Runway 32R-14L.

runway, measured clockwise from the magnetic north. In the case where there are parallel runways, the letters differentiate You should never allow any part of your aircraft to cross the between left (L), right (R), or center (C). [Figure 14-16] For runway holding position sign (either a vertical or surface example, if there are two parallel runways, they would show painted sign) without a clearance from ATC. Doing so poses the designation number and then either L or R beneath it.

a hazard to yourself and others.

For three parallel runways, the designation number would be presented with L, C, or R beneath it.

When the tower is closed or you are operating at a nontowered airport, you may taxi past a runway holding position sign only when the runway is clear of aircraft, and there are no aircraft on final approach. You may then proceed with extreme caution.

14-8 A Runway 13 B Runway 31 B 31-13 35-17 35-17 31-13 N C- 3, 08 MAR 2012 to 05 APR 2012 3, 08 MAR 2012 to 05 APR 2012 C- N

Not to be used for navigation

Figure 14-11. (A) Taxiway Bravo location sign collocated with runway/runway intersection holding signs at Sioux Gateway Airport (SUX) (B) Airport diagram of Sioux Gateway Airport (SUX), Sioux City, Iowa. The area outlined in red is a designated “ hot spot ” (HS1).

14-9 Figure 14-12. Surface painted runway holding position signs for Runway 32R-14L along with the enhanced taxiway centerline marking.

Figure 14-15. Runway distance remaining sign indicating that there is 2,000 feet of runway remaining.

compliance. As pilot in command (PIC), you have the final authority to accept or decline any LAHSO clearance.

If issued a land and hold short clearance, you must be aware of the reduced runway distances and whether or not you can comply before accepting the clearance. You do not have to accept a LAHSO clearance. Pilots should only receive a LAHSO clearance when there is a minimum ceiling of 1,000 feet and 3 statute miles of visibility.

Runway holding position signs and markings are installed Figure 14-13. Surface painted holding position marking along with on those runways used for LAHSO. The signs and markings enhanced taxiway centerline.

are placed at the LAHSO point to aid you in determining where to stop and hold the aircraft and are located prior to the runway/runway intersection. [Figure 14-17] The holding position sign has a white inscription with black border around the numbers on a red background and is installed adjacent to the holding position markings. If you accept a land and hold short clearance, you must comply so that no portion of the aircraft extends beyond these hold markings.

If receiving “cleared to land” instructions from ATC, you are authorized to use the entire landing length of the runway and should disregard any LAHSO holding position markings located on the runway. If you receive and accept LAHSO instructions, you must stop short of the intersecting runway Figure 14-14. Runway holding position markings as seen when prior to the LAHSO signs and markings.

exiting the runway. When exiting the runway, no ATC clearance is required to cross.

Below is a list of items which, if thoroughly understood and complied with, will ensure that LAHSO operations are Land and Hold Short Operations (LAHSO) conducted properly.

When simultaneous operations (takeoffs and landings) are • Know landing distance available.

being conducted on intersecting runways, Land and Hold • Be advised by ATC as to why LAHSO are being Short Operations (LAHSO) may also be in effect. LAHSO conducted.

is an ATC procedure that may require your participation and 14-10

35 35

L C

Figure 14-16. Two of three parallel runways.

• Advise ATC if you cannot comply with LAHSO. If you accept the following clearance from ATC: “Cleared to land Runway 36 hold short of Runway 23,” you must either exit • Know what signs and markings are at the LAHSO point.

Runway 36 or stop at the holding position prior to Runway 23.

• LAHSO are not authorized for student pilots who are performing a solo flight.

Taxiway Markings and Signs • At many airports air carrier aircraft are not authorized Taxiway direction signs have a yellow background and black characters, which identifies the designation or to participate in LAHSO if the other aircraft is a general aviation aircraft. intersecting taxiways. Arrows indicate the direction of turn that would place the aircraft on the designated taxiway.

• Generally, LAHSO are not authorized at night.

[Figure 14-18] Direction signs are normally located on • LAHSO are not authorized on wet runways.

the left side of the taxiway and prior to the intersection.

These signs and markings (with a yellow background and black characters) indicate the direction toward a different taxiway, leading off a runway, or out of an intersection.

Figure 14-18 shows Taxiway Delta and how Taxiway Bravo intersects ahead at 90° both left and right.

Taxiway direction signs can also be displayed as surface painted markings. Figure 14-19 shows Taxiway Bravo as proceeding straight ahead while Taxiway Alpha turns to the right at approximately 45°.

Figure 14-17. Runway holding position sign and marking for LAHSO.

14-11 signs always have an arrow showing the direction of the taxi route to that destination. [Figure 14-22] When the arrow on the destination sign indicates a turn, the sign is located prior to the intersection. Destinations commonly shown on these types of signs include runways, aprons, terminals, military areas, civil aviation areas, cargo areas, international areas, and fixed-base operators. When the inscription for two or more destinations having a common taxi route are placed on a sign, the destinations are separated by a “dot” (•) and one arrow would be used as shown in Figure 14-22. When the inscription on a sign contains two or more destinations having different taxi routes, each destination is accompanied by an arrow and separated from the other destination(s) on the sign with a vertical black message divider as shown in Figure 14-18. Taxiway Bravo direction sign with a collocated Figure 14-23. The example shown in Figure 14-23 shows Taxiway Delta location sign. When the arrow on the direction two signs. The sign in the foreground explains that Runway sign indicates a turn, the sign is located prior to the intersection.

20 threshold is to the left, and Runways 32, 2, and 14 are to the right. The sign in the background indicates that you are Figure 14-20A and B shows an example of a direction sign at located on Taxiway Bravo and Taxiway November will take a complex taxiway intersection. Figure 14-20A and B shows you to those runways.

Taxiway Bravo intersects with Taxiway Sierra at 90°, but at 45° with Taxiway Foxtrot. This type of array can be displayed Holding Position Signs and Markings for an with or without the taxiway location sign, which in this case Instrument Landing System (ILS) Critical Area would be Taxiway Bravo.

The instrument landing system (ILS) broadcasts signals to arriving instrument aircraft to guide them to the runway. Each Enhanced Taxiway Centerline Markings of these ILSs have critical areas that must be kept clear of all At most towered airports, the enhanced taxiway centerline obstacles in order to ensure quality of the broadcast signal. At marking is used to warn you of an upcoming runway. It consists many airports, taxiways extend into the ILS critical area. Most of yellow dashed lines on either side of the normal solid taxiway of the time, this is of no concern; however, during times of centerline and the dashes extend up to 150 feet prior to a poor weather, an aircraft on approach may depend on a good runway holding position marking. [Figure 14-21A and B] They signal quality. When necessary, ATC will protect the ILS are used to aid you in maintaining awareness during surface critical area for arrival instrument traffic by instructing taxiing m ov ement to reduce runway incursions.

aircraft to “ hold short ” of Runway (XX) ILS critical area.

Destination Signs The ILS critical area hold sign has white characters, outlined Destination signs have black characters on a yellow in black, on a red background and is installed adjacent to the background indicating a destination at the airport. These ILS holding position markings. [Figure 14-24] The holding position markings for the ILS critical area appear on the pavement as a horizontal yellow ladder extending across the width of the taxiway.

When instructed to “hold short of Runway (XX) ILS critical area,” you must ensure no portion of the aircraft extends beyond these markings. [Figure 14-25] If ATC does not instruct you to hold at this point, then you may bypass the ILS critical area hold position markings and continue with your taxi. Figure 14-24 shows that the ILS hold sign is located on Taxiway Golf and the ILS ladder hold position marking is adjacent to the hold sign.

Figure 14-19. Surface painted taxiway direction signs.

14-12 A F S S A F S S B F F B Figure 14-20. Orientation of signs is from left to right in a clockwise manner. Left turn signs are on the left and right turn on the right.

Enhanced taxiway centerline marking extends 150 feet prior to a runway holding position marking. Prepare to STOP .

In this view, the pilot is on Taxiway Bravo.

B A B Enhanced taxiway centerline marking extends 150 feet prior to a runway holding position marking. Prepare to STOP .

Prepare to STOP unless you have been cleared onto or across the runway by ATC.

B Figure 14-21. (A) Enhanced taxiway centerline marking. (B) Enhanced taxiway centerline marking and runway holding position marking.

14-13 ILS Figure 14-22. Destination sign to the fixed-base operator (FBO).

The yellow surface Hold only ILS Critical Area boundary painted “ladder” when marking and red ILS specifically sign are located instructed by ATC on taxiways where the taxiways intersect the ILS critical area.

Figure 14-25. Holding position sign and marking for instrument landing system (ILS) critical area boundary.

Holding Position Markings for Taxiway/Taxiway Intersections Holding position markings for taxiway/taxiway intersections consist of a single dashed yellow line extending across the width of the taxiway. [Figure 14-26] They are painted on Figure 14-23. Runway destination sign with different taxi routes.

taxiways where ATC normally holds aircraft short of a taxiway intersection. When instructed by ATC “hold short of Taxiway X,” you should stop so that no part of your aircraft extends beyond the holding position marking. When the marking is not present, you should stop your aircraft at a point that provides adequate clearance from an aircraft on the intersecting taxiway.

Marking and Lighting of Permanently Closed Runways and Taxiways For runways and taxiways that are permanently closed, the lighting circuits are disconnected. The runway threshold, runway designation, and touchdown markings are obliterated and yellow “Xs” are placed at each end of the runway and at 1,000-foot intervals.

Figure 14-24. Instrument landing system (ILS) holding position sign and marking on Taxiway Golf.

14-14 B A G B G G G B G B Figure 14-26. Holding position marking on a taxiway.

B Temporarily Closed Runways and Taxiways For temporarily closed runways and taxiways, a visual indication is often provided with yellow “Xs” or raised lighted yellow “Xs” placed at each end of the runway.

Depending on the reason for the closure, duration of closure, airfield configuration, and the existence and the hours of operation of an ATC tower, a visual indication may not be present. As discussed previously in the chapter, you must always check NOTAMs and ATIS for runway and taxiway closure information.

Figure 14-27A shows an example of a yellow “X” laid flat with an adequate number of heavy sand bags to keep the wind from getting under and displacing the vinyl material.

C A very effective and preferable visual aid to depict temporary closure is the lighted “X” placed on or near the runway designation numbers. [Figure 14-27B and C] This device is much more discernible to approaching aircraft than the other materials described above.

Other Markings Some other markings found on the airport include vehicle roadway markings, VOR receiver checkpoint markings, and non-movement area boundary markings.

Airport Signs Figure 14-27. (A) Yellow “X” placed on surface of temporarily closed There are six types of signs that may be found at airports. The runways. (B) Lighted “X” placed on temporarily closed runways.

more complex the layout of an airport, the more important (C) Lighted “X” at night showing a temporarily closed runway.

the signs become to pilots. Appendix C of this publication shows examples of some signs that are found at most airports, • Location signs—black with yellow inscription and a their purpose, and appropriate pilot action. The six types of yellow border, no arrows. They are used to identify a signs are: taxiway or runway location, to identify the boundary • Mandatory instruction signs—red background with of the runway, or identify an instrument landing white inscription. These signs denote an entrance to a system (ILS) critical area.

runway, critical area, or prohibited area.

14-15 • Direction signs—yellow background with black inscription. The inscription identifies the designation of the intersecting taxiway(s) leading out of an White Green intersection. White Yellow • Destination signs—yellow background with black inscription and arrows. These signs provide information on locating areas, such as runways, terminals, cargo areas, and civil aviation areas.

• Information signs—yellow background with black inscription. These signs are used to provide the pilot with information on areas that cannot be seen from the control tower, applicable radio frequencies, and noise Figure 14-28. Airport rotating beacons.

abatement procedures. The airport operator determines the need, size, and location of these signs.

runway is a precision or nonprecision instrument runway.

• Runway distance remaining signs—black background Some systems include sequenced flashing lights that appear with white numbers. The numbers indicate the to the pilot as a ball of light traveling toward the runway at distance of the remaining runway in thousands of feet.

high speed. Approach lights can also aid pilots operating under VFR at night.

Airport Lighting Visual Glideslope Indicators The majority of airports have some type of lighting for night Visual glideslope indicators provide the pilot with glidepath operations. The variety and type of lighting systems depends information that can be used for day or night approaches. By on the volume and complexity of operations at a given airport.

maintaining the proper glidepath as provided by the system, Airport lighting is standardized so that airports use the same a pilot should have adequate obstacle clearance and should light colors for runways and taxiways.

touch down within a specified portion of the runway.

Airport Beacon Visual Approach Slope Indicator (VASI) Airport beacons help a pilot identify an airport at night.

The beacons are normally operated from dusk until dawn. VASI installations are the most common visual glidepath Sometimes they are turned on if the ceiling is less than 1,000 systems in use. The VASI provides obstruction clearance feet and/or the ground visibility is less than 3 statute miles (VFR within 10° of the extended runway centerline and up to four minimums). However, there is no requirement for this, so a nautical miles (NM) from the runway threshold.

pilot has the responsibility of determining if the weather meets VFR requirements. The beacon has a vertical light distribution The VASI consists of light units arranged in bars. There are to make it most effective from 1–10° above the horizon, 2-bar and 3-bar VASIs. The 2-bar VASI has near and far light although it can be seen well above or below this spread. The bars and the 3-bar VASI has near, middle, and far light bars.

beacon may be an omnidirectional capacitor-discharge device, Two-bar VASI installations provide one visual glidepath or it may rotate at a constant speed, that produces the visual that is normally set at 3°. The 3-bar system provides two effect of flashes at regular intervals. The combination of light glidepaths, the lower glidepath normally set at 3° and the colors from an airport beacon indicates the type of airport. upper glidepath ¼ degree above the lower glidepath.

[Figure 14-28] Some of the most common beacons are: The basic principle of the VASI is that of color differentiation • Flashing white and green for civilian land airports between red and white. Each light unit projects a beam of • Flashing white and yellow for a water airport light, a white segment in the upper part of the beam and a red segment in the lower part of the beam. The lights are • Flashing white, yellow, and green for a heliport arranged so the pilot sees the combination of lights shown in • Two quick white flashes alternating with a green flash Figure 14-29 to indicate below, on, or above the glidepath.

identifying a military airport Other Glidepath Systems Approach Light Systems A precision approach path indicator (PAPI) uses lights similar Approach light systems are primarily intended to provide a to the VASI system, except they are installed in a single row, means to transition from instrument flight to visual flight for normally on the left side of the runway. [Figure 14-30] landing. The system configuration depends on whether the 14-16 light. The “slightly below glidepath” indication is a steady red On Glidepath Below Glidepath Above Glidepath light. If the aircraft descends further below the glidepath, the red light starts to pulsate. The “above glidepath” indication Far Bar Far Bar Far Bar is a pulsating white light. The pulsating rate increases as the aircraft gets further above or below the desired glideslope.

The useful range of the system is about four miles during the Near Bar Near Bar Near Bar day and up to ten miles at night. [Figure 14-32] Runway Lighting There are various lights that identify parts of the runway complex. These assist a pilot in safely making a takeoff or landing during night operations.

Figure 14-29. Two-bar VASI system.

Runway End Identifier Lights (REIL) Runway end identifier lights (REIL) are installed at many A tri-color system consists of a single-light unit projecting airfields to provide rapid and positive identification of the a three-color visual approach path. Below the glidepath is approach end of a particular runway. The system consists indicated by red, on the glidepath is indicated by green, and of a pair of synchronized flashing lights located laterally above the glidepath is indicated by amber. When descending on each side of the runway threshold. REILs may be either below the glidepath, there is a small area of dark amber. Pilots omnidirectional or unidirectional facing the approach area.

should not mistake this area for an “above the glidepath” indication. [Figure 14-31] Runway Edge Lights Runway edge lights are used to outline the edges of Pulsating VASIs normally consist of a single-light unit runways at night or during low visibility conditions.

projecting a two-color visual approach path into the final [Figure 14-33] These lights are classified according to the approach area of the runway upon which the indicator is intensity they are capable of producing: high intensity runway installed. The “on glidepath” indication is a steady white lights (HIRL), medium intensity runway lights (MIRL), and High Slightly High On Glidepath Slightly Low Low more than 3.5° 3.2° 3° 2.8° less than 2.5° Figure 14-30. Precision approach path indicator for a typical 3° glide slope.

Amber Amber Above glidepath Green On glidepath Red Below glidepath Figure 14-31. Tri-color visual approach slope indicator.

14-17 Pulsating white Above glidepath Steady Steady red white On glidepath Slightly below glidepath Pulsating red Below glidepath Threshold Figure 14-32. Pulsating visual approach slope indicator.

low intensity runway lights (LIRL). The HIRL and MIRL Taxiway centerline lead-off lights—provide visual guidance have variable intensity settings. These lights are white, except to persons exiting the runway. They are color-coded to warn on instrument runways where amber lights are used on the pilots and vehicle drivers that they are within the runway last 2,000 feet or half the length of the runway, whichever environment or ILS critical area, whichever is more restrictive.

is less. The lights marking the end of the runway are red. Alternate green and yellow lights are installed, beginning with green, from the runway centerline to one centerline light In-Runway Lighting position beyond the runway holding position or ILS critical area holding position.

Runway centerline lighting system (RCLS)—installed on some precision approach runways to facilitate landing under adverse Taxiway centerline lead-on lights—provide visual guidance visibility conditions. They are located along the runway to persons entering the runway. These “lead-on” lights are centerline and are spaced at 50-foot intervals. When viewed also color-coded with the same color pattern as lead-off from the landing threshold, the runway centerline lights are lights to warn pilots and vehicle drivers that they are within white until the last 3,000 feet of the runway. The white lights the runway environment or ILS critical area, whichever is begin to alternate with red for the next 2,000 feet. For the more conservative. The fixtures used for lead-on lights are remaining 1,000 feet of the runway, all centerline lights are red.

bidirectional (i.e., one side emits light for the lead-on function while the other side emits light for the lead-off function). Any Touchdown zone lights (TDZL)—installed on some precision fixture that emits yellow light for the lead-off function also approach runways to indicate the touchdown zone when emits yellow light for the lead-on function.

landing under adverse visibility conditions. They consist of two rows of transverse light bars disposed symmetrically Land and hold short lights—used to indicate the hold short about the runway centerline. The system consists of steady- point on certain runways which are approved for LAHSO.

burning white lights that start 100 feet beyond the landing Land and hold short lights consist of a row of pulsing white threshold and extend to 3,000 feet beyond the landing lights installed across the runway at the hold short point.

threshold or to the midpoint of the runway, whichever is less.

Where installed, the lights are on anytime LAHSO is in effect.

These lights are off when LAHSO is not in effect.

Control of Airport Lighting Airport lighting is controlled by ATC at towered airports. At nontowered airports, the lights may be on a timer, or where an FSS is located at an airport, the FSS personnel may control the lighting. A pilot may request various light systems be turned on or off and also request a specified intensity, if available, from ATC or FSS personnel. At selected nontowered airports, the pilot may control the lighting by using the radio. This is done by selecting a specified frequency and clicking the radio microphone. [Figure 14-34] For information on pilot controlled lighting at various airports, refer to the Chart Supplement U.S. (formerly Airport/Facility Directory).

Figure 14-33. Runway lights.

14-18 red lights on each side. A controlled stop bar is operated in Function Key Mike conjunction with the taxiway centerline lead-on lights which Highest intensity available 7 times within 5 seconds extend from the stop bar toward the runway. Following the ATC clearance to proceed, the stop bar is turned off and the Medium or lower intensity 5 times within 5 seconds (Lower REIL or REIL off) lead-on lights are turned on. The stop bar and lead-on lights Lowest intensity available are automatically reset by a sensor or backup timer.

3 times within 5 seconds (Lower REIL or REIL off) Obstruction Lights Figure 14-34. Radio controlled runway lighting.

Obstructions are marked or lighted to warn pilots of their presence during daytime and nighttime conditions.

Taxiway Lights Obstruction lighting can be found both on and off an airport Similar to runway lighting, taxiways also have various lights to identify obstructions. They may be marked or lighted in which help pilots identify areas of the taxiway and any any of the following conditions.

surrounding runways.

• Red obstruction lights—flash or emit a steady red Omnidirectional color during nighttime operations, and the obstructions are painted orange and white for daytime operations.

Omnidirectional taxiway lights outline the edges of the taxiway and are blue in color. At many airports, these • High intensity white obstruction lights—flash high edge lights may have variable intensity settings that may intensity white lights during the daytime with the be adjusted by an ATC when deemed necessary or when intensity reduced for nighttime.

requested by the pilot. Some airports also have taxiway • Dual lighting—a combination of flashing red beacons centerline lights that are green in color.

and steady red lights for nighttime operation and high intensity white lights for daytime operations.

Clearance Bar Lights Clearance bar lights are installed at holding positions on New Lighting Technologies taxiways in order to increase the conspicuity of the holding A top priority of the FAA is to continue to enhance airport position in low visibility conditions. They may also be safety while maintaining airport capacity. Reducing runway installed to indicate the location of an intersecting taxiway incursions is a major component of this effort. Runway during periods of darkness. Clearance bars consist of three incursions develop quickly and without warning during routine in-pavement steady-burning yellow lights.

traffic situations on the airport surface, leaving little time for corrective action. The Runway Status Lights (RWSL) System Runway Guard Lights is designed to provide a direct indication to you that it is unsafe Runway guard lights are installed at taxiway/runway to enter a runway, cross a runway, or takeoff from or land on intersections. They are primarily used to enhance the a runway when the system is activated.

conspicuity of taxiway/runway intersections during low visibility conditions, but may be used in all weather conditions.

Runway status lights are red in color and indicate runway Runway guard lights consist of either a pair of elevated flashing status only; they do not indicate clearance to enter a runway yellow lights installed on either side of the taxiway, or a row of or clearance to takeoff. The RWSL system provides warning in-pavement yellow lights installed across the entire taxiway, lights on runways and taxiways, illuminating when it is unsafe at the runway holding position marking.

to enter, cross, or begin takeoff on a runway. Currently, there are two types: Runway Entrance Lights (REL) and Takeoff Note: Some airports may have a row of three or five Hold Lights (THL). [Figures 14-35 and 14-36] in-pavement yellow lights installed at taxiway/runway intersections. They should not be confused with clearance REL provide a warning to aircraft crossing or entering a bar lights described previously in this section.

runway from intersecting taxiways that there is conflicting traffic on the runway. THL provide a warning signal to Stop Bar Lights aircraft in position for takeoff that the runway is occupied and it is unsafe to take off. As of 2016, the RWSL system is Stop bar lights, when installed, are used to confirm the ATC clearance to enter or cross the active runway in low visibility operational at 14 of the nation’s busiest airports with 3 more airports scheduled to receive the system by 2017.

conditions (below 1,200 ft Runway Visual Range (RVR)).

A stop bar consists of a row of red, unidirectional, steady- burning in-pavement lights installed across the entire taxiway at the runway holding position, and elevated steady-burning 14-19 out straighter in strong winds and tends to move back and forth when the wind is gusting. Wind tees and tetrahedrons can swing freely and align themselves with the wind direction.

Since a wind tee or tetrahedron can also be manually set to align with the runway in use, a pilot should also look at the wind sock for wind information, if one is available.

Traffic Patterns At airports without an operating control tower, a segmented circle visual indicator system , if installed, is designed to provide traffic pattern information. [Figure 14-38] Usually located in a position affording maximum visibility to pilots in Figure 14-35. Runway Entrance Lights (REL).

the air and on the ground and providing a centralized location for other elements of the system, the segmented circle consists of the following components: wind direction indicators, landing direction indicators, landing strip indicators, and traffic pattern indicators.

A tetrahedron is installed to indicate the direction of landings and takeoffs when conditions at the airport warrant its use.

It may be located at the center of a segmented circle and may be lighted for night operations. The small end of the tetrahedron points in the direction of landing. Pilots are cautioned against using a tetrahedron for any purpose other than as an indicator of landing direction. At airports with Figure 14-36. Takeoff Hold Lights (THL).

control towers, the tetrahedron should only be referenced when the control tower is not in operation. Tower instructions Wind Direction Indicators supersede tetrahedron indications.

It is important for a pilot to know the direction of the wind. At facilities with an operating control tower, this information is Landing strip indicators are installed in pairs and are used to provided by ATC. Information may also be provided by FSS show the alignment of landing strips. [Figure 14-38] Traffic personnel either located at a particular airport or remotely pattern indicators are arranged in pairs in conjunction with available through a remote communication outlet (RCO), or landing strip indicators and used to indicate the direction of by requesting information on a CTAF at airports that have the turns when there is a variation from the normal left traffic capacity to receive and broadcast on this frequency.

pattern. (If there is no segmented circle installed at the airport, traffic pattern indicators may be installed on or near the end When none of these services is available, it is possible of the runway.)

to determine wind direction and runway in use by visual wind indicators. A pilot should check these wind indicators At most airports and military air bases, traffic pattern altitudes even when information is provided on the CTAF at a given for propeller-driven aircraft generally extend from 600 feet airport because there is no assurance that the information to as high as 1,500 feet above ground level (AGL). Pilots provided is accurate.

can obtain the traffic pattern altitude for an airport from the Chart Supplement U.S. (formerly Airport/Facility Directory).

The wind direction indicator can be a wind cone, wind sock, Also, traffic pattern altitudes for military turbojet aircraft tetrahedron, or wind tee. These are usually located in a central sometimes extend up to 2,500 feet AGL. Therefore, pilots of location near the runway and may be placed in the center en route aircraft should be constantly on alert for other aircraft of a segmented circle, which identifies the traffic pattern in traffic patterns and avoid these areas whenever possible.

direction if it is other than the standard left-hand pattern.

When operating at an airport, traffic pattern altitudes should [Figures 14-37 and 14-38] be maintained unless otherwise required by the applicable distance from cloud criteria according to Title 14 of the Code The wind sock is a good source of information since it not of Federal Regulations (14 CFR) part 91, section 91.155.

only indicates wind direction but allows the pilot to estimate Additional information on airport traffic pattern operations the wind velocity and/or gust factor. The wind sock extends 14-20 Tetrahedron WIND Wind tee Wind sock or cone Figure 14-37. Wind direction indicators.

2. Maintain pattern altitude until abeam approach end of Traffic pattern the landing runway on downwind leg. [Figure 14-39] indicators 3. Complete turn to final at least ¼ mile from the runway.

[Figure 14-39] Landing direction indicator 4. After takeoff or go-around, continue straight ahead until beyond departure end of runway. [Figure 14-39] 5. If remaining in the traffic pattern, commence turn to crosswind leg beyond the departure end of the runway within 300 feet of pattern altitude. [Figure 14-39] 6. If departing the traffic pattern, continue straight out, or exit with a 45° turn (to the left when in a left-hand traffic pattern; to the right when in a right-hand traffic pattern) beyond the departure end of the runway, after reaching pattern altitude. [Figure 14-39] Wind cone Landing runway or landing strip Example: Key to Traffic Pattern Operations— indicators Parallel Runways 1. Enter pattern in level flight, abeam the midpoint Figure 14-38. Segmented circle.

of the runway, at pattern altitude. (1,000' AGL is recommended pattern altitude unless otherwise can be found in Chapter 4, “Air Traffic Control,” of the AIM.

established.) [Figure 14-40] Pilots can find traffic pattern information and restrictions, such 2. Maintain pattern altitude until abeam approach end of as noise abatement in the Chart Supplement U.S. (formerly the landing runway on downwind leg. [Figure 14-40] Airport/Facility Directory).

3. Complete turn to final at least ¼ mile from the runway.

Example: Key to Traffic Pattern Operations— [Figure 14-40] Single Runway 4. Do not overshoot final or continue on a track that 1. Enter pattern in level flight, abeam the midpoint penetrates the final approach of the parallel runway of the runway, at pattern altitude. (1,000' AGL is 5. After takeoff or go-around, continue straight ahead recommended pattern altitude unless otherwise until beyond departure end of runway. [Figure 14-40] established.) [Figure 14-39] 14-21 Application of traffic LEGEND pattern indicators Entry Recommended standard left-hand traffic pattern (depicted) (standard right-hand traffic pattern would be mirror image) Downwind 2 Segmented circle Departure Base Crosswind Final Departure Departure 4 6 RUNWAY Figure 14-39. Traffic pattern operations—single runway.

6. If remaining in the traffic pattern, commence turn to Radio Equipment crosswind leg beyond the departure end of the runway In general aviation, the most common types of radios are within 300 feet of pattern altitude. [Figure 14-40] VHF. A VHF radio operates on frequencies between 118.0 megahertz (MHz) and 136.975 MHz and is classified as 7. If departing the traffic pattern, continue straight out, 720 or 760 depending on the number of channels it can or exit with a 45° turn (to the left when in a left-hand accommodate. The 720 and 760 use .025 MHz (25 kilohertz traffic pattern; to the right when in a right-hand traffic (KHz) spacing (118.025, 118.050) with the 720 having a pattern) beyond the departure end of the runway, after frequency range up to 135.975 MHz and the 760 reaching reaching pattern altitude. [Figure 14-40] up to 136.975 MHz. VHF radios are limited to line of sight 8. Do not continue on a track that penetrates the departure transmissions; therefore, aircraft at higher altitudes are able path of the parallel runway. [Figure 14-40] to transmit and receive at greater distances.

Radio Communications In March of 1997, the International Civil Aviation Organization Operating in and out of a towered airport, as well as in a good (ICAO) amended its International Standards and Recommended portion of the airspace system, requires that an aircraft have two- Practices to incorporate a channel plan specifying 8.33 kHz way radio communication capability. For this reason, a pilot channel spacings in the Aeronautical Mobile Service. The should be knowledgeable of radio station license requirements 8.33 kHz channel plan was adopted to alleviate the shortage of and radio communications equipment and procedures.

VHF ATC channels experienced in western Europe and in the United Kingdom. Seven western European countries and the Radio License United Kingdom implemented the 8.33 kHz channel plan on There is no license requirement for a pilot operating in the January 1, 1999. Accordingly, aircraft operating in the airspace United States; however, a pilot who operates internationally of these countries must have the capability of transmitting and is required to hold a restricted radiotelephone permit issued receiving on the 8.33 kHz spaced channels.

by the Federal Communications Commission (FCC). There is also no station license requirement for most general Using Proper Radio Procedures aviation aircraft operating in the United States. A station Using proper radio phraseology and procedures contribute to license is required, however, for an aircraft that is operating a pilot’s ability to operate safely and efficiently in the airspace internationally, that uses other than a VHF radio, and that system. A review of the Pilot/Controller Glossary contained meets other criteria.

in the AIM assists a pilot in the use and understanding of 14-22 LEGEND Standard left-hand traffic pattern (depicted) Right-hand traffic pattern (depicted) Base Crosswind Final Departure 4 6 No transgression zone No transgression zone Segmented circle 4 6 Final Departure Base Crosswind Downwind 2 Entry Figure 14-40. Traffic pattern operation—parallel runways.

standard terminology. The AIM also contains many examples If the transmitter becomes inoperative, a pilot should follow of radio communications. the previously stated procedures and also monitor the appropriate ATC frequency. During daylight hours, ATC ICAO has adopted a phonetic alphabet that should be used in transmissions may be acknowledged by rocking the wings radio communications. When communicating with ATC, pilots and at night by blinking the landing light.

should use this alphabet to identify their aircraft. [Figure 14-41] When both receiver and transmitter are inoperative, the pilot Lost Communication Procedures should remain outside of Class D airspace until the flow of traffic has been determined and then enter the pattern and It is possible that a pilot might experience a malfunction of watch for light signals.

the radio. This might cause the transmitter, receiver, or both to become inoperative. If a receiver becomes inoperative and a Radio malfunctions should be repaired before further pilot needs to land at a towered airport, it is advisable to remain flight. If this is not possible, ATC may be contacted by outside or above Class D airspace until the direction and flow telephone requesting a VFR departure without two-way radio of traffic is determined. A pilot should then advise the tower of communications. No radio (NORDO) procedure arrivals the aircraft type, position, altitude, and intention to land. The are not accepted at busy airports. If authorization is given pilot should continue, enter the pattern, report a position as to depart, the pilot is advised to monitor the appropriate appropriate, and watch for light signals from the tower. Light frequency and/or watch for light signals as appropriate.

signal colors and their meanings are contained in Figure 14-42 .

14-23 easily be aware of your presence when they are expecting Morse Code Telephony Phonic Pronunciation Character the standard radio calls.

A A a B Air Traffic Control (ATC) Services B b C Besides the services provided by an FSS as discussed in C c D Chapter 12, “Aviation Weather Services,” numerous other D d services are provided by ATC. In many instances a pilot E E e is required to have contact with ATC, but even when not F F f required, a pilot may find their services helpful.

G g G h Primary Radar H h Radar is a device that provides information on range, azimuth, I I i and/or elevation of objects in the path of the transmitted J J j pulses. It measures the time interval between transmission and K K k reception of radio pulses and correlates the angular orientation L L L of the radiated antenna beam or beams in azimuth and/or M M elevation. Range is determined by measuring the time it takes m N for the radio wave to go out to the object and then return to the N n receiving antenna. The direction of a detected object from a O O o radar site is determined by the position of the rotating antenna P P p when the reflected portion of the radio wave is received.

Q Q q R R Modern radar is very reliable and there are seldom outages.

r S This is due to reliable maintenance and improved equipment.

S s There are, however, some limitations that may affect ATC T T t services and prevent a controller from issuing advisories U U u concerning aircraft that are not under his or her control and V V v cannot be seen on radar.

W W w X The characteristics of radio waves are such that they normally X x travel in a continuous straight line unless they are “bent” by Y Y y atmospheric phenomena, such as temperature inversions, Z Z z reflected or attenuated by dense objects such as heavy clouds and precipitation, or screened by high terrain features. Radar 2 signals degrade over distance, cannot penetrate through solid objects such as mountains, and the fastest radar updates every 4.7 seconds. By contrast, the satellite signals used with Automatic Dependent Surveillance−Broadcast (ADS−B) do not degrade over distance, provide better visibility around N n mountainous terrain and allows equipped aircraft to update O 7 their own position once a second with better accuracy.

o P p ATC Radar Beacon System (ATCRBS) Q q The ATC radar beacon system (ATCRBS) is often referred to R r as “secondary surveillance radar.” This system consists of three components and helps in alleviating some of the limitations Figure 14-41. Phonetic alphabet.

associated with primary radar. The three components are an interrogator, transponder, and radarscope. The advantages of If radio communication is lost, it may be a prudent decision ATCRBS are the reinforcement of radar targets, rapid target to land at a non-towered airport with lower traffic volume, if identification, and a unique display of selected codes.

practical. When operating at a non-towered airport, no radio communication is necessary. However, pilots should be extra Growing air traffic in the National Airspace System (NAS) vigilant when not using the radio. Other traffic may not as will be addressed through the use of ADS-B, which not only 14-24 Movement of Vehicles, Color and Type of Signal Aircraft on the Ground Aircraft in Flight Equipment and Personnel Steady green Cleared to cross, Cleared for takeoff Cleared to land proceed or go Flashing green Return for landing (to be followed Not applicable Cleared for taxi by steady green at the proper time) Give way to other aircraft and Steady red Stop continue circling Stop Flashing red Taxi clear of the runway Clear the taxiway/runway Airport unsafe, do not land in use Flashing white Return to starting point Return to starting point Not applicable on airport on airport Alternating red and green Exercise extreme caution!!!! Exercise extreme caution!!!! Exercise extreme caution!!!!

Figure 14-42. Light gun signals.

provides all the same information the ATCRBS, but will do information unless an aircraft is equipped with a transponder.

so more rapidly and with significantly more accuracy. By A transponder is also required to operate in certain controlled broadcasting aircraft position information to a ground station, airspace as discussed in Chapter 15, “Airspace.” ADS–B can also provide coverage in areas that do not have radar coverage. In addition, ADS–B provides trajectory A transponder code consists of four numbers from 0 to 7 information that includes speed and direction of motion. (4,096 possible codes). There are some standard codes or ATC may issue a four-digit code to an aircraft. When a controller Transponder requests a code or function on the transponder, the word “squawk” may be used. Figure 14-43 lists some standard The transponder is the airborne portion of the secondary surveillance radar system and a system with which a pilot transponder phraseology. Additional information concerning transponder operation can be found in the AIM, Chapter 4.

should be familiar. The ATCRBS cannot display the secondary Radar Beacon Phraseology Operate radar beacon transponder on designated code in MODE A/3.

SQUAWK (number) Engage the “IDENT” feature (military I/P) of the transponder.

IDENT Operate transponder on specified code in MODE A/3 and engage the “IDENT” SQUAWK (number) and IDENT (military I/P) feature.

Switch transponder to standby position.

SQUAWK Standby Operate transponder on low or normal sensitivity as specified. Transponder is SQUAWK Low/Normal operated in “NORMAL” position unless ATC specifies “LOW” (“ON” is used instead of “NORMAL” as a master control label on some types of transponders).

Activate MODE C with automatic altitude reporting.

SQUAWK Altitude Turn off altitude reporting switch and continue transmitting MODE C framing pulses.

STOP Altitude SQUAWK If your equipment does not have this capability, turn off MODE C.

Switch off specified mode. (Used for military aircraft when the controller is unaware of STOP SQUAWK (mode in use) military service requirements for the aircraft to continue operation on another MODE.)

Switch off transponder.

STOP SQUAWK Operate transponder in the emergency position (MODE A Code 7700 for civil SQUAWK Mayday transponder, MODE 3 Code 7700 and emergency feature for military transponder).

Operate radar beacon transponder on Code 1200 in MODE A/3, or other SQUAWK VFR appropriate VFR code.

Figure 14-43. Transponder phraseology.

14-25 Automatic Dependent Surveillance–Broadcast (ADS-B) A B Automatic Dependent Surveillance−Broadcast (ADS−B) is a Wind surveillance technology being deployed throughout the NAS to facilitate improvements needed to increase the capacity TRACK TRACK and efficiency of the NAS, while maintaining safety. ADS-B supports these improvements by providing a higher update rate and enhanced accuracy of surveillance information over the current radar-based surveillance system. In addition, ADS-B enables the expansion of air traffic control (ATC) surveillance Traffic information would be issued to the pilot of aircraft “A” services into areas where none existed previously. The ADS-B as 12 o’clock. The actual position of the traffic as seen by ground system also provides Traffic Information Services- the pilot of aircraft “A” would be 1 o’clock. Traffic information Broadcast (TIS-B) and Flight Information Services-Broadcast issued to aircraft “B” would also be given as 12 o’clock, but in this case, the pilot of “B” would see traffic at 10 o’clock.

(FIS-B) for use on appropriately equipped aircraft, enhancing the user’s situational awareness (SA) and improving the overall safety of the NAS. Figure 14-44. Traffic advisories.

The ADS−B system is composed of aircraft avionics and a area (TRSA) has been implemented at certain terminal ground infrastructure. Onboard avionics determine the position locations. TRSAs are depicted on sectional aeronautical of the aircraft by using the GPS and transmit its position, charts and listed in the Chart Supplement U.S. (formerly along with additional information about the aircraft, to ground Airport/Facility Directory). The purpose of this service is to stations for use by ATC and nearby ADS-B equipped aircraft.

provide separation between all participating VFR aircraft and all IFR aircraft operating within the TRSA. Class C service In the United States, ADS−B equipped aircraft exchange provides approved separation between IFR and VFR aircraft information on one of two frequencies: 978 or 1090 MHz.

and sequencing of VFR aircraft to the primary airport. Class The 1090 MHz frequency is associated with Mode A, C, and S B service provides approved separation of aircraft based on transponder operations. 1090 MHz transponders with integrated IFR, VFR, and/or weight and sequencing of VFR arrivals to ADS−B functionality extend the transponder message sets with the primary airport(s).

additional ADS−B information. This additional information is known as an “extended squitter” message and referred to as Wake Turbulence 1090ES. ADS−B equipment operating on 978 MHz is known All aircraft generate wake turbulence during flight. This as the Universal Access Transceiver (UAT).

disturbance is caused by a pair of counter-rotating vortices trailing from the wingtips. The vortices from larger aircraft Radar Traffic Advisories pose problems to encountering aircraft. The wake of these Radar equipped ATC facilities provide radar assistance aircraft can impose rolling moments exceeding the roll- to aircraft on instrument flight plans and VFR aircraft control authority of the encountering aircraft. Also, the provided the aircraft can communicate with the facility and turbulence generated within the vortices can damage aircraft are within radar coverage. This basic service includes safety components and equipment if encountered at close range. For alerts, traffic advisories, limited vectoring when requested, this reason, a pilot must envision the location of the vortex and sequencing at locations where this procedure has been wake and adjust the flight path accordingly.

established. ATC issues traffic advisories based on observed radar targets. The traffic is referenced by azimuth from the Vortex Generation aircraft in terms of the 12-hour clock. Also, distance in Lift is generated by the creation of a pressure differential over nautical miles, direction in which the target is moving, and the wing surface. The lowest pressure occurs over the upper type and altitude of the aircraft, if known, are given.

wing surface and the highest pressure under the wing. This pressure differential triggers the rollup of the airflow aft of An example would be: “Traffic 10 o’clock 5 miles east the wing resulting in swirling air masses trailing downstream bound, Cessna 152, 3,000 feet.” The pilot should note that of the wingtips. After the rollup is completed, the wake traffic position is based on the aircraft track and that wind consists of two counter rotating cylindrical vortices. Most of correction can affect the clock position at which a pilot locates the energy lies within a few feet of the center of each vortex.

traffic. This service is not intended to relieve the pilot of the [Figure 14-45] responsibility to see and avoid other aircraft. [Figure 14-44] In addition to basic radar service, terminal radar service 14-26 Figure 14-45. Vortex generation.

operating in the NAS. There have been wake turbulence Vortex Strength events in excess of 30NM and 2000 feet lower than the wake Terminal Area generating aircraft. Air density is also a factor in wake strength.

Wake turbulence has historically been thought of as only Even though the speeds are higher in cruise at high altitude, a function of aircraft weight, but recent research considers the reduced air density may result in wake strength comparable additional parameters, such as speed, aspects of the wing, wake to that in the terminal area. In addition, for a given separation decay rates, and aircraft resistance to wake, just to name a few.

distance, the higher speeds in cruise result in less time for the The vortex characteristics of any aircraft will be changed with wake to decay before being encountered by a trailing aircraft.

the extension of flaps or other wing configuration devices, as well as changing speed. However, as the basic factors are weight Vortex Behavior and speed, the vortex strength increases proportionately with Trailing vortices have certain behavioral characteristics an increase in aircraft operating weight or decrease in aircraft that can help a pilot visualize the wake location and take speed. The greatest vortex strength occurs when the generating avoidance precautions.

aircraft is heavy, slow, and clean, since the turbulence from a “dirty” aircraft configuration hastens wake decay.

Vortices are generated from the moment an aircraft leaves the ground (until it touches down), since trailing vortices are the En Route byproduct of wing lift. [Figure 14-46] The vortex circulation En route wake turbulence events have been influenced by is outward, upward, and around the wingtips when viewed changes to the aircraft fleet mix that have more “Super” from either ahead or behind the aircraft. Tests with large (A380) and “Heavy” (B-747, B-777, A340, etc.) aircraft Wake ends Wake begins Touchdown Rotation Figure 14-46. Vortex behavior.

14-27 aircraft have shown that vortices remain spaced a bit less than landing (since vortices settle and move laterally a wingspan apart, drifting with the wind, at altitudes greater near the ground, the vortex hazard may exist along than a wingspan from the ground. Tests have also shown that the runway and in the flight path, particularly in a the vortices sink at a rate of several hundred feet per minute, quartering tailwind), it is prudent to wait at least 2 slowing their descent and diminishing in strength with time minutes prior to a takeoff or landing.

and distance behind the generating aircraft.

• En route, it is advisable to avoid a path below and behind a large aircraft, and if a large aircraft is When the vortices of larger aircraft sink close to the ground observed above on the same track, change the aircraft (within 100 to 200 feet), they tend to move laterally over position laterally and preferably upwind.

the ground at a speed of 2–3 knots. A crosswind decreases the lateral movement of the upwind vortex and increases Collision Avoidance the movement of the downwind vortex. A light quartering Title 14 of the CFR part 91 has established right-of-way tailwind presents the worst case scenario as the wake rules, minimum safe altitudes, and VFR cruising altitudes vortices could be all present along a significant portion of to enhance flight safety. The pilot can contribute to collision the final approach and extended centerline and not just in the avoidance by being alert and scanning for other aircraft. This touchdown zone as typically expected.

is particularly important in the vicinity of an airport.

Vortex Avoidance Procedures Effective scanning is accomplished with a series of short, The following procedures are in place to assist pilots in vortex regularly spaced eye movements that bring successive areas of avoidance in the given scenario.

the sky into the central visual field. Each movement should not • Landing behind a larger aircraft on the same runway— exceed 10°, and each should be observed for at least 1 second stay at or above the larger aircraft’s approach to enable detection. Although back and forth eye movements flight path and land beyond its touchdown point.

seem preferred by most pilots, each pilot should develop a [Figure 14-47A] scanning pattern that is most comfortable and then adhere to • Landing behind a larger aircraft on a parallel runway it to assure optimum scanning. Even if entitled to the right-of closer than 2,500 feet—consider the possibility of drift way, a pilot should yield if another aircraft seems too close.

and stay at or above the larger aircraft’s final approach flight path and note its touchdown point. [Figure 14-47B] Clearing Procedures The following procedures and considerations are in place to • Landing behind a larger aircraft on crossing runway— assist pilots in collision avoidance under various situations: cross above the larger aircraft’s flight path.

• Before takeoff—prior to taxiing onto a runway or • Landing behind a departing aircraft on the same landing area in preparation for takeoff, pilots should runway—land prior to the departing aircraft’s scan the approach area for possible landing traffic, rotating point.

executing appropriate maneuvers to provide a clear • Landing behind a larger aircraft on a crossing view of the approach areas.

runway—note the aircraft’s rotation point and, if that • Climbs and descents—during climbs and descents in point is past the intersection, continue and land prior flight conditions that permit visual detection of other to the intersection. If the larger aircraft rotates prior traffic, pilots should execute gentle banks left and right to the intersection, avoid flight below its flight path.

at a frequency that permits continuous visual scanning Abandon the approach unless a landing is ensured well of the airspace.

before reaching the intersection. [Figure 14-47C] • Straight and level—during sustained periods of • Departing behind a large aircraft—rotate prior to the straight-and-level flight, a pilot should execute large aircraft’s rotation point and climb above its climb appropriate clearing procedures at periodic intervals.

path until turning clear of the wake.

• Traffic patterns—entries into traffic patterns while • For intersection takeoffs on the same runway— descending should be avoided.

be alert to adjacent larger aircraft operations, particularly upwind of the runway of intended use.

• Traffic at VOR sites—due to converging traffic, If an intersection takeoff clearance is received, avoid sustained vigilance should be maintained in the headings that cross below the larger aircraft’s path.

vicinity of VORs and intersections.

• If departing or landing after a large aircraft executing • Training operations—vigilance should be maintained a low approach, missed approach, or touch-and-go and clearing turns should be made prior to a practice 14-28 A WIND Touchdown point of larger aircraft Side view B Aircraft altitude is above wake Less than 2500 feet Parallel Runway Situation Touchdown point WIND C Aircraft altitude is above wake Aircraft crossing over wake turbulence Figure 14-47. Vortex avoidance procedures.

14-29 maneuver. During instruction, the pilot should be with aircraft operations by entering or moving on the runway asked to verbalize the clearing procedures (call out movement area without authorization from air traffic control.

“clear left, right, above, and below”). In serious instances, any ground deviation (PD or VPD) can result in a runway incursion. Best practices in preventing ground deviations can be found in the following section High-wing and low-wing aircraft have their respective blind under runway incursion avoidance.

spots. The pilot of a high-wing aircraft should momentarily raise the wing in the direction of the intended turn and look Runway Incursion Avoidance for traffic prior to commencing the turn. The pilot of a low- A runway incursion is “any occurrence in the airport runway wing aircraft should momentarily lower the wing and look environment involving an aircraft, vehicle, person, or object for traffic prior to commencing the turn.

on the ground that creates a collision hazard or results in a loss of required separation with an aircraft taking off, intending Pilot Deviations (PDs) to take off, landing, or intending to land.” It is important A pilot deviation (PD) is an action of a pilot that violates any to give the same attention to operating on the surface as in Federal Aviation Regulation. While PDs should be avoided, other phases of flights. Proper planning can prevent runway the regulations do authorize deviations from a clearance in incursions and the possibility of a ground collision. A pilot response to a traffic alert and collision avoidance system should always be aware of the aircraft’s position on the resolution advisory. You must notify ATC as soon as possible surface at all times and be aware of other aircraft and vehicle following a deviation.

operations on the airport. At times, towered airports can be busy and taxi instructions complex. In this situation, it may Pilot deviations can occur in several different ways.

be advisable to write down taxi instructions. The following Airborne deviations result when a pilot strays from are some practices to help prevent a runway incursion: an assigned heading or altitude or from an instrument procedure, or if the pilot penetrates controlled or restricted • Read back all runway crossing and/or hold instructions.

airspace without ATC clearance.

• Review airport layouts as part of preflight planning, before descending to land and while taxiing, as To prevent airborne deviations, follow these steps: needed.

• Plan each flight—you may have flown the flight many • Know airport signage.

times before but conditions and situations can change • Review NOTAM for information on runway/taxiway rapidly, such as in the case of a pop-up temporary closures and construction areas.

flight restriction (TFR). Take a few minutes prior to each flight to plan accordingly.

• Request progressive taxi instructions from ATC when unsure of the taxi route.

• Talk and squawk—Proper communication with ATC has its benefits. Flight following often makes the • Check for traffic before crossing any runway hold line controller’s job easier because they can better integrate and before entering a taxiway.

VFR and IFR traffic.

• Turn on aircraft lights and the rotating beacon or strobe • Give yourself some room—GPS is usually more lights while taxing.

precise than ATC radar. Using your GPS to fly up • When landing, clear the active runway as soon as to and along the line of the airspace you are trying to possible, then wait for taxi instructions before further avoid could result in a pilot deviation because ATC movement.

radar may show you within the restricted airspace.

• Study and use proper phraseology in order to Ground deviations (also called surface deviations) include understand and respond to ground control instructions.

taxiing, taking off, or landing without clearance, deviating • Write down complex taxi instructions at unfamiliar from an assigned taxi route, or failing to hold short of an airports.

assigned clearance limit. To prevent ground deviations, stay alert during ground operations. Pilot deviations can and Approximately three runway incursions occur each day at frequently do occur on the ground. Many strategies and tactics towered airports within the United States. The potential pilots use to avoid airborne deviations also work on the ground.

that these numbers present for a catastrophic accident is unacceptable. The following are examples of pilot deviations, Pilots should also remain vigilant about vehicle/pedestrian operational incidents (OI), and vehicle (driver) deviations deviations (V/PDs). A vehicle or pedestrian deviation that may lead to runway incursions.

includes pedestrians, vehicles or other objects interfering 14-30 Pilot Deviations: • Crossing a runway hold marking without clearance from ATC • Taking off without clearance • Landing without clearance Operational Incidents (OI): • Clearing an aircraft onto a runway while another aircraft is landing on the same runway • Issuing a takeoff clearance while the runway is occupied by another aircraft or vehicle Figure 14-48. Heads-up, eyes outside.

Vehicle (Driver) Deviations: In August 2006, the flight crew of a commercial regional jet • Crossing a runway hold marking without ATC was cleared for takeoff on Runway 22 but mistakenly lined clearance up and departed on Runway 26, a much shorter runway. As a result, the aircraft crashed off the end of the runway.

According to FAA data, approximately 65 percent of all runway incursions are caused by pilots. Of the pilot runway Causal Factors of Runway Confusion incursions, FAA data shows almost half of those incursions There are three major factors that increase the risk of runway are caused by GA pilots.

confusion and can lead to a wrong runway departure: • Airport complexity Causal Factors of Runway Incursions Detailed investigations of runway incursions over the past • Close proximity of runway thresholds 10 years have identified three major areas contributing to • Joint use of a runway as a taxiway these events: • Failure to comply with ATC instructions Not only can airport complexity contribute to a runway incursion; it can also play a significant role in runway • Lack of airport familiarity confusion. If you are operating at an unfamiliar airport and • Nonconformance with standard operating procedures need assistance in executing the taxi clearance, do not hesitate to ask ATC for help. Always carry a current airport diagram Clear, concise, and effective pilot/controller communication is and trace or highlight your taxi route to the departure runway paramount to safe airport surface operations. You must fully prior to leaving the ramp.

understand and comply with all ATC instructions. It is mandatory to read back all runway “ hold short ” instructions verbatim.

If you are operating from an airport with runway thresholds in close proximity to one another, exercise extreme caution Taxiing on an unfamiliar airport can be very challenging, when taxiing onto the runway. Figure 14-49 shows a perfect especially during hours of darkness or low visibility. A example of a taxiway leading to multiple runways that may request may be made for progressive taxi instructions which cause confusion. If departing on Runway 36, ensure that you include step by step taxi routing instructions. Ensure you set your aircraft heading “bug” to 360°, and align your aircraft have a current airport diagram, remain “heads-up” with eyes to the runway heading to avoid departing from the wrong outside, and devote your entire attention to surface navigation runway. Before adding power, make one last instrument scan per ATC clearance. All checklists should be completed while to ensure the aircraft heading and runway heading are aligned.

the aircraft is stopped. There is no place for non-essential Under certain circumstances, it may be necessary to chatter or other activities while maintaining vigilance during use a runway as a taxiway. For example, during airport taxi. [Figure 14-48] construction some taxiways may be closed requiring re routing of traffic onto runways. In other cases, departing Runway Confusion traffic may be required to back taxi on the runway in order Runway confusion is a subset of runway incursions and to utilize the full runway length.

often results in you unintentionally taking off or landing on a taxiway or wrong runway. Generally, you are unaware of the mistake until after it has occurred.

14-31 Another way to mitigate the risk of runway incursions is to write down all taxi instructions as soon as they are received from ATC. [Figure 14-50] It is also helpful to monitor ATC clearances and instructions that are issued to other aircraft.

You should be especially vigilant if another aircraft has a similar sounding call sign so there is no mistake about who ATC is contacting or to whom they are giving instructions and clearances.

Read back your complete ATC clearance with your aircraft call sign. This gives ATC the opportunity to clarify any misunderstandings and ensure that instructions were given to the correct aircraft. If, at any time, there is uncertainty about any ATC instructions or clearances, ask ATC to “say again” or ask for progressive taxi instructions.

ATC Instructions — “ Hold Short” The most important sign and marking on the airport is the hold sign and hold marking. These are located on a stub taxiway leading directly to a runway. They depict the holding position or the location where the aircraft is to stop so as not to enter the runway environment. [Figure 14-51] For example, Figure 14-52 shows the holding position sign and marking for Runway 13 and Runway 31.

When ATC issues a “ hold short ” clearance, you are expected to taxi up to, but not cross any part of the runway holding marking. At a towered airport, runway hold markings should never be crossed without explicit ATC instructions. Do not enter a runway at a towered airport unless instructions are given from ATC to cross, takeoff from, or “line up and wait” on that specific runway.

Figure 14-49. Confusing runway/runway intersection.

ATC is required to obtain a read-back from the pilot of Since inattention and confusion often are factors contributing to all runway “ hold short ” instructions. Therefore, you runway incursion, it is important to remain extremely cautious must read back the entire clearance and “ hold short ” and maintain situational awareness (SA). When instructed to instruction, to include runway identifier and your call sign.

use a runway as a taxiway, do not become confused and take off on the runway you are using as a taxiway.

ATC Instructions Title 14 of the Code of Federal Regulations (14 CFR) part 91, section 91.123 requires you to follow all ATC clearances and instructions. Request clarification if you are unsure of the clearance or instruction to be followed. If you are unfamiliar with the airport or unsure of a taxi route, ask ATC for a “progressive taxi.” Progressive taxi requires the controller to provide step-by-step taxi instructions.

The final decision to act on ATC’s instruction rests with you.

If you cannot safely comply with any of ATC’s instructions, inform them immediately by using the word “UNABLE.” There is nothing wrong with telling a controller that you are Figure 14-50. A sound practice is to write down taxi instructions unable to safely comply with the clearance. from ATC.

14-32 Controller November 477ZA, Runway four, taxi via Echo, hold short of Runway two five at Taxiway Delta.

Pilot November 477ZA, Runway four via Echo, hold short of Runway two five at Delta.

Figure 14-53. Example of taxi and “ hold short ” instructions from ATC to a pilot.

Figure 14-51. Do NOT cross a runway holding position marking without ATC clearance. If the tower is closed or you are operating short ” or crossing instructions when approaching an entrance from a non-towered airport, check both directions for conflicting to a runway. Scan the full length of the runway and the final traffic before crossing the hold position marking.

approaches before entering or crossing any runway, even if ATC has issued a clearance.

Figure 14-53 shows an example of a controller’s taxi and “ hold short ” instructions and the reply from the pilot.

ATC Instructions—“Line Up and Wait” (LUAW) ATC now uses the “line up and wait” (LUAW) instruction ATC Instructions—Explicit Runway Crossing when a takeoff clearance cannot be issued immediately due As of June 30, 2010, ATC is required to issue explicit to traffic or other reasons. The words “line up and wait” have instructions to “ cross ” or “ hold short ” of each runway.

replaced “position and hold” in directing you to taxi onto a Instructions to “ cross ” a runway are normally issued one at a runway and await takeoff clearance.

time, and an aircraft must have crossed the previous runway before another runway crossing is issued. Exceptions may An ATC instruction to “line up and wait” is not a clearance apply for closely spaced runways that have less than 1,000 for takeoff. It is only a clearance to enter the runway and feet between centerlines. This applies to all runways to include hold in position for takeoff. Under LUAW phraseology, the active, inactive, or closed. Figure 14-54 shows communication controller states the aircraft call sign, departure runway, and between ATC and a pilot who is requesting a taxi clearance.

“line up and wait.” Be aware that “traffic holding in position” Extra caution should be used when directed by ATC to will continue to be used to advise other aircraft that traffic taxi onto or across a runway, especially at night and during has been authorized to line up and wait on an active runway.

reduced visibility conditions. Always comply with “ hold Pay close attention when instructed to “line up and wait,” especially at night or during periods of low visibility. Before Pilot “Ground, November 1234 ready to taxi from the GA ramp with Bravo.” ATC “November 1234, Runway two seven, taxi via Alpha, hold short of Runway three one.” Pilot “November 1234, Runway two seven, taxi via Alpha, hold short Runway three one.” ATC When able, tower will issue crossing clearance: “November 1234, cross Runway three one.” Figure 14-54. Communication between ATC and a pilot who is Figure 14-52. Runway 13-31 holding position sign and marking requesting taxi procedures.

located on Taxiway Charlie.

14-33 entering the runway, remember to scan the full length of the • In cases where ATC is not permitted to issue landing runway and its approach end for other aircraft. clearances with traffic in the LUAW position, traffic information is issued to the closest aircraft that is There have been collisions and incidents involving aircraft requesting a full-stop, touch-and-go, stop-and-go, instructed to “line up and wait” while ATC waits for the option, or unrestricted low approach.

necessary conditions to issue a takeoff clearance. An OI Example – “N456HK, Runway One-Eight, continue, caused a 737 to land on a runway occupied by a twin-engine traffic holding in position.” turboprop. The turboprop was holding in position awaiting takeoff clearance. Upon landing, the 737 collided with the ATC Instructions — “ Runway Shortened” twin-engine turboprop.

You should review NOTAMs in your preflight planning to determine any airport changes that will affect your departure When ATC instructs you to “line up and wait,” they should or arrival. When the available runway length has been advise you of any anticipated delay in receiving your takeoff temporarily or permanently shortened due to construction, clearance. Possible reasons for ATC takeoff clearance delays the ATIS includes the words “warning” and “shortened” in may include other aircraft landing and/or departing, wake the text of the message. For the duration of the construction turbulence, or traffic crossing an intersecting runway.

when the runway is temporarily shortened, ATC will • If advised of a reason for the delay, or the reason is include the word “shortened” in their clearance instructions.

clearly visible, expect an imminent takeoff clearance Furthermore, the use of the term “full length” will not be used once the reason is no longer an issue.

by ATC during this period of the construction.

• If a takeoff clearance is not received within 90 seconds Some examples of ATC instructions are: after receiving the “line up and wait” instruction, contact ATC immediately.

• “Runway three six shortened, line up and wait.” • When ATC issues “line up and wait” instructions • “Runway three six shortened, cleared for takeoff.” and takeoff clearances from taxiway intersection, the • “Runway three six shortened, cleared to land.” taxiway designator is included.

Example – “N123AG Runway One-Eight, at Charlie When an intersection departure is requested on a temporarily Three, line up and wait.” or permanently shortened runway during the construction, the remaining length of runway is included in the clearance.

Example – “N123AG Runway One-Eight, at Charlie For example, “Runway three six at Echo, intersection Three, cleared for takeoff.” departure, 5,600 feet available.” If following the construction, the runway is permanently shortened, ATC will include If LUAW procedures are being used and landing traffic is a the word “shortened” until the Chart Supplement U.S.

factor, ATC is required to: (formerly Airport/Facility Directory) is updated to include • Inform the aircraft in the LUAW position of the closest the permanent changes to the runway length.

aircraft that is requesting a full-stop, touch-and-go, stop-and-go, option, or unrestricted low approach.

Pre-Landing, Landing, and After-Landing Example – “N123AG, Runway One-Eight, line up While en route and after receiving the destination airport and wait, traffic a Cessna 210 on a six-mile final.” ATIS/landing information, review the airport diagram and brief yourself as to your exit taxiway. Determine the following: • In some cases, where safety logic is being used, ATC is permitted to issue landing clearances with traffic in • Are there any runway hold markings in close proximity the LUAW position. Traffic information is issued to to the exit taxiway?

the landing traffic.

• Do not cross any hold markings or exit onto any Example – “N456HK, Runway One-Eight, cleared to runways without ATC clearance.

land, traffic a DeHavilland Otter holding in position.” After landing, use the utmost caution where the exit taxiways NOTE: ATC will/must issue a takeoff clearance to the intersect another runway, and do not exit onto another runway traffic holding in position in sufficient time to ensure without ATC authorization. Do not accept last minute no conflict exists with landing aircraft. Prescribed turnoff instructions from the control tower unless you clearly runway separation must exist no later than when the understand the instructions and are at a speed that ensures you landing aircraft crosses the threshold.

14-34 can safely comply. Finally, after landing and upon exiting the runway, ensure your aircraft has completely crossed over the runway hold markings. Once all parts of the aircraft have crossed the runway holding position markings, you must hold unless further instructions have been issued by ATC. Do not initiate non-essential communications or actions until the aircraft has stopped and the brakes set.

Engineered Materials Arresting Systems (EMAS) Aircraft can and do overrun the ends of runways and sometimes with devastating results. An overrun occurs Figure 14-55. Engineered material arresting system (EMAS) located at Yeager Airport, Charleston, West Virginia.

when an aircraft passes beyond the end of a runway during an aborted takeoff or on landing rollout. To minimize the • May 2003—A Cargo McDonnell Douglas (MD)-11 hazards of overruns, the FAA incorporated the concept of a runway safety area (RSA) beyond the runway end into overran the runway at JFK.

airport design standards. At most commercial airports, the • January 2005—A Boeing 747 overran the runway at RSA is 500 feet wide and extends 1,000 feet beyond each JFK.

end of the runway. The FAA implemented this requirement • July 2006—A Mystere Falcon 900 overran the in the event that an aircraft overruns, undershoots, or veers runway at Greenville Downtown Airport (KGMU) off the side of the runway.

in Greenville, South Carolina.

The most dangerous of these incidents are overruns, but • July 2008—An Airbus A320 overran the runway at since many airports were built before the 1,000-foot RSA O’Hare International Airport (ORD).

length was adopted some 20 years ago, the area beyond the • January 2010—A Bombardier CRJ-200 regional jet end of the runway is where many airports cannot achieve the overran the runway at Yeager Airport (KCRW) in full standard RSA. This is due to obstacles, such as bodies Charleston, West Virginia (WV). [Figure 14-58] of water, highways, railroads, populated areas, or severe • October 2010—A G-4 Gulfstream overran the drop-off of terrain. Under these specific circumstances, the runway at Teterboro Airport (KTEB) in Teterboro, installation of an Engineered Materials Arresting System New Jersey (NJ).

(EMAS) is an acceptable alternative to a RSA beyond the runway end. It provides a level of safety that is generally • November 2011—A Cessna Citation 550 overran the equivalent to a full RSA. [Figure 14-55] runway at Key West International Airport (KEYW) in Key West, Florida.

An EMAS uses materials of closely controlled strength and density placed at the end of a runway to stop or greatly slow EMAS Installations and Information an aircraft that overruns the runway. The best material found Currently, EMAS is installed at 63 runway ends at 42 airports to date is a lightweight, crushable concrete. When an aircraft in the United States with plans to install more throughout the rolls into an EMAS arrestor bed, the tires of the aircraft sink next few years.

into the lightweight concrete and the aircraft is decelerated by having to roll through the material. [Figure 14-56] EMAS information is available in the Chart Supplement U.S. (formerly Airport/Facility Directory) under the specific Incidents airport information. Figure 14-59 shows airport information To date, there have been several incidents listed below where for Boston Logan International Airport. At the bottom of the the EMAS technology has worked successfully to arrest page, it shows which runways are equipped with arresting aircraft that overrun the runway. All cases have resulted in systems and the type that they have. It is important for pilots minimal to do damage to the aircraft. The only known injury to study airport information, become familiar with the details was an ankle injury to a passenger during egress following and limitations of the arresting system, and the runways that the arrestment. [Figure 14-57] are equipped with them. [Figure 14-60] • May 1999—A Saab 340 commuter aircraft overran the runway at John F. Kennedy International Airport (JFK).

14-35 Typical Plan View Runway safety area length Runway Set back ARRESTOR BED Runway width Side steps An EMASMAX bed is typically the full width of the runway and the arrestor bed is set-back from the end of the runway.

Typical Profile View Debris deflector Arrestor bed over concrete beam Lead in ramp Side steps Base surface The front of an EMASMAX bed includes a lead-in ramp to transition the aircraft into the material.

Typical Section View Arrestor bed Stepped sides provide arff access and passenger egress Base surface • Beyond the runway width, the sides of an EMASMAX bed are stepped to provide emergency vehicle access and passenger egress.

• The length of the EMAS bed is dependent upon the space available in the existing RSA and the design aircraft for the EMAS.

• As stated in FAA Advisory Circular 150/5220-22A, Engineered Materials Arresting Systems (EMAS) for Aircraft Overruns, the EMAS is designed to arrest aircraft exiting the runway at speeds between 40 and 70 knots. 70 knots is the preferred EMAS design runway exit speed but in limited spaces, the EMAS may have design runway exit speeds as low as 40 knots.

Figure 14-56. Diagram of an EMASMAX system.

Pilot Considerations to commencing the approach. Following the guidance below ensures that the aircraft engages the EMAS according to the Although engaging an EMAS should not be a desired design entry parameters.

outcome for the end of a flight, pilots need to know what EMAS is, how to identify it on the airfield diagram and During the takeoff or landing phase, if a pilot determines that on the airfield, as well as knowing what to do should they the aircraft will exit the runway end and enter the EMAS, the find themselves approaching an installation in an overrun following guidance should be adhered to: situation. [Figure 14-59 and Figure 14-60] Pilots also need to know that an EMAS may not stop lightweight general 1. Continue deceleration - Regardless of aircraft speed aviation aircraft that are not heavy enough to sink into the upon exiting the runway, continue to follow Rejected/ crushable concrete. The time to discuss whether or not a Aborted Takeoff procedures, or if landing, Maximum runway has an EMAS at the end is during the pre-departure Braking procedures outlined in the Flight Manual.

briefing prior to takeoff or during the approach briefing prior 14-36 Figure 14-58. A Bombardier CRJ-200 regional jet overran the Figure 14-57. There have been several incidents where the EMAS runway at Yeager Airport (KCRW) in Charleston, West Virginia.

has successfully arrested the aircraft.

The chapter identifies best practices to help you avoid errors 2. Maintain runway centerline - Not veering left or right that may potentially lead to runway incursions. Although the of the bed and continuing straight ahead will maximize chapter pertains mostly to surface movements for single-pilot stopping capability of the EMAS bed. The quality of operations, all of the information is relevant for flight crew deceleration will be best within the confines of the bed.

operations as well.

3. Maintain deceleration efforts - The arrestor bed is a passive system, so this is the only action required by Additional information about surface operations is available the pilot.

through the following sources: 4. Once stopped, do not attempt to taxi or otherwise move • Federal Aviation Administration (FAA) Runway the aircraft.

Safety website—www.faa.gov/go/runwaysafety • FAA National Aeronautical Navigation Services Chapter Summary (AeroNav), formerly known as the National This chapter focused on airport operations both in the air and Aeronautical Charting Office (NACO)—www.faa.

on the surface. For specific information about an unfamiliar gov/air_traffic/flight_info/aeronav airport, consult the Chart Supplement U.S. (formerly Airport/Facility Directory) and NOTAMS before flying. For • Chart Supplement U.S. (formerly Airport/Facility Directory)—www.faa.gov/air_traffic/flight_info/ further information regarding procedures discussed in this chapter, refer to 14 CFR part 91 and the AIM. By adhering aeronav/digital_products/dafd/search/ to established procedures, both airport operations and safety • Automatic Terminal Information Service (ATIS) are enhanced.

• Notice to Airmen (NOTAMs)—http://www.faa.gov/ pilots/flt_plan/notams This chapter is also designed to help you attain an understanding of the risks associated with surface navigation • Advisory Circular (AC) 91-73, part 91 and part 135, and is intended to provide you with basic information Single-Pilot and Flight School Procedures During Taxi regarding the safe operation of aircraft at towered and Operations nontowered airports. This chapter focuses on the following • Aeronautical Information Manual (AIM)—www.faa.

major areas: gov/air_traffic/publications/atpubs/aim/ • Runway incursion overview • AC 120-74, parts 91, 121, 125, and 135, Flight Crew • Taxi route planning Procedures During Taxi Operations • Taxi procedures • Communications • Airport signs, markings and lighting 14-37

Not to be used for navigation

Figure 14-59. EMAS information for Boston Logan International Airport located in the Chart Supplement U.S. (formerly Airport/ Facility Directory).

14-38 NE-1, 28 JUL 2011 to 25 AUG 2011 NE-1, 28 JUL 2011 to 25 AUG 2011

Not to be used for navigation

Figure 14-60. An airport diagram with EMAS information.

14-39 14-40

Chapter 15

Airspace

Introduction The two categories of airspace are: regulatory and nonregulatory. Within these two categories, there are four types: controlled, uncontrolled, special use, and other airspace. The categories and types of airspace are dictated by the complexity or density of aircraft movements, nature of the operations conducted within the airspace, the level of safety required, and national and public interest. Figure 15-1 presents a profile view of the dimensions of various classes of airspace. Also, there are excerpts from sectional charts that are discussed in Chapter 16, Navigation, that are used to illustrate how airspace is depicted.

15-1 FL 600 Class A 18,000' MSL Class B Class E 14,500' MSL Class C 1,200' 1,200' 1,200' AGL AGL AGL Nontowered Class Nontowered 700' G airport with 700' 700' Class AGL airport with AGL D no instrument AGL instrument approach approach Class Class Class G G G Figure 15-1. Airspace profile.

Class C Airspace Controlled Airspace Class C airspace is generally airspace from the surface to Controlled airspace is a generic term that covers the 4,000 feet above the airport elevation (charted in MSL) different classifications of airspace and defined dimensions surrounding those airports that have an operational control within which air traffic control (ATC) service is provided tower, are serviced by a radar approach control, and have a in accordance with the airspace classification. Controlled certain number of IFR operations or passenger enplanements.

airspace consists of: Although the configuration of each Class C area is • Class A individually tailored, the airspace usually consists of a surface area with a five NM radius, an outer circle with a ten NM • Class B radius that extends from 1,200 feet to 4,000 feet above the • Class C airport elevation. Each aircraft must establish two-way radio • Class D communications with the ATC facility providing air traffic services prior to entering the airspace and thereafter must • Class E maintain those communications while within the airspace.

Class A Airspace Class D Airspace Class A airspace is generally the airspace from 18,000 feet Class D airspace is generally airspace from the surface to mean sea level (MSL) up to and including flight level (FL) 2,500 feet above the airport elevation (charted in MSL) 600, including the airspace overlying the waters within 12 surrounding those airports that have an operational control nautical miles (NM) of the coast of the 48 contiguous states tower. The configuration of each Class D airspace area is and Alaska. Unless otherwise authorized, all operation in Class individually tailored and, when instrument procedures are A airspace is conducted under instrument flight rules (IFR).

published, the airspace is normally designed to contain the procedures. Arrival extensions for instrument approach Class B Airspace procedures (IAPs) may be Class D or Class E airspace. Unless Class B airspace is generally airspace from the surface to otherwise authorized, each aircraft must establish two-way 10,000 feet MSL surrounding the nation’s busiest airports in radio communications with the ATC facility providing air terms of airport operations or passenger enplanements. The traffic services prior to entering the airspace and thereafter configuration of each Class B airspace area is individually maintain those communications while in the airspace.

tailored, consists of a surface area and two or more layers (some Class B airspace areas resemble upside-down wedding Class E Airspace cakes), and is designed to contain all published instrument Class E airspace is the controlled airspace not classified as procedures once an aircraft enters the airspace. ATC Class A, B, C, or D airspace. A large amount of the airspace clearance is required for all aircraft to operate in the area, over the United States is designated as Class E airspace.

and all aircraft that are so cleared receive separation services within the airspace.

15-2 This provides sufficient airspace for the safe control and Prohibited Areas separation of aircraft during IFR operations. Chapter 3 of Prohibited areas contain airspace of defined dimensions the Aeronautical Information Manual (AIM) explains the within which the flight of aircraft is prohibited. Such areas various types of Class E airspace.

are established for security or other reasons associated with the national welfare. These areas are published in the Federal Sectional and other charts depict all locations of Class E Register and are depicted on aeronautical charts. The area is airspace with bases below 14,500 feet MSL. In areas where charted as a “P” followed by a number (e.g., P-40). Examples charts do not depict a class E base, class E begins at 14,500 of prohibited areas include Camp David and the National feet MSL.

Mall in Washington, D.C., where the White House and the Congressional buildings are located. [Figure 15-2] In most areas, the Class E airspace base is 1,200 feet AGL. In many other areas, the Class E airspace base is either the surface Restricted Areas or 700 feet AGL. Some Class E airspace begins at an MSL Restricted areas are areas where operations are hazardous to altitude depicted on the charts, instead of an AGL altitude.

nonparticipating aircraft and contain airspace within which the flight of aircraft, while not wholly prohibited, is subject Class E airspace typically extends up to, but not including, to restrictions. Activities within these areas must be confined 18,000 feet MSL (the lower limit of Class A airspace). All because of their nature, or limitations may be imposed upon airspace above FL 600 is Class E airspace.

aircraft operations that are not a part of those activities, or both. Restricted areas denote the existence of unusual, often Uncontrolled Airspace invisible, hazards to aircraft (e.g., artillery firing, aerial gunnery, or guided missiles). IFR flights may be authorized Class G Airspace to transit the airspace and are routed accordingly. Penetration Uncontrolled airspace or Class G airspace is the portion of of restricted areas without authorization from the using the airspace that has not been designated as Class A, B, C, or controlling agency may be extremely hazardous to the D, or E. It is therefore designated uncontrolled airspace.

aircraft and its occupants. ATC facilities apply the following Class G airspace extends from the surface to the base of the procedures when aircraft are operating on an IFR clearance overlying Class E airspace. Although ATC has no authority (including those cleared by ATC to maintain VFR on top) via or responsibility to control air traffic, pilots should remember a route that lies within joint-use restricted airspace: there are visual flight rules (VFR) minimums that apply to Class G airspace.

1. If the restricted area is not active and has been released to the Federal Aviation Administration (FAA), the Special Use Airspace ATC facility allows the aircraft to operate in the restricted airspace without issuing specific clearance Special use airspace or special area of operation (SAO) for it to do so.

is the designation for airspace in which certain activities must be confined, or where limitations may be imposed 2. If the restricted area is active and has not been released on aircraft operations that are not part of those activities.

to the FAA, the ATC facility issues a clearance that Certain special use airspace areas can create limitations on ensures the aircraft avoids the restricted airspace.

the mixed use of airspace. The special use airspace depicted on instrument charts includes the area name or number, effective altitude, time and weather conditions of operation, the controlling agency, and the chart panel location. On National Aeronautical Charting Group (NACG) en route charts, this information is available on one of the end panels.

Special use airspace usually consists of: • Prohibited areas • Restricted areas • Warning areas • Military operation areas (MOAs) • Alert areas Figure 15-2. An example of a prohibited area, P-40 around Camp • Controlled firing areas (CFAs) David.

15-3 Restricted areas are charted with an “R” followed by a number (e.g., R-4401) and are depicted on the en route chart appropriate for use at the altitude or FL being flown.

[Figure 15-3] Restricted area information can be obtained on the back of the chart.

Warning Areas Warning areas are similar in nature to restricted areas; however, the United States government does not have sole jurisdiction over the airspace. A warning area is airspace of defined dimensions, extending from 3 NM outward from the coast of the United States, containing activity that may be hazardous to nonparticipating aircraft. The purpose of Figure 15-4. Requirements for airspace operations.

such areas is to warn nonparticipating pilots of the potential danger. A warning area may be located over domestic or pilots of areas that may contain a high volume of pilot training international waters or both. The airspace is designated with or an unusual type of aerial activity. Pilots should exercise a “W” followed by a number (e.g., W-237). [Figure 15-4] caution in alert areas. All activity within an alert area shall be conducted in accordance with regulations, without waiver, Military Operation Areas (MOAs) and pilots of participating aircraft, as well as pilots transiting MOAs consist of airspace with defined vertical and lateral the area, shall be equally responsible for collision avoidance.

limits established for the purpose of separating certain [Figure 15-6] military training activities from IFR traffic. Whenever an MOA is being used, nonparticipating IFR traffic may be Controlled Firing Areas (CFAs) cleared through an MOA if IFR separation can be provided by CFAs contain activities that, if not conducted in a controlled ATC. Otherwise, ATC reroutes or restricts nonparticipating environment, could be hazardous to nonparticipating aircraft.

IFR traffic. MOAs are depicted on sectional, VFR terminal The difference between CFAs and other special use airspace area, and en route low altitude charts and are not numbered is that activities must be suspended when a spotter aircraft, (e.g., “Camden Ridge MOA”). [Figure 15-5] However, the radar, or ground lookout position indicates an aircraft might MOA is also further defined on the back of the sectional be approaching the area. There is no need to chart CFAs charts with times of operation, altitudes affected, and the since they do not cause a nonparticipating aircraft to change controlling agency.

its flight path.

Alert Areas Other Airspace Areas Alert areas are depicted on aeronautical charts with an “A” followed by a number (e.g., A-211) to inform nonparticipating “Other airspace areas” is a general term referring to the majority of the remaining airspace. It includes: • Local airport advisory (LAA) • Military training route (MTR) • Temporary flight restriction (TFR) • Parachute jump aircraft operations • Published VFR routes • Terminal radar service area (TRSA) • National security area (NSA) • Air Defense Identification Zones (ADIZ) land and water based and need for Defense VFR (DVFR) flight plan to operate VFR in this airspace • Intercept Procedures and use of 121.5 for communication if not on ATC already Figure 15-3. Restricted areas on a sectional chart.

15-4 Figure 15-5. Camden Ridge MOA is an example of a military operations area.

Figure 15-6. Alert area (A-211).

15-5 • Flight Restricted Zones (FRZ) in vicinity of Capitol accommodate operations above 1,500 feet AGL. IR routes and White House are conducted in accordance with IFR regardless of weather conditions. VFR sectional charts depict military training • S p e c i a l A w a r e n e s s T r a i n i n g r e q u i r e d b y activities, such as IR, VR, MOA, restricted area, warning 14 CFR 91.161 for pilots to operate VFR within 60 area, and alert area information.

NM of the Washington, DC VOR/DME • Wildlife Areas/Wilderness Areas/National Parks and Temporary Flight Restrictions (TFR) request to operate above 2,000 AGL A flight data center (FDC) Notice to Airmen (NOTAM) is issued to designate a TFR. The NOTAM begins with • National Oceanic and Atmospheric Administration (NOAA) Marine Areas off the coast with requirement the phrase “FLIGHT RESTRICTIONS” followed by the location of the temporary restriction, effective time period, to operate above 2,000 AGL area defined in statute miles, and altitudes affected. The • Tethered Balloons for observation and weather NOTAM also contains the FAA coordination facility and recordings that extend on cables up to 60,000 telephone number, the reason for the restriction, and any other information deemed appropriate. The pilot should check the Local Airport Advisory (LAA) NOTAMs as part of flight planning.

An advisory service provided by Flight Service Station (FSS) facilities, which are located on the landing airport, Some of the purposes for establishing a TFR are: using a discrete ground-to-air frequency or the tower • Protect persons and property in the air or on the surface frequency when the tower is closed. LAA services include from an existing or imminent hazard.

local airport advisories, automated weather reporting with voice broadcasting, and a continuous Automated Surface • Provide a safe environment for the operation of Observing System (ASOS)/Automated Weather Observing disaster relief aircraft.

Station (AWOS) data display, other continuous direct reading • Prevent an unsafe congestion of sightseeing aircraft instruments, or manual observations available to the specialist.

above an incident or event, that may generate a high degree of public interest.

Military Training Routes (MTRs) MTRs are routes used by military aircraft to maintain • Protect declared national disasters for humanitarian reasons in the State of Hawaii.

proficiency in tactical flying. These routes are usually established below 10,000 feet MSL for operations at speeds • Protect the President, Vice President, or other public in excess of 250 knots. Some route segments may be defined figures.

at higher altitudes for purposes of route continuity. Routes • Provide a safe environment for space agency are identified as IFR (IR), and VFR (VR), followed by operations.

a number. [Figure 15-7] MTRs with no segment above 1,500 feet AGL are identified by four number characters Since the events of September 11, 2001, the use of TFRs has (e.g., IR1206, VR1207). MTRs that include one or more become much more common. There have been a number of segments above 1,500 feet AGL are identified by three incidents of aircraft incursions into TFRs that have resulted number characters (e.g., IR206, VR207). IFR low altitude in pilots undergoing security investigations and certificate en route charts depict all IR routes and all VR routes that suspensions. It is a pilot’s responsibility to be aware of TFRs in their proposed area of flight. One way to check is to visit the FAA website, www.tfr.faa.gov, and verify that there is not a TFR in the area.

Parachute Jump Aircraft Operations Parachute jump aircraft operations are published in the Chart Supplement U.S. (formerly Airport/Facility Directory). Sites that are used frequently are depicted on sectional charts.

Military Training Published VFR Routes Route (MTR) Published VFR routes are for transitioning around, under, or through some complex airspace. Terms such as VFR flyway, VFR corridor, Class B airspace VFR transition route, and Figure 15-7. Military training route (MTR) chart symbols.

terminal area VFR route have been applied to such routes.

15-6 These routes are generally found on VFR terminal area 1. A deviation is necessary to conform to ICAO planning charts. Documents, National Rules of the Air, or special agreements where the United States provides ATC Terminal Radar Service Areas (TRSAs) service in airspace outside the country and its TRSAs are areas where participating pilots can receive possessions additional radar services. The purpose of the service is 2. Other procedures/minima are prescribed in a letter of to provide separation between all IFR operations and agreement, FAA directive, or a military document participating VFR aircraft.

3. A deviation is necessary to assist an aircraft when an emergency has been declared The primary airport(s) within the TRSA become(s) Class D airspace. The remaining portion of the TRSA overlies other Coordinating the Use of Airspace controlled airspace, which is normally Class E airspace ATC is responsible for ensuring that the necessary beginning at 700 or 1,200 feet and established to transition to/ coordination has been accomplished before allowing an from the en route/terminal environment. TRSAs are depicted aircraft under their control to enter another controller’s area on VFR sectional charts and terminal area charts with a solid of jurisdiction.

black line and altitudes for each segment. The Class D portion is charted with a blue segmented line. Participation in TRSA Before issuing control instructions directly or relaying services is voluntary; however, pilots operating under VFR through another source to an aircraft that is within another are encouraged to contact the radar approach control and take controller’s area of jurisdiction that will change that advantage of TRSA service.

aircraft’s heading, route, speed, or altitude, ATC ensures that coordination has been accomplished with each of the National Security Areas (NSAs) controllers listed below whose area of jurisdiction is affected NSAs consist of airspace of defined vertical and lateral by those instructions unless otherwise specified by a letter dimensions established at locations where there is a of agreement or a facility directive: requirement for increased security and safety of ground facilities. Flight in NSAs may be temporarily prohibited by 1. The controller within whose area of jurisdiction the regulation under the provisions of Title 14 of the Code of control instructions are issued Federal Regulations (14 CFR) part 99, and prohibitions are 2. The controller receiving the transfer of control disseminated via NOTAM. Pilots are requested to voluntarily 3. Any intervening controller(s) through whose area of avoid flying through these depicted areas.

jurisdiction the aircraft will pass Air Traffic Control and the National If ATC issues control instructions to an aircraft through a Airspace System source other than another controller (e.g., Aeronautical Radio, The primary purpose of the ATC system is to prevent a Incorporated (ARINC), FSS, another pilot), they ensure that collision between aircraft operating in the system and to the necessary coordination has been accomplished with any organize and expedite the flow of traffic. In addition to controllers listed above, whose area of jurisdiction is affected its primary function, the ATC system has the capability to by those instructions unless otherwise specified by a letter provide (with certain limitations) additional services. The of agreement or a facility directive.

ability to provide additional services is limited by many factors, such as the volume of traffic, frequency congestion, Operating in the Various Types of Airspace quality of radar, controller workload, higher priority duties, It is important that pilots be familiar with the operational and the pure physical inability to scan and detect those requirements for each of the various types or classes of situations that fall in this category. It is recognized that these airspace. Subsequent sections cover each class in sufficient services cannot be provided in cases in which the provision detail to facilitate understanding regarding weather, type of of services is precluded by the above factors.

pilot certificate held, and equipment required.

Consistent with the aforementioned conditions, controllers Basic VFR Weather Minimums shall provide additional service procedures to the extent No pilot may operate an aircraft under basic VFR when the permitted by higher priority duties and other circumstances.

flight visibility is less, or at a distance from clouds that is The provision of additional services is not optional on the less, than that prescribed for the corresponding altitude and part of the controller, but rather is required when the work class of airspace. [Figure 15-8] Except as provided in 14 CFR situation permits. Provide ATC service in accordance with part 91, section 91.157, “Special VFR Weather Minimums,” the procedures and minima in this order except when: 15-7 Basic VFR Weather Minimums Airspace Flight Visibility Distance from Clouds Class Not applicable Not applicable A Class 3 statute miles Clear of clouds B 3 statute miles 1,000 feet above Class 500 feet below C 2,000 feet horizontal 3 statute miles 1,000 feet above Class 500 feet below D 2,000 feet horizontal 5 statute miles 1,000 feet above At or above 1,000 feet below 10,000 feet MSL 1 statute mile horizontal Class E 3 statute miles 1,000 feet above Less than 500 feet below 10,000 feet MSL 2,000 feet horizontal Day, except as provided in section 91.155(b) 1 statute mile Clear of clouds 1,200 feet or less above the surface Night, except as provided in section 91.155(b) 3 statute miles 1,000 feet above (regardless of 500 feet below MSL altitude).

2,000 feet horizontal Day 1 statute mile 1,000 feet above More than 1,200 500 feet below feet above the 2,000 feet horizontal Class surface but less G than 10,000 feet Night 3 statute miles 1,000 feet above MSL.

500 feet below 2,000 feet horizontal More than 1,200 5 statute miles 1,000 feet above feet above the 1,000 feet below surface and at or 1 statute mile horizontal above 10,000 feet MSL.

Figure 15-8. Visual flight rule weather minimums.

no person may operate an aircraft beneath the ceiling under All aircraft operating in today’s National Airspace System VFR within the lateral boundaries of controlled airspace (NAS) has complied with the CFR governing its certification designated to the surface for an airport when the ceiling is and maintenance; all pilots operating today have completed less than 1,000 feet. Additional information can be found in rigorous pilot certification training and testing. Of equal 14 CFR part 91, section 91.155(c). importance is the proper execution of preflight planning, aeronautical decision-making (ADM) and risk management.

ADM involves a systematic approach to risk assessment Operating Rules and Pilot/Equipment Requirements and stress management in aviation, illustrates how personal The safety of flight is a top priority of all pilots and the attitudes can influence decision-making, and how those responsibilities associated with operating an aircraft attitudes can be modified to enhance safety in the flight should always be taken seriously. The air traffic system deck. More detailed information regarding ADM and maintains a high degree of safety and efficiency with strict risk mitigation can be found in Chapter 2, “Aeronautical regulatory oversight of the FAA. Pilots fly in accordance Decision-Making.” with regulations that have served the United States well, as evidenced by the fact that the country has the safest aviation system in the world.

15-8 Pilots also comply with very strict FAA general operating 2. A recreational pilot certificate and all requirements and flight rules as outlined in the CFR, including the FAA’s contained within 14 CFR part 61, section 61.101(d), or important “see and avoid” mandate. These regulations provide the requirements for a student pilot seeking a recreational the historical foundation of the FAA regulations governing pilot certificate in 14 CFR part 61, section 61.94.

the aviation system and the individual classes of airspace.

3. A sport pilot certificate and all requirements contained Figure 15-9 lists the operational and equipment requirements within 14 CFR part 61, section 61.325, or the for these various classes of airspace. It is helpful to refer to this requirements for a student pilot seeking a recreational figure as the specific classes are discussed in greater detail.

pilot certificate in 14 CFR part 61, section 61.94, or the aircraft is operated by a student pilot who has met Class A the requirements of 14 CFR part 61, sections 61.94 Pilots operating an aircraft in Class A airspace must conduct and 61.95, as applicable.

that operation under IFR and only under an ATC clearance received prior to entering the airspace. Unless otherwise Unless otherwise authorized by ATC, all aircraft within Class authorized by ATC, each aircraft operating in Class A B airspace must be equipped with the applicable operating airspace must be equipped with a two-way radio capable of transponder and automatic altitude reporting equipment communicating with ATC on a frequency assigned by ATC.

specified in 14 CFR part 91, section 91.215(a) and an Unless otherwise authorized by ATC, all aircraft within operable two-way radio capable of communications with Class A airspace must be equipped with the appropriate ATC on appropriate frequencies for that Class B airspace transponder equipment meeting all applicable specifications area. Additionally, beginning January 1, 2020, aircraft found in 14 CFR part 91, section 91.215. Additionally, operating in the Class B airspace described in 14 CFR part 91, beginning January 1, 2020, aircraft operating in the Class section 91.225, must have ADS-B Out equipment installed, A airspace described in 14 CFR part 91, section 91.225, which meets the performance requirements of 14 CFR part must have ADS-B Out equipment installed, which meets the 91, section 91.227.

performance requirements of 14 CFR part 91, section 91.227.

Class C Class B For the purpose of this section, the primary airport is the All pilots operating an aircraft within a Class B airspace area airport for which the Class C airspace area is designated. A must receive an ATC clearance from the ATC facility having satellite airport is any other airport within the Class C airspace jurisdiction for that area. The pilot in command (PIC) may area. No pilot may take off or land an aircraft at a satellite not take off or land an aircraft at an airport within a Class airport within a Class C airspace area except in compliance B airspace unless he or she has met one of the following with FAA arrival and departure traffic patterns.

requirements: Two-way radio communications must be established and 1. A private pilot certificate maintained with the ATC facility providing air traffic services Class Entry Requirements Equipment* Minimum Pilot Certificate Airspace Class ATC clearance IFR equipped Instrument rating A Class ATC clearance Two-way radio, transponder Private—(However, a student or B with altitude reporting capability recreational pilot may operate at other than the primary airport if seeking private pilot certification and if regulatory requirements are met.)

Two-way radio communications Two-way radio, transponder No specific requirement Class C prior to entry with altitude reporting capability Two-way radio communications Two-way radio No specific requirement Class D prior to entry None for VFR No specific requirement No specific requirement Class E Class G None No specific requirement No specific requirement *Beginning January 1, 2020, ADS-B Out equipment may be required in accordance with 14 CFR part 91, section 91.225.

Figure 15-9. Requirements for airspace operations.

15-9 prior to entering the airspace and thereafter maintained while If the aircraft radio fails in flight under VFR, the PIC may within the airspace. operate that aircraft and land if weather conditions are at or above basic VFR weather minimums, visual contact with A pilot departing from the primary airport or satellite airport the tower is maintained, and a clearance to land is received.

with an operating control tower must establish and maintain two-way radio communications with the control tower, Class E and thereafter as instructed by ATC while operating in the Unless otherwise required by 14 CFR part 93 or unless Class C airspace area. If departing from a satellite airport otherwise authorized or required by the ATC facility having without an operating control tower, the pilot must establish jurisdiction over the Class E airspace area, each pilot and maintain two-way radio communications with the ATC operating an aircraft on or in the vicinity of an airport in a facility having jurisdiction over the Class C airspace area as Class E airspace area must comply with the requirements soon as practicable after departing.

of Class G airspace. Each pilot must also comply with any traffic patterns established for that airport in 14 CFR part 93.

Unless otherwise authorized by the ATC having jurisdiction over the Class C airspace area, all aircraft within Class C Unless otherwise authorized or required by ATC, no person airspace must be equipped with the appropriate transponder may operate an aircraft to, from, through, or on an airport equipment meeting all applicable specifications found in 14 having an operational control tower unless two-way radio CFR part 91, section 91.215. Additionally, beginning January communications are maintained between that aircraft and the 1, 2020, aircraft operating in the Class C airspace described control tower. Communications must be established within in 14 CFR part 91, section 91.225, must have ADS-B four nautical miles from the airport, up to and including 2,500 Out equipment installed, which meets the performance feet AGL. However, if the aircraft radio fails in flight, the PIC requirements of 14 CFR part 91, section 91.227.

may operate that aircraft and land if weather conditions are at or above basic VFR weather minimums, visual contact with Class D the tower is maintained, and a clearance to land is received.

No pilot may take off or land an aircraft at a satellite airport within a Class D airspace area except in compliance with If the aircraft radio fails in flight under IFR, the pilot should FAA arrival and departure traffic patterns. A pilot departing continue the flight by the route assigned in the last ATC from the primary airport or satellite airport with an operating clearance received; or, if being radar vectored, by the direct control tower must establish and maintain two-way radio route from the point of radio failure to the fix, route, or communications with the control tower, and thereafter as airway specified in the vector clearance. In the absence of instructed by ATC while operating in the Class D airspace an assigned route, the pilot should continue by the route area. If departing from a satellite airport without an operating that ATC advised may be expected in a further clearance; control tower, the pilot must establish and maintain two- or, if a route had not been advised, by the route filed in the way radio communications with the ATC facility having flight plan. Additionally, beginning January 1, 2020, aircraft jurisdiction over the Class D airspace area as soon as operating in the Class E airspace described in 14 CFR part 91, practicable after departing. section 91.225, must have ADS-B Out equipment installed, which meets the performance requirements of 14 CFR part Two-way radio communications must be established and 91, section 91.227.

maintained with the ATC facility providing air traffic services prior to entering the airspace and thereafter maintained while Class G within the airspace.

When approaching to land at an airport without an operating control tower in Class G airspace: If the aircraft radio fails in flight under IFR, the pilot should 1. Each pilot of an airplane must make all turns of that continue the flight by the route assigned in the last ATC airplane to the left unless the airport displays approved clearance received; or, if being radar vectored, by the direct light signals or visual markings indicating that turns route from the point of radio failure to the fix, route, or should be made to the right, in which case the pilot airway specified in the vector clearance. In the absence of must make all turns to the right.

an assigned route, the pilot should continue by the route 2. Each pilot of a helicopter or a powered parachute must that ATC advised may be expected in a further clearance; avoid the flow of fixed-wing aircraft.

or, if a route had not been advised, by the route filed in the flight plan.

15-10 Unless otherwise authorized or required by ATC, no person Unmanned Free Balloons may operate an aircraft to, from, through, or on an airport Unless otherwise authorized by ATC, no person may operate having an operational control tower unless two-way radio an unmanned free balloon below 2,000 feet above the surface communications are maintained between that aircraft and the within the lateral boundaries of Class B, Class C, Class D, control tower. Communications must be established within or Class E airspace designated for an airport. (See 14 CFR four nautical miles from the airport, up to and including 2,500 part 101.)

feet AGL. However, if the aircraft radio fails in flight, the PIC may operate that aircraft and land if weather conditions are at Unmanned Aircraft Systems or above basic VFR weather minimums, visual contact with Regulations regarding unmanned aircraft systems (UAS) are the tower is maintained, and a clearance to land is received.

currently being developed and are expected to be published by summer 2016 as 14 CFR part 107.

If the aircraft radio fails in flight under IFR, the pilot should continue the flight by the route assigned in the last ATC Parachute Jumps clearance received; or, if being radar vectored, by the direct No person may make a parachute jump, and no PIC may route from the point of radio failure to the fix, route, or airway allow a parachute jump to be made from an aircraft, in or specified in the vector clearance. In the absence of an assigned into Class A, Class B, Class C, or Class D airspace without, route, the pilot should continue by the route that ATC advised or in violation of, the terms of an ATC authorization issued may be expected in a further clearance; or, if a route had not by the ATC facility having jurisdiction over the airspace.

been advised, by the route filed in the flight plan.

(See 14 CFR part 105.)

Uncontrolled Airspace Chapter Summary It is possible for some airports within Class G airspace to have a control tower (Lake City, FL, for example). Be sure to This chapter introduces the various classifications of airspace check the Chart Supplement U.S. (formerly Airport/Facility and provides information on the requirements to operate in Directory) to be familiar with the airport and associated such airspace. For further information, consult the AIM and airspace prior to flight.

14 CFR parts 71, 73, and 91.

Ultralight Vehicles No person may operate an ultralight vehicle within Class A, Class B, Class C, or Class D airspace or within the lateral boundaries of the surface area of Class E airspace designated for an airport unless that person has prior authorization from the ATC facility having jurisdiction over that airspace. (See 14 CFR part 103.)

15-11 15-12

Chapter 16

Navigation

Introduction This chapter provides an introduction to cross-country flying under visual flight rules (VFR). It contains practical information for planning and executing cross-country flights for the beginning pilot.

Air navigation is the process of piloting an aircraft from one geographic position to another while monitoring one’s position as the flight progresses. It introduces the need for planning, which includes plotting the course on an aeronautical chart, selecting checkpoints, measuring distances, obtaining pertinent weather information, and computing flight time, headings, and fuel requirements. The methods used in this chapter include pilotage—navigating by reference to visible landmarks, dead reckoning—computations of direction and distance from a known position, and radio navigation—by use of radio aids.

16-1 The charts provide an abundance of information, including Aeronautical Charts airport data, navigational aids, airspace, and topography.

An aeronautical chart is the road map for a pilot flying under Figure 16-1 is an excerpt from the legend of a sectional VFR. The chart provides information that allows pilots to track chart. By referring to the chart legend, a pilot can interpret their position and provides available information that enhances most of the information on the chart. A pilot should also safety. The three aeronautical charts used by VFR pilots are: check the chart for other legend information, which includes • Sectional air traffic control (ATC) frequencies and information on airspace. These charts are revised semiannually except for • VFR Terminal Area some areas outside the conterminous United States where • World Aeronautical they are revised annually.

A free catalog listing aeronautical charts and related VFR Terminal Area Charts publications including prices and instructions for ordering is VFR terminal area charts are helpful when flying in or near available at the Aeronautical Navigation Products website: Class B airspace. They have a scale of 1:250,000 (1 inch www.aeronav.faa.gov .

= 3.43 NM or approximately 4 SM). These charts provide a more detailed display of topographical information and Sectional Charts are revised semiannually, except for several Alaskan and Sectional charts are the most common charts used by pilots Caribbean charts. [Figure 16-2] today. The charts have a scale of 1:500,000 (1 inch = 6.86 nautical miles (NM) or approximately 8 statute miles (SM)), World Aeronautical Charts which allows for more detailed information to be included World aeronautical charts are designed to provide a standard on the chart.

series of aeronautical charts, covering land areas of the world, Figure 16-1. Sectional chart and legend.

16-2 Figure 16-2. VFR Terminal Area Chart and legend.

at a size and scale convenient for navigation by moderate speed Meridian,” which passes through Greenwich, England, is aircraft. They are produced at a scale of 1:1,000,000 (1 inch = used as the zero line from which measurements are made in 13.7 NM or approximately 16 SM). These charts are similar to degrees east (E) and west (W) to 180°. The 48 conterminous sectional charts, and the symbols are the same except there is states of the United States are between 67° and 125° W less detail due to the smaller scale. [Figure 16-3] These charts longitude. The arrows in Figure 16-4 labeled “Longitude” are revised annually except several Alaskan charts and the point to lines of longitude.

Mexican/Caribbean charts, which are revised every 2 years.

Any specific geographical point can be located by reference Latitude and Longitude (Meridians and to its longitude and latitude. Washington, D.C., for example, is approximately 39° N latitude, 77° W longitude. Chicago Parallels) is approximately 42° N latitude, 88° W longitude.

The equator is an imaginary circle equidistant from the poles of the Earth. Circles parallel to the equator (lines running east Time Zones and west) are parallels of latitude. They are used to measure The meridians are also useful for designating time zones. A degrees of latitude north (N) or south (S) of the equator. The day is defined as the time required for the Earth to make one angular distance from the equator to the pole is one-fourth complete rotation of 360°. Since the day is divided into 24 of a circle or 90°. The 48 conterminous states of the United hours, the Earth revolves at the rate of 15° an hour. Noon is States are located between 25° and 49° N latitude. The arrows the time when the sun is directly above a meridian; to the in Figure 16-4 labeled “Latitude” point to lines of latitude.

west of that meridian is morning, to the east is afternoon.

Meridians of longitude are drawn from the North Pole to the South Pole and are at right angles to the Equator. The “Prime 16-3 Figure 16-3. World aeronautical chart.

The standard practice is to establish a time zone for each 90°N 90°N 15° of longitude. This makes a difference of exactly 1 hour ° N 7 5 ° N 7 5 between each zone. In the conterminous United States, 6 0 ° N N 6 0 ° L there are four time zones. The time zones are Eastern (75°), a t P Central (90°), Mountain (105°), and Pacific (120°). The i P t 4 4 N N 5 5 ° ° r r u i i m m dividing lines are somewhat irregular because communities d e e e m m near the boundaries often find it more convenient to use time 3 3 0 0 ° ° N N e e r r designations of neighboring communities or trade centers.

L o 1 i i n 5 d d g i t u 0 0 1 1 1 1 d i i e ° 3 a a ° 3 5 1 1 3 5 W 3 W 5 5 n n 2 2 1 1 ° ° 4 4 0 0 ° N 1 1 5 ° N ° ° W W 5 0 0 0 9 9 6 7 7 0 6 ° W W 5 5 ° Figure 16-5 shows the time zones in the conterminous United ° 0 ° 5 5 0 0 0 W W 5 5 ° ° W W ° ° ° ° ° W ° W ° ° W W W W W W W W States. When the sun is directly above the 90th meridian, it is noon Central Standard Time. At the same time, it is 1 p.m.

a a t t o o r r E E q q u u Eastern Standard Time, 11 a.m. Mountain Standard Time, ° S 1 5 ° S 1 5 and 10 a.m. Pacific Standard Time. When Daylight Saving Time is in effect, generally between the second Sunday in ° ° S S 3 3 0 0 March and the first Sunday in November, the sun is directly ° ° S S 4 4 5 5 above the 75th meridian at noon, Central Daylight Time.

° S 6 0 ° S 6 0 These time zone differences must be taken into account during long flights eastward—especially if the flight must Figure 16-4. Meridians and parallels—the basis of measuring time, be completed before dark. Remember, an hour is lost when distance, and direction.

16-4 Mountain standard time Central standard time Eastern standard time Pacific standard time 75° 120° 105° 90° Figure 16-5. Time zones in the conterminous United States.

flying eastward from one time zone to another, or perhaps For Daylight Saving Time, 1 hour should be subtracted from even when flying from the western edge to the eastern edge the calculated times.

of the same time zone. Determine the time of sunset at the Measurement of Direction destination by consulting the flight service station (FSS) and take this into account when planning an eastbound flight.

By using the meridians, direction from one point to another can be measured in degrees, in a clockwise direction from In most aviation operations, time is expressed in terms of true north. To indicate a course to be followed in flight, the 24-hour clock. ATC instructions, weather reports and draw a line on the chart from the point of departure to the broadcasts, and estimated times of arrival are all based on destination and measure the angle that this line forms with this system. For example: 9 a.m. is expressed as 0900, 1 p.m. a meridian. Direction is expressed in degrees, as shown by is 1300, and 10 p.m. is 2200.

the compass rose in Figure 16-6.

Because a pilot may cross several time zones during a flight, a Because meridians converge toward the poles, course standard time system has been adopted. It is called Universal measurement should be taken at a meridian near the midpoint Coordinated Time (UTC) and is often referred to as Zulu of the course rather than at the point of departure. The course time. UTC is the time at the 0° line of longitude which passes measured on the chart is known as the true course (TC). This through Greenwich, England. All of the time zones around is the direction measured by reference to a meridian or true the world are based on this reference. To convert to this time, north (TN). It is the direction of intended flight as measured a pilot should do the following: in degrees clockwise from TN.

Eastern Standard Time ..........Add 5 hours As shown in Figure 16-7, the direction from A to B would be Central Standard Time ..........Add 6 hours a TC of 065°, whereas the return trip (called the reciprocal) Mountain Standard Time.......Add 7 hours would be a TC of 245°.

Pacific Standard Time ...........Add 8 hours 16-5 The north magnetic pole is located close to 71° N latitude, 96° W longitude and is about 1,300 miles from the geographic 33 or true north pole, as indicated in Figure 16-8. If the Earth were uniformly magnetized, the compass needle would point N N W N N E N toward the magnetic pole, in which case the variation between N E W TN (as shown by the geographical meridians) and MN (as 6 N N shown by the magnetic meridians) could be measured at any E W N N intersection of the meridians.

W E Actually, the Earth is not uniformly magnetized. In the United W States, the needle usually points in the general direction of E S W the magnetic pole, but it may vary in certain geographical E S W localities by many degrees. Consequently, the exact amount S E of variation at thousands of selected locations in the United W S S States has been carefully determined. The amount and the S W E S S S direction of variation, which change slightly from time to time, are shown on most aeronautical charts as broken magenta lines called isogonic lines that connect points of equal magnetic variation. (The line connecting points at which there is no variation between TN and MN is the agonic Figure 16-6. Compass rose.

line.) An isogonic chart is shown in Figure 16-9 . Minor bends and turns in the isogonic and agonic lines are caused The true heading (TH) is the direction in which the nose of by unusual geological conditions affecting magnetic forces the aircraft points during a flight when measured in degrees in these areas.

clockwise from TN. Usually, it is necessary to head the aircraft in a direction slightly different from the TC to offset On the west coast of the United States, the compass needle the effect of wind. Consequently, numerical value of the TH points to the east of TN; on the east coast, the compass needle may not correspond with that of the TC. This is discussed points to the west of TN.

more fully in subsequent sections in this chapter. For the purpose of this discussion, assume a no-wind condition exists under which heading and course would coincide. Thus, for a TC of 065°, the TH would be 065°. To use the compass accurately, however, corrections must be made for magnetic variation and compass deviation.

Variation Variation is the angle between TN and magnetic north (MN).

It is expressed as east variation or west variation depending TN upon whether MN is to the east or west of TN.

Course A to B 065° MN B ° ° A Figure 16-8. Magnetic meridians are in red while the lines of Course B to A 245° longitude and latitude are in blue. From these lines of variation (magnetic meridians), one can determine the effect of local magnetic Figure 16-7. Courses are determined by reference to meridians on variations on a magnetic compass.

aeronautical charts.

16-6 this course off the magnetic compass would not provide an accurate course between the two points due to three elements Easterly variation Westerly variation that must be considered. The first is magnetic variation, the second is compass deviation, and the third is wind correction.

All three must be considered for accurate navigation.

Magnetic Variation As mentioned in the paragraph discussing variation, the appropriate variation for the geographical location of the flight must be considered and added or subtracted as appropriate. If flying across an area where the variation changes, then the values must be applied along the route of flight appropriately. Once applied, this new course is called the magnetic course.

Agonic line Magnetic Deviation Because each aircraft has its own internal effect upon the onboard compass systems from its own localized magnetic Figure 16-9. Note the agonic line where magnetic variation is zero.

influencers, the pilot must add or subtract these influencers based upon the direction he or she is flying. The application of Zero degree variation exists on the agonic line where deviation (taken from a compass deviation card) compensates MN and TN coincide. This line runs roughly west of the the magnetic course unique to that aircraft’s compass system Great Lakes, south through Wisconsin, Illinois, western (as affected by localized magnetic influencers) and it now Tennessee, and along the border of Mississippi and Alabama.

becomes the compass course. Therefore, the compass course, Compare Figures 16-9 and 16-10.

when followed (in a no wind condition), takes the aircraft from point A to point B even though the aircraft heading Because courses are measured in reference to geographical may not match the original course line drawn on the chart.

meridians that point toward TN, and these courses are maintained by reference to the compass that points along a If the variation is shown as “9° E,” this means that MN is magnetic meridian in the general direction of MN, the true 9° east of TN. If a TC of 360° is to be flown, 9° must be direction must be converted into magnetic direction for the subtracted from 360°, which results in a magnetic heading purpose of flight. This conversion is made by adding or of 351°. To fly east, a magnetic course of 081° (090° – 9°) subtracting the variation indicated by the nearest isogonic would be flown. To fly south, the magnetic course would be line on the chart.

171° (180° – 9°). To fly west, it would be 261° (270° – 9°).

To fly a TH of 060°, a magnetic course of 051° (060° – 9°) For example, a line drawn between two points on a chart would be flown.

is called a TC as it is measured from TN. However, flying NP NP NP E t a n v a s i o s r i a e t t MP MP i a t i r o n W a MP v Zero variation N N N 33 3 33 3 33 3 30 30 30 6 6 6 W W W E E E 24 24 24 12 12 12 21 21 21 15 15 15 S S S SP SP SP Figure 16-10. Effect of variation on the compass.

16-7 Remember, if variation is west, add; if east, subtract. One The aircraft is placed on a magnetic compass rose, the engine method for remembering whether to add or subtract variation started, and electrical devices normally used (such as radio) is the phrase “east is least (subtract) and west is best (add).” are turned on. Tailwheel-type aircraft should be jacked up into flying position. The aircraft is aligned with MN indicated on Deviation the compass rose and the reading shown on the compass is recorded on a deviation card. The aircraft is then aligned at Determining the magnetic heading is an intermediate step necessary to obtain the correct compass heading for the flight. 30° intervals and each reading is recorded. If the aircraft is to be flown at night, the lights are turned on and any significant To determine compass heading, a correction for deviation must be made. Because of magnetic influences within an changes in the readings are noted. If so, additional entries are made for use at night. The accuracy of the compass can aircraft, such as electrical circuits, radio, lights, tools, engine, and magnetized metal parts, the compass needle is frequently also be checked by comparing the compass reading with the known runway headings.

deflected from its normal reading. This deflection is called deviation. The deviation is different for each aircraft, and A deviation card, similar to Figure 16-12, is mounted near it also may vary for different headings in the same aircraft.

For instance, if magnetism in the engine attracts the north the compass showing the addition or subtraction required to correct for deviation on various headings, usually at intervals end of the compass, there would be no effect when the plane is on a heading of MN. On easterly or westerly headings, of 30°. For intermediate readings, the pilot should be able to interpolate mentally with sufficient accuracy. For example, however, the compass indications would be in error, as shown in Figure 16-11 . Magnetic attraction can come from many if the pilot needed the correction for 195° and noted the correction for 180° to be 0° and for 210° to be +2°, it could other parts of the aircraft; the assumption of attraction in the engine is merely used for the purpose of illustration. be assumed that the correction for 195° would be +1°. The magnetic heading, when corrected for deviation, is known Some adjustment of the compass, referred to as compensation, as compass heading.

can be made to reduce this error, but the remaining correction Effect of Wind must be applied by the pilot.

The preceding discussion explained how to measure a TC Proper compensation of the compass is best performed by on the aeronautical chart and how to make corrections for a competent technician. Since the magnetic forces within variation and deviation, but one important factor has not the aircraft change because of landing shocks, vibration, been considered—wind. As discussed in the study of the mechanical work, or changes in equipment, the pilot should atmosphere, wind is a mass of air moving over the surface of occasionally have the deviation of the compass checked. The the Earth in a definite direction. When the wind is blowing procedure used to check the deviation is called “swinging the from the north at 25 knots, it simply means that air is moving compass” and is briefly outlined as follows.

southward over the Earth’s surface at the rate of 25 NM in 1 hour.

Magnetic North Under these conditions, any inert object free from contact with the Earth is carried 25 NM southward in 1 hour. This effect becomes apparent when such things as clouds, dust, Magnetic North Magnetic North and toy balloons are observed being blown along by the wind.

N Obviously, an aircraft flying within the moving mass of air is similarly affected. Even though the aircraft does not float W E freely with the wind, it moves through the air at the same N N 33 33 21 3 3 15 time the air is moving over the ground, and thus is affected S 30 6 6 W W by wind. Consequently, at the end of 1 hour of flight, the E E 24 24 aircraft is in a position that results from a combination of 12 12 21 21 15 15 S S the following two motions: For (Magnetic) N 30 60 E 120 150 Steer (Compass) 0 28 57 86 117 148 Magnetized engine For (Magnetic S 210 240 W 300 330 Steer (Compass) 180 212 243 274 303 332 Figure 16-12. Compass deviation card.

Figure 16-11. Magnetized portions of the airplane cause the compass to deviate from its normal indications.

16-8 • Movement of the air mass in reference to the ground mass of air is moving westward at 20 knots, the airspeed of the aircraft remains the same, but GS becomes 120 minus • Forward movement of the aircraft through the air mass 20 or 100 knots.

Actually, these two motions are independent. It makes no Assuming no correction is made for wind effect, if an aircraft difference whether the mass of air through which the aircraft is heading eastward at 120 knots and the air mass moving is flying is moving or is stationary. A pilot flying in a 70- southward at 20 knots, the aircraft at the end of 1 hour is knot gale would be totally unaware of any wind (except for almost 120 miles east of its point of departure because of its possible turbulence) unless the ground were observed. In progress through the air. It is 20 miles south because of the reference to the ground, however, the aircraft would appear motion of the air. Under these circumstances, the airspeed to fly faster with a tailwind or slower with a headwind, or to remains 120 knots, but the GS is determined by combining drift right or left with a crosswind.

the movement of the aircraft with that of the air mass. GS can be measured as the distance from the point of departure to As shown in Figure 16-13, an aircraft flying eastward at the position of the aircraft at the end of 1 hour. The GS can an airspeed of 120 knots in still air has a groundspeed (GS) be computed by the time required to fly between two points a exactly the same—120 knots. If the mass of air is moving known distance apart. It also can be determined before flight eastward at 20 knots, the airspeed of the aircraft is not by constructing a wind triangle, which is explained later in affected, but the progress of the aircraft over the ground is this chapter. [Figure 16-14] 120 plus 20 or a GS of 140 knots. On the other hand, if the The direction in which the aircraft is pointing as it flies is WINDS ARE CALM called heading. Its actual path over the ground, which is a combination of the motion of the aircraft and the motion of the air, is called track. The angle between the heading and the track is called drift angle. If the aircraft heading coincides 090° with the TC and the wind is blowing from the left, the track does not coincide with the TC. The wind causes the aircraft to drift to the right, so the track falls to the right of the desired course or TC. [Figure 16-15] Groundspeed 120 knots The following method is used by many pilots to determine WINDS 270° AT 20 KNOTS 090° compass heading: after the TC is measured, and wind correction applied resulting in a TH, the sequence TH ± variation (V) = magnetic heading (MH) ± deviation (D) = compass heading (CH) is followed to arrive at compass heading. [Figure 16-16] By determining the amount of drift, the pilot can counteract the effect of the wind and make the track of the aircraft Groundspeed 140 knots coincide with the desired course. If the mass of air is moving across the course from the left, the aircraft drifts to the WINDS 090° AT 20 KNOTS right, and a correction must be made by heading the aircraft sufficiently to the left to offset this drift. In other words, if the wind is from the left, the correction is made by pointing 090° the aircraft to the left a certain number of degrees, therefore correcting for wind drift. This is the wind correction angle (WCA) and is expressed in terms of degrees right or left of the TC. [Figure 16-17] Groundspeed 100 knots Figure 16-13. Motion of the air affects the speed with which aircraft move over the Earth’s surface. Airspeed, the rate at which an aircraft moves through the air, is not affected by air motion.

16-9 Airspeed effect (1 hour) Distance covered over ground (1 hour) 20 knots Figure 16-14. Aircraft flight path resulting from its airspeed and direction and the wind speed and direction.

Wind Heading Desired course Drift angle Track Figure 16-15. Effects of wind drift on maintaining desired course.

To summarize: TN MN CN • Course—intended path of an aircraft over the ground or the direction of a line drawn on a chart representing DEV 4° C the intended aircraft path, expressed as the angle H - measured from a specific reference datum clockwise ° M H from 0° through 360° to the line.

° T • Heading—direction in which the nose of the aircraft H - points during flight.

° VAR 10° E • Track—actual path made over the ground in flight. (If proper correction has been made for the wind, track and course are identical.)

• Drift angle—angle between heading and track.

Heading • WCA—correction applied to the course to establish a heading so that track coincides with course.

• Airspeed—rate of the aircraft’s progress through the air.

Figure 16-16. Relationship between true, magnetic, and compass • GS—rate of the aircraft’s inflight progress over headings for a particular instance.

the ground.

16-10 075° Wind Heading Wind correction angle 090° Track Desired course Figure 16-17. Establishing a wind correction angle that counteracts wind drift and maintains the desired course.

knots). Pilots, therefore, should learn to convert wind speeds Basic Calculations that are reported in knots to mph.

Before a cross-country flight, a pilot should make common calculations for time, speed, and distance, and the amount A knot is 1 nautical mile per hour (NMPH). Because there are of fuel required.

6,076.1 feet in 1 NM and 5,280 feet in 1 SM, the conversion factor is 1.15. To convert knots to mph, multiply speed in Converting Minutes to Equivalent Hours knots by 1.15. For example: a wind speed of 20 knots is Frequently, it is necessary to convert minutes into equivalent equivalent to 23 mph.

hours when solving speed, time, and distance problems. To convert minutes to hours, divide by 60 (60 minutes = 1 hour).

Most flight computers or electronic calculators have a Thus, 30 minutes is 30/60 = 0.5 hour. To convert hours to means of making this conversion. Another quick method of minutes, multiply by 60. Thus, 0.75 hour equals 0.75 × 60 conversion is to use the scales of NM and SM at the bottom = 45 minutes.

of aeronautical charts.

Time T = D/GS Fuel Consumption To find the time (T) in flight, divide the distance (D) by the To ensure that sufficient fuel is available for your intended GS. The time to fly 210 NM at a GS of 140 knots is 210 ÷ flight, you must be able to accurately compute aircraft fuel 140 or 1.5 hours. (The 0.5 hour multiplied by 60 minutes consumption during preflight planning. Typically, fuel equals 30 minutes.) Answer: 1:30.

consumption in gasoline-fueled aircraft is measured in gallons per hour. Since turbine engines consume much more fuel than reciprocating engines, turbine-powered aircraft Distance D = GS X T require much more fuel, and thus much larger fuel tanks.

To find the distance flown in a given time, multiply GS by When determining these large fuel quantities, using a volume time. The distance flown in 1 hour 45 minutes at a GS of 120 measurement such as gallons presents a problem because knots is 120 × 1.75 or 210 NM.

the volume of fuel varies greatly in relation to temperature.

In contrast, density (weight) is less affected by temperature GS GS = D/T and therefore, provides a more uniform and repeatable To find the GS, divide the distance flown by the time measurement. For this reason, jet fuel is generally quantified required. If an aircraft flies 270 NM in 3 hours, the GS is by its density and volume.

270 ÷ 3 = 90 knots.

This standard industry convention yields a pounds-of-fuel Converting Knots to Miles Per Hour per-hour value which, when divided into the nautical miles Another conversion is that of changing knots to miles per hour (NM) per hour of travel (TAS ± winds) value, results in a (mph). The aviation industry is using knots more frequently specific range value. The typical label for specific range is than mph, but is important to understand the conversion for NM per pound of fuel, or often NM per 1,000 pounds of fuel.

those that use mph when working with speed problems. The Preflight planning should be supported by proper monitoring NWS reports both surface winds and winds aloft in knots.

of past fuel consumption as well as use of specified fuel However, airspeed indicators in some aircraft are calibrated management and mixture adjustment procedures in flight.

in mph (although many are now calibrated in both mph and 16-11 For simple aircraft with reciprocating engines, the Aircraft computer has an instruction book that probably includes Flight Manual/Pilot’s Operating Handbook (AFM/POH) sample problems so the pilot can become familiar with its supplied by the aircraft manufacturer provides gallons-per functions and operation. [Figure 16-18] hour values to assist with preflight planning.

Plotter When planning a flight, you must determine how much Another aid in flight planning is a plotter, which is a protractor fuel is needed to reach your destination by calculating the and ruler. The pilot can use this when determining TC and distance the aircraft can travel (with winds considered) at measuring distance. Most plotters have a ruler that measures a known rate of fuel consumption (gal/hr or lbs/hr) for the in both NM and SM and has a scale for a sectional chart on one expected groundspeed (GS) and ensure this amount, plus an side and a world aeronautical chart on the other. [Figure 16-18] adequate reserve, is available on board. GS determines the time the flight will take. The amount of fuel needed for a Pilotage given flight can be calculated by multiplying the estimated Pilotage is navigation by reference to landmarks or flight time by the rate of consumption. For example, a flight checkpoints. It is a method of navigation that can be used of 400 NM at 100 knots GS takes 4 hours to complete. If an on any course that has adequate checkpoints, but it is more aircraft consumes 5 gallons of fuel per hour, the total fuel commonly used in conjunction with dead reckoning and consumption is 20 gallons (4 hours times 5 gallons). In this VFR radio navigation.

example, there is no wind; therefore, true airspeed (TAS) is also 100 knots, the same as GS. Since the rate of fuel The checkpoints selected should be prominent features consumption remains relatively constant at a given TAS, common to the area of the flight. Choose checkpoints that can you must use GS to calculate fuel consumption when wind be readily identified by other features, such as roads, rivers, is present. Specific range (NM/lb or NM/gal) is also useful railroad tracks, lakes, and power lines. If possible, select in calculating fuel consumption when wind is a factor.

features that make useful boundaries or brackets on each side of the course, such as highways, rivers, railroads, and You should always plan to be on the surface before any of mountains. A pilot can keep from drifting too far off course the following occur: by referring to and not crossing the selected brackets. Never • Your flight time exceeds the amount of flight time place complete reliance on any single checkpoint. Choose you calculated for the consumption of your preflight ample checkpoints. If one is missed, look for the next one while fuel amount maintaining the heading. When determining position from checkpoints, remember that the scale of a sectional chart is 1 • Your fuel gauge indicates low fuel level inch = 8 SM or 6.86 NM. For example, if a checkpoint selected was approximately one-half inch from the course line on the The rate of fuel consumption depends on many factors: chart, it is 4 SM or 3.43 NM from the course on the ground.

condition of the engine, propeller/rotor pitch, propeller/ In the more congested areas, some of the smaller features are rotor revolutions per minute (rpm), richness of the mixture, not included on the chart. If confused, hold the heading. If a and the percentage of horsepower used for flight at cruising turn is made away from the heading, it is easy to become lost.

speed. The pilot should know the approximate consumption rate from cruise performance charts or from experience.

Roads shown on the chart are primarily the well-traveled In addition to the amount of fuel required for the flight, roads or those most apparent when viewed from the air.

there should be sufficient fuel for reserve. When estimating New roads and structures are constantly being built and consumption you must plan for cruise flight as well as startup may not be shown on the chart until the next chart is issued.

and taxi, and higher fuel burn during climb. Remember that Some structures, such as antennas, may be difficult to see.

ground speed during climb is less than during cruise flight Sometimes TV antennas are grouped together in an area near at the same airspeed. Additional fuel for adequate reserve a town. They are supported by almost invisible guy wires.

should also be added as a safety measure.

Never approach an area of antennas less than 500 feet above the tallest one. Most of the taller structures are marked with Flight Computers strobe lights to make them more visible to pilots. However, Up to this point, only mathematical formulas have been used some weather conditions or background lighting may make to determine such items as time, distance, speed, and fuel them difficult to see. Aeronautical charts display the best consumption. In reality, most pilots use a mechanical flight information available at the time of printing, but a pilot should computer called an E6B or electronic flight calculator. These be cautious for new structures or changes that have occurred devices can compute numerous problems associated with since the chart was printed.

flight planning and navigation. The mechanical or electronic 16-12 270 120 260 180 170 240 190 160 130 200 300 0 350 310 140 340 220 30 320 DEGREES 170 A Plotter NAUTICAL 5 MILES 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 NAUTICAL 85 MILES INSTRUCTIONS FOR USE 1. Place hole over intersection of true course and true north line.

2. Without changing position rotate plotter until edge is over true course line.

SECTIONAL CHART SIDE - 1:500,000 NAVIGATIONAL FLIGHT PLOTTER 3. From hole follow true north line to curved scale with arrow pointing in direction of flight.

4. Read true course in degrees, on proper scale, over true north line. read scales counter-clockwise.

0 STATUTE 5 MILES 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 95 85 100 90 TSD Alt: As Wind Wt. Bal Timer Conv: Dist Vol Wt Wx C M P Mode Clr On/Off Dist Vol Wt Wx ÷ : 9 x 7 8 Sto 4 5 6 − 3 + Rcl 1 2 = Bksp +/ 0 .

C Electronic flight computer B Mechanical flight computer Figure 16-18. A plotter (A), the computational and wind side of a mechanical flight computer (E6B) (B), and an electronic flight computer (C).

Wind Triangle or Vector Analysis Dead Reckoning If there is no wind, the aircraft’s ground track is the same as Dead reckoning is navigation solely by means of computations the heading and the GS is the same as the true airspeed. This based on time, airspeed, distance, and direction. The products condition rarely exists. A wind triangle, the pilot’s version derived from these variables, when adjusted by wind speed of vector analysis, is the basis of dead reckoning.

and velocity, are heading and GS. The predicted heading takes the aircraft along the intended path and the GS The wind triangle is a graphic explanation of the effect of establishes the time to arrive at each checkpoint and the wind upon flight. GS, heading, and time for any flight can be destination. Except for flights over water, dead reckoning determined by using the wind triangle. It can be applied to is usually used with pilotage for cross-country flying. The the simplest kind of cross-country flight, as well as the most heading and GS, as calculated, is constantly monitored and complicated instrument flight. The experienced pilot becomes corrected by pilotage as observed from checkpoints.

16-13 so familiar with the fundamental principles that estimates can the blue, yellow, and black lines in Figure 16-20, which is be made that are adequate for visual flight without actually explained in the following example.

drawing the diagrams. The beginning student, however, needs to develop skill in constructing these diagrams as an aid to the Suppose a flight is to be flown from E to P. Draw a line on complete understanding of wind effect. Either consciously or the aeronautical chart connecting these two points; measure unconsciously, every good pilot thinks of the flight in terms its direction with a protractor, or plotter, in reference to a of wind triangle. meridian. This is the TC, which in this example is assumed to be 090° (east). From the NWS, it is learned that the wind If flight is to be made on a course to the east, with a wind at the altitude of the intended flight is 40 knots from the blowing from the northeast, the aircraft must be headed northeast (045°). Since the NWS reports the wind speed in somewhat to the north of east to counteract drift. This can knots, if the true airspeed of the aircraft is 120 knots, there is be represented by a diagram as shown in Figure 16-19. Each no need to convert speeds from knots to mph or vice versa.

line represents direction and speed. The long blue and white hashed line shows the direction the aircraft is heading, and Now, on a plain sheet of paper draw a vertical line representing its length represents the distance traveled at the indicated north to south. (The various steps are shown in Figure 16-21. ) airspeed for 1 hour. The short blue arrow at the right shows the wind direction, and its length represents the wind velocity Step 1 for 1 hour. The solid yellow line shows the direction of the Place the protractor with the base resting on the vertical line track or the path of the aircraft as measured over the earth, and and the curved edge facing east. At the center point of the its length represents the distance traveled in 1 hour or the GS.

base, make a dot labeled “E” (point of departure) and at the curved edge, make a dot at 90° (indicating the direction of the In actual practice, the triangle illustrated in Figure 16-19 is true course) and another at 45° (indicating wind direction).

not drawn; instead, construct a similar triangle as shown by N Wind at 20° 080° heading and 120 knots airspeed N direction and 35 knots velocity Drift Angle 10° W E 090° course and 110 knots groundspeed S 8° left correction S Figure 16-19. Principle of the wind triangle.

N N W E P E Course and groundspeed S Wind direction and velocity Heading and airspeed W S Figure 16-20. The wind triangle as is drawn in navigation practice.

16-14 N N STEP 1 STEP 2 and 3 30 5 ° 60 40 10 50 70 30 Mid point 60 50 0 ° TC 090° 90 E 80 100 100 160 Wind W S 130 150 N 160 33 140 170 W E 170 E P TC 090° GS 88 S Airspeed 120 knots W S STEP 4 Figure 16-21. Steps in drawing the wind triangle.

Step 2 • By placing the straight side of the protractor along the north-south line, with its center point at the With the ruler, draw the true course line from E, extending it intersection of the airspeed line and north-south line, somewhat beyond the dot by 90°, and labeling it “TC 090°.” read the TH directly in degrees (076°). [Figure 16-22] Step 3 • By placing the straight side of the protractor along the Next, align the ruler with E and the dot at 45°, and draw TC line, with its center at P, read the angle between the TC and the airspeed line. This is the WCA, which the wind arrow from E, not toward 045°, but downwind in the direction the wind is blowing making it 40 units long to must be applied to the TC to obtain the TH. If the wind blows from the right of TC, the angle is added; if from correspond with the wind velocity of 40 knots. Identify this line as the wind line by placing the letter “W” at the end to the left, it is subtracted. In the example given, the WCA is 14° and the wind is from the left; therefore, show the wind direction.

subtract 14° from TC of 090°, making the TH 076°.

[Figure 16-23] Step 4 Finally, measure 120 units on the ruler to represent the After obtaining the TH, apply the correction for magnetic airspeed, making a dot on the ruler at this point. The units variation to obtain magnetic heading and the correction used may be of any convenient scale or value (such as ¼ for compass deviation to obtain a compass heading. The inch = 10 knots), but once selected, the same scale must compass heading can be used to fly to the destination by be used for each of the linear movements involved. Then dead reckoning.

place the ruler so that the end is on the arrowhead (W) and the 120-knot dot intercepts the TC line. Draw the line and To determine the time and fuel required for the flight, first label it “AS 120.” The point “P” placed at the intersection find the distance to your destination by measuring the length represents the position of the aircraft at the end of 1 hour.

of the course line drawn on the aeronautical chart (using the The diagram is now complete.

appropriate scale at the bottom of the chart). If the distance measures 220 NM, divide by the GS of 88 knots, which gives The distance flown in 1 hour (GS) is measured as the numbers 2.5 hours, or 2:30, as the time required. If fuel consumption of units on the TC line (88 NMPH or 88 knots). The TH is 8 gallons an hour, 8 × 2.5 or about 20 gallons is used.

necessary to offset drift is indicated by the direction of the airspeed line, which can be determined in one of two ways: 16-15 N TC 090° GS 88 P E 7 6 ° TH 076° AS 120 W S Figure 16-22. Finding true heading by the wind correction angle.

N TC 090° GS 88 E 170 P WCA =14° L 80 100 1 ° 90 4 TH 076° AS 120 W 90 110 100 S Figure 16-23. Finding true heading by direct measurement.

Briefly summarized, the steps in obtaining flight information • Variation—obtained from the isogonic line on the are as follows: chart (added to TH if west; subtracted if east) • TC—direction of the line connecting two desired • MH—an intermediate step in the conversion (obtained points, drawn on the chart and measured clockwise by applying variation to TH) in degrees from TN on the mid-meridian • Deviation—obtained from the deviation card on the • WCA—determined from the wind triangle. (Added aircraft (added to or subtracted from MH, as indicated) to TC if the wind is from the right; subtracted if wind • Compass heading—reading on the compass (found by is from the left) applying deviation to MH) that is followed to remain • TH—direction measured in degrees clockwise from on the desired course TN, in which the nose of the plane should point to remain on the desired course 16-16 • Total distance—obtained by measuring the length of the TC line on the chart (using the scale at the bottom of the chart) • GS—obtained by measuring the length of the TC line on the wind triangle (using the scale employed for drawing the diagram) • Estimated time en route (ETE)—total distance divided by GS • Fuel rate—predetermined gallons per hour used at cruising speed NOTE: Additional fuel for adequate reserve should be added as a safety measure.

Flight Planning Title 14 of the Code of Federal Regulations (14 CFR) part 91 states, in part, that before beginning a flight, the pilot in command (PIC) of an aircraft shall become familiar with all available information concerning that flight. For flights not in the vicinity of an airport, this must include information on available current weather reports and forecasts, fuel requirements, alternatives available if the planned flight Figure 16-24. Chart Supplement U.S. (formerly Airport/Facility cannot be completed, and any known traffic delays of which Directory).

the PIC has been advised by ATC.

decide on refueling stops), FSS located on the airport, control Assembling Necessary Material tower and ground control frequencies, traffic information, The pilot should collect the necessary material well before remarks, and other pertinent information. The NOTAMs, beginning the flight. An appropriate current sectional chart issued every 28 days, should be checked for additional and charts for areas adjoining the flight route should be among information on hazardous conditions or changes that have this material if the route of flight is near the border of a chart.

been made since issuance of the Chart Supplement U.S.

Additional equipment should include a flight computer or The sectional chart bulletin subsection should be checked for electronic calculator, plotter, and any other item appropriate major changes that have occurred since the last publication date to the particular flight. For example, if a night flight is to of each sectional chart being used. Remember, the chart may be undertaken, carry a flashlight; if a flight is over desert be up to 6 months old. The effective date of the chart appears country, carry a supply of water and other necessities.

at the top of the front of the chart. The Chart Supplement U.S.

generally has the latest information pertaining to such matters Weather Check and should be used in preference to the information on the It is wise to check the weather before continuing with other back of the chart, if there are differences.

aspects of flight planning to see, first of all, if the flight is feasible and, if it is, which route is best. Chapter 12, “Aviation Airplane Flight Manual or Pilot’s Operating Weather Services,” discusses obtaining a weather briefing.

Handbook (AFM/POH) The Aircraft Flight Manual or Pilot’s Operating Handbook Use of Chart Supplement U.S. (formerly Airport/ (AFM/POH) should be checked to determine the proper Facility Directory) loading of the aircraft (weight and balance data). The weight Study available information about each airport at which a of the usable fuel and drainable oil aboard must be known.

landing is intended. This should include a study of the Notices Also, check the weight of the passengers, the weight of all to Airmen (NOTAMs) and the Chart Supplement U.S.

baggage to be carried, and the empty weight of the aircraft to (formerly Airport/Facility Directory). [Figure 16-24] This be sure that the total weight does not exceed the maximum includes location, elevation, runway and lighting facilities, allowable weight. The distribution of the load must be known available services, availability of aeronautical advisory to tell if the resulting center of gravity (CG) is within limits.

station frequency (UNICOM), types of fuel available (use to 16-17 Be sure to use the latest weight and balance information in VOR station that is off the direct route, but makes navigating the FAA-approved AFM or other permanent aircraft records, easier, may be chosen (radio navigation is discussed later in as appropriate, to obtain empty weight and empty weight this chapter).

CG information.

Appropriate checkpoints should be selected along the route Determine the takeoff and landing distances from the and noted in some way. These should be easy-to-locate appropriate charts, based on the calculated load, elevation points, such as large towns, large lakes and rivers, or of the airport, and temperature; then compare these distances combinations of recognizable points, such as towns with with the amount of runway available. Remember, the an airport, towns with a network of highways, and railroads heavier the load and the higher the elevation, temperature, entering and departing.

or humidity, the longer the takeoff roll and landing roll and the lower the rate of climb. Normally, choose only towns indicated by splashes of yellow on the chart. Do not choose towns represented by a small Check the fuel consumption charts to determine the rate of circle—these may turn out to be only a half-dozen houses. (In fuel consumption at the estimated flight altitude and power isolated areas, however, towns represented by a small circle settings. Calculate the rate of fuel consumption, and compare can be prominent checkpoints.) For this trip, four checkpoints it with the estimated time for the flight so that refueling points have been selected. Checkpoint 1 consists of a tower located along the route can be included in the plan. east of the course and can be further identified by the highway and railroad track, which almost parallels the course at this point. Checkpoint 2 is the obstruction just to the west of the Charting the Course course and can be further identified by Will Rogers World Once the weather has been checked and some preliminary Airport, which is directly to the east. Checkpoint 3 is Wiley planning completed, it is time to chart the course and Post Airport, which the aircraft should fly directly over.

determine the data needed to accomplish the flight. The Checkpoint 4 is a private, non-surfaced airport to the west of following sections provide a logical sequence to follow in the course and can be further identified by the railroad track charting the course, complete a flight log, and filing a flight and highway to the east of the course.

plan. In the following example, a trip is planned based on the following data and the sectional chart excerpt in Figure 16-25.

The course and areas on either side of the planned route should be checked to determine if there is any type of airspace Route of flight: Chickasha Airport direct to Guthrie Airport with which the pilot should be concerned or which has True airspeed (TAS)........................................115 knots special operational requirements. For this trip, it should be noted that the course passes through a segment of the Class Winds aloft...........................................360° at 10 knots C airspace surrounding Will Rogers World Airport where the Usable fuel.....................................................38 gallons floor of the airspace is 2,500 feet mean sea level (MSL) and Fuel rate...............................................................8 GPH the ceiling is 5,300 feet MSL (point B). Also, there is Class D airspace from the surface to 3,800 feet MSL surrounding Deviation..................................................................+2° Wiley Post Airport (point C) during the time the control tower is in operation.

Steps in Charting the Course The following is a suggested sequence for arriving at the Study the terrain and obstructions along the route. This is pertinent information for the trip. As information is determined, necessary to determine the highest and lowest elevations, it may be noted as illustrated in the example of a flight log in as well as the highest obstruction to be encountered so Figure 16-26. Where calculations are required, the pilot may an appropriate altitude that conforms to 14 CFR part 91 use a mathematical formula or a manual or electronic flight regulations can be selected. If the flight is to be flown computer. If unfamiliar with the use of a manual or electronic at an altitude of more than 3,000 feet above the terrain, computer, it would be advantageous to read the operation conformance to the cruising altitude appropriate to the manual and work several practice problems at this point.

direction of flight is required. Check the route for particularly rugged terrain so it can be avoided. Areas where a takeoff First, draw a line from Chickasha Airport (point A) directly or landing is made should be carefully checked for tall to Guthrie Airport (point F). The course line should begin at obstructions. Television transmitting towers may extend to the center of the airport of departure and end at the center of altitudes over 1,500 feet above the surrounding terrain. It is the destination airport. If the route is direct, the course line essential that pilots be aware of their presence and location.

consists of a single straight line. If the route is not direct, it For this trip, it should be noted that the tallest obstruction is consists of two or more straight line segments. For example, a 16-18

F

Checkpoint R Highest elevation

E

Tallest obstruction

D

Checkpoint

Class D Airspace C

Checkpoint 2 Class C Airspace

B

Checkpoint Course line

A

Route of flight: Chickasha Airport direct to Guthrie Airport True airspeed (TAS) . . . . . . . . . . . . . . . . . . . . 115 knots Winds aloft . . . . . . . . . . . . . . . . . . . . . . . 360° at 10 knots Usable fuel . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 gallons Fuel rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8 GPH Deviation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +2° Figure 16-25. Sectional chart excerpt.

16-19 PILOT’S PLANNING SHEET PLANE IDENTIFICATION DATE N123DB WIND WCA MAG VAR TOTAL TOTAL FUEL TOTAL COURSE TC TH MH DEV CH GS ALTITUDE R+ L W+ E MILES TIME RATE FUEL Knots From From Chickasha 031° 10 360° 8000 3° L 28 7° E 21° +2° 23 53 106 kts 35 min 8 GPH 38 gal To Guthrie From To VISUAL FLIGHT LOG TIME OF NAVIGATION ALTITUDE COURSE DISTANCE ELAPSED TIME GS CH REMARKS DEPARTURE AIDS POINT OF NAVAID TO TO WEATHER DEPARTURE IDENT.

ESTIMATED FROM FROM AIRSPACE ETC.

ACTUAL STIMATED STIMATED Chickasha Airport POINT TO POINT E E FREQ. CUMULATIVE ACTUAL ACTUAL 106 kts 023° 11 NM 6 min CHECKPOINT +5 #1 10000 106 kts 023° 10 NM 6 min CHECKPOINT 10000 #2 21 NM 106 kts 023° 10.5 NM 6 min CHECKPOINT 8000 #3 10000 31.5 NM 106 kts 023° 8000 13 NM 7 min CHECKPOINT #4 10000 44.5 NM 8.5 NM 5 min DESTINATION Guthrie Airport 53 NM Figure 16-26. Pilot’s planning sheet and visual flight log.

part of a series of antennas with a height of 2,749 feet MSL The formula is: (point D). The highest elevation should be located in the northeast quadrant and is 2,900 feet MSL (point E). TC ± WCA = TH ± V = MH ± D = CH Since the wind is no factor and it is desirable and within the The WCA can be determined by using a manual or electronic aircraft’s capability to fly above the Class C and D airspace flight computer. Using a wind of 360° at 10 knots, it is to be encountered, an altitude of 5,500 feet MSL is chosen. determined the WCA is 3° left. This is subtracted from the This altitude also gives adequate clearance of all obstructions, TC making the TH 28°. Next, the pilot should locate the as well as conforms to the 14 CFR part 91 requirement to isogonic line closest to the route of the flight to determine fly at an altitude of odd thousand plus 500 feet when on a variation. Figure 16-25 shows the variation to be 6.30° E magnetic course between 0 and 179°. (rounded to 7° E), which means it should be subtracted from the TH, giving an MH of 21°. Next, add 2° to the MH for Next, the pilot should measure the total distance of the the deviation correction. This gives the pilot the compass course, as well as the distance between checkpoints. The total heading of 23°.

distance is 53 NM, and the distance between checkpoints is as noted on the flight log in Figure 16-26. Now, the GS can be determined. This is done using a manual or electronic calculator. The GS is determined to be 106 After determining the distance, the TC should be measured. knots. Based on this information, the total trip time, as well If using a plotter, follow the directions on the plotter. The TC as time between checkpoints, and the fuel burned can be is 031°. Once the TH is established, the pilot can determine determined. These numbers can be calculated by using a the compass heading. This is done by following the formula manual or electronic calculator.

given earlier in this chapter.

16-20 For this trip, the GS is 106 knots and the total time is 35 met, but actual time cannot be given because of inadequate minutes (30 minutes plus 5 minutes for climb) with a fuel communication. The FSS specialist who accepts the flight burn of 4.7 gallons. Refer to the flight log in Figure 16-26 plan does not inform the pilot of this procedure, however.

for the time between checkpoints.

Figure 16-27 shows the flight plan form a pilot files with the As the trip progresses, the pilot can note headings and time FSS. When filing a flight plan by telephone or radio, give and make adjustments in heading, GS, and time. the information in the order of the numbered spaces. This enables the FSS specialist to copy the information more Filing a VFR Flight Plan efficiently. Most of the fields are either self-explanatory or non-applicable to the VFR flight plan (such as item 13).

Filing a flight plan is not required by regulations; however, it However, some fields may need explanation.

is a good operating practice since the information contained in the flight plan can be used in search and rescue in the • Item 3 is the aircraft type and special equipment. An event of an emergency.

example would be C-150/X, which means the aircraft has no transponder. A listing of special equipment Flight plans can be filed in the air by radio, but it is best to codes is found in the Aeronautical Information Manual file a flight plan by phone just before departing. After takeoff, (AIM).

contact the FSS by radio and give them the takeoff time so • Item 6 is the proposed departure time in UTC the flight plan can be activated.

(indicated by the “Z”).

• Item 7 is the cruising altitude. Normally, “VFR” can be When a VFR flight plan is filed, it is held by the FSS until entered in this block since the pilot chooses a cruising 1 hour after the proposed departure time and then canceled altitude to conform to FAA regulations.

unless: the actual departure time is received; a revised proposed departure time is received; or at the time of filing, the FSS is informed that the proposed departure time is X N123DB C150/X 115 CHK, CHICKASHA AIRPORT 1400 5500 Chickasha direct Guthrie GOK, Guthrie Airport Guthrie, OK Jane Smith Aero Air, Oklahoma City, OK (405) 555-4149 4 45 1 Red/White McAlester Figure 16-27. Domestic flight plan form.

16-21 • Item 8 is the route of flight. If the flight is to be direct, The prefix “omni-” means all, and an omnidirectional range enter the word “direct;” if not, enter the actual route to is a VHF radio transmitting ground station that projects be followed, such as via certain towns or navigation straight line courses (radials) from the station in all directions.

aids. From a top view, it can be visualized as being similar to the spokes from the hub of a wheel. The distance VOR radials are • Item 10 is the estimated time en route. In the sample projected depends upon the power output of the transmitter.

flight plan, 5 minutes was added to the total time to allow for the climb.

The course or radials projected from the station are referenced • Item 12 is the fuel on board in hours and minutes. This to MN. Therefore, a radial is defined as a line of magnetic is determined by dividing the total usable fuel aboard bearing extending outward from the VOR station. Radials are in gallons by the estimated rate of fuel consumption identified by numbers beginning with 001, which is 1° east in gallons.

of MN and progress in sequence through all the degrees of a circle until reaching 360. To aid in orientation, a compass rose Remember, there is every advantage in filing a flight plan; reference to magnetic north is superimposed on aeronautical but do not forget to close the flight plan upon arrival. This charts at the station location.

should be done via telephone to avoid radio congestion.

VOR ground stations transmit within a VHF frequency band Ground-Based Navigation of 108.0–117.95 MHz. Because the equipment is VHF, the Advances in navigational radio receivers installed in aircraft, signals transmitted are subject to line-of-sight restrictions.

the development of aeronautical charts that show the exact Therefore, its range varies in direct proportion to the altitude location of ground transmitting stations and their frequencies, of receiving equipment. Generally, the reception range of along with refined flight deck instrumentation make it the signals at an altitude of 1,000 feet above ground level possible for pilots to navigate with precision to almost any (AGL) is about 40 to 45 miles. This distance increases with point desired. Although precision in navigation is obtainable altitude. [Figure 16-28] through the proper use of this equipment, beginning pilots should use this equipment to supplement navigation by visual “A” and “B” signal received reference to the ground (pilotage). This method provides the pilot with an effective safeguard against disorientation in the event of radio malfunction.

Only “A” signal received Only “B” signal received There are three radio navigation systems available for use for VFR navigation. These are: Neither “A” nor “B” • VHF Omnidirectional Range (VOR) signal received • Nondirectional Radio Beacon (NDB) • Global Positioning System (GPS) Very High Frequency (VHF) Omnidirectional Range (VOR) The VOR system is present in three slightly different navigation aids (NAVAIDs): VOR, VOR/distance measuring equipment (DME)(discussed in a later section), and VOR VOR VORTAC. By itself it is known as a VOR, and it provides station station “A” “B” magnetic bearing information to and from the station. When DME is also installed with a VOR, the NAVAID is referred to as a VOR/DME. When military tactical air navigation Figure 16-28. VHF transmissions follow a line-of-sight course.

(TACAN) equipment is installed with a VOR, the NAVAID is known as a VORTAC. DME is always an integral part of a VORTAC. Regardless of the type of NAVAID utilized (VOR, VOR/DME, or VORTAC), the VOR indicator behaves the same. Unless otherwise noted in this section, VOR, VOR/DME, and VORTAC NAVAIDs are all referred to hereafter as VORs.

16-22 VORs and VORTACs are classed according to operational Basically, these checks consist of verifying that the VOR use. There are three classes: radials the aircraft equipment receives are aligned with the radials the station transmits. There are not specific tolerances • T (Terminal) in VOR checks required for VFR flight. But as a guide to • L (Low altitude) assure acceptable accuracy, the required IFR tolerances can be used—±4° for ground checks and ±6° for airborne checks.

• H (High altitude) These checks can be performed by the pilot.

The normal useful range for the various classes is shown in The VOR transmitting station can be positively identified the following table: by its Morse code identification or by a recorded voice VOR/VORTAC NAVAIDS identification that states the name of the station followed by Normal Usable Altitudes and Radius Distances “VOR.” Many FSSs transmit voice messages on the same frequency that the VOR operates. Voice transmissions should D i s t a n c e not be relied upon to identify stations because many FSSs Class Altitudes ( M i l e s ) remotely transmit over several omniranges that have names T 12,000' and below 25 different from that of the transmitting FSS. If the VOR is L Below 18,000' 40 out of service for maintenance, the coded identification is H Below 14,500' 40 removed and not transmitted. This serves to alert pilots that H Within the conterminous 48 states this station should not be used for navigation. VOR receivers only, between 14,500 and 17,999' 100 are designed with an alarm flag to indicate when signal H 18,000'—FL 450 130 strength is inadequate to operate the navigational equipment.

H FL 450—60,000' 100 This happens if the aircraft is too far from the VOR or the aircraft is too low and, therefore, is out of the line of sight The useful range of certain facilities may be less than 50 of the transmitting signals.

miles. For further information concerning these restrictions, refer to the Communication/NAVAID Remarks in the Chart Using the VOR Supplement U.S.

In review, for VOR radio navigation, there are two components required: ground transmitter and aircraft The accuracy of course alignment of VOR radials is receiving equipment. The ground transmitter is located at a considered to be excellent. It is generally within plus or minus specific position on the ground and transmits on an assigned 1°. However, certain parts of the VOR receiver equipment frequency. The aircraft equipment includes a receiver with deteriorate, affecting its accuracy. This is particularly true a tuning device and a VOR or omninavigation instrument.

at great distances from the VOR station. The best assurance The navigation instrument could be a course deviation of maintaining an accurate VOR receiver is periodic checks indicator (CDI), horizontal situation indicator (HSI), or a and calibrations. VOR accuracy checks are not a regulatory radio magnetic indicator (RMI). Each of these instruments requirement for VFR flight. However, to assure accuracy of indicates the course to the tuned VOR.

the equipment, these checks should be accomplished quite frequently and a complete calibration should be performed Course Deviation Indicator (CDI) each year. The following means are provided for pilots to The CDI is found in most training aircraft. It consists of an check VOR accuracy: omnibearing selector (OBS) sometimes referred to as the • FAA VOR test facility (VOT) course selector, a CDI needle (left-right needle), and a TO/ • Certified airborne checkpoints FROM indicator.

• Certified ground checkpoints located on airport The course selector is an azimuth dial that can be rotated to surfaces select a desired radial or to determine the radial over which the aircraft is flying. In addition, the magnetic course “TO” If an aircraft has two VOR receivers installed, a dual VOR or “FROM” the station can be determined.

receiver check can be made. To accomplish the dual receiver check, a pilot must tune both VOR receivers to the same VOR When the course selector is rotated, it moves the CDI or ground facility. The maximum permissible variation between needle to indicate the position of the radial relative to the the two indicated bearings is 4°. A list of the airborne and aircraft. If the course selector is rotated until the deviation ground checkpoints is published in the Chart Supplement U.S.

16-23 needle is centered, the radial (magnetic course “FROM” the Glideslope deviation scale station) or its reciprocal (magnetic course “TO” the station) can be determined. The course deviation needle also moves To/From indicator Course deviation scale to the right or left if the aircraft is flown or drifting away from the radial which is set in the course selector.

Compass warning flag Compass card By centering the needle, the course selector indicates either Lubber line NAV warning flag the course “FROM” the station or the course “TO” the station.

If the flag displays a “TO,” the course shown on the course DC selector must be flown to the station. [Figure 16-29] If “FROM” is displayed and the course shown is followed, the aircraft is flown away from the station.

2I I5 GS GS NAV HDG Horizontal Situation Indicator I2 The HSI is a direction indicator that uses the output from a flux valve to drive the compass card. The HSI [Figure 16-30] combines the magnetic compass with navigation signals and a glideslope. The HSI gives the pilot an indication of the location of the aircraft in relation to the chosen course or radial.

In Figure 16-30, the aircraft magnetic heading displayed on the compass card under the lubber line is 184°. The course select pointer shown is set to 295°; the tail of the Course select knob pointer indicates the reciprocal, 115°. The course deviation bar operates with a VOR/Localizer (VOR/LOC) or GPS Course deviation bar Symbolic aircraft navigation receiver to indicate left or right deviations from the course selected with the course select pointer; operating Course select pointer Heading select bug in the same manner, the angular movement of a conventional VOR/LOC needle indicates deviation from course.

Heading select knob The desired course is selected by rotating the course select pointer, in relation to the compass card, by means of the Figure 16-30. Horizontal situation indicator.

course select knob. The HSI has a fixed aircraft symbol and the course deviation bar displays the aircraft’s position Unreliable signal flag Course index relative to the selected course. The TO/FROM indicator is a

N

33 triangular pointer. When the indicator points to the head of the

course select pointer, the arrow shows the course selected. If N properly intercepted and flown, the course takes the aircraft TO A V CDI needle to the chosen facility. When the indicator points to the tail of the course, the arrow shows that the course selected, if

E

properly intercepted and flown, takes the aircraft directly

W

away from the chosen facility.

Approximately 2 degrees in the VOR mode TO/FROM indicator When the NAV warning flag appears, it indicates no reliable signal is being received. The appearance of the HDG flag indicates the compass card is not functioning properly.

S 21

OBS Radio Magnetic Indicator (RMI) The RMI is a navigational aid providing aircraft magnetic OBS knob or directional gyro heading and very high frequency omnidirectional range (VOR), GPS, and automatic direction Figure 16-29. VOR indicator.

16-24 N 7 W E I2 S 21 24 24 FROM 12 I5 2I HDG 21 S 15 15 OBS 33 3 I2 I5 2I W N E A 30 A 30 6 6 3 D W D I2 E 33 I5 F F 12 30 FROM 33 21 15 2I S 24 OBS N 3 6 N 0 E 33 12 33 6 30 NAV NAV 18 FROM W S I2 24 21 I5 2I OBS N 30 TO Figure 16-31. Radio magnetic indicator.

W E S finder (ADF) bearing information. [Figure 16-31] Remote OBS indicating compasses were developed to compensate for N errors in and limitations of older types of heading indicators.

33 TO 6 6 The remote compass transmitter is a separate unit usually W WIND E I2 mounted in a wingtip to eliminate the possibility of magnetic 24 24 12 I5 2I 4 S interference. The RMI consists of a compass card, a heading OBS index, two bearing pointers, and pointer function switches.

The two pointers are driven by any two combinations of a N 3 GPS, an ADF, and/or a VOR. The pilot has the ability to select 30 33 TO W the navigation aid to be indicated. The pointer indicates the E I2 24 24 12 I5 2I course to the selected NAVAID or waypoint. In Figure 16-31, S OBS the green pointer is indicating the station tuned on the ADF.

The yellow pointer is indicating the course to a VOR or GPS waypoint. Note that there is no requirement for a pilot to 30 I2 select a course with the RMI. Only the selected navigation I5 2I source is pointed to by the needle(s).

BRAVO BRA 115.0 N Tracking With VOR 30 TO W E The following describes a step-by-step procedure for tracking to and from a VOR station using a CDI. Figure 16-32 S OBS illustrates the procedure.

N 30 3 First, tune the VOR receiver to the frequency of the selected TO 6 1 W E VOR station. For example, 115.0 to receive Bravo VOR.

24 I2 2I I5 Next, check the identifiers to verify that the desired VOR S OBS is being received. As soon as the VOR is properly tuned, the course deviation needle deflects either left or right.

Figure 16-32. Tracking a radial in a crosswind.

Then, rotate the azimuth dial to the course selector until the course deviation needle centers and the TO-FROM indicator If a heading of 350° is maintained with a wind from the right indicates “TO.” If the needle centers with a “FROM” as shown, the aircraft drifts to the left of the intended track.

indication, the azimuth should be rotated 180° because, in As the aircraft drifts off course, the VOR course deviation this case, it is desired to fly “TO” the station. Now, turn the needle gradually moves to the right of center or indicates the aircraft to the heading indicated on the VOR azimuth dial or direction of the desired radial or track.

course selector, 350° in this example.

16-25 To return to the desired radial, the aircraft heading must be maintain the course. If the aircraft drifts, fly a heading altered to the right. As the aircraft returns to the desired track, to re-intercept the course then apply a correction to the deviation needle slowly returns to center. When centered, compensate for wind drift.

the aircraft is on the desired radial and a left turn must be • If minor needle fluctuations occur, avoid changing made toward, but not to the original heading of 350° because headings immediately. Wait a moment to see if the a wind drift correction must be established. The amount of needle recenters; if it does not, then you must correctly correction depends upon the strength of the wind. If the wind recenter the course to the needle.

velocity is unknown, a trial-and-error method can be used • When flying “TO” a station, always fly the selected to find the correct heading. Assume, for this example, a 10° course with a “TO” indication. When flying “FROM” a correction for a heading of 360° is maintained.

station, always fly the selected course with a “FROM” indication. If this is not done, the action of the course While maintaining a heading of 360°, assume that the course deviation needle is reversed. To further explain this deviation begins to move to the left. This means that the wind reverse action, if the aircraft is flown toward a station correction of 10° is too great and the aircraft is flying to the with a “FROM” indication or away from a station right of course. A slight turn to the left should be made to with a “TO” indication, the course deviation needle permit the aircraft to return to the desired radial.

indicates in a direction opposite to that which it should indicate. For example, if the aircraft drifts to the right When the deviation needle centers, a small wind drift of a radial being flown, the needle moves to the right correction of 5° or a heading correction of 355° should be or points away from the radial. If the aircraft drifts to flown. If this correction is adequate, the aircraft remains the left of the radial being flown, the needle moves on the radial. If not, small variations in heading should be left or in the direction opposite of the radial.

made to keep the needle centered and consequently keep the aircraft on the radial.

• When navigating using the VOR, it is important to fly headings that maintain or re-intercept the course.

As the VOR station is passed, the course deviation needle Just turning toward the needle will cause overshooting fluctuates, then settles down, and the “TO” indication the radial and flying an S turn to the left and right of changes to “FROM.” If the aircraft passes to one side of the course.

station, the needle deflects in the direction of the station as the indicator changes to “FROM.” Time and Distance Check From a Station Using a RMI Generally, the same techniques apply when tracking To compute time and distance from a station, first turn the outbound as those used for tracking inbound. If the intent is aircraft to place the RMI bearing pointer on the nearest 90° to fly over the station and track outbound on the reciprocal of index. Note the time and maintain the heading. When the the inbound radial, the course selector should not be changed.

RMI bearing pointer has moved 10°, note the elapsed time Corrections are made in the same manner to keep the needle in seconds and apply the formulas in the following example centered. The only difference is that the omnidirectional to determine the approximate time and distance from a given range indicator indicates “FROM.” station. [Figure 16-33] If tracking outbound on a course other than the reciprocal of The time from station may also be calculated by using a short the inbound radial, this new course or radial must be set in method based on the above formula, if a 10° bearing change the course selector and a turn made to intercept this course.

is flown. If the elapsed time for the bearing change is noted After this course is reached, tracking procedures are the same as previously discussed.

Time-Distance Check Example Tips on Using the VOR Time in seconds between bearings = Minutes to station Degrees of bearing change • Positively identify the station by its code or voice identification.

For example, if 2 minutes (120 seconds) is required to fly a • Remember that VOR signals are “line-of-sight.” A bearing change of 10 degrees, the aircraft is— weak signal or no signal at all is received if the aircraft = 12 minutes to the station is too low or too far from the station.

• When navigating to a station, determine the inbound radial and use this radial. Fly a heading that will Figure 16-33. Time-distance check example.

16-26 in seconds and a 10° bearing change is made, the time from Rate of Intercept the station, in minutes, is determined by counting off one Rate of intercept, seen by the aviator as bearing pointer or decimal point. Thus, if 75 seconds are required to fly a 10° HSI movement, is a result of the following factors: bearing change, the aircraft is 7.5 minutes from the station.

• The angle at which the aircraft is flown toward a When the RMI bearing pointer is moving rapidly or when desired course (angle of intercept) several corrections are required to place the pointer on the • True airspeed and wind (GS) wingtip position, the aircraft is at station passage.

• Distance from the station The distance from the station is computed by multiplying TAS or GS (in miles per minute) by the previously determined time Angle of Intercept in minutes. For example, if the aircraft is 7.5 minutes from The angle of intercept is the angle between the heading station, flying at a TAS of 120 knots or 2 NM per minute, of the aircraft (intercept heading) and the desired course.

the distance from station is 15 NM (7.5 × 2 = 15).

Controlling this angle by selection/adjustment of the intercept heading is the easiest and most effective way to control The accuracy of time and distance checks is governed by course interceptions. Angle of intercept must be greater than existing wind, degree of bearing change, and accuracy of the degrees from course, but should not exceed 90°. Within timing. The number of variables involved causes the result this limit, make adjustments as needed, to achieve the most to be only an approximation. However, by flying an accurate desirable rate of intercept.

heading and checking the time and bearing closely, the pilot can make a reasonable estimate of time and distance from When selecting an intercept heading, the key factor is the the station.

relationship between distance from the station and degrees from the course. Each degree, or radial, is 1 NM wide at Time and Distance Check From a Station Using a a distance of 60 NM from the station. Width increases or CDI decreases in proportion to the 60 NM distance. For example, To compute time and distance from a station using a CDI, 1 degree is 2 NM wide at 120 NM—and ½ NM wide at 30 first tune and identify the VOR station and determine the NM. For a given GS and angle of intercept, the resultant rate radial on which you are located. Then turn inbound and of intercept varies according to the distance from the station.

re-center the needle if necessary. Turn 90° left or right, of When selecting an intercept heading to form an angle of the inbound course, rotating the OBS to the nearest 10° intercept, consider the following factors: increment opposite the direction of turn. Maintain heading • Degrees from course and when the CDI centers, note the time. Maintaining the same heading, rotate the OBS 10° in the same direction as • Distance from the station was done previously and note the elapsed time when the • True airspeed and wind (GS) CDI again centers. Time and distance from the station is determined from the formula shown in Figure 16-34.

Distance Measuring Equipment (DME) Distance measuring equipment (DME) consists of an ultra Course Intercept high frequency (UHF) navigational aid with VOR/DMEs and Course interceptions are performed in most phases of VORTACs. It measures, in NM, the slant range distance of instrument navigation. The equipment used varies, but an an aircraft from a VOR/DME or VORTAC (both hereafter intercept heading must be flown that results in an angle or referred to as a VORTAC). Although DME equipment is rate of intercept sufficient for solving a particular problem.

very popular, not all aircraft are DME equipped.

Time-Distance Check Formula To utilize DME, the pilot should select, tune, and identify a VORTAC, as previously described. The DME receiver, 60 x minutes flown between bearing change Time to utilizing what is called a “paired frequency” concept, A = station degrees of bearing change automatically selects and tunes the UHF DME frequency associated with the VHF VORTAC frequency selected by the pilot. This process is entirely transparent to the pilot.

TAS x minutes flown After a brief pause, the DME display shows the slant range = Distance to station B degrees of bearing change distance to or from the VORTAC. Slant range distance is the direct distance between the aircraft and the VORTAC and is therefore affected by aircraft altitude. (Station passage Figure 16-34. Time-distance check formula using a CDI.

directly over a VORTAC from an altitude of 6,076 feet AGL 16-27 would show approximately 1.0 NM on the DME.) DME is a While the capabilities and methods of operation of VOR/ very useful adjunct to VOR navigation. A VOR radial alone DME RNAV units differ, there are basic principles of merely gives line of position information. With DME, a pilot operation that are common to all. Pilots are urged to study may precisely locate the aircraft on a given line (radial). the manufacturer’s operating guide and receive instruction prior to the use of VOR/DME RNAV or any unfamiliar Most DME receivers also provide GS and time-to-station navigational system. Operational information and limitations modes of operation. The GS is displayed in knots (NMPH). should also be sought from placards and the supplement The time-to-station mode displays the minutes remaining to section of the AFM/POH.

VORTAC station passage, predicated upon the present GS.

GS and time-to-station information is only accurate when VOR/DME-based RNAV units operate in at least three tracking directly to or from a VORTAC. DME receivers modes: VOR, en route, and approach. A fourth mode, VOR typically need a minute or two of stabilized flight directly Parallel, may also be found on some models. The units need to or from a VORTAC before displaying accurate GS or both VOR and DME signals to operate in any RNAV mode.

time-to-station information. If the NAVAID selected is a VOR without DME, RNAV mode will not function.

Some DME installations have a hold feature that permits a DME signal to be retained from one VORTAC while the In the VOR (or non-RNAV) mode, the unit simply functions course indicator displays course deviation information from as a VOR receiver with DME capability. [Figure 16-36] The an ILS or another VORTAC. unit’s display on the VOR indicator is conventional in all respects. For operation on established airways or any other VOR/DME RNAV ordinary VOR navigation, the VOR mode is used.

Area navigation (RNAV) permits electronic course guidance on any direct route between points established by the pilot. To utilize the unit’s RNAV capability, the pilot selects and establishes a waypoint or a series of waypoints to define a While RNAV is a generic term that applies to a variety of NAVAIDS, such as GPS and others, this section deals course. A VORTAC (or VOR/DME) needs to be selected as a NAVAID, since both radial and distance signals are with VOR/DME-based RNAV. VOR/DME RNAV is not a separate ground-based NAVAID, but a method of navigation available from these stations. To establish a waypoint, a point somewhere within the service range of a VORTAC is using VOR/DME and VORTAC signals specially processed by the aircraft’s RNAV computer. [Figure 16-35] defined on the basis of radial and distance. Once the waypoint is entered into the unit and the RNAV en route mode is NOTE: In this section, the term “VORTAC” also includes selected, the CDI displays course guidance to the waypoint, not the original VORTAC. DME also displays distance to VOR/DME NAVAIDs.

the waypoint. Many units have the capability to store several waypoints, allowing them to be programmed prior to flight, In its simplest form, VOR/DME RNAV allows the pilot to electronically move VORTACs around to more convenient if desired, and called up in flight.

locations. Once electronically relocated, they are referred to as waypoints. These waypoints are described as a RNAV waypoints are entered into the unit in magnetic bearings (radials) of degrees and tenths (i.e., 275.5°) and combination of a selected radial and distance within the service volume of the VORTAC to be used. These waypoints distances in NM and tenths (i.e., 25.2 NM). When plotting RNAV waypoints on an aeronautical chart, pilots find it allow a straight course to be flown between almost any origin and destination, without regard to the orientation of VORTACs or the existence of airways.

OFFSET EN ROUTE 3 3 R BEARING LOAD DISTANCE N A V 4 4 4 3

3 9 7 2 8 8

12 12 Area Navigation Direct Route Figure 16-36. RNAV controls.

Figure 16-35. Flying an RNAV course.

16-28 difficult to measure to that level of accuracy, and in practical of 200 to 415 kHz. The frequencies are readily available on application, it is rarely necessary. A number of flight planning aeronautical charts or in the Chart Supplement U.S.

publications publish airport coordinates and waypoints with this precision and the unit accepts those figures. There is a All radio beacons, except compass locators, transmit subtle but important difference in CDI operation and display a continuous three-letter identification in code, except in the RNAV modes. during voice transmissions. A compass locator, which is associated with an instrument landing system, transmits a In the RNAV modes, course deviation is displayed in terms two-letter identification.

of linear deviation. In the RNAV en route mode, maximum deflection of the CDI typically represents 5 NM on either Standard broadcast stations can also be used in conjunction side of the selected course without regard to distance from the with ADF. Positive identification of all radio stations is waypoint. In the RNAV approach mode, maximum deflection extremely important and this is particularly true when using of the CDI typically represents 1¼ NM on either side of the standard broadcast stations for navigation.

selected course. There is no increase in CDI sensitivity as the aircraft approaches a waypoint in RNAV mode. NDBs have one advantage over the VOR in that low or medium frequencies are not affected by line-of-sight. The The RNAV approach mode is used for instrument approaches. signals follow the curvature of the Earth; therefore, if the Its narrow scale width (¼ of the en route mode) permits very aircraft is within the range of the station, the signals can be precise tracking to or from the selected waypoint. In VFR received regardless of altitude.

cross-country navigation, tracking a course in the approach mode is not desirable because it requires a great deal of The following table gives the class of NDB stations, their attention and soon becomes tedious. power, and their usable range: A fourth, lesser-used mode on some units is the VOR NONDIRECTIONAL RADIO BEACON (NDB) Parallel mode. This permits the CDI to display linear (Usable radius distances for all altitudes) (not angular) deviation as the aircraft tracks to and from VORTACs. It derives its name from permitting the pilot Power Distance to offset (or parallel) a selected course or airway at a fixed Class (Watts) (Miles) distance of the pilot’s choosing, if desired. The VOR parallel Compass Locator Under 25 15 mode has the same effect as placing a waypoint directly MH Under 50 2 5 * over an existing VORTAC. Some pilots select the VOR H 50–1999 5 0 parallel mode when utilizing the navigation (NAV) tracking HH 2 0 0 0 o r m o r e 7 5 function of their autopilot for smoother course following * near the VORTAC. Service range of individual facilities may be less than 50 miles.

Navigating an aircraft with VOR/DME-based RNAV can be confusing, and it is essential that the pilot become familiar One of the disadvantages that should be considered when with the equipment installed. It is not unknown for pilots to using low frequency (LF) for navigation is that LF signals are operate inadvertently in one of the RNAV modes when the very susceptible to electrical disturbances, such as lightning.

operation was not intended, by overlooking switch positions These disturbances create excessive static, needle deviations, or annunciators. The reverse has also occurred with a pilot and signal fades. There may be interference from distant neglecting to place the unit into one of the RNAV modes by stations. Pilots should know the conditions under which these overlooking switch positions or annunciators. As always, the disturbances can occur so they can be more alert to possible prudent pilot is not only familiar with the equipment used, interference when using the ADF.

but never places complete reliance in just one method of navigation when others are available for cross-check. Basically, the ADF aircraft equipment consists of a tuner, which is used to set the desired station frequency, and the Automatic Direction Finder (ADF) navigational display.

Many general aviation-type aircraft are equipped with ADF The navigational display consists of a dial upon which the radio receiving equipment. To navigate using the ADF, the pilot tunes the receiving equipment to a ground station azimuth is printed and a needle which rotates around the dial and points to the station to which the receiver is tuned.

known as a nondirectional radio beacon (NDB). The NDB stations normally operate in a low or medium frequency band 16-29 Some of the ADF dials can be rotated to align the Keep in mind that the needle of fixed azimuth points to the azimuth with the aircraft heading; others are fixed with 0° station in relation to the nose of the aircraft. If the needle representing the nose of the aircraft and 180° representing is deflected 30° to the left for a relative bearing of 330°, the tail. Only the fixed azimuth dial is discussed in this this means that the station is located 30° left. If the aircraft handbook. [Figure 16-37] is turned left 30°, the needle moves to the right 30° and indicates a relative bearing of 0° meaning that the aircraft Figure 16-38 illustrates terms that are used with the ADF is pointing toward the station. If the pilot continues flight and should be understood by the pilot. toward the station keeping the needle on 0°, the procedure is called homing to the station. If a crosswind exists, the To determine the magnetic bearing “FROM” the station, ADF needle continues to drift away from zero. To keep the 180° is added to or subtracted from the magnetic bearing to needle on zero, the aircraft must be turned slightly resulting the station. This is the reciprocal bearing and is used when in a curved flight path to the station. Homing to the station plotting position fixes. is a common procedure but may result in drifting downwind, thus lengthening the distance to the station.

Tracking to the station requires correcting for wind drift and results in maintaining flight along a straight track or bearing to the station. When the wind drift correction is established, the ADF needle indicates the amount of correction to the right or left. For instance, if the magnetic bearing to the station is 340°, a correction for a left crosswind would result in a magnetic heading of 330°, and the ADF needle E-W E would indicate 10° to the right or a relative bearing of 010°.

N N-S [Figure 16-39] S When tracking away from the station, wind corrections are W made similar to tracking to the station, but the ADF needle points toward the tail of the aircraft or the 180° position on the azimuth dial. Attempting to keep the ADF needle on the 180° position during winds results in the aircraft flying a curved flight leading further and further from the desired track. When tracking outbound, corrections for wind should Figure 16-37. ADF with fixed azimuth and magnetic compass. be made in the direction opposite of that in which the needle is pointing.

Although the ADF is not as popular as the VOR for radio navigation, with proper precautions and intelligent use, the ADF can be a valuable aid to navigation.

M a g n e t i Magnetic North c b Global Positioning System e a R r e i n l a The GPS is a satellite-based radio navigation system.

g t i v t o e Magnetic heading Its RNAV guidance is worldwide in scope. There are no s b 30 t e N a W a t symbols for GPS on aeronautical charts as it is a space-based i r 24 o i 6 n n 21 g E system with global coverage. Development of the system is S underway so that GPS is capable of providing the primary means of electronic navigation. Portable and yoke-mounted N-S E-W units are proving to be very popular in addition to those Radio station permanently installed in the aircraft. Extensive navigation databases are common features in aircraft GPS receivers.

Figure 16-38. ADF terms.

16-30 Defense (DOD) is responsible for operating the GPS satellite constellation and monitors the GPS satellites to ensure proper operation.

° The status of a GPS satellite is broadcast as part of the data message transmitted by the satellite. GPS status information N E is also available from the U.S. Coast Guard navigation information service at (703) 313-5907 or online at www.

W S navcen.uscg.gov . Additionally, satellite status is available through the NOTAM system.

The GPS receiver verifies the integrity (usability) of the signals received from the GPS constellation through receiver autonomous integrity monitoring (RAIM) to determine if a satellite is providing corrupted information. At least one satellite, in addition to those required for navigation, must be in view for the receiver to perform the RAIM function; thus, RAIM needs a minimum of five satellites in view or ° four satellites and a barometric altimeter (baro-aiding) to detect an integrity anomaly. For receivers capable of doing N E so, RAIM needs six satellites in view (or five satellites with baro-aiding) to isolate the corrupt satellite signal and remove W S it from the navigation solution. Baro-aiding is a method of augmenting the GPS integrity solution by using a nonsatellite input source. GPS derived altitude should not be relied upon 340° bearing to station to determine aircraft altitude since the vertical error can be quite large and no integrity is provided. To ensure that baro-aiding is available, the current altimeter setting must be entered into the receiver as described in the operating manual.

RAIM messages vary somewhat between receivers; however, generally there are two types. One type indicates that there are not enough satellites available to provide RAIM integrity monitoring and another type indicates that the RAIM integrity Figure 16-39. ADF tracking.

monitor has detected a potential error that exceeds the limit for the current phase of flight. Without RAIM capability, the The GPS is a satellite radio navigation and time dissemination pilot has no assurance of the accuracy of the GPS position.

system developed and operated by the U.S. Department of Defense (DOD). Civilian interface and GPS system status Selective Availability is available from the U.S. Coast Guard.

Selective Availability (SA) is a method by which the accuracy of GPS is intentionally degraded. This feature is designed It is not necessary to understand the technical aspects of to deny hostile use of precise GPS positioning data. SA was GPS operation to use it in VFR/IFR navigation. It does differ discontinued on May 1, 2000, but many GPS receivers are significantly from conventional, ground-based electronic designed to assume that SA is still active.

navigation and awareness of those differences is important.

Awareness of equipment approvals and limitations is critical The baseline GPS satellite constellation consists of 24 to the safety of flight.

satellites positioned in six earth-centered orbital planes with four operation satellites and a spare satellite slot in The GPS navigation system broadcasts a signal that is used each orbital plane. The system can support a constellation by receivers to determine precise position anywhere in the of up to thirty satellites in orbit. The orbital period of a GPS world. The receiver tracks multiple satellites and determines satellite is one-half of a sidereal day or 11 hours 58 minutes.

a pseudorange measurement to determine the user location.

The orbits are nearly circular and equally spaced about the A minimum of four satellites is necessary to establish an equator at a 60-degree separation with an inclination of accurate three-dimensional position. The Department of 16-31 55 degrees relative to the equator. The orbital radius (i.e. each type of receiver installation or use must be understood distance from the center of mass of the earth to the satellite) by the pilot to avoid misusing navigation information. In all is approximately 26,600 km. cases, VFR pilots should never rely solely on one system of navigation. GPS navigation must be integrated with With the baseline satellite constellation, users with a clear other forms of electronic navigation, as well as pilotage view of the sky have a minimum of four satellites in view. and dead reckoning. Only through the integration of these It is more likely that a user would see six to eight satellites. techniques can the VFR pilot ensure accuracy in navigation.

The satellites broadcast ranging signals and navigation data Some critical concerns in VFR use of GPS include RAIM allowing users to measure their pseudoranges in order to capability, database currency, and antenna location.

estimate their position, velocity and time, in a passive, listen- only mode. The receiver uses data from a minimum of four RAIM Capability satellites above the mask angle (the lowest angle above the Many VFR GPS receivers and all hand-held units are not horizon at which a receiver can use a satellite). The exact equipped with RAIM alerting capability. Loss of the required number of satellites operating at any one particular time number of satellites in view, or the detection of a position varies depending on the number of satellite outages and error, cannot be displayed to the pilot by such receivers.

operational spares in orbit. For current status of the GPS In receivers with no RAIM capability, no alert would constellation, please visit http://tycho.usno.navy.mil/gpscurr.

be provided to the pilot that the navigation solution had html. [Figure 16-40] deteriorated and an undetected navigation error could occur.

A systematic cross-check with other navigation techniques VFR Use of GPS would identify this failure and prevent a serious deviation.

GPS navigation has become a great asset to VFR pilots In many receivers, an updatable database is used for providing increased navigation capability and enhanced navigation fixes, airports, and instrument procedures.

situational awareness while reducing operating costs due These databases must be maintained to the current update to greater ease in flying direct routes. While GPS has many for IFR operation, but no such requirement exists for VFR benefits to the VFR pilot, care must be exercised to ensure use. However, in many cases, the database drives a moving that system capabilities are not exceeded.

map display that indicates Special Use Airspace and the various classes of airspace in addition to other operational Types of receivers used for GPS navigation under VFR are information. Without a current database, the moving map varied from a full IFR installation being used to support a display may be outdated and offer erroneous information VFR flight to a VFR only installation (in either a VFR or IFR to VFR pilots wishing to fly around critical airspace areas, capable aircraft) to a hand-held receiver. The limitations of such as a Restricted Area or a Class B airspace segment.

Numerous pilots have ventured into airspace they were trying to avoid by using an outdated database. If there is not a current database in the receiver, disregard the moving map display when making critical navigation decisions.

In addition, waypoints are added, removed, relocated, or re named as required to meet operational needs. When using GPS to navigate relative to a named fix, a current database must be used to properly locate a named waypoint. Without the update, it is the pilot’s responsibility to verify the waypoint location referencing to an official current source, such as the Chart Supplement U.S., sectional chart, or en route chart.

In many VFR installations of GPS receivers, antenna location is more a matter of convenience than performance. In IFR installations, care is exercised to ensure that an adequate clear view is provided for the antenna to communicate with satellites. If an alternate location is used, some portion of the aircraft may block the view of the antenna increasing the Figure 16-40. Satellite constellation.

possibility of losing navigation signal.

16-32 This is especially true in the case of hand-held receivers. The Another way to minimize head-down time is to become very use of hand-held receivers for VFR operations is a growing familiar with the receiver’s operation. Most receivers are not trend, especially among rental pilots. Typically, suction cups intuitive. The pilot must take the time to learn the various are used to place the GPS antennas on the inside of aircraft keystrokes, knob functions, and displays that are used in windows. While this method has great utility, the antenna the operation of the receiver. Some manufacturers provide location is limited by aircraft structure for optimal reception computer-based tutorials or simulations of their receivers.

of available satellites. Consequently, signal loss may occur Take the time to learn about the particular unit before using in certain situations where aircraft-satellite geometry causes it in flight.

a loss of navigation signal. These losses, coupled with a lack of RAIM capability, could present erroneous position and In summary, be careful not to rely on GPS to solve all VFR navigation information with no warning to the pilot. navigational problems. Unless an IFR receiver is installed in accordance with IFR requirements, no standard of accuracy While the use of hand-held GPS receivers for VFR operations or integrity can be assured. While the practicality of GPS is is not limited by regulation, modification of the aircraft, such compelling, the fact remains that only the pilot can navigate the as installing a panel- or yoke-mounted holder, is governed by aircraft, and GPS is just one of the pilot’s tools to do the job.

14 CFR part 43. Pilots should consult a mechanic to ensure VFR Waypoints compliance with the regulation and a safe installation.

VFR waypoints provide VFR pilots with a supplementary Tips for Using GPS for VFR Operations tool to assist with position awareness while navigating Always check to see if the unit has RAIM capability. If no visually in aircraft equipped with area navigation receivers.

RAIM capability exists, be suspicious of a GPS displayed VFR waypoints should be used as a tool to supplement current position when any disagreement exists with the position navigation procedures. The use of VFR waypoints include derived from other radio navigation systems, pilotage, or providing navigational aids for pilots unfamiliar with an area, dead reckoning. waypoint definition of existing reporting points, enhanced navigation in and around Class B and Class C airspace, and Check the currency of the database, if any. If expired, update enhanced navigation around Special Use Airspace. VFR the database using the current revision. If an update of an pilots should rely on appropriate and current aeronautical expired database is not possible, disregard any moving map charts published specifically for visual navigation. If display of airspace for critical navigation decisions. Be aware operating in a terminal area, pilots should take advantage of that named waypoints may no longer exist or may have been the Terminal Area Chart available for the area, if published.

relocated since the database expired. At a minimum, the The use of VFR waypoints does not relieve the pilot of any waypoints to be used should be verified against a current responsibility to comply with the operational requirements official source, such as the Chart Supplement U.S. or a of 14 CFR part 91.

Sectional Aeronautical Chart.

VFR waypoint names (for computer entry and flight plans) While a hand-held GPS receiver can provide excellent consist of five letters beginning with the letters “VP” and are navigation capability to VFR pilots, be prepared for retrievable from navigation databases. The VFR waypoint intermittent loss of navigation signal, possibly with no RAIM names are not intended to be pronounceable, and they are not warning to the pilot. If mounting the receiver in the aircraft, for use in ATC communications. On VFR charts, a stand be sure to comply with 14 CFR part 43. alone VFR waypoint is portrayed using the same four-point star symbol used for IFR waypoints. VFR waypoint collocated Plan flights carefully before taking off. If navigating to user- with a visual checkpoint on the chart is identified by a small defined waypoints, enter them prior to flight, not on the fly. magenta flag symbol. A VFR waypoint collocated with a Verify the planned flight against a current source, such as a visual checkpoint is pronounceable based on the name of the current sectional chart. There have been cases in which one visual checkpoint and may be used for ATC communications.

pilot used waypoints created by another pilot that were not Each VFR waypoint name appears in parentheses adjacent where the pilot flying was expecting. This generally resulted to the geographic location on the chart. Latitude/longitude in a navigation error. Minimize head-down time in the aircraft data for all established VFR waypoints may be found in the and maintain a sharp lookout for traffic, terrain, and obstacles. appropriate regional Chart Supplement U.S.

Just a few minutes of preparation and planning on the ground makes a great difference in the air.

16-33 When filing VFR flight plans, use the five-letter identifier as information to plot the aircraft position and then give vectors a waypoint in the route of flight section if there is an intended to a suitable landing site. If the situation becomes threatening, course change at that point or if used to describe the planned transmit the situation on the emergency frequency 121.5 MHz route of flight. This VFR filing would be similar to VOR use and set the transponder to 7700. Most facilities, and even in a route of flight. Pilots must use the VFR waypoints only airliners, monitor the emergency frequency.

when operating under VFR conditions.

Flight Diversion Any VFR waypoints intended for use during a flight should There may come a time when a pilot is not able to make it to be loaded into the receiver while on the ground and prior to the planned destination. This can be the result of unpredicted departure. Once airborne, pilots should avoid programming weather conditions, a system malfunction, or poor preflight routes or VFR waypoint chains into their receivers.

planning. In any case, the pilot needs to be able to safely and efficiently divert to an alternate destination. Risk Pilots should be especially vigilant for other traffic while management procedures become a priority during any type operating near VFR waypoints. The same effort to see and of flight diversion and should be used the pilot. For example, avoid other aircraft near VFR waypoints is necessary, as the hazards of inadvertent VFR into IMC involve a risk that is the case when operating near VORs and NDBs. In fact, the pilot can identify and assess and then mitigate through a the increased accuracy of navigation through the use of pre-planned or in-flight diversion around hazardous weather.

GPS demands even greater vigilance as there are fewer Before any cross-country flight, check the charts for airports off-course deviations among different pilots and receivers.

or suitable landing areas along or near the route of flight.

When operating near a VFR waypoint, use all available Also, check for navigational aids that can be used during a ATC services, even if outside a class of airspace where diversion. Risk management is explained in greater detail in communications are required. Regardless of the class of Chapter 2, Aeronautical Decision-making.

airspace, monitor the available ATC frequency closely for information on other aircraft operating in the vicinity. It is Computing course, time, speed, and distance information in also a good idea to turn on landing light(s) when operating flight requires the same computations used during preflight near a VFR waypoint to make the aircraft more conspicuous planning. However, because of the limited flight deck space to other pilots, especially when visibility is reduced.

and because attention must be divided between flying the aircraft, making calculations, and scanning for other aircraft, Lost Procedures take advantage of all possible shortcuts and rule-of-thumb Getting lost in flight is a potentially dangerous situation, computations.

especially when low on fuel. If a pilot becomes lost, there are some good common sense procedures to follow. If a town When in flight, it is rarely practical to actually plot a course or city cannot be seen, the first thing to do is climb, being on a sectional chart and mark checkpoints and distances.

mindful of traffic and weather conditions. An increase in Furthermore, because an alternate airport is usually not very far altitude increases radio and navigation reception range and from your original course, actual plotting is seldom necessary.

also increases radar coverage. If flying near a town or city, it may be possible to read the name of the town on a water tower. The course to an alternate destination can be measured accurately with a protractor or plotter but can also be If the aircraft has a navigational radio, such as a VOR or ADF measured with reasonable accuracy using a straightedge receiver, it can be possible to determine position by plotting and the compass rose depicted around VOR stations. This an azimuth from two or more navigational facilities. If GPS approximation can be made on the basis of a radial from a is installed, or a pilot has a portable aviation GPS on board, nearby VOR or an airway that closely parallels the course it can be used to determine the position and the location of to your alternate destination. However, remember that the the nearest airport. magnetic heading associated with a VOR radial or printed airway is outbound from the station. To find the course to Communicate with any available facility using frequencies the station, it may be necessary to determine the reciprocal of shown on the sectional chart. If contact is made with a that heading. It is typically easier to navigate to an alternate controller, radar vectors may be offered. Other facilities may airport that has a VOR or NDB facility on the field.

offer direction finding (DF) assistance. To use this procedure, the controller requests the pilot to hold down the transmit After selecting the most appropriate alternate destination, button for a few seconds and then release it. The controller approximate the magnetic course to the alternate using a may ask the pilot to change directions a few times and repeat compass rose or airway on the sectional chart. If time permits, the transmit procedure. This gives the controller enough try to start the diversion over a prominent ground feature.

16-34 However, in an emergency, divert promptly toward your alternate destination. Attempting to complete all plotting, measuring, and computations involved before diverting to the alternate destination may only aggravate an actual emergency.

Once established on course, note the time, and then use the winds aloft nearest to your diversion point to calculate a heading and GS. Once a GS has been calculated, determine a new arrival time and fuel consumption. Give priority to flying the aircraft while dividing attention between navigation and planning. When determining an altitude to use while diverting, consider cloud heights, winds, terrain, and radio reception.

Chapter Summary This chapter has discussed the fundamentals of VFR navigation. Beginning with an introduction to the charts that can be used for navigation to the more technically advanced concept of GPS, there is one aspect of navigation that remains the same—the pilot is responsible for proper planning and the execution of that planning to ensure a safe flight.

16-35 16-36

Chapter 17

Aeromedical

Factors

Introduction It is important for a pilot to be aware of the mental and physical standards required for the type of flying performed.

This chapter provides information on medical certification and on a variety of aeromedical factors related to flight activities.

17-1 demonstrated ability” (SODA) can be issued. This waiver, Obtaining a Medical Certificate or SODA, is valid as long as the physical impairment does Most pilots must have a valid medical certificate to exercise not worsen. Contact the local Flight Standards District Office the privileges of their airman certificates. Glider and free (FSDO) for more information on this subject.

balloon pilots are not required to hold a medical certificate.

Sport pilots may hold either a medical certificate or a valid The FAA medical standards, 14 CFR part 67, specify fifteen state driver’s license. Regardless of whether a medical medical conditions that are considered disqualifying by certificate or drivers license is required, 14 CFR 61.53 “history or clinical diagnosis.” Regardless of when one of requires every pilot not to act as a crewmember if they know, these conditions was diagnosed and treated, an airman may or have reason to know, of any medical condition that would not be issued a medical certificate except through a process make them unable to operate the aircraft in a safe manner.

called a “Special Issuance Authorization,” as explained in 14 CFR part 67, section 67.401. A special issuance is a Acquisition of a medical certificate requires an examination discretionary issuance by the FAA Federal Air Surgeon and by an aviation medical examiner (AME), a physician requires satisfactory completion of special testing determined with training in aviation medicine designated by the Civil by the FAA to demonstrate that an airman is safe to fly for Aerospace Medical Institute (CAMI). There are three classes the duration of the medical certificate issued. The specific of medical certificates. The class of certificate needed disqualifying conditions include: depends on the type of flying the pilot plans to perform.

• Diabetes mellitus requiring oral hypoglycemic medication or insulin A third-class medical certificate is required for a private or recreational pilot certificate. It is valid for 5 years for those • Angina pectoris individuals who have not reached the age of 40; otherwise it • Coronary heart disease that has been treated or, if is valid for 2 years. A commercial pilot certificate requires at untreated, that has been symptomatic or clinically least a second-class medical certificate, which is valid for 1 significant year. First-class medical certificates are required for airline • Myocardial infarction transport pilots and are valid for one year if the airman is 40 or younger; 40 and older it is valid for 6 months.

• Cardiac valve replacement • Permanent cardiac pacemaker The standards are more rigorous for the higher classes of certificates. A pilot with a higher class medical certificate • Heart replacement has met the requirements for the lower classes as well. Since • Psychosis the required medical class applies only when exercising the • Bipolar disorder privileges of the pilot certificate for which it is required, a first-class medical certificate would be valid for 1 year if • Personality disorder that is severe enough to have exercising the privileges of a commercial certificate and 2 or 5 repeatedly manifested itself by overt acts years, as appropriate, for exercising the privileges of a private • Substance dependence (including alcohol) or recreational certificate. The same applies for a second-class • Substance abuse medical certificate. The standards for medical certification are contained in Title 14 of the Code of Federal Regulations • Epilepsy (14 CFR) part 67 and the requirements for obtaining medical • Disturbance of consciousness and without satisfactory certificates can be found in 14 CFR part 61.

explanation of cause • Transient loss of control of nervous system function(s) Students who have physical limitations, such as impaired without satisfactory explanation of cause vision, loss of a limb, or hearing impairment may be issued a medical certificate valid for “student pilot privileges only” However, this list includes only the mandatory disqualifying while learning to fly. Pilots with disabilities may require conditions. There are many other medical conditions that fall special equipment to be installed in the aircraft, such as into the General Medical Condition section of the regulations hand controls for pilots with paraplegia. Some disabilities that are considered by the FAA to be disqualifying even necessitate a limitation on the individual’s certificate; for though they are not stated in the regulations. Conditions example, impaired hearing would require the limitation such as cancer, kidney stones, neurologic and neuromuscular “not valid for flight requiring the use of radio.” When all the conditions including Parkinson’s disease and multiple knowledge, experience, and proficiency requirements have sclerosis, certain blood disorders, and other conditions that been met and a student can demonstrate the ability to operate the aircraft with the normal level of safety, a “statement of 17-2 may progress over time require review by the FAA before a to pass between the membranes in the respiratory system.

medical certificate may be issued. This decrease in number of oxygen molecules at sufficient pressure can lead to hypoxic hypoxia.

The important thing to remember is that with very few exceptions, all disqualifying medical conditions may Dangers of Transporting Dry Ice be considered for special issuance. If you can present Sublimation is a process in which a substance transitions satisfactory medical documentation to the FAA that your from a solid to a gaseous state without passing through condition is stable, the chances are good that you will be an intermediate liquid state. Dry ice sublimates into large able to qualify for an Authorization.

quantities of CO gas, which can rapidly displace oxygen- containing air and potentially cause hypoxia via carbon Health and Physiological Factors dioxide intoxication. Case studies have shown that both illness Affecting Pilot Performance and death can be caused by occupational and/or unintentional exposure when transporting dry ice in small, confined A number of health factors and physiological effects can be spaces such as a flightdeck or airplane. Exposure to high linked to flying. Some are minor, while others are important concentration of CO gas may lead to increased respiration, enough to require special attention to ensure safety of flight.

tachycardia, cardiac arrhythmia, and unconsciousness.

In some cases, physiological factors can lead to inflight Exposure to concentration of CO gas in excess of 10 percent emergencies. Some important medical factors that a pilot may cause convulsions, coma, and/or death.

should be aware of include hypoxia, hyperventilation, middle ear and sinus problems, spatial disorientation, motion The tendency of dry ice to rapidly sublimate also means that sickness, carbon monoxide (CO) poisoning, stress and without proper ventilation, it can rapidly pressurize. For fatigue, dehydration, and heatstroke. Other subjects include this reason, dry ice should never be placed inside a sealed the effects of alcohol and drugs, anxiety, and excess nitrogen transport container (i.e., leak-proof secondary container) in the blood after scuba diving.

and must be placed within an outer shipping container or storage container that allows adequate ventilation to release Hypoxia the CO gas and avoid pressurization. Sealing dry ice within a Hypoxia means “reduced oxygen” or “not enough oxygen.” leak-proof container may result in explosion of the container Although any tissue will die if deprived of oxygen long potentially leading to serious physical injury or death.

enough, the greatest concern regarding hypoxia during flight is lack of oxygen to the brain, since it is particularly Hypemic Hypoxia vulnerable to oxygen deprivation. Any reduction in mental Hypemic hypoxia occurs when the blood is not able to take function while flying can result in life-threatening errors.

up and transport a sufficient amount of oxygen to the cells Hypoxia can be caused by several factors, including an in the body. Hypemic means “not enough blood.” This type insufficient supply of oxygen, inadequate transportation of of hypoxia is a result of oxygen deficiency in the blood, oxygen, or the inability of the body tissues to use oxygen.

rather than a lack of inhaled oxygen, and can be caused by The forms of hypoxia are based on their causes: a variety of factors. It may be due to reduced blood volume • Hypoxic hypoxia (from severe bleeding), or it may result from certain blood • Hypemic hypoxia diseases, such as anemia. More often, hypemic hypoxia occurs because hemoglobin, the actual blood molecule that • Stagnant hypoxia transports oxygen, is chemically unable to bind oxygen • Histotoxic hypoxia molecules. The most common form of hypemic hypoxia is CO poisoning. This is explained in greater detail later in this Hypoxic Hypoxia chapter. Hypemic hypoxia can also be caused by the loss Hypoxic hypoxia is a result of insufficient oxygen available of blood due to blood donation. Blood volume can require to the body as a whole. A blocked airway and drowning several weeks to return to normal following a donation.

are obvious examples of how the lungs can be deprived of Although the effects of the blood loss are slight at ground oxygen, but the reduction in partial pressure of oxygen at high level, there are risks when flying during this time.

altitude is an appropriate example for pilots. Although the percentage of oxygen in the atmosphere is constant, its partial Stagnant Hypoxia pressure decreases proportionately as atmospheric pressure Stagnant means “not flowing,” and stagnant hypoxia or decreases. As an aircraft ascends during flight, the percentage ischemia results when the oxygen-rich blood in the lungs of each gas in the atmosphere remains the same, but there are is not moving, for one reason or another, to the tissues that fewer molecules available at the pressure required for them 17-3 need it. An arm or leg “going to sleep” because the blood endurance or acclimatization. When flying at high altitudes, flow has accidentally been shut off is one form of stagnant it is paramount that oxygen be used to avoid the effects of hypoxia. This kind of hypoxia can also result from shock, hypoxia. The term “time of useful consciousness” describes the heart failing to pump blood effectively, or a constricted the maximum time the pilot has to make rational, life-saving artery. During flight, stagnant hypoxia can occur with decisions and carry them out at a given altitude without excessive acceleration of gravity (Gs). Cold temperatures supplemental oxygen. As altitude increases above 10,000 can also reduce circulation and decrease the blood supplied feet, the symptoms of hypoxia increase in severity, and the to extremities. time of useful consciousness rapidly decreases. [Figure 17-1] Since symptoms of hypoxia can be different for each individual, the ability to recognize hypoxia can be greatly Histotoxic Hypoxia improved by experiencing and witnessing the effects of it The inability of the cells to effectively use oxygen is defined during an altitude chamber “flight.” The Federal Aviation as histotoxic hypoxia. “Histo” refers to tissues or cells, and Administration (FAA) provides this opportunity through “toxic” means poisonous. In this case, enough oxygen is being aviation physiology training, which is conducted at the FAA transported to the cells that need it, but they are unable to make CAMI in Oklahoma City, Oklahoma, and at many military use of it. This impairment of cellular respiration can be caused facilities across the United States. For information about the by alcohol and other drugs, such as narcotics and poisons.

FAA’s one-day physiological training course with altitude Research has shown that drinking one ounce of alcohol can chamber and vertigo demonstrations, visit the FAA website equate to an additional 2,000 feet of physiological altitude.

at www.faa.gov .

Symptoms of Hypoxia Hyperventilation High-altitude flying can place a pilot in danger of becoming Hyperventilation is the excessive rate and depth of respiration hypoxic. Oxygen starvation causes the brain and other vital leading to abnormal loss of carbon dioxide from the blood.

organs to become impaired. The first symptoms of hypoxia This condition occurs more often among pilots than is can include euphoria and a carefree feeling. With increased generally recognized. It seldom incapacitates completely, but oxygen starvation, the extremities become less responsive and it causes disturbing symptoms that can alarm the uninformed flying becomes less coordinated. The symptoms of hypoxia pilot. In such cases, increased breathing rate and anxiety vary with the individual, but common symptoms include: further aggravate the problem. Hyperventilation can lead to • Cyanosis (blue fingernails and lips) unconsciousness due to the respiratory system’s overriding • Headache mechanism to regain control of breathing.

• Decreased response to stimuli and increased reaction Pilots encountering an unexpected stressful situation may time subconsciously increase their breathing rate. If flying at • Impaired judgment higher altitudes, either with or without oxygen, a pilot may • Euphoria have a tendency to breathe more rapidly than normal, which often leads to hyperventilation.

• Visual impairment • Drowsiness Since many of the symptoms of hyperventilation are similar to those of hypoxia, it is important to correctly diagnose and • Lightheaded or dizzy sensation treat the proper condition. If using supplemental oxygen, • Tingling in fingers and toes check the equipment and flow rate to ensure the symptoms are • Numbness Altitude Time of useful consciousness As hypoxia worsens, the field of vision begins to narrow and 45,000 feet MSL 9 to 15 seconds instrument interpretation can become difficult. Even with all 40,000 feet MSL 15 to 20 seconds these symptoms, the effects of hypoxia can cause a pilot to 35,000 feet MSL 30 to 60 seconds have a false sense of security and be deceived into believing 30,000 feet MSL 1 to 2 minutes everything is normal.

28,000 feet MSL 2½ to 3 minutes 25,000 feet MSL 3 to 5 minutes Treatment of Hypoxia 22,000 feet MSL 5 to 10 minutes Treatment for hypoxia includes flying at lower altitudes and/ 20,000 feet MSL 30 minutes or more or using supplemental oxygen. All pilots are susceptible to the effects of oxygen starvation, regardless of physical Figure 17-1. Time of useful consciousness.

17-4 not hypoxia related. Common symptoms of hyperventilation Middle ear Eustachian tube include: • Visual impairment Eardrum • Unconsciousness • Lightheaded or dizzy sensation • Tingling sensations • Hot and cold sensations • Muscle spasms Auditory canal The treatment for hyperventilation involves restoring the proper carbon dioxide level in the body. Breathing Opening to throat Outer ear normally is both the best prevention and the best cure for hyperventilation. In addition to slowing the breathing Figure 17-2. The Eustachian tube allows air pressure to equalize rate, breathing into a paper bag or talking aloud helps to in the middle ear.

overcome hyperventilation. Recovery is usually rapid once the breathing rate is returned to normal.

sensitivity, pinch the nostrils shut, close the mouth and lips, and blow slowly and gently into the mouth and nose.

Middle Ear and Sinus Problems During climbs and descents, the free gas formerly present in This procedure forces air through the Eustachian tube into the various body cavities expands due to a difference between middle ear. It may not be possible to equalize the pressure in the pressure of the air outside the body and that of the air the ears if a pilot has a cold, an ear infection, or sore throat.

inside the body. If the escape of the expanded gas is impeded, A flight in this condition can be extremely painful, as well as pressure builds up within the cavity and pain is experienced.

damaging to the eardrums. If experiencing minor congestion, Trapped gas expansion accounts for ear pain and sinus pain, nose drops or nasal sprays may reduce the risk of a painful as well as a temporary reduction in the ability to hear.

ear blockage. Before using any medication, check with an AME to ensure that it will not affect the ability to fly.

The middle ear is a small cavity located in the bone of the skull. It is closed off from the external ear canal by the In a similar way, air pressure in the sinuses equalizes with eardrum. Normally, pressure differences between the middle the pressure in the flight deck through small openings ear and the outside world are equalized by a tube leading that connect the sinuses to the nasal passages. An upper from inside each ear to the back of the throat on each side respiratory infection, such as a cold or sinusitis, or a nasal called the Eustachian tube. These tubes are usually closed but allergic condition can produce enough congestion around an open during chewing, yawning, or swallowing to equalize opening to slow equalization. As the difference in pressure pressure. Even a slight difference between external pressure between the sinuses and the flight deck increases, congestion and middle ear pressure can cause discomfort. [Figure 17-2] may plug the opening. This “sinus block” occurs most frequently during descent. Slow descent rates can reduce the During a climb, middle ear air pressure may exceed the associated pain. A sinus block can occur in the frontal sinuses, pressure of the air in the external ear canal causing the located above each eyebrow, or in the maxillary sinuses, eardrum to bulge outward. Pilots become aware of this located in each upper cheek. It usually produces excruciating pressure change when they experience alternate sensations pain over the sinus area. A maxillary sinus block can also of “fullness” and “clearing.” During descent, the reverse make the upper teeth ache. Bloody mucus may discharge happens. While the pressure of the air in the external ear from the nasal passages.

canal increases, the middle ear cavity, which equalized with the lower pressure at altitude, is at lower pressure than the Sinus block can be avoided by not flying with an upper external ear canal. This results in the higher outside pressure respiratory infection or nasal allergic condition. Adequate causing the eardrum to bulge inward.

protection is usually not provided by decongestant sprays or drops to reduce congestion around the sinus openings.

This condition can be more difficult to relieve due to the Oral decongestants have side effects that can impair pilot fact that the partial vacuum tends to constrict the walls of performance. If a sinus block does not clear shortly after the Eustachian tube. To remedy this often painful condition, landing, a physician should be consulted.

which also causes a temporary reduction in hearing 17-5 Spatial Disorientation and Illusions ear in any direction causes the tiny hairs to deflect, which in turn stimulates nerve impulses, sending messages to the Spatial disorientation specifically refers to the lack of brain. The vestibular nerve transmits the impulses from orientation with regard to the position, attitude, or movement the utricle, saccule, and semicircular canals to the brain to of the airplane in space. The body uses three integrated interpret motion.

systems that work together to ascertain orientation and movement in space.

The somatosensory system sends signals from the skin, joints, • Vestibular system—organs found in the inner ear that and muscles to the brain that are interpreted in relation to the sense position by the way we are balanced Earth’s gravitational pull. These signals determine posture.

• Somatosensory system—nerves in the skin, muscles, Inputs from each movement update the body’s position to the and joints that, along with hearing, sense position brain on a constant basis. “Seat of the pants” flying is largely based on gravity, feeling, and sound dependent upon these signals. Used in conjunction with visual and vestibular clues, these sensations can be fairly reliable.

• Visual system—eyes, which sense position based on However, the body cannot distinguish between acceleration what is seen forces due to gravity and those resulting from maneuvering the aircraft, which can lead to sensory illusions and false All this information comes together in the brain and, most impressions of an aircraft’s orientation and movement.

of the time, the three streams of information agree, giving a clear idea of where and how the body is moving. Flying Under normal flight conditions, when there is a visual can sometimes cause these systems to supply conflicting reference to the horizon and ground, the sensory system in the information to the brain, which can lead to disorientation.

inner ear helps to identify the pitch, roll, and yaw movements During flight in visual meteorological conditions (VMC), of the aircraft. When visual contact with the horizon is lost, the eyes are the major orientation source and usually prevail the vestibular system becomes unreliable. Without visual over false sensations from other sensory systems. When references outside the aircraft, there are many situations in these visual cues are removed, as they are in instrument which combinations of normal motions and forces create meteorological conditions (IMC), false sensations can cause convincing illusions that are difficult to overcome.

a pilot to quickly become disoriented.

Prevention is usually the best remedy for spatial disorientation.

The vestibular system in the inner ear allows the pilot to Unless a pilot has many hours of training in instrument flight, sense movement and determine orientation in the surrounding flight should be avoided in reduced visibility or at night when environment. In both the left and right inner ear, three the horizon is not visible. A pilot can reduce susceptibility semicircular canals are positioned at approximate right angles to disorienting illusions through training and awareness and to each other. [Figure 17-3] Each canal is filled with fluid learning to rely totally on flight instruments.

and has a section full of fine hairs. Acceleration of the inner Ampulla of semicircular canal YAW Semicircular canals Otolith organ ROLL PITCH PITCH ROLL YAW Endolymph fluid Cupola The semicircular tubes are arranged at approximately, right angles to each Vestibular nerve other in the roll, pitch, and yaw axes.

Hair cells Figure 17-3. The semicircular canals lie in three planes and sense motions of roll, pitch, and yaw.

17-6 Vestibular Illusions direction causing the disoriented pilot to return the aircraft to its original turn. Because an aircraft tends to lose altitude The Leans in turns unless the pilot compensates for the loss in lift, A condition called the leans, is the most common illusion the pilot may notice a loss of altitude. The absence of any during flight and is caused by a sudden return to level flight sensation of turning creates the illusion of being in a level following a gradual and prolonged turn that went unnoticed by descent. The pilot may pull back on the controls in an attempt the pilot. The reason a pilot can be unaware of such a gradual to climb or stop the descent. This action tightens the spiral turn is that human exposure to a rotational acceleration of 2 and increases the loss of altitude; this illusion is referred to degrees per second or lower is below the detection threshold as a “graveyard spiral.” [Figure 17-5] This may lead to a of the semicircular canals. [Figure 17-4] Leveling the wings loss of aircraft control.

after such a turn may cause an illusion that the aircraft is banking in the opposite direction. In response to such an Somatogravic Illusion illusion, a pilot may lean in the direction of the original turn A rapid acceleration, such as experienced during takeoff, in a corrective attempt to regain the perception of a correct stimulates the otolith organs in the same way as tilting the vertical posture.

head backwards. This action may create what is known as the “somatogravic illusion” of being in a nose-up attitude, Coriolis Illusion especially in conditions with poor visual references. The The “coriolis illusion” occurs when a pilot has been in a turn disoriented pilot may push the aircraft into a nose-low or long enough for the fluid in the ear canal to move at the same dive attitude. A rapid deceleration by quick reduction of the speed as the canal. A movement of the head in a different throttle(s) can have the opposite effect, with the disoriented plane, such as looking at something in a different part of the pilot pulling the aircraft into a nose-up or stall attitude.

flight deck, may set the fluid moving, creating the illusion of turning or accelerating on an entirely different axis. This action causes the pilot to think the aircraft is performing a maneuver it is not. The disoriented pilot may maneuver the aircraft into a dangerous attitude in an attempt to correct the aircraft’s perceived attitude.

Graveyard spin For this reason, it is important that pilots develop an instrument cross-check or scan that involves minimal head movement. Take care when retrieving charts and other objects in the flight deck—if something is dropped, retrieve it with minimal head movement and be alert for the coriolis illusion.

Graveyard Spiral As in other illusions, a pilot in a prolonged coordinated, constant-rate turn may experience the illusion of not Graveyard spiral turning. During the recovery to level flight, the pilot will then experience the sensation of turning in the opposite Figure 17-5. Graveyard spiral.

Endolymph Cupola Tube No turning Start of turn Constant rate turn Turn stopped No sensation. Sensation of turning No sensation after fluid Sensation of turning in as moving fluid deflects accelerates to same opposite direction as moving hairs. speed as tube wall. fluid deflects hairs in opposite direction.

Figure 17-4. Human sensation of angular acceleration.

17-7 Inversion Illusion Autokinesis An abrupt change from climb to straight-and-level flight can When flying in the dark, a stationary light may appear to stimulate the otolith organs enough to create the illusion of move if it is stared at for a prolonged period of time. As tumbling backwards, known as “inversion illusion.” The a result, a pilot may attempt to align the aircraft with the disoriented pilot may push the aircraft abruptly into a nose- perceived moving light potentially causing him/her to lose low attitude, which may intensify this illusion. control of the aircraft. This illusion is known as “autokinesis.” Postural Considerations Elevator Illusion The postural system sends signals from the skin, joints, and An abrupt upward vertical acceleration, as can occur in an muscles to the brain that are interpreted in relation to the updraft, can stimulate the otolith organs to create the illusion Earth’s gravitational pull. These signals determine posture.

of being in a climb. This is known as “elevator illusion.” Inputs from each movement update the body’s position to The disoriented pilot may push the aircraft into a nose-low the brain on a constant basis. “Seat of the pants” flying is attitude. An abrupt downward vertical acceleration, usually largely dependent upon these signals. Used in conjunction in a downdraft, has the opposite effect with the disoriented with visual and vestibular clues, these sensations can be pilot pulling the aircraft into a nose-up attitude.

fairly reliable. However, because of the forces acting upon the body in certain flight situations, many false sensations Visual Illusions can occur due to acceleration forces overpowering gravity.

Visual illusions are especially hazardous because pilots rely [Figure 17-6] These situations include uncoordinated turns, on their eyes for correct information. Two illusions that lead climbing turns, and turbulence.

to spatial disorientation, false horizon and autokinesis, affect the visual system only.

Demonstration of Spatial Disorientation There are a number of controlled aircraft maneuvers a pilot False Horizon can perform to experiment with spatial disorientation. While A sloping cloud formation, an obscured horizon, an aurora each maneuver normally creates a specific illusion, any false borealis, a dark scene spread with ground lights and stars, sensation is an effective demonstration of disorientation.

and certain geometric patterns of ground lights can provide Thus, even if there is no sensation during any of these inaccurate visual information, or “false horizon,” when maneuvers, the absence of sensation is still an effective attempting to align the aircraft with the actual horizon.

demonstration because it illustrates the inability to detect The disoriented pilots as a result may place the aircraft in a bank or roll.

dangerous attitude.

Level Coordinated turn Pull out Level skid Forward slip Uncoordinated turn Skid, slip, and uncoordinated turns feel similar.

Pilots feel they are being forced sideways in their seat.

Figure 17-6. Sensations from centrifugal force.

17-8 There are several objectives in demonstrating these various aircraft to approximately 45° bank attitude while maintaining maneuvers. heading and pitch attitude. This creates the illusion of a strong sense of rotation in the opposite direction. After this illusion 1. They teach pilots to understand the susceptibility of is noted, the pilot should open his or her eyes and observe the human system to spatial disorientation.

that the aircraft is in a banked attitude.

2. They demonstrate that judgments of aircraft attitude based on bodily sensations are frequently false.

Diving or Rolling Beyond the Vertical Plane 3. They help decrease the occurrence and degree This maneuver may produce extreme disorientation. While of disorientation through a better understanding in straight-and-level flight, the pilot should sit normally, of the relationship between aircraft motion, head either with eyes closed or gaze lowered to the floor. The movements, and resulting disorientation.

instructor pilot starts a positive, coordinated roll toward a 30° or 40° angle of bank. As this is in progress, the pilot 4. They help instill a greater confidence in relying on tilts his or her head forward, looks to the right or left, then flight instruments for assessing true aircraft attitude.

immediately returns his or her head to an upright position.

The instructor pilot should time the maneuver so the roll is A pilot should not attempt any of these maneuvers at stopped as the pilot returns his or her head upright. An intense low altitudes or in the absence of an instructor pilot or an disorientation is usually produced by this maneuver, and the appropriate safety pilot.

pilot experiences the sensation of falling downward into the direction of the roll.

Climbing While Accelerating With the pilot’s eyes closed, the instructor pilot maintains In the descriptions of these maneuvers, the instructor pilot is approach airspeed in a straight-and-level attitude for several doing the flying, but having the pilot do the flying can also seconds, then accelerates while maintaining straight-and be a very effective demonstration. The pilot should close his level attitude. The usual illusion during this maneuver, or her eyes and tilt the head to one side. The instructor pilot without visual references, is that the aircraft is climbing.

tells the pilot what control inputs to perform. The pilot then attempts to establish the correct attitude or control input with Climbing While Turning eyes closed and head tilted. While it is clear the pilot has no With the pilot’s eyes still closed and the aircraft in a straight idea of the actual attitude, he or she will react to what the and-level attitude, the instructor pilot now executes, with a senses are saying. After a short time, the pilot will become relatively slow entry, a well coordinated turn of about 1.5 disoriented and the instructor pilot will tell the pilot to look positive G (approximately 50° bank) for 90°. While in the up and recover. This exercise allows the pilot to experience turn, without outside visual references and under the effect of the disorientation while flying the aircraft.

the slight positive G, the usual illusion produced is that of a climb. Upon sensing the climb, the pilot should immediately Coping with Spatial Disorientation open the eyes to see that a slowly established, coordinated To prevent illusions and their potentially disastrous turn produces the same sensation as a climb.

consequences, pilots can: Diving While Turning 1. Understand the causes of these illusions and remain constantly alert for them. Take the opportunity to Repeating the previous procedure, but with the pilot’s experience spatial disorientation illusions in a device, eyes should be kept closed until recovery from the turn is such as a Barany chair, a Vertigon, or a Virtual Reality approximately one-half completed, can create the illusion of Spatial Disorientation Demonstrator.

diving while turning.

2. Always obtain and understand preflight weather Tilting to Right or Left briefings.

While in a straight-and-level attitude, with the pilot’s eyes 3. Before flying in marginal visibility (less than 3 miles) closed, the instructor pilot executes a moderate or slight skid or where a visible horizon is not evident, such as flight to the left with wings level. This creates the illusion of the over open water during the night, obtain training and body being tilted to the right.

maintain proficiency in aircraft control by reference to instruments.

Reversal of Motion 4. Do not fly into adverse weather conditions or into This illusion can be demonstrated in any of the three planes dusk or darkness unless proficient in the use of flight of motion. While straight and level, with the pilot’s eyes instruments. If intending to fly at night, maintain closed, the instructor pilot smoothly and positively rolls the 17-9 night-flight currency and proficiency. Include cross- is. [Figure 17-7] The pilot who does not recognize this country and local operations at various airfields. illusion will fly a lower approach. Downsloping runways and downsloping approach terrain can have the opposite effect.

5. Ensure that when outside visual references are used, they are reliable, fixed points on the Earth’s surface.

Featureless Terrain Illusion 6. Avoid sudden head movement, particularly during An absence of surrounding ground features, as in an takeoffs, turns, and approaches to landing.

overwater approach over darkened areas or terrain made 7. Be physically tuned for flight into reduced visibility.

featureless by snow, can create an illusion that the aircraft is Ensure proper rest, adequate diet, and, if flying at at a higher altitude than it actually is. This illusion, sometimes night, allow for night adaptation. Remember that referred to as the “black hole approach,” causes pilots to fly illness, medication, alcohol, fatigue, sleep loss, and a lower approach than is desired.

mild hypoxia are likely to increase susceptibility to spatial disorientation.

Water Refraction Rain on the windscreen can create an illusion of being at a 8. Most importantly, become proficient in the use of flight instruments and rely upon them. Trust the higher altitude due to the horizon appearing lower than it is.

This can result in the pilot flying a lower approach.

instruments and disregard your sensory perceptions.

The sensations that lead to illusions during instrument Haze flight conditions are normal perceptions experienced by Atmospheric haze can create an illusion of being at a greater pilots. These undesirable sensations cannot be completely distance and height from the runway. As a result, the pilot prevented, but through training and awareness, pilots can has a tendency to be low on the approach. Conversely, ignore or suppress them by developing absolute reliance extremely clear air (clear bright conditions of a high attitude on the flight instruments. As pilots gain proficiency in airport) can give the pilot the illusion of being closer than instrument flying, they become less susceptible to these he or she actually is, resulting in a high approach that may illusions and their effects.

result in an overshoot or go around. The diffusion of light due to water particles on the windshield can adversely affect Optical Illusions depth perception. The lights and terrain features normally Of the senses, vision is the most important for safe flight.

used to gauge height during landing become less effective However, various terrain features and atmospheric conditions for the pilot.

can create optical illusions. These illusions are primarily associated with landing. Since pilots must transition from Fog reliance on instruments to visual cues outside the flight Flying into fog can create an illusion of pitching up. Pilots deck for landing at the end of an instrument approach, it who do not recognize this illusion often steepen the approach is imperative that they be aware of the potential problems abruptly.

associated with these illusions and take appropriate corrective action. The major illusions leading to landing errors are Ground Lighting Illusions described below.

Lights along a straight path, such as a road or lights on moving trains, can be mistaken for runway and approach lights. Bright Runway Width Illusion runway and approach lighting systems, especially where A narrower-than-usual runway can create an illusion that the few lights illuminate the surrounding terrain, may create the aircraft is at a higher altitude than it actually is, especially illusion of less distance to the runway. The pilot who does when runway length-to-width relationships are comparable.

not recognize this illusion will often fly a higher approach.

[Figure 17-7] The pilot who does not recognize this illusion will fly a lower approach, with the risk of striking objects How To Prevent Landing Errors Due to Optical along the approach path or landing short. A wider-than Illusions usual runway can have the opposite effect with the risk of To prevent these illusions and their potentially hazardous the pilot leveling out the aircraft high and landing hard or consequences, pilots can: overshooting the runway.

1. Anticipate the possibility of visual illusions during approaches to unfamiliar airports, particularly at night Runway and Terrain Slopes Illusion or in adverse weather conditions. Consult airport An upsloping runway, upsloping terrain, or both can create an illusion that the aircraft is at a higher altitude than it actually 17-10 Runway width illusion Wider runway Narrower runway • A narrower-than-usual runway can create an illusion that the aircraft is higher than it actually is, leading to a lower approach.

• A wider-than-usual runway can create an illusion that the aircraft is Normal Approach Normal Approach lower than it actually is, leading to a higher approach.

Wider runway Narrower runway

25 25

Runway slope illusion Upsloping runway Downsloping runway • A downsloping runway can create the illusion that the aircraft is lower than it actually is, leading to a higher approach.

• An upsloping runway can create Normal Approach 25 the illusion that the aircraft is higher Normal Approach than it actually is, leading to a lower approach.

Downsloping runway Upsloping runway Normal approach Approach due to illusion Figure 17-7. Runway illusions.

diagrams and the Chart Supplement U.S. (formerly 4. Use Visual Approach Slope Indicator (VASI) or Airport/Facility Directory) for information on runway Precision Approach Path Indicator (PAPI) systems slope, terrain, and lighting. for a visual reference, or an electronic glideslope, whenever they are available.

2. Make frequent reference to the altimeter, especially during all approaches, day and night. 5. Utilize the visual descent point (VDP) found on many nonprecision instrument approach procedure charts.

3. If possible, conduct an aerial visual inspection of unfamiliar airports before landing.

17-11 6. Recognize that the chances of being involved in an can result in death. Aircraft heater vents and defrost vents approach accident increase when an emergency or may provide CO a passageway into the cabin, particularly if other activity distracts from usual procedures. the engine exhaust system has a leak or is damaged. If a strong odor of exhaust gases is detected, assume that CO is present.

7. Maintain optimum proficiency in landing procedures.

However, CO may be present in dangerous amounts even if no exhaust odor is detected. Disposable, inexpensive CO In addition to the sensory illusions due to misleading inputs to detectors are widely available. In the presence of CO, these the vestibular system, a pilot may also encounter various visual detectors change color to alert the pilot of the presence of CO.

illusions during flight. Illusions rank among the most common Some effects of CO poisoning are headache, blurred vision, factors cited as contributing to fatal aviation accidents.

dizziness, drowsiness, and/or loss of muscle power. Any time a pilot smells exhaust odor, or any time these symptoms are Sloping cloud formations, an obscured horizon, a dark scene experienced, immediate corrective action should be taken spread with ground lights and stars, and certain geometric including turning off the heater, opening fresh air vents and patterns of ground light can create illusions of not being windows, and using supplemental oxygen, if available.

aligned correctly with the actual horizon. Various surface features and atmospheric conditions encountered in landing Tobacco smoke also causes CO poisoning. Smoking at can create illusions of being on the wrong approach path.

sea level can raise the CO concentration in the blood and Landing errors due to these illusions can be prevented by result in physiological effects similar to flying at 8,000 feet.

anticipating them during approaches, inspecting unfamiliar Besides hypoxia, tobacco causes diseases and physiological airports before landing, using electronic glideslope or VASI debilitation that can be medically disqualifying for pilots.

systems when available, and maintaining proficiency in landing procedures.

Stress Stress is the body’s response to physical and psychological Motion Sickness demands placed upon it. The body’s reaction to stress includes Motion sickness, or airsickness, is caused by the brain releasing chemical hormones (such as adrenaline) into the receiving conflicting messages about the state of the body. A blood and increasing metabolism to provide more energy pilot may experience motion sickness during initial flights, but to the muscles. Blood sugar, heart rate, respiration, blood it generally goes away within the first few lessons. Anxiety pressure, and perspiration all increase. The term “stressor” and stress, which may be experienced at the beginning of is used to describe an element that causes an individual to flight training, can contribute to motion sickness. Symptoms experience stress. Examples of stressors include physical of motion sickness include general discomfort, nausea, stress (noise or vibration), physiological stress (fatigue), and dizziness, paleness, sweating, and vomiting.

psychological stress (difficult work or personal situations).

It is important to remember that experiencing airsickness is Stress falls into two broad categories: acute (short term) and no reflection on one’s ability as a pilot. If prone to motion chronic (long term). Acute stress involves an immediate sickness, let the flight instructor know, there are techniques threat that is perceived as danger. This is the type of stress that that can be used to overcome this problem. For example, triggers a “fight or flight” response in an individual, whether avoid lessons in turbulent conditions until becoming more the threat is real or imagined. Normally, a healthy person can comfortable in the aircraft or start with shorter flights and cope with acute stress and prevent stress overload. However, graduate to longer instruction periods. If symptoms of motion ongoing acute stress can develop into chronic stress.

sickness are experienced during a lesson, opening fresh air vents, focusing on objects outside the airplane, and avoiding Chronic stress can be defined as a level of stress that presents unnecessary head movements may help alleviate some of the an intolerable burden, exceeds the ability of an individual discomfort. Although medications like Dramamine can prevent to cope, and causes individual performance to fall sharply.

airsickness in passengers, they are not recommended while Unrelenting psychological pressures, such as loneliness, flying since they can cause drowsiness and other problems.

financial worries, and relationship or work problems can produce a cumulative level of stress that exceeds a person’s Carbon Monoxide (CO) Poisoning ability to cope with the situation. When stress reaches these CO is a colorless and odorless gas produced by all internal levels, performance falls off rapidly. Pilots experiencing combustion engines. Attaching itself to the hemoglobin in this level of stress are not safe and should not exercise their the blood about 200 times more easily than oxygen, CO airman privileges. Pilots who suspect they are suffering from prevents the hemoglobin from carrying oxygen to the cells, chronic stress should consult a physician.

resulting in hypemic hypoxia. The body requires up to 48 hours to dispose of CO. If severe enough, the CO poisoning 17-12 Fatigue Chronic fatigue, extending over a long period of time, usually has psychological roots, although an underlying disease is Fatigue is frequently associated with pilot error. Some of sometimes responsible. Continuous high-stress levels produce the effects of fatigue include degradation of attention and chronic fatigue. Chronic fatigue is not relieved by proper diet concentration, impaired coordination, and decreased ability and adequate rest and sleep and usually requires treatment to communicate. These factors seriously influence the by a physician. An individual may experience this condition ability to make effective decisions. Physical fatigue results in the form of weakness, tiredness, palpitations of the heart, from sleep loss, exercise, or physical work. Factors such as breathlessness, headaches, or irritability. Sometimes chronic stress and prolonged performance of cognitive work result fatigue even creates stomach or intestinal problems and in mental fatigue.

generalized aches and pains throughout the body. When the condition becomes serious enough, it leads to emotional illness.

Like stress, fatigue falls into two broad categories: acute and chronic. Acute fatigue is short term and is a normal If suffering from acute fatigue, stay on the ground. If fatigue occurrence in everyday living. It is the kind of tiredness occurs in the flight deck, no amount of training or experience people feel after a period of strenuous effort, excitement, or can overcome the detrimental effects. Getting adequate rest lack of sleep. Rest after exertion and 8 hours of sound sleep is the only way to prevent fatigue from occurring. Avoid ordinarily cures this condition.

flying without a full night’s rest, after working excessive hours, or after an especially exhausting or stressful day. Pilots A special type of acute fatigue is skill fatigue. This type of who suspect they are suffering from chronic fatigue should fatigue has two main effects on performance: consult a physician.

• Timing disruption—appearing to perform a task as usual, but the timing of each component is slightly off.

Exposure to Chemicals This makes the pattern of the operation less smooth When conducting preflight and post-flight inspections, pilots because the pilot performs each component as though it must verify that the fluid levels in their aircraft meet the were separate, instead of part of an integrated activity.

levels specified for safe operations as stated in the Pilot's • Disruption of the perceptual field—concentrating Operating Handbook. These fluids include, but are not limited attention upon movements or objects in the center of to hydraulic fluid, engine oil, and fuel.

vision and neglecting those in the periphery. This is accompanied by loss of accuracy and smoothness in It is important that every pilot recognize the potential hazards control movements.

of working with these fluids as well as the recommended first aid measures to follow should any of these fluids come in Acute fatigue has many causes, but the following are among contact with their eyes, skin, and/or respiratory system. As the most important for the pilot: the specific first aid measures for dealing with exposure to these chemicals can vary by chemical type, it is important that • Mild hypoxia (oxygen deficiency) every pilot be familiar with the location and use of the Material • Physical stress Safety Data Sheet (MSDS) for each chemical they encounter.

• Psychological stress The procedures described in the following sections are • Depletion of physical energy resulting from minimum guideline for first aid for each of the indicated psychological stress scenarios. Ultimately, the pilot should consult the MSDS • Sustained psychological stress for first aid procedures specific to the type of chemical and exposure scenario.

Sustained psychological stress accelerates the glandular secretions that prepare the body for quick reactions during Hydraulic Fluid an emergency. These secretions make the circulatory and • Eye Contact—immediately flush the eyes with clean respiratory systems work harder, and the liver releases energy water and seek medical attention if irritation occurs.

to provide the extra fuel needed for brain and muscle work.

When this reserve energy supply is depleted, the body lapses • Skin Contact—remove all contaminated clothing and into generalized and severe fatigue.

thoroughly cleanse the affected areas with mild soap and water or a waterless hand cleaner. If irritation or Acute fatigue can be prevented by proper diet and adequate redness develops and persists, seek medical attention.

rest and sleep. A well-balanced diet prevents the body from Should the hydraulic fluid get into or under the skin, needing to consume its own tissues as an energy source.

or into any other part of the body, regardless of the Adequate rest maintains the body’s store of vital energy.

17-13 appearance of the wound or its size, seek medical lung damage. Should vomiting occur, keep head below attention immediately. the hips to reduce the risks of aspiration. Monitor for breathing difficulties. Rinse out any material which • Inhalation—if respiratory symptoms develop, move enters the mouth until the taste is dissipated.

away from the source of exposure and into fresh air in a position comfortable for breathing. If symptoms Dehydration and Heatstroke persist, seek medical attention.

Dehydration is the term given to a critical loss of water from • Ingestion—first aid is not normally required; however, the body. Causes of dehydration are hot flight decks and if swallowed and symptoms develop, seek medical flight lines, wind, humidity, and diuretic drinks—coffee, tea, attention.

alcohol, and caffeinated soft drinks. Some common signs of dehydration are headache, fatigue, cramps, sleepiness, and Engine Oil dizziness.

• Eye Contact—immediately flush the eyes with clean The first noticeable effect of dehydration is fatigue, which water and seek medical attention if irritation occurs.

in turn makes top physical and mental performance difficult, • Skin Contact—remove all contaminated clothing and if not impossible. Flying for long periods in hot summer thoroughly cleanse the affected areas with soap and temperatures or at high altitudes increases the susceptibility water. Launder contaminated clothing before reuse.

to dehydration because these conditions tend to increase the • Inhalation—move away from the source of exposure rate of water loss from the body.

and into fresh air. If respiratory irritation, dizziness, nausea, or unconsciousness occurs, seek immediate To help prevent dehydration, drink two to four quarts of medical attention. If breathing stops, assisted water every 24 hours. Since each person is physiologically ventilation is required via a bag-valve-mask or different, this is only a guide. Most people are aware of the cardiopulmonary resuscitation (CPR).

eight-glasses-a-day guide: If each glass of water is eight ounces, this equates to 64 ounces, which is two quarts. If • Ingestion—seek immediate medical attention. If this fluid is not replaced, fatigue progresses to dizziness, immediate medical attention is not available, contact weakness, nausea, tingling of hands and feet, abdominal a regional poison control center or emergency medical cramps, and extreme thirst.

professional regarding the induction of vomiting or use of activated charcoal. Vomiting should never be The key for pilots is to be continually aware of their condition.

induced to a person who is groggy or unconscious.

Most people become thirsty with a 1.5 quart deficit or a loss of 2 percent of total body weight. This level of dehydration Fuel triggers the “thirst mechanism.” The problem is that the thirst • Eye Contact—immediately flush the eyes with mechanism arrives too late and is turned off too easily. A clean water for at least 15 minutes and seek medical small amount of fluid in the mouth turns this mechanism off attention immediately.

and the replacement of needed body fluid is delayed.

• Skin Contact—remove all contaminated clothing Other steps to prevent dehydration include: and thoroughly cleanse the affected areas with mild soap and water or a waterless hand cleaner. If skin • Carrying a container in order to measure daily water surface is damaged, apply a clean dressing and seek intake.

medical attention. If irritation or redness develops, • Staying ahead—not relying on the thirst sensation as seek medical attention. Launder contaminated clothing an alarm. If plain water is not preferred, add some before reuse.

sport drink flavoring to make it more acceptable.

• Inhalation—move away from the source of exposure • Limiting daily intake of caffeine and alcohol (both are and into fresh air. If breathing stops, assisted diuretics and stimulate increased production of urine).

ventilation is required via a bag-valve-mask or cardiopulmonary resuscitation (CPR). Once breathing Heatstroke is a condition caused by any inability of the body is restored, the use of additional oxygen may be to control its temperature. Onset of this condition may be necessary. Seek medical attention immediately.

recognized by the symptoms of dehydration, but also has • Ingestion—seek immediate medical attention. Do not been known to be recognized only upon complete collapse.

induce vomiting or take anything by mouth as this may cause the material to enter the lungs and cause severe 17-14 To prevent these symptoms, it is recommended that an the appropriate actions during routine occurrences, as well ample supply of water be carried and used at frequent as abnormal situations. The influence of alcohol drastically intervals on any long flight, whether thirsty or not. The body reduces the chances of completing a flight without incident.

normally absorbs water at a rate of 1.2 to 1.5 quarts per hour. Even in small amounts, alcohol can impair judgment, Individuals should drink one quart per hour for severe heat decrease sense of responsibility, affect coordination, constrict stress conditions or one pint per hour for moderate stress visual field, diminish memory, reduce reasoning ability, and conditions. If the aircraft has a canopy or roof window, lower attention span. As little as one ounce of alcohol can wearing light-colored, porous clothing and a hat will help decrease the speed and strength of muscular reflexes, lessen provide protection from the sun. Keeping the flight deck well the efficiency of eye movements while reading, and increase ventilated aids in dissipating excess heat. the frequency at which errors are committed. Impairments in vision and hearing can occur from consuming as little as Alcohol one drink.

Alcohol impairs the efficiency of the human body.

The alcohol consumed in beer and mixed drinks is ethyl [Figure 17-8] Studies have shown that consuming alcohol is closely linked to performance deterioration. Pilots must alcohol, a central nervous system depressant. From a medical point of view, it acts on the body much like a general make hundreds of decisions, some of them time-critical, during the course of a flight. The safe outcome of any flight anesthetic. The “dose” is generally much lower and more slowly consumed in the case of alcohol, but the basic effects depends on the ability to make the correct decisions and take on the human body are similar. Alcohol is easily and quickly absorbed by the digestive tract. The bloodstream absorbs Type Beverage Typical Serving Pure Alcohol about 80 to 90 percent of the alcohol in a drink within 30 (oz) Content (oz) minutes when ingested on an empty stomach. The body Table wine 4.0 .48 requires about 3 hours to rid itself of all the alcohol contained Light beer 12.0 .48 Aperitif liquor 1.5 .38 in one mixed drink or one beer.

Champagne 4.0 .48 Vodka 1.0 .50 While experiencing a hangover, a pilot is still under the Whiskey 1.25 .50 influence of alcohol. Although a pilot may think he or she is 0.01–0.05% average individual appears normal functioning normally, motor and mental response impairment (10–50 mg) is still present. Considerable amounts of alcohol can remain 0.03–0.12%* mild euphoria, talkativeness, decreased in the body for over 16 hours, so pilots should be cautious (30–120 mg) inhibitions, decreased attention, impaired about flying too soon after drinking.

judgment, increased reaction time 0.09–0.25% emotional instability, loss of critical Altitude multiplies the effects of alcohol on the brain. When (90–250 mg) judgment, impairment of memory and combined with altitude, the alcohol from two drinks may have comprehension, decreased sensory response, mild muscular incoordination the same effect as three or four drinks. Alcohol interferes with the brain’s ability to utilize oxygen, producing a form 0.18–0.30% confusion, dizziness, exaggerated of histotoxic hypoxia. The effects are rapid because alcohol (180–300 mg) emotions (anger, fear, grief), impaired passes quickly into the bloodstream. In addition, the brain visual perception, decreased pain sensation, impaired balance, staggering is a highly vascular organ that is immediately sensitive to gait, slurred speech, moderate muscular changes in the blood’s composition. For a pilot, the lower incoordination oxygen availability at altitude and the lower capability of 0.27–0.40% apathy, impaired consciousness, stupor, the brain to use the oxygen that is available can add up to a (270–400 mg) significantly decreased response to deadly combination.

stimulation, severe muscular incoordination, inability to stand or walk, vomiting, incontinence of urine and feces Intoxication is determined by the amount of alcohol in the bloodstream. This is usually measured as a percentage by 0.35–0.50% unconsciousness, depressed or weight in the blood. 14 CFR part 91 requires that blood (350–500 mg) abolished reflexes, abnormal body alcohol level be less than .04 percent and that 8 hours pass temperature, coma, possible death from respiratory paralysis (450 mg or above) between drinking alcohol and piloting an aircraft. A pilot with a blood alcohol level of .04 percent or greater after 8 hours * Legal limit for motor vehicle operation in most states is 0.08 cannot fly until the blood alcohol falls below that amount.

or 0.10% (80–100 mg of alcohol per dL of blood).

Even though blood alcohol may be well below .04 percent, a pilot cannot fly sooner than 8 hours after drinking alcohol.

Figure 17-8. Impairment scale with alcohol use.

17-15 Although the regulations are quite specific, it is a good idea as well for cognitive impairment, and either or both could be to be more conservative than the regulations. found unacceptable for medical certification.

Drugs Some of the most commonly used OTC drugs, antihistamines The Federal Aviation Regulations include no specific and decongestants, have the potential to cause noticeable adverse side effects, including drowsiness and cognitive references to medication usage. Two regulations, though, are important to keep in mind. Title 14 of the CFR part 61, deficits. The symptoms associated with common upper respiratory infections, including the common cold, often section 61.53 prohibits acting as pilot-in-command or in any other capacity as a required pilot flight crewmember, while suppress a pilot’s desire to fly, and treating symptoms with a drug that causes adverse side effects only compounds that person: the problem. Particularly, medications containing 1. Knows or has reason to know of any medical condition diphenhydramine (e.g., Benadryl) are known to cause that would make the person unable to meet the drowsiness and have a prolonged half-life, meaning the drugs requirement for the medical certificate necessary for stay in one’s system for an extended time, which lengthens the pilot operation, or the time that side effects are present.

2. Is taking medication or receiving other treatment for a medical condition that results in the person being Many medications, such as tranquilizers, sedatives, strong unable to meet the requirements for the medical pain relievers, and cough suppressants, have primary certificate necessary for the pilot operation.

effects that may impair judgment, memory, alertness, coordination, vision, and the ability to make calculations.

Further, 14 CFR part 91, section 91.17 prohibits the use [Figure 17-9] Others, such as antihistamines, blood pressure of any drug that affects the person’s faculties in any way drugs, muscle relaxants, and agents to control diarrhea and contrary to safety.

motion sickness, have side effects that may impair the same critical functions. Any medication that depresses the nervous There are several thousand medications currently approved system, such as a sedative, tranquilizer, or antihistamine, can by the U.S. Food and Drug Administration (FDA), not make a pilot more susceptible to hypoxia.

including OTC (over the counter) drugs. Virtually all medications have the potential for adverse side effects in Painkillers are grouped into two broad categories: analgesics some people. Additionally, herbal and dietary supplements, and anesthetics. Analgesics are drugs that reduce pain, sport and energy boosters, and some other “natural” products while anesthetics are drugs that deaden pain or cause loss are derived from substances often found in medications that of consciousness.

could also have adverse side effects. While some individuals experience no side effects with a particular drug or product, Over-the-counter analgesics, such as acetylsalicylic acid others may be noticeably affected. The FAA regularly (aspirin), acetaminophen (Tylenol), and ibuprofen (Advil), reviews FDA and other data to assure that medications found have few side effects when taken in the correct dosage.

acceptable for aviation duties do not pose an adverse safety Although some people are allergic to certain analgesics or may risk. Drugs that cause no apparent side effects on the ground suffer from stomach irritation, flying usually is not restricted can create serious problems at even relatively low altitudes.

when taking these drugs. However, flying is almost always Even at typical general aviation altitudes, the changes in precluded while using prescription analgesics, such as drugs concentrations of atmospheric gases in the blood can enhance containing propoxyphene (e.g., Darvon), oxycodone (e.g., the effects of seemingly innocuous drugs that can result in Percodan), meperidine (e.g., Demerol), and codeine, since impaired judgment, decision-making, and performance. In these drugs are known to cause side effects, such as mental addition, fatigue, stress, dehydration, and inadequate nutrition confusion, dizziness, headaches, nausea, and vision problems.

can increase an airman’s susceptibility to adverse effects from various drugs, even if they appeared to tolerate them in the Anesthetic drugs are commonly used for dental and surgical past. If multiple medications are being taken at the same time, procedures. Most local anesthetics used for minor dental and the adverse effects can be even more pronounced.

outpatient procedures wear off within a relatively short period of time. The anesthetic itself may not limit flying as much Another important consideration is that the medical as the actual procedure and subsequent pain.

condition for which a medication is prescribed may itself be disqualifying. The FAA will consider the condition in the context of risk for medical incapacitation, and the medication 17-16 Stimulants are drugs that excite the central nervous Depressants are drugs that reduce the body’s functioning in many areas. These drugs lower blood pressure, reduce mental system and produce an increase in alertness and activity.

Amphetamines, caffeine, and nicotine are all forms of processing, and slow motor and reaction responses. There are several types of drugs that can cause a depressing effect on the stimulants. Common uses of these drugs include appetite suppression, fatigue reduction, and mood elevation. Some body, including tranquilizers, motion sickness medication, some types of stomach medication, decongestants, and of these drugs may cause a stimulant reaction, even though this reaction is not their primary function. In some cases, antihistamines. The most common depressant is alcohol.

stimulants can produce anxiety and mood swings, both of which are dangerous when flying.

Generic Or Treatment Substance Possible Side Effects Brand Name for Alcohol Beer N/A Impaired judgment and perception Liquor Impaired coordination and motor control Wine Reduced reaction time Impaired sensory perception Reduced intellectual functions Reduced tolerance to G-forces Inner-ear disturbance and spatial disorientation (up to 48 hours) Central nervous system depression Nicotine Cigars N/A Sinus and respiratory system infection and irritation Cigarettes Impaired night vision Pipe tobacco Hypertension Chewing tobacco Carbon monoxide poisoning (from smoking) Snuff Amphetamines Ritalin Obesity (diet pills) Prolonged wakefulness Obetrol Tiredness Nervousness Eskatrol Impaired vision Suppressed appetite Shakiness Excessive sweating Rapid heart rate Sleep disturbance Seriously impaired judgment Caffeine Coffee N/A Impaired judgment Tea Reduced reaction time Chocolate Sleep disturbance No-Doz Increased motor activity and tremors Hypertension Irregular heart rate Rapid heart rate Body dehydration (through increased urine output) Headaches Antacid Alka-2 Stomach acids Liberations of carbon dioxide at altitude (distension may cause Di-Gel acute abdominal pain and may mask other medical problems) Maalox Antihistamines Coricidin Allergies Drowsiness and dizziness (sometimes recurring) Contac Colds Visual disturbances (when medications also contain antispasmodic drugs) Dristan Dimetapp Omade Chlor-Trimeton Diphenhydramine Aspirin Bayer Headaches Irregular body temperature Bufferin Fevers Variation in rate and depth of respiration Alka-Seltzer Aches Hypoxia and hyperventilation (two aspirin can contribute to) Pains Nausea, ringing in ears, deafness, diarrhea, and hallucinations when taken in excessive dosages Corrosive action on the stomach lining Gastrointestinal problems Decreased clotting ability of the blood (clotting ability could be the difference between life and death in a survival situation) Figure 17-9. Adverse affects of various drugs.

17-17 Some drugs that are classified as neither stimulants nor everyone metabolizes medications differently. However, depressants have adverse effects on flying. For example, five times the dosing interval is a reasonable rule of thumb.

some antibiotics can produce dangerous side effects, such as balance disorders, hearing loss, nausea, and vomiting. Altitude-Induced Decompression Sickness (DCS) While many antibiotics are safe for use while flying, the Decompression sickness (DCS) describes a condition infection requiring the antibiotic may prohibit flying. In characterized by a variety of symptoms resulting from addition, unless specifically prescribed by a physician, do exposure to low barometric pressures that cause inert gases not take more than one drug at a time, and never mix drugs (mainly nitrogen), normally dissolved in body fluids and with alcohol because the effects are often unpredictable. tissues, to come out of physical solution and form bubbles.

Nitrogen is an inert gas normally stored throughout the The dangers of illegal drugs also are well documented. human body (tissues and fluids) in physical solution. When Certain illegal drugs can have hallucinatory effects that occur the body is exposed to decreased barometric pressures (as in days or weeks after the drug is taken. Obviously, these drugs flying an unpressurized aircraft to altitude or during a rapid have no place in the aviation community.

decompression), the nitrogen dissolved in the body comes out of solution. If the nitrogen is forced to leave the solution too 14 CFR prohibits pilots from performing crewmember rapidly, bubbles form in different areas of the body causing a duties while using any medication that affects the body in variety of signs and symptoms. The most common symptom any way contrary to safety. The safest rule is not to fly as a is joint pain, which is known as “the bends.” [Figure 17-10] crewmember while taking any medication, unless approved to do so by the FAA. If there is any doubt regarding the effects What to do when altitude-induced DCS occurs: of any medication, consult an AME before flying.

• Put on oxygen mask immediately and switch the regulator to 100 percent oxygen.

Prior to each and every flight, all pilots must do a proper • Begin an emergency descent and land as soon as physical self-assessment to ensure safety. A great mnemonic, possible. Even if the symptoms disappear during covered in Chapter 2 on Aeronautical Decision-Making, descent, land and seek medical evaluation while is IMSAFE, which stands for Illness, Medication, Stress, continuing to breathe oxygen.

Alcohol, Fatigue, and Emotion.

• If one of the symptoms is joint pain, keep the affected For the medication component of IMSAFE, pilots need to area still; do not try to work pain out by moving the ask themselves, “Am I taking any medicines that might affect joint around.

my judgment or make me drowsy? For any new medication, • Upon landing, seek medical assistance from an FAA OTC or prescribed, you should wait at least 48 hours after medical officer, AME, military flight surgeon, or the first dose before flying to determine you do not have any a hyperbaric medicine specialist. Be aware that a adverse side effects that would make it unsafe to operate an physician not specialized in aviation or hypobaric aircraft. In addition to medication questions, pilots should medicine may not be familiar with this type of medical also consider the following – problem.

• Do not take any unnecessary or elective medications; • Definitive medical treatment may involve the use of • Make sure you eat regular balanced meals; a hyperbaric chamber operated by specially-trained personnel.

• Bring a snack for both you and your passengers for the flight; • Delayed signs and symptoms of altitude-induced DCS can occur after return to ground level regardless of • Maintain good hydration - bring plenty of water; presence during flight.

• Ensure adequate sleep the night prior to the flight; and • Stay physically fit.

DCS After Scuba Diving Scuba diving subjects the body to increased pressure, which Additionally, you should wait at least five maximal dosing allows more nitrogen to dissolve in body tissues and fluids.

intervals, the time between recommended or prescribed [Figure 17-11] The reduction of atmospheric pressure that dosing, (e.g., a dosing interval of 5 to 6 hours would require accompanies flying can produce physical problems for scuba you to wait 30 hours) before flying after taking any medication divers. A pilot or passenger who intends to fly after scuba that has potentially adverse side effects (e.g., sedating or diving should allow the body sufficient time to rid itself of dizziness). Observing the recommended dosing interval excess nitrogen absorbed during diving. If not, DCS due to doesn’t eliminate the risk for adverse side effects because 17-18 DCS Type Bubble Location Signs and Symptoms (Clinical Manifestations) BENDS Mostly large joints • Localized deep pain, ranging from mild (a “niggle”) to excruciating–sometimes a dull of the body (elbows, ache, but rarely a sharp pain shoulders, hip, wrists, • Active and passive motion of the joint aggravating the pain knees, ankles) • Pain occurring at altitude, during the descent, or many hours later NEUROLOGIC Brain • Confusion or memory loss Manifestations • Headache • Spots in visual field (scotoma), tunnel vision, double vision (diplopia), or blurry vision • Unexplained extreme fatigue or behavior changes • Seizures, dizziness, vertigo, nausea, vomiting, and unconsciousness Spinal cord • Abnormal sensations, such as burning, stinging, and tingling, around the lower chest and back • Symptoms spreading from the feet up and possibly accompanied by ascending weakness or paralysis • Girdling abdominal or chest pain Peripheral nerves • Urinary and rectal incontinence • Abnormal sensations, such as numbness, burning, stinging and tingling (paresthesia) • Muscle weakness or twitching CHOKES Lungs • Burning deep chest pain (under the sternum) • Pain aggravated by breathing • Shortness of breath (dyspnea) • Dry constant cough SKIN BENDS Skin • Itching usually around the ears, face, neck, arms, and upper torso • Sensation of tiny insects crawling over the skin • Mottled or marbled skin usually around the shoulders, upper chest, and abdomen accompanied by itching • Swelling of the skin, accompanied by tiny scar-like skin depressions (pitting edema) Figure 17-10. Signs and symptoms of altitude decompression sickness.

evolved gas can occur during exposure to low altitude and The eye functions much like a camera. Its structure includes create a serious inflight emergency. an aperture, a lens, a mechanism for focusing, and a surface for registering images. Light enters through the cornea at the The recommended waiting time before going to flight front of the eyeball, travels through the lens, and falls on the altitudes of up to 8,000 feet is at least 12 hours after diving retina. The retina contains light sensitive cells that convert that does not require controlled ascent (nondecompression stop diving), and at least 24 hours after diving that does require controlled ascent (decompression stop diving). The waiting time before going to flight altitudes above 8,000 feet should be at least 24 hours after any scuba dive. These recommended altitudes are actual flight altitudes above mean sea level (MSL) and not pressurized cabin altitudes.

This takes into consideration the risk of decompression of the aircraft during flight.

Vision in Flight Of all the senses, vision is the most important for safe flight.

Most of the things perceived while flying are visual or heavily supplemented by vision. As remarkable and vital as it is, vision is subject to limitations, such as illusions and blind spots. The more a pilot understands about the eyes and how Figure 17-11. To avoid the bends, scuba divers must not fly for they function, the easier it is to use vision effectively and specific time periods following dives.

compensate for potential problems.

17-19 The rods and cones (film) of Rods and the retina are cones the receptors which record the image and transmit it through the Fovea optic nerve to Fovea centralis (all cones) the brain for interpretation.

Rod Lens concentration Optic disk (blind spot) Iris Optic nerve Retina PUPIL CORNEA The pupil (aperture) is the opening at Light passes through the cornea (the the center of the iris. The size of the transparent window on the front of the pupil is adjusted to control the amount eye) and then through the lens to of light entering the eye. focus on the retina.

Figure 17-12. The human eye.

light energy into electrical impulses that travel through nerves that a large amount of light overwhelms them, and they take to the brain. The brain interprets the electrical signals to form longer to “reset” and adapt to the dark again. There are so images. There are two kinds of light-sensitive cells in the many cones in the fovea that are at the very center of the eyes: rods and cones. [Figure 17-12] visual field but virtually has no rods at all. So in low light, the middle of the visual field is not very sensitive, but farther The cones are responsible for all color vision, from from the fovea, the rods are more numerous and provide the appreciating a glorious sunset to discerning the subtle shades major portion of night vision.

in a fine painting. Cones are present throughout the retina, but are concentrated toward the center of the field of vision at the Vision Types back of the retina. There is a small pit called the fovea where There are three types of vision: photopic, mesopic, and almost all the light sensing cells are cones. This is the area scotopic. Each type functions under different sensory stimuli where most “looking” occurs (the center of the visual field or ambient light conditions. [Figure 17-13] where detail, color sensitivity, and resolution are highest).

Photopic Vision While the cones and their associated nerves are well suited Photopic vision provides the capability for seeing color and to detecting fine detail and color in high light levels, the resolving fine detail (20/20 or better), but it functions only rods are better able to detect movement and provide vision in good illumination. Photopic vision is experienced during in dim light. The rods are unable to discern color but are daylight or when a high level of artificial illumination exists.

very sensitive at low-light levels. The trouble with rods is Types of Vision Types of vision used Light level Technique of viewing Color perception Receptors used Acuity best Blind spot Photopic High Central Good Cones 20/20 Day Mesopic Medium/Low Both Some Cones/Rods Varies Day/Night Scotopic Low Scanning None Rods 20/200 Day/Night Figure 17-13. Types of vision.

17-20 The cones concentrated in the fovea centralis of the eye are Center of vision primarily responsible for vision in bright light. [Figure 17-12 ] Because of the high light level, rhodopsin, which is a biological pigment of the retina that is responsible for both the formation of the photoreceptor cells and the first events in the perception of light, is bleached out causing the rod Blind spot cells to become less effective.

Pupil Mesopic Vision Retina Mesopic vision is achieved by a combination of rods and cones and is experienced at dawn, dusk, and during full Optic nerve moonlight. Visual acuity steadily decreases as available light decreases and color perception changes because the cones Right LEFT become less effective. Mesopic viewing period is considered the most dangerous period for viewing. As cone sensitivity Figure 17-14. Central blind spot.

decreases, pilots should use off-center vision and proper scanning techniques to detect objects during low-light levels.

has in each eye. Under normal binocular vision conditions (both eyes are used together), this is not a problem because Scotopic Vision an object cannot be in the blind spot of both eyes at the same Scotopic vision is experienced under low-light levels and time. On the other hand, where the field of vision of one eye the cones become ineffective, resulting in poor resolution of is obstructed by an object (windshield divider or another detail. Visual acuity decreases to 20/200 or less and enables aircraft), a visual target could fall in the blind spot of the a person to see only objects the size of or larger than the other eye and remain undetected.

big “E” on visual acuity testing charts from 20 feet away.

In other words, a person must stand at 20 feet to see what Figure 17-15 provides a dramatic example of the eye’s can normally be seen at 200 feet under daylight conditions.

blind spot.

When using scotopic vision, color perception is lost and a 1. Hold this page at an arm’s length.

night blind spot in the central field of view appears at low 2. Completely cover your left eye (without closing or light levels when the cone-cell sensitivity is lost.

pressing on it) using your hand or other flat object.

Central Blind Spot 3. With your right eye, stare directly at the airplane on The area where the optic nerve connects to the retina in the the left side of the picture page. In your periphery, you back of each eye is known as the optic disk. There is a total will notice the black X on the right side of the picture.

absence of cones and rods in this area, and consequently, 4. Slowly move the page closer to you while continuing each eye is completely blind in this spot. [Figure 17-14] to stare at the airplane.

As a result, it is referred to as the blind spot that everyone Figure 17-15. The eye’s blind spot.

17-21 5. When the page is about 16–18 inches from you, the black X should disappear completely because it has been imaged onto the blind spot of your right eye.

(Resist the temptation to move your right eye while the black X is gone or else it reappears. Keep staring at the airplane.)

6. As you continue to look at the airplane, keep moving the page closer to you a few more inches, and the black X will come back into view.

7. There is an interval where you are able to move the page a few inches backward and forward, and the black X will be gone. This demonstrates to you the extent of your blind spot.

Figure 17-16. Night vision.

8. You can try the same thing again, except this time with expose the rods to the image. This can be done by looking 5° your right eye covered stare at the black X with your to 10° off center of the object to be seen. This can be tried in left eye. Move the page in closer and the airplane will a dim light in a darkened room. When looking directly at the disappear.

light, it dims or disappears altogether. When looking slightly off center, it becomes clearer and brighter.

Another way to check your blind spot is to do a similar test outside at night when there is a full moon. Cover your left When looking directly at an object, the image is focused eye, looking at the full moon with your right eye. Gradually mainly on the fovea, where detail is best seen. At night, the move your right eye to the left (and maybe slightly up or ability to see an object in the center of the visual field is down). Before long, all you will be able to see is the large reduced as the cones lose much of their sensitivity and the halo around the full moon; the entire moon itself will seem rods become more sensitive. Looking off center can help to have disappeared.

compensate for this night blind spot. Along with the loss of Empty-Field Myopia Empty-field myopia is a condition that usually occurs when flying above the clouds or in a haze layer that provides nothing specific to focus on outside the aircraft. This causes the eyes to relax and seek a comfortable focal distance that may range from 10 to 30 feet. For the pilot, this means looking without seeing, which is dangerous. Searching out and focusing on distant light sources, no matter how dim, helps prevent the onset of empty-field myopia.

Cones active Night Vision There are many good reasons to fly at night, but pilots must keep in mind that the risks of night flying are different than during the day and often times higher. [Figure 17-16] Pilots who are cautious and educated on night-flying techniques can mitigate those risks and become very comfortable and proficient in the task.

Night blind spot Night Blind Spot It is estimated that once fully adapted to darkness, the rods are 10,000 times more sensitive to light than the cones, making Rods active them the primary receptors for night vision. Since the cones Pilots must look 5°–10° off center of the are concentrated near the fovea, the rods are also responsible object in order for the object to be seen.

for much of the peripheral vision. The concentration of cones in the fovea can make a night blind spot in the center of the field of vision. To see an object clearly at night, the pilot must Figure 17-17. Night blind spot.

17-22 sharpness (acuity) and color at night, depth perception and moving from one viewing point to the next, pilots should judgment of size may be lost. [Figure 17-17] overlap the previous field of view by 10°. [Figure 17-18] Off-center viewing is another type of scan that pilots can use Dark Adaptation during night flying. It is a technique that requires an object be Dark adaptation is the adjustment of the human eye to a dark viewed by looking 10° above, below, or to either side of the environment. That adjustment takes longer depending on the object. [Figure 17-19] In this manner, the peripheral vision amount of light in the environment that a person has just left.

can maintain contact with an object.

Moving from a bright room into a dark one takes longer than moving from a dim room and going into a dark one.

With off-center vision, the images of an object viewed longer than 2 to 3 seconds will disappear. This occurs because the While the cones adapt rapidly to changes in light intensities, rods reach a photochemical equilibrium that prevents any the rods take much longer. Walking from bright sunlight into further response until the scene changes. This produces a dark movie theater is an example of this dark adaptation a potentially unsafe operating condition. To overcome period experience. The rods can take approximately 30 this night vision limitation, pilots must be aware of the minutes to fully adapt to darkness. A bright light, however, phenomenon and avoid viewing an object for longer than 2 can completely destroy night adaptation, leaving night or 3 seconds. The peripheral field of vision will continue to vision severely compromised while the adaptation process pick up the object when the eyes are shifted from one off- is repeated.

center point to another.

Scanning Techniques Night Vision Protection Scanning techniques are very important in identifying objects Several things can be done to help with the dark adaptation at night. To scan effectively, pilots must look from right to process and to keep the eyes adapted to darkness. Some of left or left to right. They should begin scanning at the greatest the steps pilots and flight crews can take to protect their night distance an object can be perceived (top) and move inward vision are described in the following paragraphs.

toward the position of the aircraft (bottom). For each stop, an area approximately 30° wide should be scanned. The duration of each stop is based on the degree of detail that is required, but no stop should last longer than 2 to 3 seconds. When 10° 2 1 4 3 Figure 17-18. Scanning techniques.

17-23 Focal points X 10 degrees X X X OBSERVER 10 degrees 10 degrees Once an object is detected in the peripheral field of dark- adapted vision, continued surveillance is maintained by ° use of “off-center” vision. Looking 10 right or left and above and below the object, viewing no longer than 2 to 3 seconds at each position.

X 10 degrees Figure 17-19. Off-center viewing.

Sunglasses High Intensity Lighting If a night flight is scheduled, pilots and crew members should If, during the flight, any high intensity lighting areas are wear neutral density (N-15) sunglasses or equivalent filter encountered, attempt to turn the aircraft away and fly in the lenses when exposed to bright sunlight. This precaution periphery of the lighted area. This will not expose the eyes to increases the rate of dark adaptation at night and improves such a large amount of light all at once. If possible, plan your night visual sensitivity. route to avoid direct over flight of built-up, brightly lit areas.

Oxygen Supply Flightdeck Lighting Unaided night vision depends on optimum function and Flightdeck lighting should be kept as low as possible so that sensitivity of the rods of the retina. Lack of oxygen to the rods the light does not monopolize night vision. After reaching (hypoxia) significantly reduces their sensitivity. Sharp clear the desired flight altitude, pilots should allow time to vision (with the best being equal to 20–20 vision) requires adjust to the flight conditions. This includes readjustment significant oxygen especially at night. Without supplemental of instrument lights and orientation to outside references.

oxygen, an individual’s night vision declines measurably at During the adjustment period, night vision should continue pressure altitudes above 4,000 feet. As altitude increases, to improve until optimum night adaptation is achieved. When the available oxygen decreases, degrading night vision.

it is necessary to read maps, charts, and checklists, use a dim Compounding the problem is fatigue, which minimizes white light flashlight and avoid shining it in your or any other physiological well being. Adding fatigue to high altitude crewmember’s eyes.

exposure is a recipe for disaster. In fact, if flying at night at an altitude of 12,000 feet, the pilot may actually see elements Airfield Precautions of his or her normal vision missing or not in focus. Missing Often time, pilots have no say in how airfield operations are visual elements resemble the missing pixels in a digital image handled, but listed below are some precautions that can be while unfocused vision is dim and washed out.

taken to make night flying safer and help protect night vision.

• Airfield lighting should be reduced to the lowest For the pilot suffering the effects of hypoxic hypoxia, a simple usable intensity.

descent to a lower altitude may not be sufficient to reestablish vision. For example, a climb from 8,000 feet to 12,000 feet for • Maintenance personnel should practice light discipline 30 minutes does not mean a descent to 8,000 feet will rectify with headlights and flashlights.

the problem. Visual acuity may not be regained for over an • Position the aircraft at a part of the airfield where the hour. Thus, it is important to remember, altitude and fatigue least amount of lighting exists.

have a profound effect on a pilot’s ability to see.

17-24 • Select approach and departure routes that avoid highways and residential areas where illumination can impair night vision. DRUGS DRUGS DRUGS DRUGS Self-Imposed Stress HYPOGLYCEMIA HYPOGLYCEMIA HYPOGLYCEMIA HYPOGLYCEMIA Night flight can be more fatiguing and stressful than day EXHAUSTION EXHAUSTION EXHAUSTION EXHAUSTION NUTRITIONAL NUTRITIONAL NUTRITIONAL NUTRITIONAL flight, and many self- imposed stressors can limit night vision.

DEFICIENCY DEFICIENCY DEFICIENCY DEFICIENCY Pilots can control this type of stress by knowing the factors that can cause self-imposed stressors. Some of these factors POOR PHYSICAL POOL PHYSICAL POOR PHYSICAL CONDITION CONDITION are listed in the following paragraphs. [Figure 17-20] CONDITION ALCOHOL ALCOHOL ALCOHOL ALCOHOL TOBACCO TOBACCO TOBACCO TOBACCO Drugs Drugs can seriously degrade visual acuity during the day and Figure 17-20. Self-imposed stress.

especially at night. Pilots who become ill should consult an aviation medical examiner (AME) or flight surgeon as to affects peripheral vision and dark adaptation. The results which drugs are appropriate to take while flying.

are the same as those for hypoxia caused by high altitude.

Smoking 3 cigarettes in rapid succession or 20 to 30 cigarettes Exhaustion within a 24-hour period may saturate from 8 to 10 percent Pilots who become fatigued during a night flight will not be of the capacity of hemoglobin. Smokers lose 20 percent of mentally alert and will respond more slowly to situations their night vision capability at sea level, which is equal to a requiring immediate action. Exhausted pilots tend to physiological altitude of 5,000 feet.

concentrate on one aspect of a situation without considering the total requirement. Their performance may become a Hypoglycemia and Nutritional Deficiency safety hazard depending on the degree of fatigue and instead Missing or postponing meals can cause low blood sugar, of using proper scanning techniques may get fixated on the which impairs night flight performance. Low blood sugar instruments or stare off rather than multitask.

levels may result in stomach contractions, distraction, breakdown in habit pattern, and a shortened attention span.

Poor Physical Conditioning Likewise, an insufficient consumption of vitamin A may To overcome poor physical conditioning, pilots should also impair night vision. Foods high in vitamin A include participate in regular exercise programs. People who are eggs, butter, cheese, liver, apricots, peaches, carrots, squash, physically fit become less fatigued during flight and have spinach, peas, and most types of greens. High quantities of better night scanning efficiency. However, too much exercise vitamin A do not increase night vision but a lack of vitamin in a given day may leave crew members too fatigued for A certainly impairs it.

night flying.

Distance Estimation and Depth Perception Alcohol Knowledge of the mechanisms and cues affecting distance Alcohol is a sedative and its use impairs both coordination estimation and depth perception assist pilots in judging and judgment. As a result, pilots who are impaired by alcohol distances at night. These cues may be monocular or binocular.

fail to apply the proper techniques of night vision. They are The monocular cues that aid in distance estimation and depth likely to stare at objects and to neglect scanning techniques.

perception include motion parallax, geometric perspective, The amount of alcohol consumed determines the degree to retinal image size, and aerial perspective.

which night vision is affected. The effects of alcohol are long lasting and the residual effects of alcohol can also impair Motion Parallax visual scanning efficiency.

Motion parallax refers to the apparent motion of stationary objects as viewed by an observer moving across the Tobacco landscape. When the pilot or crewmember looks outside the Of all the self-imposed stressors, cigarette smoking most aircraft perpendicular to the direction of travel, near objects decreases visual sensitivity at night. Smoking significantly appear to move backward, past, or opposite the path of increases the amount of carbon monoxide carried by the motion; far objects seem to move in the direction of motion hemoglobin in red blood cells. This reduces the blood’s or remain fixed. The rate of apparent movement depends on capacity to combine with oxygen, so less oxygen is carried the distance the observer is from the object.

in the blood. Hypoxia caused by carbon monoxide poisoning 17-25 Geometric Perspective make an obvious difference in the viewing angle of both eyes.

In the flight environment, most distances outside the cockpit An object may appear to have a different shape when viewed are so great that binocular cues are of little, if any, value. In at varying distances and from different angles. Geometric addition, binocular cues operate on a more subconscious perspective cues include linear perspective, apparent level than monocular cues and are performed automatically.

foreshortening, and vertical position in the field.

• Linear perspective—parallel lines, such as runway Night Vision Illusions lights, power lines and railroad tracks, tend to There are many different types of visual illusions that converge as distance from the observer increases.

commonly occur at night. Anticipating and maintaining [Figure 17-21A] awareness of them is usually the best way to avoid them.

• Apparent foreshortening—the true shape of an object or a terrain feature appears elliptical when viewed Autokinesis from a distance. [Figure 17-21B] Autokinesis is caused by staring at a single point of light • Vertical position in the field—objects or terrain against a dark background for more than a few seconds.

features farther away from the observer appear higher After a few moments, the light appears to move on its own.

on the horizon than those closer to the observer. Apparent movement of the light source will begin in about [Figure 17-21C] 8 to 10 seconds. To prevent this illusion, focus the eyes on objects at varying distances and avoid fixating on one source Aerial Perspective of light. This illusion can be eliminated or reduced by visual scanning, by increasing the number of lights, or by varying The clarity of an object and the shadow cast by it are the light intensity. The most important of the three solutions perceived by the brain and are cues for estimating distance.

is visual scanning. A light or lights should not be stared at Subtle variations in color or shade are clearer the closer the for more than 10 seconds.

observer is to an object. However, as distance increases, these distinctions may become blurry. The same applies to False Horizon an object detail or texture. As a person gets farther from an object, its discrete details become less apparent. Another A false horizon can occur when the natural horizon is important fact to remember while flying at night is that every obscured or not readily apparent. It can be generated by object casts a shadow from a light source. The direction in confusing bright stars and city lights. It can also occur while which the shadow is cast depends on the position of the light flying toward the shore of an ocean or a large lake. Because source. If the shadow of an object is cast toward the observer, of the relative darkness of the water, the lights along the the object is closer than the light source is to the observer. shoreline can be mistaken for stars in the sky. [Figure 17-22] Binocular Cues Reversible Perspective Illusion Binocular cues of an object are dependent upon the slightly At night, an aircraft may appear to be moving away from different viewing angle of each eye of an object. Binocular a second aircraft when it is, in fact, approaching a second perception is useful only when the object is close enough to aircraft. This illusion often occurs when an aircraft is flying A B C Figure 17-21. Geometric perspective.

17-26 Apparent horizon Actual horizon Figure 17-22. At night, the horizon may be hard to discern due to dark terrain and misleading light patterns on the ground.

parallel to another’s course. To determine the direction of steep surrounding terrain, and a wide runway can produce the flight, pilots should observe aircraft lights and their relative illusion of being too low with a tendency to fly a higher-than position to the horizon. If the intensity of the lights increases, normal approach. A set of regularly spaced lights along a road the aircraft is approaching; if the lights dim, the aircraft is or highway can appear to be runway lights. Pilots have even moving away. mistaken the lights on moving trains as runway or approach lights. Bright runway or approach lighting systems can create Size-Distance Illusion the illusion that the aircraft is closer to the runway, especially where few lights illuminate the surrounding terrain.

This illusion results from viewing a source of light that is increasing or decreasing in luminance (brightness). Pilots Prior to flying at night, it is best to learn and know the may interpret the light as approaching or retreating.

challenges of the area in which you are flying in. Study the area and know how to navigate your way through areas that Fascination (Fixation) may pose a problem at night. For example, many areas near This illusion occurs when pilots ignore orientation cues and water may be obscured by low lying clouds or fog. To help fix their attention on a goal or an object. Student pilots tend to deal with this type of situation, it is important to have a plan have this happen when they are concentrating on the aircraft before you leave the ground. In the daytime, fly the routes instruments or attempting to land. They become fixated on and passes that you will be flying at night and determine the one task and forget to look at what is going on around them.

minimum altitude you are willing to use at night. If weather At night, this can be especially dangerous because aircraft prevents you from maintaining the altitude that you planned, ground-closure rates are difficult to determine, and there may make a decision early to turn 180° and land at an alternate be minimal time to correct the situation.

airport with better weather conditions. Always consider safer alternatives rather than hope things will work out by Flicker Vertigo taking a chance.

A light flickering at a rate between 4 and 20 cycles per second can produce unpleasant and dangerous reactions. Such Pilots who fly at night should strongly consider oxygen conditions as nausea, vomiting, and vertigo may occur. On supplementation at altitudes and times not required by the rare occasions, convulsions and unconsciousness may also FAA, especially at night when critical judgment and hand-eye occur. Proper scanning techniques at night can prevent pilots coordination is necessary (e.g., IFR) or if he/she is a smoker from getting flicker vertigo.

or not perfectly healthy.

Night Landing Illusions Enhanced Night Vision Systems Landing illusions occur in many forms. Above featureless Synthetic Vision Systems (SVS) and Enhanced Flight Vision terrain at night, there is a natural tendency to fly a lower Systems (EFVS) are two systems that can improve the safety than-normal approach. Elements that cause any type of of flight at night. The technology of both is evolving rapidly visual obscurities, such as rain, haze, or a dark runway and being used more and more. [Figure 17-23] environment, can also cause low approaches. Bright lights, 17-27 Synthetic vision system Enhanced vision system Figure 17-23. Synthetic and enha n ced vision systems.

obvious advantages of SVS are that the digital terrain image Synthetic Vision System remains on the pilot’s display regardless of how poor the A Synthetic Vision System (SVS) is an electronic means visibility is outside.

to display a synthetic vision image of the external scene topography to the flight crew. [Figure 17-24] It is not a An SVS image can be displayed on either a head-down real-time image like that produced by an EFVS. Unlike display or head-up display (HUD); however, to date, SVS EFVS, SVS requires a terrain and obstacle database, a has only been certified on head-down displays. Development precise navigation solution, and a display. The terrain efforts to display a synthetic image on a HUD are currently image is based on the use of data from a Digital Elevation underway as are efforts that would combine SVS with a real- Model (DEM) that is stored within the SVS. With SVS, the time sensor image produced by an EFVS. These systems are synthetic terrain/vision image is intended to enhance pilot known as Combined Vision Systems. While SVS is currently awareness of spatial position relative to important features certified as an aid to situation awareness only, the FAA in all visibility conditions. This is particularly useful during and aviation industry are working on defining operational critical phases of flight, such as takeoff, approach, and concepts and airworthiness criteria that would enable SVS landing, where important features, such as terrain, obstacles, to be used for operational credit in certain low visibility runways, and landmarks, may be depicted on the SVS conditions. Other future enhancements to SVS displays could display. [Figure 17-25] During approach operations, the include integrating ADS-B to display traffic information.

Enhanced Flight Vision System Enhanced Vision (EV) or Enhanced Flight Vision System (EFVS) is an electronic means to provide a display of Figure 17-25. Night time SVS system.

Figure 17-24. SVS system.

17-28 the external scene by use of an imaging sensor, such as a Forward-Looking InfraRed (FLIR) or millimeter wave radar (MMWR). In 2004, 14 CFR part 91, section 91.175 was amended to reflect that operators conducting straight- in instrument approach procedures (in other than Category II or Category III operations) may now operate below the published decision height (DH) or minimum descent altitude (MDA) when using an approved EFVS shown on the pilot’s HUD. This rule change provides “operational credit” for EV equipage. No such credit exists for SV.

Chapter Summary This chapter provides an introduction to aeromedical factors relating to flight activities. More detailed information on the subjects discussed in this chapter is available in the Aeronautical Information Manual (AIM) and online at www.

faa.gov.

17-29 17-30

Appendix A

Performance Data for Cessna

Model 172R and Challenger 605

Short Field Takeoff Distance at 2,450 Pounds for a Cessna Model 172R

A-1

Time, Fuel, and Distance to Climb at 2,450 Pounds for a Cessna Model 172R

A-2

Cruise Performance for a Cessna Model 172R

A-3

Short Field Landing Distance at 2,450 Pounds for a Cessna Model 172R

A-4

Challenger 605 Range/Payload Profile

Fuel Takeoff Field Length (feet) 3,190 6,570 10,230 14,200 18,105 Burn (lb) Gross SL 5,000 ft Takeoff 2:00 4:00 6:00 8:00 9:50 Time (hour) ISA ISA +20°C Weight (lb) 50,000 5,840 9,400 4,940 7,755 46,000 4,219 6,432 40,000 Conditions: 26,985 lb BOW, M 0.74 cruise speed, ISA, zero wind, NBAA Max IFR reserves (200 NM) Payload 3,600 5,234 35,000 3,000 lb 3,465 4,804 Payload Note: Fuel burn figures provided on top of graph are based on 1,000 lb 1,000 lb 3,401 4,535 Payload Zero Payload payload performance computations.

30,000 0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000 4,500 Range (NM) A-5

Challenger 605 Time and Fuel Versus Distance

CHALLENGER 605 TIME AND FUEL VERSUS DISTANCE 4,500 3,700 NM M0.80 Cruise Speed 4,000 4,045 NM 18,105 lb 3,512 NM M0.74 Cruise Speed 18,105 lb 16,820 lb 3,500 3,272 NM 3,000 2,599 NM 14,200 lb 11,980 lb 2,500 2,424 NM 1,685 NM 10,230 lb 2,000 7,570 lb Distance (NM) 1,500 1,577 NM 6,570 lb 771 NM 1,000 Conditions: 26,985 lb BOW, 1,000 3,550 lb lb payload, ISA, zero wind, NBAA 730 NM IFR reserves (200 NM) 3,190 lb 0:00 1:00 2:00 3:00 4:00 5:00 6:00 7:00 8:00 9:00 10:00 11:00 Time (hour) M0.80 Cruise Speed Time 0:00 2:00 4:00 6:00 8:00 8:25 Distance (NM) 0 771 1,685 2,599 3,512 3,701 Fuel (lb) 0 3,550 7,570 11,980 16,820 18,105 M0.74 Cruise Speed Time 0:00 2:00 4:00 6:00 8:00 9:50 Distance (NM) 0 730 1,577 2,424 3,272 4,045 Fuel (lb) 0 3,190 6,570 10,230 14,200 18,105 Conditions: 1,000 lb payload, ISA, zero wind, NBAA IFR reserves (200 NM alternate), 26,985 lb BOW Note: All Challenger 605 performance data are for discussion purposes only. By this document, Bombardier Inc., does not intend to make, and is not making, any offer, commitment, representation or warranty of any kind whatsoever.

All data are subject to change without prior notice.

A-6

Challenger 605 Time and Fuel Versus Distance

CHALLENGER 605 SPECIFIC RANGE 0.240 0.230 0.220 FL 390 0.210 FL 370 FL 350 M 0.74 0.200 Cruise Speed FL 330 M 0.80 Cruise Speed FL 310 0.190 0.180 M 0.82 Cruise Speed Specific Range (NM/lb) 0.170 0.160 Conditions: 40,000 lb mid-cruise weight, zero wind, ISA 0.150 420 430 440 450 460 470 480 490 Speed (KTAS) Plotting of constant FL lines M0.82 M0.80 M0.74 Flight Level 290 Speed Spc Range 310 Speed 481 469 434 Spc Range 0.165 0.178 0.199 330 Speed 477 465 430 Spc Range 0.174 0.188 0.208 350 Speed 473 461 427 Spc Range 0.181 0.197 0.216 370 Speed 470 459 424 Spc Range 0.185 0.204 0.222 390 Speed 459 424 Spc Range 0.205 0.223 Plotting of Long Range Cruise and High Speed Cruise lines FL290 FL310 FL330 FL350 FL370 FL390 M0.74 "X" 434 430 427 424 424 M0.74 "Y" 0.199 0.208 0.216 0.222 0.223 M0.80 "X" 469 465 461 459 459 M0.80 "Y" 0.178 0.188 0.197 0.204 0.205 M0.82 "X" 481 477 473 470 M0.82 "Y" 0.165 0.174 0.181 0.185 Note: Based on 40,000 lb mid-cruise weight, ISA Conditions, zero wind Note: All Challenger 605 performance data are for discussion purposes only. By this document, Bombardier Inc., does not intend to make, and is not making, any offer, commitment, representation or warranty of any kind whatsoever.

All data are subject to change without prior notice.

A-7 A-8

Appendix B

Acronyms, Abbreviations, and

NOTAM Contractions

This is a list of common acronyms and abbreviations used in the aviation industry as well as NOTAM contractions. For a more complete list of contractions used in aviation, see FAA Order JO 7340.2 (as amended). Additional information regarding NOTAMs can be found at pilotweb.nas.faa.gov/PilotWeb/.

ADIN —AUTODIN service A ADIZ —air defense identification zone A/C —aircraft ADJ —adjacent A/FD —airport/facility directory ADL —aeronautical data-link A/G —air to ground ADLY —arrival delay A/HA —altitude/height ADO —airline dispatch office AAF —Army Air Field ADP —automated data processing AAI —arrival aircraft interval ADS —automatic dependent surveillance AAP —advanced automation program ADSIM —airfield delay simulation model AAR —airport acceptance rate ADSY —administrative equipment systems ABDIS —Automated Data Interchange System Service B ADTN —Administrative Data Transmission Network ABN —aerodrome beacon ADTN2000 —Administrative Data Transmission Network ABV —above ACAIS —air carrier activity information system ADVO —administrative voice ACAS —aircraft collision avoidance system ADZD —advised ACC —area control center; Airports Consultants Council AEG —Aircraft Evaluation Group ACCT —accounting records AERA —automated en route air traffic control ACCUM —accumulate AEX —automated execution ACD —Automatic Call Distributor AF —airway facilities ACDO —Air Carrier District Office AFB —Air Force Base ACF —Area Control Facility AFIS —automated flight inspection system ACFO —Aircraft Certification Field Office AFP —area flight plan ACFT —aircraft AFRES —Air Force Reserve Station ACID —aircraft identification AFS —airways facilities sector ACI-NA —Airports Council International-North America AFSFO —AFS field office ACIP —airport capital improvement plan AFSFU —AFS field unit ACLS —automatic carrier landing system AFSOU —AFS field office unit (standard is AFSFOU) ACLT —actual landing time calculated AFSS —automated flight service station ACO —Office of Airports Compliance and Field Operations; AFTN —Automated Fixed Telecommunications Network Aircraft Certification Office AGIS —airports geographic information system ACR —air carrier AGL —above ground level ACRP —Airport Cooperative Research Program AID —airport information desk ACS —Airman Certification Standard AIG —Airbus Industries Group ACT —active, activated, or activity AIM —Airman’s Information Manual ADA —air defense area AlP —airport improvement plan ADAP —Airport Development Aid Program AIRMET —Airmen’s Meteorological Information ADAS —AWOS data acquisition system AIRNET —Airport Network Simulation Model ADCCP —advanced data communications control procedure AIS —aeronautical lnformation service ADDA —administrative data AlT —automated information transfer ADF —automatic direction finding ALP —airport layout plan ADI —automatic de-ice and inhibitor B-1 ALS —approach light system ASP —arrival sequencing program ALSFl —ALS with sequenced flashers I ASPH —asphalt ALSF2 —ALS with sequenced flashers II ASQP —airline service quality performance ALSIP —Approach Lighting System Improvement Plan ASR —airport surveillance radar ALSTG —altimeter setting ASTA —airport surface traffic automation ALT —altitude ASV —airline schedule vendor ALTM —altimeter AT —air traffic ALTN —alternate ATA —Air Transport Association of America ALTNLY —alternately ATAS —airspace and traffic advisory service ALTRV —altitude reservation ATC —air traffic control AMASS —airport movement area safety system ATCAA —air traffic control assigned airspace AMCC —ADF/ARTCC Maintenance Control Center ATCBI —air traffic control beacon indicator AMDT —amendment ATCCC —Air Traffic Control Command Center AMGR —Airport Manager ATCO —Air Taxi Commercial Operator AMOS —Automatic meteorological observing system ATCRB —air traffic control radar beacon AMP —ARINC Message Processor; Airport Master Plan ATCRBS —air traffic control radar beacon system AMVER —automated mutual assistance vessel rescue system ATCSCC —Air Traffic Control System Command Center ANC —alternate network connectivity ATCT —airport traffic control tower ANCA —Airport Noise and Capacity Act ATIS —automatic terminal information service ANG —Air National Guard ATISR —ATIS recorder ANGB —Air National Guard Base ATM —air traffic management; asynchronous transfer mode ANMS —automated network monitoring system ATMS —advanced traffic management system ANSI —American National Standards Group ATN —Aeronautical Telecommunications Network AOA —air operations area ATODN —AUTODIN terminal (FUS) AP —airport; acquisition plan ATOMS —air traffic operations management system APCH —approach ATOVN —AUOTVON (facility) APL —airport lights ATS —air traffic service APP —approach; approach control; Approach Control Office ATSCCP —ATS contingency command post APS —airport planning standard AUTH —authority AQAFO —Aeronautical Quality Assurance Field Office AUTOB —automatic weather reporting system ARAC —Army Radar Approach Control (AAF); Aviation AUTODIN —DoD Automatic Digital Network Rulemaking Advisory Committee AUTOVON —DoD Automatic Voice Network ARCTR —FAA Aeronautical Center or Academy AVBL —available ARF —airport reservation function AVN —Aviation Standards National Field Office, Oklahoma ARFF —aircraft rescue and fire fighting City ARINC —Aeronautical Radio, Inc. AVON —AUTOVON service ARLNO —Airline Office AWlS —airport weather information ARO —Airport Reservation Office AWOS —automatic weather; observing/reporting system ARP —airport reference point AWP —Aviation Weather Processor ARR —arrive; arrival AWPG —aviation weather products generator ARRA —American Recovery and Reinvestment Act of 2009 AWS —air weather station ARSA —airport service radar area AWY —airway ARSR —air route surveillance radar AZM —azimuth ARTCC —air route traffic control center B ARTS —automated radar terminal system ASAS —aviation safety analysis system BA FAIR —braking action fair ASC —AUTODIN switching center BA NIL —braking action nil ASCP —Aviation System Capacity Plan BA POOR —braking action poor ASD —aircraft situation display BANS —BRITE alphanumeric system ASDA —accelerate-stop distance available BART —billing analysis reporting tool (GSA software tool) ASLAR —aircraft surge launch and recovery BASIC —basic contract observing station ASM —available seat mile BASOP —military base operations ASOS —automated surface observing system B-2 BC —back course CERAP —center radar approach control; combined center BCA —benefit/cost analysis radar approach control BCN —beacon CESA —Class E surface area BCR —benefit/cost ratio CFC —central flow control BDAT —digitized beacon data CFCF —Central Flow Control Facility BERM —snowbank(s) containing earth/gravel CFCS —central flow control service BLW —below CFR —Code of Federal Regulations BMP —best management practices CFWP —central flow weather processor BND —bound CFWU —central flow weather unit BOC —Bell Operating Company CGAS —Class G Airspace; Coast Guard Air Station bps —bits per second CHG —change BRG —bearing CIG —ceiling BRI —basic rate interface CK —check BRITE —bright radar indicator terminal equipment CL —centerline BRL —building restriction line CLC —course line computer BUEC —back-up emergency communications CLIN —contract line item BUECE —back-up emergency communications equipment CLKWS —clockwise BYD —beyond CLR —clearance, clear(s), cleared to CLSD —closed C CLT —calculated landing time CM —commercial service airport C/S/S/N —capacity/safety/security/noise CMB —climb CAA —civil aviation authority; Clean Air Act CMSND —commissioned CAAS —Class A Airspace CNL —cancel CAB —civil aeronautics board CNMPS —Canadian Minimum Navigation Performance CARF —Central Altitude Reservation Facility Specification Airspace CASFO —Civil Aviation Security Office CNS —consolidated NOTAM system CAT —category; clear-air turbulence CNSP —consolidated NOTAM system processor CAU —Crypto Ancillary Unit CO —central office CBAS —Class B airspace COE —U.S. Army Corps of Engineers CBI —computer based instruction COM —communications CBSA —Class B surface area COMCO —command communications outlet CC&O —customer cost and obligation CONC —concrete CCAS —Class C Airspace CONUS —Continental United States CCC —Communications Command Center CORP —private corporation other than ARINC or MITRE CCCC —staff communications CPD —coupled CCCH —central computer complex host CPE —customer premise equipment CCLKWS —counterclockwise CPMIS —consolidated personnel management information CCS7-NI —Communication Channel Signal-7-Network system Interconnect CRA —conflict resolution advisory CCSA —Class C surface area CRDA —converging runway display aid CCSD —Command Communications Service Designator CRS —course CCU —Central Control Unit CRT —cathode ray tube CD —clearance delivery; common digitizer CSA —communications service authorization CDAS —Class D Airspace CSIS —centralized storm information system CDR —cost detail report CSO —customer service office CDSA —Class D surface area CSR —communications service request CDT —controlled departure time CSS —central site system CDTI —cockpit display of traffic information CTA —controlled time of arrival; control area CEAS —Class E Airspace CTA/FIR —control area/flight information region CENTX —central telephone exchange CTAF —common traffic advisory frequency CEP —capacity enhancement program CTAS —center-TRACON automation system CEQ —council on environmental quality B-3 CTC —contact DLA —delay or delayed CTL —control DLT —delete CTMA —Center Traffic Management Advisor DLY —daily CUPS —consolidated uniform payroll system DME —distance measuring equipment CVFR —controlled visual flight rules DME/P —precision distance measuring equipment CVTS —compressed video transmission service DMN —Data Multiplexing Network CW —continuous wave DMSTN —demonstration CWSU —Central Weather Service Unit DNL —day-night equivalent sound level (also called Ldn) CWY —clearway DOD —direct outward dial DoD —Department of Defense D DOI —Department of Interior DOS —Department of State DA —direct access; decision altitude/decision height; DOT —Department of Transportation Descent Advisor DOTCC —Department of Transportation Computer Center DABBS —DITCO automated bulletin board system DOTS —dynamic ocean tracking system DAIR —direct altitude and identity readout DP —dew point temperature DALGT —daylight DRFT —snowbank(s) caused by wind action DAR —Designated Agency Representative DSCS —digital satellite compression service DARC —direct access radar channel DSPLCD —displaced dBA —decibels A-weighted DSUA —dynamic special use airspace DBCRC —Defense Base Closure and Realignment DTS —dedicated transmission service Commission DUAT —direct user access terminal DBE —disadvantaged business enterprise DVFR —defense visual flight rules; day visual flight rules DBMS —database management system DVOR —doppler very high frequency omni-directional range DBRITE —digital bright radar indicator tower equipment DYSIM —dynamic simulator DCA —Defense Communications Agency DCAA —dual call, automatic answer device E DCCU —Data Communications Control Unit DCE —data communications equipment E —east EA —environmental assessment DCMSND —decommissioned DCT —direct EARTS —en route automated radar tracking system EB —eastbound DDA —dedicated digital access DDD —direct distance dialing ECOM —en route communications ECVFP —expanded charted visual flight procedures DDM —difference in depth of modulation DDS —Digital Data Service EDCT —expedite departure path EFC —expect further clearance DEA —Drug Enforcement Agency DEDS —data entry and display system EFIS —electronic flight information systems EIAF —expanded inward access features DEGS —degrees DEIS —Draft Environmental Impact Statement EIS —environmental impact statement ELEV —elevation DEP —depart/departure DEPPROC —departure procedures ELT —emergency locator transmitter ELWRT —electrowriter DEWIZ —distance early warning identification zone DF —direction finder EMAS —engineered materials arresting system EMPS —en route maintenance processor system DFAX —digital facsimile DFI —direction finding indicator EMS —environmental management system E-MSAW —en route automated minimum safe altitude DGPS —Differential Global Positioning Satellite (System) DH —decision height warning ENAV —en route navigational aids DID —direct inward dial DIP —drop and insert point ENG —engine ENRT —en route DIRF —direction finding DISABLD —disabled ENTR —entire EOF —emergency Operating Facility DIST —distance DITCO —Defense Information Technology Contracting EPA —Environmental Protection Agency EPS —Engineered Performance Standards Office Agency B-4 EPSS —enhanced packet switched service FIG —flight inspection group ERAD —en route broadband radar FINO —Flight Inspection National Field Office ESEC —en route broadband secondary radar FIPS —federal information publication standard ESF —extended superframe format FIR —flight information region ESP —en route spacing program FIRE —fire station ESYS —en route equipment systems FIRMR —Federal Information Resource Management ETA —estimated time of arrival Regulation ETE —estimated time en route FL —flight level ETG —enhanced target generator FLOWSIM —traffic flow planning simulation ETMS —enhanced traffic management system FM —from ETN —Electronic Telecommunications Network FMA —final monitor aid EVAS —enhanced vortex advisory system FMF —facility master file EVCS —emergency voice communications system FMIS —FTS2000 management information system EXC —except FMS —flight management system FNA —final approach F FNMS —FTS2000 network management system FOIA —Freedom Of Information Act F&E— facility and equipment FONSI —finding of no significant impact FAA —Federal Aviation Administration FP —flight plan FAAAC —FAA aeronautical center FPM —feet per minute FAACIS —FAA communications information system FRC —request full route clearance FAATC —FAA technical center FREQ —frequency FAATSAT —FAA telecommunications satellite FRH —fly runway heading FAC —facility/facilities FRI —Friday FAF —final approach fix FRZN —frozen FAN —MKR fan marker FSAS —flight service automation system FAP —final approach point FSDO —Flight Standards District Office FAPM —FTS2000 associate program manager FSDPS —flight service data processing system FAR —Federal Aviation Regulation FSEP —facility/service/equipment profile FAST —final approach spacing tool FSP —flight strip printer FAX —facsimile equipment FSPD —freeze speed parameter FBO —fixed base operator FSS —flight service station FBS —fall back switch FSSA —flight service station automated service FCC —Federal Communications Commission FSTS —federal secure telephone service FCLT —freeze calculated landing time FSYS —flight service station equipment systems FCOM —FSS radio voice communications FTS —federal telecommunications system FCPU —Facility Central Processing Unit FT —feet/foot FDAT —flight data entry and printout (FDEP) and flight FTS2000 —Federal Telecommunications System 2000 data service FUS —functional units or systems FDC —flight data center FWCS —flight watch control station FDE —flight data entry FDEP —flight data entry and printout G FDIO —flight data input/output FDIOC —flight data input/output center GA —general aviation FDIOR —flight data input/output remote GAA —general aviation activity FDM —frequency division multiplexing GAAA —general aviation activity and avionics FDP —flight data processing GADO —General Aviation District Office FED —federal GC —ground control FEIS —Final Environmental Impact Statement GCA —ground control approach FEP —front end processor GIS —geographic information system FFAC —from facility GNAS —general national airspace system FI/P —flight inspection permanent GNSS —global navigation satellite system FI/T —flight inspection temporary GOES —Geostationary Operational Environmental Satellite FIFO —Flight Inspection Field Office GOESF —GOES feed point B-5 GOEST —GOES terminal equipment ID —identification GOVT —government IDAT —interfacility data GP —glide path IDENT —identify/identifier/identification GPRA —Government Performance Results Act IF —intermediate fix GPS —global positioning system IFCP —interfacility communications processor GPWS —ground proximity warning system IFDS —interfacility data system GRADE —graphical airspace design environment IFEA —in-flight emergency assistance GRVL —gravel IFO —International Field Office GS —glide slope indicator IFR —instrument flight rules GSA —General Services Administration IFSS —international flight service station GSE —ground support equipment ILS —instrument landing system IM —inner marker IMC —instrument meteorological conditions H IN —inch/inches H —non-directional radio homing beacon (NDB) INBD —inbound HAA —height above airport INDEFLY —indefinitely HAL —height above landing INFO —information HARS —high altitude route system INM —integrated noise model HAT —height above touchdown INOP —inoperative HAZMAT —hazardous materials INS —inertial navigation system HCAP —high capacity carriers INSTR —instrument HDG —heading INT —intersection HDME —NDB with distance measuring equipment INTL —international HDQ —FAA headquarters INTST —intensity HEL —helicopter IR —ice on runway(s) HELI —heliport IRMP —information resources management plan HF —high frequency ISDN —integrated services digital network HH —NDB, 2kw or more ISMLS —interim standard microwave landing system HI-EFAS —high altitude EFAS ITI —interactive terminal interface HIRL —high intensity runway lights IVRS —interim voice response system HIWAS —Hazardous lnflight Weather Advisory Service IW —inside wiring HLDC —high level data link control HLDG —holding K HOL —holiday Kbps —Kilobits per second HOV —high occupancy vehicle Khz —Kilohertz HP —holding pattern KT —knots HR —hour KVDT —keyboard video display terminal HSI —horizontal situation indicators HUD —housing and urban development L HWAS —hazardous in-flight weather advisory L —left Hz —Hertz LAA —local airport advisory LAAS —low altitude alert system I LABS —leased A B service I/AFSS —international AFSS LABSC —LABS GS-200 computer IA —indirect access LABSR —LABS remote equipment IAF —initial approach fix LABSW —LABS switch system IAP —instrument approach procedures LAHSO —land and hold short operation IAPA —instrument approach procedures automation LAN —local area network IBM —International Business Machines LAT —latitude IBP —international boundary point LATA —local access and transport area IBR —intermediate bit rate LAWRS —limited aviation weather reporting station ICAO —International Civil Aviation Organization LB —pound/pounds ICSS —international communications switching systems B-6 LC —local control MED —medium LCF —local control facility METI —meteorological information LCN —local communications network MF —middle frequency LCTD —located MFJ —modified final judgment LDA —localizer-type directional aid; landing directional aid MFT —meter fix crossing time/slot time LDG —landing MHA —minimum holding altitude LDIN —lead-in lights Mhg —Meghertz LEC —local exchange carrier MIA —minimum IFR altitudes LF —low frequency MIDO —Manufacturing Inspection District Office LGT —light or lighting MIN —minute LGTD —lighted MIRL —medium intensity runway lights LINCS —leased interfacility NAS C MIS —Meteorological Impact Statement LIRL —low intensity runway lights MISC —miscellaneous LIS —logistics and inventory system MISO —Manufacturing Inspection Satellite Office LLWAS —low level wind shear alert system MIT —miles in trail LLZ —localizer MITRE —Mitre Corporation LM —compass locator at ILS middle marker MLS —microwave landing system LM/MS —low/medium frequency MM —middle marker LMM —locator middle marker MMAC —Mike Monroney Aeronautical Center LO —compass locator at ILS outer marker MMC —maintenance monitoring console LOC —local; locally; location; localizer MMS —maintenance monitoring system LOCID —location identifier MNM —minimum LOI —letter of intent MNPS —minimum navigation performance specification LOM —compass locator at outer marker MNPSA —minimum navigation performance specifications LONG —longitude airspace LPV —lateral precision performance with vertical guidance MNT —monitor; monitoring; monitored LRCO —limited remote communications outlet MOA —memorandum of agreement; military operations area LRNAV —long range navigation MOC —minimum obstruction clearance LRR —long range radar MOCA —minimum obstruction clearance altitude LSR —loose snow on runway(s) MODE C —altitude-encoded beacon reply; altitude reporting LT —left turn mode of secondary radar MODE S —mode select beacon system MON —Monday M MOU —memorandum of understanding MAA —maximum authorized altitude MPO —Metropolitan Planning Organization MAG —magnetic MPS —maintenance processor subsystem or master plan MAINT —maintain, maintenance supplement MALS —medium intensity approach light system MRA —minimum reception altitude MALSF —medium intensity approach light system with MRC —monthly recurring charge sequenced flashers MSA —minimum safe altitude; minimum sector altitude MALSR —medium intensity approach light system with MSAW —minimum safe altitude warning runway alignment indicator lights MSG —message MAP —maintenance automation program; military airport MSL —mean sea level program; missed approach point; modified access pricing MSN —message switching network MAPT —missed approach point MTCS —modular terminal communications system Mbps —megabits per second MTI —moving target indicator MCA —minimum crossing altitude MU —mu meters MCAS —Marine Corps air station MUD —mud MCC —maintenance control center MUNI —municipal MCL —middle compass locater MUX —multiplexor MCS —maintenance and control system MVA —minimum vectoring altitude MDA —minimum descent altitude MVFR —marginal visual flight rules MDT —maintenance data terminal MEA —minimum en route altitude B-7 NPIAS —national plan of integrated airport systems N NR —number N —north NRC —non-recurring charge NA —not authorized NRCS —national radio communications systems NAAQS —national ambient air quality standards NSAP —National Service Assurance Plan NADA —ADIN concentrator NSRCATN —National Strategy to Reduce Congestion on NADIN —National Airspace Data Interchange Network America’s Transportation Network NADSW —NADIN switches NSSFC —National Severe Storms Forecast Center NAILS —National Airspace Integrated Logistics Support NSSL —National Severe Storms Laboratory, Norman, OK NAMS —NADIN IA NSWRH —NWS Regional Headquarters NAPRS —National Airspace Performance Reporting System NTAP —Notices To Airmen Publication NAS —National Airspace System or Naval Air Station NTP —National Transportation Policy NASDC —National Aviation Safety Data NTSB —National Transportation Safety Board NASP —National Airspace System Plan NTZ —no transgression zone NASPAC —National Airspace System Performance Analysis NW —northwest Capability NWS —National Weather Service NATCO —National Communications Switching Center NWSR —NWS weather excluding NXRD NAV —navigation NXRD —advanced weather radar system NAVAID —navigation aid NAVMN —navigation monitor and control O NAWAU —National Aviation Weather Advisory Unit OAG —official airline guide NAWPF —National Aviation Weather Processing Facility OALT —operational acceptable level of traffic NB —northbound OAW —off-airway weather station NCAR —National Center for Atmospheric Research, OBSC —obscured Boulder, CO OBST —obstruction NCF —National Control Facility ODAL —omnidirectional approach lighting system NCIU —NEXRAD Communications Interface Unit ODAPS —oceanic display and processing station NCP —noise compatibility program OEP —operational evolution plan/partnership NCS —national communications system OFA —object free area NDB —non-directional radio beacon OFDPS —offshore flight data processing system NDNB —NADIN II OFT —outer fix time NE —northeast OFZ —obstacle free zone NEM —noise exposure map OM —outer marker NEPA —National Environmental Policy Act OMB —Office Of Management and Budget NEXRAD —next generation weather radar ONER —Oceanic Navigational Error Report NFAX —National Facsimile Service OPLT —operational acceptable level of traffic NFDC —National Flight Data Center OPR —operate NFIS —NAS Facilities Information System OPS —operation NGT —night OPSW —operational switch NI —network interface OPX —off premises exchange NICS —national interfacility communications system ORD —operational readiness demonstration NM —nautical mile(s) ORIG —original NMAC —near mid-air collision OTR —oceanic transition route NMC —National Meteorological Center OTS —out of service; organized track system NMCE —network monitoring and control equipment OVR —over NMCS —network monitoring and control system NMR —nautical mile radius P NOAA —National Oceanic and Atmospheric Administration NOC —notice of completion PABX —private automated branch exchange NONSTD —nonstandard PAD —packet assembler/disassembler NOPT —no procedure turn required PAEW —personnel and equipment working NOTAM —notice to airmen PAM —peripheral adapter module NPDES —National pollutant discharge elimination system PAPI —precision approach path indicator NPE —non-primary airport entitlement PAR —precision approach radar; preferential arrival route B-8 PARL —parallel R PAT —pattern RAIL —runway alignment indicator lights PATWAS —Pilots Automatic Telephone Weather Answering RAMOS —remote automatic meteorological observing Service system PAX —passenger RAPCO —radar approach control (USAF) PBCT —proposed boundary crossing time RAPCON —radar approach control (FAA) PBRF —pilot briefing RATCC —Radar Air Traffic Control Center PBX —private branch exchange RATCF —Radar Air Traffic Control Facility (USN) PCA —positive control airspace RBC —rotating beam ceilometer PCL —pilot controlled lighting RBDPE —radar beacon data processing equipment PCM —pulse code modulation RBSS —Radar Bomb Scoring Squadron PD —Pilot Deviation RCAG —remote communications air/ground facility PDAR —preferential arrival and departure route RCC —Rescue Coordination Center PDC —pre-departure clearance; program designator code RCCC —Regional Communications Control Centers PDN —Public Data Network RCF —Remote Communication Facility PDR —preferential departure route RCIU — Remote Control Interface Unit PERM —permanent/permanently RCL — runway centerline; radio communications link PFC —passenger facility charge RCLL —runway centerline light system PGP —planning grant program RCLR —RCL repeater PIC —principal interexchange carrier RCLT —RCL terminal PIDP —programmable indicator data processor RCO —remote communications outlet PIREP —pilot weather report RCU —remote control unit PJE —parachute jumping exercise RDAT —digitized radar data PLA —practice low approach RDP —radar data processing PLW —plow/plowed RDSIM —runway delay simulation model PMS —program management system REC —receive/receiver PNR —prior notice required REIL —runway end identifier lights POLIC —police station RELCTD —relocated POP —point of presence REP —report POT —point of termination RF —radio frequency PPIMS —personal property information management system RL —General Aviation Reliever Airport PPR —prior permission required RLLS —runway lead-in lights system PR —primary commercial service airport RMCC —Remote Monitor Control Center PREV —previous RMCF —Remote Monitor Control Facility PRI —primary rate interface RML —radio microwave link PRM —precision runway monitor RMLR —RML repeater PRN —pseudo random noise RMLT —RML terminal PROC —procedure RMM —remote maintenance monitoring PROP —propeller RMMS —remote maintenance monitoring system PSDN —public switched data network RMNDR —remainder PSN —packet switched network RMS —remote monitoring subsystem PSR —packed snow on runway(s) RMSC —remote monitoring subsystem concentrator PSS —packet switched service RNAV —area navigation PSTN —public switched telephone network RNP —required navigation performance PTC —presumed-to-conform ROD —record of decision PTCHY —patchy ROSA —report of service activity PTN —procedure turn ROT —runway occupancy time PUB —publication RP —restoration priority PUP —principal user processor RPC —restoration priority code PVC —permanent virtual circuit RPG —radar processing group PVD —plan view display RPLC —replace PVT —private B-9 RPZ —runway protection zone SD-ROB —radar weather report RQRD —required SDS —switched data service RRH —remote reading hygrothermometer SE —southeast RRHS —remote reading hydrometer SEL —single event level RRL —runway remaining lights SELF —simplified short approach lighting system with RRWDS —remote radar weather display sequenced flashing lights RRWSS —RWDS sensor site SFAR-38 —Special Federal Aviation Regulation 38 RSA —runway safety area SFL —sequence flashing lights RSAT —runway safety action team SHPO —State Historic Preservation Officer RSR —en route surveillance radar SIC —service initiation charge RSS —remote speaking system SID — standard instrument departure; station identifier RSVN —reservation SIGMET —significant meteorological information RT —right turn; remote transmitter SIMMOD —airport and airspace simulation model RT & BTL —radar tracking and beacon tracking level SIMUL —simultaneous RTAD —remote tower alphanumerics display SIP —state implementation plan RTCA —Radio Technical Commission for Aeronautics SIR —packed or compacted snow and ice on runway(s) RTE —route SKED —scheduled RTP —regional transportation plan SLR —slush on runway(s) RTR —remote transmitter/receiver SM —statute miles RTRD —remote tower radar display SMGC —surface movement guidance and control RTS —return to service SMPS —sector maintenance processor subsystem RUF —rough SMS —safety management system; simulation modeling RVR —runway visual range system RVRM —runway visual range midpoint SN —snow RVRR —runway visual range rollout SNBNK —snowbank(s) caused by plowing RVRT —runway visual range touchdown SNGL —single RW —runway SNR —signal-to-noise ratio, also: S/N RWDS —same as RRWDS SOAR —system of airports reporting RWP —real-time weather processor SOC —service oversight center RWY —runway SOIR —simultaneous operations on intersecting runways SOIWR —simultaneous operations on intersecting wet S runways SPD —speed S —south SRAP —sensor receiver and processor S/S —sector suite SSALF —simplified short approach lighting system with SA —sand, sanded sequenced flashers SAC —Strategic Air Command SSALR —simplified short approach lighting system with SAFI —semi-automatic flight inspection runway alignment indicator lights SALS —short approach lighting system SSALS —simplified short approach lighting system SAT —Saturday SSB —single side band SATCOM —satellite communications SSR —secondary surveillance radar SAWR —Supplementary Aviation Weather Reporting Station STA —straight-in approach SAWRS —Supplementary Aviation Weather Reporting STAR —standard terminal arrival route System STD —standard SB —southbound STMUX —statistical data multiplexer SBGP —state block grant program STOL —short takeoff and landing SCC —System Command Center SUN —Sunday SCVTS —Switched Compressed Video Telecommunications SURPIC —surface picture Service SVC —service SDF —simplified directional facility; simplified direction SVCA —service A finding; software defined network SVCB —service B SDIS —switched digital integrated service SVCC —service C SDP —service delivery point B-10 SVCO —service O TIMS —telecommunications information management system SVFB —interphone service F (B) TIPS —terminal information processing system SVFC —interphone service F (C) TKOF —takeoff SVFD —interphone service F (D) TL —taxilane SVFO —interphone service F (A) TM —traffic management SVFR —special visual flight rules TM&O —telecommunications management and operations SW —southwest TMA —Traffic Management Advisor SWEPT —swept or broom/broomed TMC —Traffic Management Coordinator TMC/MC —Traffic Management Coordinator/Military T Coordinator TMCC —terminal information processing system; Traffic T —temperature Management Computer Complex T1MUX —T1 multiplexer TMF —Traffic Management Facility TAA —terminal arrival area TML —television microwave link TAAS —terminal advance automation system TMLI —television microwave link indicator TACAN —tactical air navigation TMLR —television microwave link repeater TACR —TACAN at VOR, TACAN only TMLT —television microwave link terminal TAF —terminal area forecast TMP —Traffic Management Processor TAR —terminal area surveillance radar TMPA —traffic management program alert TARS —terminal automated radar service TMS —traffic management system TAS —true air speed TMSPS —traffic management specialists TATCA —terminal air traffic control automation TMU —traffic management unit TAVT —terminal airspace visualization tool TNAV —terminal navigational aids TCA —traffic control airport or tower control airport; TODA —takeoff distance available terminal control area TOF —time of flight TCACCIS —Transportation Coordinator Automated TOFMS —time of flight mass spectrometer Command And Control Information System TOPS —Telecommunications Ordering And Pricing System TCAS —Traffic Alert and Collision Avoidance System (GSA software tool) TCC —DOT Transportation Computer Center TORA —take-off run available TCCC —Tower Control Computer Complex TR —telecommunications request TCE —tone control equipment TRACAB —terminal radar approach control in tower cab TCLT —tentative calculated landing time TRACON —Terminal Radar Approach Control Facility TCO —Telecommunications Certification Officer TRAD —terminal radar service TCOM —Terminal Communications TRB —Transportation Research Board TCS —tower communications system TRML —terminal TDLS —Tower Data-Link Services TRNG —training TDMUX —time division data multiplexer TRSN —transition TDWR —terminal doppler weather radar TSA —taxiway safety area; Transportation Security TDZ —touchdown zone Administration TDZ LG —touchdown zone lights TSEC —terminal secondary radar service TELCO —telephone company TSNT —transient TELMS —telecommunications management system TSP —telecommunications service priority TEMPO —temporary TSR —telecommunications service request TERPS —terminal instrument procedures TSYS —terminal equipment systems TFAC —to facility TTMA —TRACON Traffic Management Advisor TFC —traffic TTY —teletype TFR —temporary flight restriction TUE —Tuesday TGL —touch-and-go landings TVOR —terminal VHF omnidirectional range TH —threshold TW —taxiway THN —thin TWEB —transcribed weather broadcast THR —threshold TWR —tower THRU —through TWY —taxiway THU —Thursday TY —type (FAACIS) TIL —until B-11 U W UAS —unmanned aircraft systems W —west UFN —until further notice WAAS —Wide Area Augmentation System UHF —ultra high frequency WAN —wide area network UNAVBL —unavailable WB —westbound UNLGTD —unlighted WC —work center UNMKD —unmarked WCP —Weather Communications Processor UNMNT —unmonitored WECO —Western Electric Company UNREL —unreliable WED —Wednesday UNUSBL —unusable WEF —with effect from; effective from URA —Uniform Relocation Assistance and Real Property WESCOM —Western Electric Satellite Communications Acquisition Policies Act of 1970 WI —within USAF —United States Air Force WIE —with immediate effect, or effective immediately USC —United States Code WKDAYS —Monday through Friday USOC —Uniform Service Order Code WKEND —Saturday and Sunday WMSC —Weather Message Switching Center V WMSCR —Weather Message Switching Center Replacement WND —wind V/PD —Vehicle/pedestrian deviation WPT —waypoint VALE —voluntary airport low emission WSCMO —Weather Service Contract Meteorological VASI —visual approach slope indicator Observatory VDME —VOR with distance measuring equipment WSFO —Weather Service Forecast Office VDP —visual descent point WSMO —Weather Service Meteorological Observatory VF —voice frequency WSO —Weather Service Office VFR —visual flight rules WSR —wet snow on runway(s) VGSI —visual glide slope indicator WTHR —weather VHF —very high frequency WTR —water on runway(s) VIA —by way of WX —weather VICE —instead/versus VIS —visibility VLF —very low frequency VMC —visual meteorological conditions VNAV —visual navigational aids VNTSC —Volpe National Transportation System Center VOL —volume VON —virtual on-net VOR —VHF omnidirectional range VOR/DME —VHF omnidirectional range/distance measuring equipment VORTAC —VOR and TACAN (collocated) VOT —VOR Test Facility VP/D —vehicle/pedestrian deviation VRS —voice recording system VSCS —voice switching and control system VTA —vertex time of arrival VTAC —VOR and TACAN (collocated) VTOL —vertical takeoff and landing VTS —voice telecommunications system B-12

Appendix C

Airport Signs and Markings

Airport Signs Type of Sign Action or Purpose Action or Purpose Type of Sign Runway Safety Area Boundary: Taxiway/Runway Hold Position: Identifies exit boundary of runway

A

4-22 Holding position for RWY 4-22 on TWY A.

safety area.

Runway/Runway Intersection: ILS Critical Area Boundary: Identifies intersecting runways or

26-8

Identifies exit boundary of ILS critical area.

holding position for LAHSO operations.

Runway Approach Hold Position: Taxiway Direction: Runway approach holding position for Defines direction and designation of

B

8-APCH

J

RWY 8 on TWY B. intersecting taxiway(s).

ILS Critical Area Hold Position: Runway Exit: Holding position for the ILS critical area Defines direction and designation of exit

C

ILS

K

on TWY C. taxiway from runway.

No Entry: Outbound Destination: Identifies paved areas where aircraft entry is Defines directions to takeoff runway(s).

prohibited.

Inbound Destination: Taxiway Location: Defines directions to destination for B MIL Identifies taxiway on which aircraft is located.

arriving aircraft.

Runway Location: Taxiway Ending Marker: 22 Identifies runway on which aircraft is located. Indicates taxiway does not continue.

Runway Distance Remaining: Direction Sign Array: Identifies location in conjunction with Provides remaining runway length in 1,000

A L G

foot increments. multiple intersecting taxiways.

Figure C-1. Samples and explanations of standard airport signs.

C-1

1 7

15-APCH D

3a

D

1 8

A1

A2

1 1 1 9 1 8

15 A1

15-33 A2

A 2

A D 2a

3a 12 10

D

15-APCH

ILS

D

A1

A

A

13 11 Figure C-2. A sample runway with various possible markings and signs.

C-2

1 Taxiway location sign Runway holding position sign at takeoff end 2a Runway holding position sign at other than takeoff end 3 Runway holding position marking Holding position marking for runway approach area 3a

33-15

Elevated runway guard lights Surface painted runway hold position sign Enhanced centerline marking (located 150' prior to runway hold position marking) Holding position sign for a runway approach area

33-15

Runway safety area boundary sign (located on the backside of holding position sign) Taxiway direction sign 9 Surface painted destination sign Holding position sign for ILS critical area Surface painted ILS critical area boundary marking 12 ILS critical area boundary sign (located on backside of ILS hold sign) Blast pad 14 Runway holding position sign and marking for Land and Hold Short Operations (LAHSO) Runway hold position sign for intersecting runways

A2

Outbound destination sign

15-33 A2

15-33

A 4 2a

15-33

A

18-36

2a 3 6 2a

A2

36-18

A 1

A

C-3

Airport Markings Action or Purpose Type of Marking Type of Marking Holding Position: Denotes entrance to a runway from a NON-USEABLE NON-USEABLE taxiway, approach hold position on a taxiway, or LAHSO holding position on a runway.

ILS Critical Area Boundary: Denotes entrance to an area to be protected for an ILS signal.

Taxiway/Taxiway Holding Position: Denotes location on taxiway or apron Taxi direction Action or Purpose where aircraft hold short of another taxiway.

Taxiway Edge: Solid Double Yellow Lines Defines edge of usable, full strength taxiway. Adjoining Non-Movement Area Boundary: pavement IS NOT intended for use by aircraft.

Delineates movement area under control of ATC, from non-movement area.

Type of Marking Surface Painted Holding Position: Denotes entrance to a runway from a USEABLE USEABLE

4-22 4-22

taxiway.

Enhanced Taxiway Centerline: Provides visual cue to help identify location of a runway holding position on a taxiway. These markings are installed 150 feet prior to the holding position markings.

Taxi direction Surface Painted Taxiway Direction: Defines designation/direction of

T

Action or Purpose intersecting taxiway(s).

Taxiway Edge: Dashed Double Yellow Lines Surface Painted Taxiway Location: Defines taxiway edge where adjoining pavement Identifies taxiway on which the B IS USABLE , such as along an apron or ramp.

aircraft is located.

Figure C-3. Samples and explanations of standard airport markings.

C-4

Glossary

ADC. See air data computer.

A 14 CFR. See Title 14 of the Code of Federal Regulations.

ADF. See automatic direction finder.

100-hour inspection. An inspection identical in scope to ADI. See attitude director indicator.

an annual inspection. Conducted every 100 hours of flight on aircraft of under 12,500 pounds that are used to carry Adiabatic cooling. A process of cooling the air through passengers for hire.

expansion. For example, as air moves up slope it expands with the reduction of atmospheric pressure and cools as it expands.

Absolute accuracy. The ability to determine present position in space independently, and is most often used by pilots.

Adiabatic heating. A process of heating dry air through compression. For example, as air moves down a slope it is Absolute altitude. The actual distance between an aircraft compressed, which results in an increase in temperature.

and the terrain over which it is flying.

Adjustable-pitch propeller. A propeller with blades whose Absolute pressure. Pressure measured from the reference pitch can be adjusted on the ground with the engine not of zero pressure, or a vacuum.

running, but which cannot be adjusted in flight. Also referred to as a ground adjustable propeller. Sometimes also used to A.C. Alternating current.

refer to constant-speed propellers that are adjustable in flight.

Acceleration. Force involved in overcoming inertia, and Adjustable stabilizer. A stabilizer that can be adjusted in which may be defined as a change in velocity per unit of time.

flight to trim the airplane, thereby allowing the airplane to fly hands-off at any given airspeed.

Acceleration error. A magnetic compass error apparent when the aircraft accelerates while flying on an easterly or westerly ADM. See aeronautical decision-making.

heading, causing the compass card to rotate toward North.

ADS-B. See automatic dependent surveillance-broadcast.

Accelerate-go distance. The distance required to accelerate to V with all engines at takeoff power, experience an engine Advection fog. Fog resulting from the movement of warm, failure at V , and continue the takeoff on the remaining humid air over a cold surface.

engine(s). The runway required includes the distance required to climb to 35 feet by which time V speed must be attained.

Adverse yaw. A condition of flight in which the nose of an airplane tends to yaw toward the outside of the turn. This is Accelerate-stop distance. The distance required to accelerate caused by the higher induced drag on the outside wing, which to V with all engines at takeoff power, experience an engine is also producing more lift. Induced drag is a by-product of failure at V , and abort the takeoff and bring the airplane to the lift associated with the outside wing.

a stop using braking action only (use of thrust reversing is not considered).

Aerodynamics. The science of the action of air on an object, and with the motion of air on other gases. Aerodynamics Accelerometer. A part of an inertial navigation system deals with the production of lift by the aircraft, the relative (INS) that accurately measures the force of acceleration in wind, and the atmosphere.

one direction.

G-1 Aeronautical chart. A map used in air navigation containing Airplane Flight Manual (AFM). A document developed all or part of the following: topographic features, hazards and by the airplane manufacturer and approved by the Federal obstructions, navigation aids, navigation routes, designated Aviation Administration (FAA). It is specific to a particular airspace, and airports. make and model airplane by serial number and it contains operating procedures and limitations.

Aeronautical decision-making (ADM). A systematic approach to the mental process used by pilots to consistently Airplane Owner/Information Manual. A document determine the best course of action in response to a given developed by the airplane manufacturer containing general set of circumstances. information about the make and model of an airplane. The airplane owner’s manual is not FAA approved and is not Agonic line. An irregular imaginary line across the surface of specific to a particular serial numbered airplane. This manual the Earth along which the magnetic and geographic poles are is not kept current, and therefore cannot be substituted for in alignment, and along which there is no magnetic variation. the AFM/POH.

Ailerons. Primary flight control surfaces mounted on the Airport diagram. The section of an instrument approach trailing edge of an airplane wing, near the tip. Ailerons control procedure chart that shows a detailed diagram of the roll about the longitudinal axis. airport. This diagram includes surface features and airport configuration information.

Aircraft. A device that is used, or intended to be used, for flight. Airport/Facility Directory (A/FD). See Chart Supplement U.S.

Aircraft altitude. The actual height above sea level at which the aircraft is flying. Airport surface detection equipment (ASDE). Radar equipment specifically designed to detect all principal Aircraft approach category. A performance grouping of features and traffic on the surface of an airport, presenting the aircraft based on a speed of 1.3 times the stall speed in the entire image on the control tower console; used to augment landing configuration at maximum gross landing weight. visual observation by tower personnel of aircraft and/or vehicular movements on runways and taxiways.

Air data computer (ADC). An aircraft computer that receives and processes pitot pressure, static pressure, and Airport surveillance radar (ASR). Approach control temperature to calculate very precise altitude, indicated radar used to detect and display an aircraft’s position in the airspeed, true airspeed, and air temperature. terminal area.

Airfoil. Any surface, such as a wing, propeller, rudder, or Airport surveillance radar approach. An instrument even a trim tab, which provides aerodynamic force when it approach in which ATC issues instructions for pilot interacts with a moving stream of air. compliance based on aircraft position in relation to the final approach course and the distance from the end of the runway Air mass. An extensive body of air having fairly uniform as displayed on the controller’s radar scope.

properties of temperature and moisture.

Air route surveillance radar (ARSR). Air route traffic AIRMET. Inflight weather advisory issued as an amendment control center (ARTCC) radar used primarily to detect to the area forecast, concerning weather phenomena of and display an aircraft’s position while en route between operational interest to all aircraft and that is potentially terminal areas.

hazardous to aircraft with limited capability due to lack of equipment, instrumentation, or pilot qualifications. Air route traffic control center (ARTCC). Provides ATC service to aircraft operating on IFR flight plans within Airplane. An engine-driven, fixed-wing aircraft heavier than controlled airspace and principally during the en route phase air that is supported in flight by the dynamic reaction of air of flight.

against its wings.

Airspeed. Rate of the aircraft’s progress through the air.

G-2 Airspeed indicator. A differential pressure gauge that Alternate static source valve. A valve in the instrument static measures the dynamic pressure of the air through which the air system that supplies reference air pressure to the altimeter, aircraft is flying. Displays the craft’s airspeed, typically in airspeed indicator, and vertical speed indicator if the normal knots, to the pilot. static pickup should become clogged or iced over.

Air traffic control radar beacon system (ATCRBS). Altimeter. A flight instrument that indicates altitude by Sometimes called secondary surveillance radar (SSR), which sensing pressure changes.

utilizes a transponder in the aircraft. The ground equipment is an interrogating unit, in which the beacon antenna is mounted Altimeter setting. Station pressure (the barometric pressure so it rotates with the surveillance antenna. The interrogating at the location the reading is taken) which has been corrected unit transmits a coded pulse sequence that actuates the aircraft for the height of the station above sea level.

transponder. The transponder answers the coded sequence by transmitting a preselected coded sequence back to the Altitude engine. A reciprocating aircraft engine having a ground equipment, providing a strong return signal and rated takeoff power that is producible from sea level to an positive aircraft identification, as well as other special data. established higher altitude.

Airway. An airway is based on a centerline that extends from Ambient pressure. The pressure in the area immediately one navigation aid or intersection to another navigation aid surrounding the aircraft.

(or through several navigation aids or intersections); used to establish a known route for en route procedures between Ambient temperature. The temperature in the area terminal areas. immediately surrounding the aircraft.

Airworthiness Certificate. A certificate issued by the FAA AME. See aviation medical examiner.

to all aircraft that have been proven to meet the minimum standards set down by the Code of Federal Regulations. Amendment status. The circulation date and revision number of an instrument approach procedure, printed above Airworthiness Directive. A regulatory notice sent out by the procedure identification.

the FAA to the registered owner of an aircraft informing the owner of a condition that prevents the aircraft from Ammeter. An instrument installed in series with an electrical continuing to meet its conditions for airworthiness. load used to measure the amount of current flowing through Airworthiness Directives (AD notes) are to be complied with the load.

within the required time limit, and the fact of compliance, the date of compliance, and the method of compliance are Aneroid. The sensitive component in an altimeter or recorded in the aircraft’s maintenance records. barometer that measures the absolute pressure of the air.

It is a sealed, flat capsule made of thin disks of corrugated Alert area. An area in which there is a high volume of pilot metal soldered together and evacuated by pumping all of training or an unusual type of aeronautical activity. the air out of it.

Almanac data. Information the global positioning system Aneroid barometer. An instrument that measures the (GPS) receiver can obtain from one satellite which describes absolute pressure of the atmosphere by balancing the weight the approximate orbital positioning of all satellites in the of the air above it against the spring action of the aneroid.

constellation. This information is necessary for the GPS receiver to know what satellites to look for in the sky at a Angle of attack. The angle of attack is the angle at which given time. relative wind meets an airfoil. It is the angle that is formed by the chord of the airfoil and the direction of the relative ALS. See approach lighting system. wind or between the chord line and the flight path. The angle of attack changes during a flight as the pilot changes Alternate airport. An airport designated in an IFR flight the direction of the aircraft and is related to the amount of plan, providing a suitable destination if a landing at the lift being produced.

intended airport becomes inadvisable.

G-3 Angle of incidence. The acute angle formed between the Asymmetric thrust. Also known as P-factor. A tendency for chord line of an airfoil and the longitudinal axis of the aircraft an aircraft to yaw to the left due to the descending propeller on which it is mounted. blade on the right producing more thrust than the ascending blade on the left. This occurs when the aircraft’s longitudinal Anhedral. A downward slant from root to tip of an aircraft’s axis is in a climbing attitude in relation to the relative wind.

wing or horizontal tail surface. The P-factor would be to the right if the aircraft had a counterclockwise rotating propeller.

Annual inspection. A complete inspection of an aircraft and engine, required by the Code of Federal Regulations, to be ATC. Air Traffic Control.

accomplished every 12 calendar months on all certificated aircraft. Only an A&P technician holding an Inspection ATCRBS. See air traffic control radar beacon system.

Authorization can conduct an annual inspection.

ATIS. See automatic terminal information service.

Anti-ice. Preventing the accumulation of ice on an aircraft structure via a system designed for that purpose. Atmospheric propagation delay. A bending of the electromagnetic (EM) wave from the satellite that creates Antiservo tab. An adjustable tab attached to the trailing edge an error in the GPS system.

of a stabilator that moves in the same direction as the primary control. It is used to make the stabilator less sensitive. Attitude. A personal motivational predisposition to respond to persons, situations, or events in a given manner that can, Approach lighting system (ALS). Provides lights that will nevertheless, be changed or modified through training as sort penetrate the atmosphere far enough from touchdown to of a mental shortcut to decision-making.

give directional, distance, and glidepath information for safe transition from instrument to visual flight. Attitude and heading reference system (AHRS). A system composed of three-axis sensors that provide heading, attitude, Area chart. Part of the low-altitude en route chart series, and yaw information for aircraft. AHRS are designed to this chart furnishes terminal data at a larger scale for replace traditional mechanical gyroscopic flight instruments congested areas. and provide superior reliability and accuracy.

Area forecast (FA). A report that gives a picture of clouds, Attitude director indicator (ADI). An aircraft attitude general weather conditions, and visual meteorological indicator that incorporates flight command bars to provide conditions (VMC) expected over a large area encompassing pitch and roll commands.

several states.

Attitude indicator. The foundation for all instrument flight, Area navigation (RNAV). Allows a pilot to fly a selected this instrument reflects the airplane’s attitude in relation to course to a predetermined point without the need to overfly the horizon.

ground-based navigation facilities, by using waypoints.

Attitude instrument flying. Controlling the aircraft by Arm. See moment arm. reference to the instruments rather than by outside visual cues.

ARSR. See air route surveillance radar. Attitude management. The ability to recognize hazardous attitudes in oneself and the willingness to modify them as ARTCC. See air route traffic control center. necessary through the application of an appropriate antidote thought.

ASDE. See airport surface detection equipment.

Autokinesis. Nighttime visual illusion that a stationary light ASOS. See Automated Surface Observing System. is moving, which becomes apparent after several seconds of staring at the light.

Aspect ratio. Span of a wing divided by its average chord.

ASR. See airport surveillance radar.

G-4 Automated Surface Observing System (ASOS). Weather Axial flow compressor. A type of compressor used in a reporting system which provides surface observations every turbine engine in which the airflow through the compressor minute via digitized voice broadcasts and printed reports. is essentially linear. An axial-flow compressor is made up of several stages of alternate rotors and stators. The compressor Automated Weather Observing System (AWOS). ratio is determined by the decrease in area of the succeeding Automated weather reporting system consisting of various stages.

sensors, a processor, a computer-generated voice subsystem, and a transmitter to broadcast weather data. Azimuth card. A card that may be set, gyroscopically controlled, or driven by a remote compass.

Automatic dependent surveillance—broadcast (ADS–B).

A function on an aircraft or vehicle that periodically B broadcasts its state vector (i.e., horizontal and vertical Back course (BC). The reciprocal of the localizer course position, horizontal and vertical velocity) and other for an ILS. When flying a back-course approach, an aircraft information.

approaches the instrument runway from the end at which the localizer antennas are installed.

Automatic direction finder (ADF). Electronic navigation equipment that operates in the low- and medium-frequency Balance tab. An auxiliary control mounted on a primary bands. Used in conjunction with the ground-based control surface, which automatically moves in the direction nondirectional beacon (NDB), the instrument displays the opposite the primary control to provide an aerodynamic number of degrees clockwise from the nose of the aircraft assist in the movement of the control.

to the station being received.

Baro-aiding. A method of augmenting the GPS integrity Automatic terminal information service (ATIS). The solution by using a nonsatellite input source. To ensure that continuous broadcast of recorded non-control information in baro-aiding is available, the current altimeter setting must selected terminal areas. Its purpose is to improve controller be entered as described in the operating manual.

effectiveness and relieve frequency congestion by automating repetitive transmission of essential but routine information.

Barometric scale. A scale on the dial of an altimeter to which the pilot sets the barometric pressure level from which the Autopilot. An automatic flight control system which keeps altitude shown by the pointers is measured.

an aircraft in level flight or on a set course. Automatic pilots can be directed by the pilot, or they may be coupled to a radio Basic empty weight (GAMA). Basic empty weight navigation signal.

includes the standard empty weight plus optional and special equipment that has been installed.

Aviation medical examiner (AME). A physician with training in aviation medicine designated by the Civil BC. See back course.

Aerospace Medical Institute (CAMI).

Bernoulli’s Principle. A principle that explains how the Aviation Routine Weather Report (METAR). Observation pressure of a moving fluid varies with its speed of motion.

of current surface weather reported in a standard international An increase in the speed of movement causes a decrease in format.

the fluid’s pressure.

AWOS. See Automated Weather Observing System.

Biplanes. Airplanes with two sets of wings.

Axes of an aircraft. Three imaginary lines that pass through Block altitude. A block of altitudes assigned by ATC to an aircraft’s center of gravity. The axes can be considered allow altitude deviations; for example, “Maintain block as imaginary axles around which the aircraft rotates. The altitude 9 to 11 thousand.” three axes pass through the center of gravity at 90° angles to each other. The axis from nose to tail is the longitudinal axis Bypass ratio. The ratio of the mass airflow in pounds per (pitch), the axis that passes from wingtip to wingtip is the second through the fan section of a turbofan engine to the lateral axis (roll), and the axis that passes vertically through mass airflow that passes through the gas generator portion the center of gravity is the vertical axis (yaw).

of the engine.

G-5 Center of gravity limits. The specified forward and aft C points within which the CG must be located during flight.

Cabin altitude. Cabin pressure in terms of equivalent altitude These limits are indicated on pertinent airplane specifications.

above sea level.

Center of gravity range. The distance between the forward Cage. The black markings on the ball instrument indicating and aft CG limits indicated on pertinent airplane specifications.

its neutral position.

Center of pressure. A point along the wing chord line where Calibrated. The instrument indication compared with a lift is considered to be concentrated. For this reason, the center standard value to determine the accuracy of the instrument.

of pressure is commonly referred to as the center of lift.

Calibrated orifice. A hole of specific diameter used to delay Centrifugal flow compressor. An impeller-shaped device the pressure change in the case of a vertical speed indicator.

that receives air at its center and slings the air outward at high velocity into a diffuser for increased pressure. Also referred Calibrated airspeed. The speed at which the aircraft to as a radial outflow compressor.

is moving through the air, found by correcting IAS for instrument and position errors.

Centrifugal force. An outward force that opposes centripetal force, resulting from the effect of inertia during a turn.

Camber. The camber of an airfoil is the characteristic curve of its upper and lower surfaces. The upper camber is more Centripetal force. A center-seeking force directed inward pronounced, while the lower camber is comparatively flat.

toward the center of rotation created by the horizontal This causes the velocity of the airflow immediately above the component of lift in turning flight.

wing to be much higher than that below the wing.

CG. See center of gravity.

Canard. A horizontal surface mounted ahead of the main wing to provide longitudinal stability and control. It may Changeover point (COP). A point along the route or be a fixed, movable, or variable geometry surface, with or airway segment between two adjacent navigation facilities without control surfaces.

or waypoints where changeover in navigation guidance should occur.

Canard configuration. A configuration in which the span of the forward wings is substantially less than that of the Chart Supplement U.S. (formerly Airport/Facility main wing.

Directory). An FAA publication containing information on all airports, communications, and NAVAIDs.

Cantilever. A wing designed to carry loads without external struts.

Checklist. A tool that is used as a human factors aid in aviation safety. It is a systematic and sequential list of all CAS. Calibrated airspeed.

operations that must be performed to properly accomplish a task.

CDI. Course deviation indicator.

Chord line. An imaginary straight line drawn through an Ceiling. The height above the earth’s surface of the lowest airfoil from the leading edge to the trailing edge.

layer of clouds, which is reported as broken or overcast, or the vertical visibility into an obscuration.

Circling approach. A maneuver initiated by the pilot to align the aircraft with a runway for landing when a straight- Center of gravity (CG). The point at which an airplane in landing from an instrument approach is not possible or is would balance if it were possible to suspend it at that point.

not desirable.

It is the mass center of the airplane, or the theoretical point at which the entire weight of the airplane is assumed to be concentrated. It may be expressed in inches from the reference datum, or in percentage of mean aerodynamic chord (MAC). The location depends on the distribution of weight in the airplane.

G-6 Class A airspace. Airspace from 18,000 feet MSL up to and Clearance delivery. Control tower position responsible for including FL 600, including the airspace overlying the waters transmitting departure clearances to IFR flights.

within 12 NM of the coast of the 48 contiguous states and Alaska; and designated international airspace beyond 12 NM Clearance limit. The fix, point, or location to which an of the coast of the 48 contiguous states and Alaska within areas aircraft is cleared when issued an air traffic clearance.

of domestic radio navigational signal or ATC radar coverage, and within which domestic procedures are applied. Clearance on request. An IFR clearance not yet received after filing a flight plan.

Class B airspace. Airspace from the surface to 10,000 feet MSL surrounding the nation’s busiest airports in terms of Clearance void time. Used by ATC, the time at which the IFR operations or passenger numbers. The configuration of departure clearance is automatically canceled if takeoff has each Class B airspace is individually tailored and consists not been made. The pilot must obtain a new clearance or of a surface area and two or more layers, and is designed to cancel the IFR flight plan if not off by the specified time.

contain all published instrument procedures once an aircraft enters the airspace. For all aircraft, an ATC clearance is Clear ice. Glossy, clear, or translucent ice formed by the required to operate in the area, and aircraft so cleared receive relatively slow freezing of large, supercooled water droplets.

separation services within the airspace.

Coefficient of lift (C ). The ratio between lift pressure and L Class C airspace. Airspace from the surface to 4,000 feet dynamic pressure.

above the airport elevation (charted in MSL) surrounding those airports having an operational control tower, serviced Cold front. The boundary between two air masses where by radar approach control, and having a certain number of IFR cold air is replacing warm air.

operations or passenger numbers. Although the configuration of each Class C airspace area is individually tailored, the Compass course. A true course corrected for variation and airspace usually consists of a 5 NM radius core surface area deviation errors.

that extends from the surface up to 4,000 feet above the airport elevation, and a 10 NM radius shelf area that extends from Compass locator. A low-power, low- or medium-frequency 1,200 feet to 4,000 feet above the airport elevation. (L/MF) radio beacon installed at the site of the outer or middle marker of an ILS.

Class D airspace. Airspace from the surface to 2,500 feet above the airport elevation (charted in MSL) surrounding Compass rose. A small circle graduated in 360° increments, those airports that have an operational control tower. The to show direction expressed in degrees.

configuration of each Class D airspace area is individually tailored, and when instrument procedures are published, the Complex aircraft. An aircraft with retractable landing gear, airspace is normally designed to contain the procedures. flaps, and a controllable-pitch propeller.

Class E airspace. Airspace that is not Class A, Class B, Class Compressor pressure ratio. The ratio of compressor C, or Class D, and is controlled airspace. discharge pressure to compressor inlet pressure.

Class G airspace. Airspace that is uncontrolled, except Compressor stall. In gas turbine engines, a condition in when associated with a temporary control tower, and has an axial-flow compressor in which one or more stages of not been designated as Class A, Class B, Class C, Class D, rotor blades fail to pass air smoothly to the succeeding or Class E airspace. stages. A stall condition is caused by a pressure ratio that is incompatible with the engine rpm. Compressor stall will be Clean configuration. A configuration in which all flight indicated by a rise in exhaust temperature or rpm fluctuation, control surfaces have been placed to create minimum drag. and if allowed to continue, may result in flameout and In most aircraft this means flaps and gear retracted. physical damage to the engine.

Clearance. ATC permission for an aircraft to proceed under Computer navigation fix. A point used to define a specified traffic conditions within controlled airspace, for navigation track for an airborne computer system such as the purpose of providing separation between known aircraft. GPS or FMS.

G-7 Concentric rings. Dashed-line circles depicted in the plan Control pressures. The amount of physical exertion on the view of IAP charts, outside of the reference circle, that show control column necessary to achieve the desired attitude.

en route and feeder facilities.

Convective weather. Unstable, rising air found in Condensation. A change of state of water from a gas (water cumiliform clouds.

vapor) to a liquid.

Convective SIGMET. Weather advisory concerning Condensation nuclei. Small particles of solid matter in the convective weather significant to the safety of all aircraft, air on which water vapor condenses. including thunderstorms, hail, and tornadoes.

Cone of confusion. A cone-shaped volume of airspace Conventional landing gear. Landing gear employing a third directly above a VOR station where no signal is received, rear-mounted wheel. These airplanes are also sometimes causing the CDI to fluctuate. referred to as tailwheel airplanes.

Configuration. This is a general term, which normally refers Coordinated flight. Flight with a minimum disturbance of to the position of the landing gear and flaps. the forces maintaining equilibrium, established via effective control use.

Constant-speed propeller. A controllable-pitch propeller whose pitch is automatically varied in flight by a governor COP. See changeover point.

to maintain a constant rpm in spite of varying air loads.

Coriolis illusion. The illusion of rotation or movement in an Continuous flow oxygen system. System that supplies entirely different axis, caused by an abrupt head movement, a constant supply of pure oxygen to a rebreather bag that while in a prolonged constant-rate turn that has ceased to dilutes the pure oxygen with exhaled gases and thus supplies a stimulate the brain’s motion sensing system.

healthy mix of oxygen and ambient air to the mask. Primarily used in passenger cabins of commercial airliners. Coupled ailerons and rudder. Rudder and ailerons are connected with interconnected springs in order to counteract Control and performance. A method of attitude instrument adverse yaw. Can be overridden if it becomes necessary to flying in which one instrument is used for making attitude slip the aircraft.

changes, and the other instruments are used to monitor the progress of the change. Course. The intended direction of flight in the horizontal plane measured in degrees from north.

Control display unit. A display interfaced with the master computer, providing the pilot with a single control point Cowl flaps. Shutter-like devices arranged around certain for all navigations systems, thereby reducing the number of air-cooled engine cowlings, which may be opened or closed required flight deck panels. to regulate the flow of air around the engine.

Controllability. A measure of the response of an aircraft Crew resource management (CRM). The application of relative to the pilot’s flight control inputs. team management concepts in the flight deck environment.

It was initially known as cockpit resource management, Controllable-pitch propeller (CPP). A type of propeller but as CRM programs evolved to include cabin crews, with blades that can be rotated around their long axis to maintenance personnel, and others, the phrase “crew change their pitch. If the pitch can be set to negative values, resource management” was adopted. This includes single the reversible propeller can also create reverse thrust for pilots, as in most general aviation aircraft. Pilots of small braking or reversing without the need of changing the aircraft, as well as crews of larger aircraft, must make direction of shaft revolutions. effective use of all available resources; human resources, hardware, and information. A current definition includes Controlled airspace. An airspace of defined dimensions all groups routinely working with the flight crew who within which ATC service is provided to IFR and VFR flights are involved in decisions required to operate a flight in accordance with the airspace classification. It includes safely. These groups include, but are not limited to pilots, Class A, Class B, Class C, Class D, and Class E airspace. dispatchers, cabin crewmembers, maintenance personnel, and air traffic controllers. CRM is one way of addressing the challenge of optimizing the human/machine interface and accompanying interpersonal activities.

G-8 Critical altitude. The maximum altitude under standard Decision altitude (DA). A specified altitude in the precision atmospheric conditions at which a turbocharged engine can approach, charted in feet MSL, at which a missed approach produce its rated horsepower. must be initiated if the required visual reference to continue the approach has not been established.

Critical angle of attack. The angle of attack at which a wing stalls regardless of airspeed, flight attitude, or weight. Decision height (DH). A specified altitude in the precision approach, charted in height above threshold elevation, Critical areas. Areas where disturbances to the ILS localizer at which a decision must be made either to continue the and glideslope courses may occur when surface vehicles or approach or to execute a missed approach.

aircraft operate near the localizer or glideslope antennas.

Deice. The act of removing ice accumulation from an CRM. See crew resource management. aircraft structure.

Cross-check. The first fundamental skill of instrument flight, Delta. A Greek letter expressed by the symbol Δ to indicate also known as “scan,” the continuous and logical observation a change of values. As an example, ΔCG indicates a change of instruments for attitude and performance information. (or movement) of the CG.

Cruise clearance. An ATC clearance issued to allow a Density altitude. Pressure altitude corrected for nonstandard pilot to conduct flight at any altitude from the minimum temperature. Density altitude is used in computing the IFR altitude up to and including the altitude specified in the performance of an aircraft and its engines.

clearance. Also authorizes a pilot to proceed to and make an approach at the destination airport. Departure procedure (DP). Preplanned IFR ATC departure, published for pilot use, in textual and graphic format.

Current induction. An electrical current being induced into, or generated in, any conductor that is crossed by lines of flux Deposition. The direct transformation of a gas to a solid from any magnet. state, in which the liquid state is bypassed. Some sources use sublimation to describe this process instead of deposition.

D Detonation. The sudden release of heat energy from fuel in DA. See decision altitude.

an aircraft engine caused by the fuel-air mixture reaching its critical pressure and temperature. Detonation occurs as Datum (Reference Datum). An imaginary vertical plane a violent explosion rather than a smooth burning process.

or line from which all measurements of arm are taken. The datum is established by the manufacturer. Once the datum Deviation. A magnetic compass error caused by local has been selected, all moment arms and the location of CG magnetic fields within the aircraft. Deviation error is different range are measured from this point.

on each heading.

D.C. Direct current.

Dew. Moisture that has condensed from water vapor. Usually found on cooler objects near the ground, such as grass, as Dark adaptation. Physical and chemical adjustments of the the near-surface layer of air cools faster than the layers of eye that make vision possible in relative darkness.

air above it.

Dead reckoning. Navigation of an airplane solely by means Dewpoint. The temperature at which air reaches a state where of computations based on airspeed, course, heading, wind it can hold no more water.

direction and speed, groundspeed, and elapsed time.

DGPS. Differential global positioning system.

Deceleration error. A magnetic compass error that occurs when the aircraft decelerates while flying on an easterly DH. See decision height.

or westerly heading, causing the compass card to rotate toward South.

G-9 Differential ailerons. Control surface rigged such that the DME arc. A flight track that is a constant distance from the aileron moving up moves a greater distance than the aileron station or waypoint.

moving down. The up aileron produces extra parasite drag to compensate for the additional induced drag caused by DOD. Department of Defense.

the down aileron. This balancing of the drag forces helps minimize adverse yaw. Doghouse. A turn-and-slip indicator dial mark in the shape of a doghouse.

Differential Global Positioning System (DGPS). A system that improves the accuracy of Global Navigation Satellite Domestic Reduced Vertical Separation Minimum Systems (GNSS) by measuring changes in variables to (DRVSM). Additional flight levels between FL 290 and FL provide satellite positioning corrections. 410 to provide operational, traffic, and airspace efficiency.

Differential pressure. A difference between two pressures. Double gimbal. A type of mount used for the gyro in an The measurement of airspeed is an example of the use of attitude instrument. The axes of the two gimbals are at right differential pressure. angles to the spin axis of the gyro, allowing free motion in two planes around the gyro.

Dihedral. The positive acute angle between the lateral axis of an airplane and a line through the center of a wing DP. See departure procedure.

or horizontal stabilizer. Dihedral contributes to the lateral stability of an airplane. Drag. The net aerodynamic force parallel to the relative wind, usually the sum of two components: induced drag Diluter-demand oxygen system. An oxygen system that and parasite drag.

delivers oxygen mixed or diluted with air in order to maintain a constant oxygen partial pressure as the altitude changes. Drag curve. The curve created when plotting induced drag and parasite drag.

Direct indication. The true and instantaneous reflection of aircraft pitch-and-bank attitude by the miniature aircraft, Drift angle. Angle between heading and track.

relative to the horizon bar of the attitude indicator.

DRVSM. See Domestic Reduced Vertical Separation Direct User Access Terminal System (DUATS). A system Minimum.

that provides current FAA weather and flight plan filing services to certified civil pilots, via personal computer, DUATS. See direct user access terminal system.

modem, or telephone access to the system. Pilots can request specific types of weather briefings and other pertinent data Duplex. Transmitting on one frequency and receiving on a for planned flights. separate frequency.

Directional stability. Stability about the vertical axis of an Dutch roll. A combination of rolling and yawing oscillations aircraft, whereby an aircraft tends to return, on its own, to that normally occurs when the dihedral effects of an aircraft flight aligned with the relative wind when disturbed from that are more powerful than the directional stability. Usually equilibrium state. The vertical tail is the primary contributor dynamically stable but objectionable in an airplane because to directional stability, causing an airplane in flight to align of the oscillatory nature.

with the relative wind.

Dynamic hydroplaning. A condition that exists when Distance circle. See reference circle. landing on a surface with standing water deeper than the tread depth of the tires. When the brakes are applied, there is Distance measuring equipment (DME). A pulse-type a possibility that the brake will lock up and the tire will ride electronic navigation system that shows the pilot, by an on the surface of the water, much like a water ski. When the instrument-panel indication, the number of nautical miles tires are hydroplaning, directional control and braking action between the aircraft and a ground station or waypoint. are virtually impossible. An effective anti-skid system can minimize the effects of hydroplaning.

DME. See distance measuring equipment.

G-10 Dynamic stability. The property of an aircraft that causes Encoding altimeter. A special type of pressure altimeter it, when disturbed from straight-and-level flight, to develop used to send a signal to the air traffic controller on the ground, forces or moments that restore the original condition of showing the pressure altitude the aircraft is flying.

straight and level.

Engine pressure ratio (EPR). The ratio of turbine discharge E pressure divided by compressor inlet pressure, which is used as an indication of the amount of thrust being developed by Eddy currents. Current induced in a metal cup or disc when a turbine engine.

it is crossed by lines of flux from a moving magnet.

En route facilities ring. Depicted in the plan view of IAP Eddy current damping. The decreased amplitude of charts, a circle which designates NAVAIDs, fixes, and oscillations by the interaction of magnetic fields. In the case intersections that are part of the en route low altitude airway of a vertical card magnetic compass, flux from the oscillating structure.

permanent magnet produces eddy currents in a damping disk or cup. The magnetic flux produced by the eddy currents En route high-altitude charts. Aeronautical charts for en opposes the flux from the permanent magnet and decreases route instrument navigation at or above 18,000 feet MSL.

the oscillations.

En route low-altitude charts. Aeronautical charts for en EFC. See expect-further-clearance.

route IFR navigation below 18,000 feet MSL.

EFD. See electronic flight display.

EPR. See engine pressure ratio.

EGT. See exhaust gas temperature.

Equilibrium. A condition that exists within a body when the sum of the moments of all of the forces acting on the body Electronic flight display (EFD). For the purpose of is equal to zero. In aerodynamics, equilibrium is when all standardization, any flight instrument display that uses LCD or opposing forces acting on an aircraft are balanced (steady, other image-producing system (cathode ray tube (CRT), etc.)

unaccelerated flight conditions).

Elevator. The horizontal, movable primary control surface in Equivalent airspeed. Airspeed equivalent to CAS in standard the tail section, or empennage, of an airplane. The elevator is atmosphere at sea level. As the airspeed and pressure altitude hinged to the trailing edge of the fixed horizontal stabilizer.

increase, the CAS becomes higher than it should be, and a correction for compression must be subtracted from the CAS.

Elevator illusion. The sensation of being in a climb or descent, caused by the kind of abrupt vertical accelerations Evaporation. The transformation of a liquid to a gaseous that result from up- or downdrafts.

state, such as the change of water to water vapor.

Emergency. A distress or urgent condition.

Exhaust gas temperature (EGT). The temperature of the exhaust gases as they leave the cylinders of a reciprocating Empennage. The section of the airplane that consists of the engine or the turbine section of a turbine engine.

vertical stabilizer, the horizontal stabilizer, and the associated control surfaces.

Expect-further-clearance (EFC). The time a pilot can expect to receive clearance beyond a clearance limit.

Emphasis error. The result of giving too much attention to a particular instrument during the cross-check, instead of Explosive decompression. A change in cabin pressure faster relying on a combination of instruments necessary for attitude than the lungs can decompress. Lung damage is possible.

and performance information.

F Empty-field myopia. Induced nearsightedness that is associated with flying at night, in instrument meteorological FA. See area forecast.

conditions and/or reduced visibility. With nothing to focus on, the eyes automatically focus on a point just slightly ahead FAA. Federal Aviation Administration.

of the airplane.

FAF. See final approach fix.

EM wave. Electromagnetic wave.

G-11 False horizon. Inaccurate visual information for aligning the Flight director indicator (FDI). One of the major aircraft, caused by various natural and geometric formations components of a flight director system, it provides steering that disorient the pilot from the actual horizon. commands that the pilot (or the autopilot, if coupled) follows.

FDI. See flight director indicator. Flight level (FL). A measure of altitude (in hundreds of feet) used by aircraft flying above 18,000 feet with the altimeter Federal airways. Class E airspace areas that extend upward set at 29.92 "Hg.

from 1,200 feet to, but not including, 18,000 feet MSL, unless otherwise specified. Flight management system (FMS). Provides pilot and crew Feeder facilities. Used by ATC to direct aircraft to with highly accurate and automatic long-range navigation intervening fixes between the en route structure and the capability, blending available inputs from long- and short- initial approach fix. range sensors.

Final approach. Part of an instrument approach procedure in Flight path. The line, course, or track along which an aircraft which alignment and descent for landing are accomplished. is flying or is intended to be flown.

Final approach fix (FAF). The fix from which the IFR Flight patterns. Basic maneuvers, flown by reference to the final approach to an airport is executed, and which identifies instruments rather than outside visual cues, for the purpose the beginning of the final approach segment. An FAF is of practicing basic attitude flying. The patterns simulate designated on government charts by a Maltese cross symbol maneuvers encountered on instrument flights such as holding for nonprecision approaches, and a lightning bolt symbol for patterns, procedure turns, and approaches.

precision approaches.

Flight strips. Paper strips containing instrument flight Fixating. Staring at a single instrument, thereby interrupting information, used by ATC when processing flight plans.

the cross-check process.

FMS. See flight management system.

Fixed-pitch propellers. Propellers with fixed blade angles.

Fixed-pitch propellers are designed as climb propellers, FOD. See foreign object damage.

cruise propellers, or standard propellers.

Fog. Cloud consisting of numerous minute water droplets Fixed slot. A fixed, nozzle shaped opening near the leading and based at the surface; droplets are small enough to be edge of a wing that ducts air onto the top surface of the wing. suspended in the earth’s atmosphere indefinitely. (Unlike Its purpose is to increase lift at higher angles of attack. drizzle, it does not fall to the surface. Fog differs from a cloud only in that a cloud is not based at the surface, and FL. See flight level. is distinguished from haze by its wetness and gray color.)

Flameout. A condition in the operation of a gas turbine Force (F). The energy applied to an object that attempts to engine in which the fire in the engine goes out due to either cause the object to change its direction, speed, or motion.

too much or too little fuel sprayed into the combustors. In aerodynamics, it is expressed as F, T (thrust), L (lift), W (weight), or D (drag), usually in pounds.

Flaps. Hinged portion of the trailing edge between the ailerons and fuselage. In some aircraft ailerons and flaps are Foreign object damage (FOD). Damage to a gas turbine interconnected to produce full-span “flaperons.” In either engine caused by some object being sucked into the engine case, flaps change the lift and drag on the wing. while it is running. Debris from runways or taxiways can cause foreign object damage during ground operations, and Floor load limit. The maximum weight the floor can sustain the ingestion of ice and birds can cause FOD in flight.

per square inch/foot as provided by the manufacturer.

Form drag. The drag created because of the shape of a Flight configurations. Adjusting the aircraft control surfaces component or the aircraft.

(including flaps and landing gear) in a manner that will achieve a specified attitude.

G-12 Frise-type aileron. Aileron having the nose portion Global positioning system (GPS). Navigation system projecting ahead of the hinge line. When the trailing edge that uses satellite rather than ground-based transmitters for of the aileron moves up, the nose projects below the wing’s location information.

lower surface and produces some parasite drag, decreasing the amount of adverse yaw. GLS. See global landing system.

Front. The boundary between two different air masses. GNSS. See global navigation satellite system.

Frost. Ice crystal deposits formed by sublimation when Goniometer. As used in radio frequency (RF) antenna temperature and dewpoint are below freezing. systems, a direction-sensing device consisting of two fixed loops of wire oriented 90° from each other, which separately Fuel load. The expendable part of the load of the airplane. sense received signal strength and send those signals to two It includes only usable fuel, not fuel required to fill the lines rotors (also oriented 90°) in the sealed direction-indicating or that which remains trapped in the tank sumps. instrument. The rotors are attached to the direction-indicating needle of the instrument and rotated by a small motor until Fundamental skills. Pilot skills of instrument cross-check, minimum magnetic field is sensed near the rotors.

instrument interpretation, and aircraft control.

GPS. See global positioning system.

Fuselage. The section of the airplane that consists of the cabin and/or cockpit, containing seats for the occupants and GPS Approach Overlay Program. An authorization for the controls for the airplane. pilots to use GPS avionics under IFR for flying designated existing nonprecision instrument approach procedures, with G the exception of LOC, LDA, and SDF procedures.

GAMA. General Aviation Manufacturers Association.

GPWS. See ground proximity warning system.

Gimbal ring. A type of support that allows an object, such Graveyard spiral. The illusion of the cessation of a turn while as a gyroscope, to remain in an upright condition when its still in a prolonged, coordinated, constant rate turn, which base is tilted.

can lead a disoriented pilot to a loss of control of the aircraft.

Glideslope (GS). Part of the ILS that projects a radio beam Great circle route. The shortest distance across the surface upward at an angle of approximately 3° from the approach of a sphere (the Earth) between two points on the surface.

end of an instrument runway. The glideslope provides vertical guidance to aircraft on the final approach course for Ground adjustable trim tab. Non-movable metal trim tab the aircraft to follow when making an ILS approach along on a control surface. Bent in one direction or another while the localizer path.

on the ground to apply trim forces to the control surface.

Glideslope intercept altitude. The minimum altitude of an Ground effect. The condition of slightly increased air pressure intermediate approach segment prescribed for a precision below an airplane wing or helicopter rotor system that increases approach that ensures obstacle clearance.

the amount of lift produced. It exists within approximately one wing span or one rotor diameter from the ground. It results Global landing system (GLS). An instrument approach with from a reduction in upwash, downwash, and wingtip vortices, lateral and vertical guidance with integrity limits (similar to and provides a corresponding decrease in induced drag.

barometric vertical navigation (BARO VNAV).

Ground proximity warning system (GPWS). A system Global navigation satellite system (GNSS). Satellite designed to determine an aircraft’s clearance above the Earth navigation system that provides autonomous geospatial and provides limited predictability about aircraft position positioning with global coverage. It allows small electronic relative to rising terrain.

receivers to determine their location (longitude, latitude, and altitude) to within a few meters using time signals transmitted along a line of sight by radio from satellites.

G-13 Groundspeed. Speed over the ground, either closing speed to Height above landing (HAL). The height above a designated the station or waypoint, or speed over the ground in whatever helicopter landing area used for helicopter instrument direction the aircraft is going at the moment, depending upon approach procedures.

the navigation system used.

Height above touchdown elevation (HAT). The DA/DH or GS. See glideslope. MDA above the highest runway elevation in the touchdown zone (first 3,000 feet of the runway).

GWPS. See ground proximity warning system.

HF. High frequency.

Gyroscopic precession. An inherent quality of rotating bodies, which causes an applied force to be manifested 90° in the Hg. Abbreviation for mercury, from the Latin hydrargyrum.

direction of rotation from the point where the force is applied.

High performance aircraft. An aircraft with an engine of H more than 200 horsepower.

HAA. See height above airport.

Histotoxic hypoxia. The inability of cells to effectively use oxygen. Plenty of oxygen is being transported to the cells HAL. See height above landing.

that need it, but they are unable to use it.

HAT. See height above touchdown elevation.

HIWAS. See Hazardous Inflight Weather Advisory Service.

Hazardous attitudes. Five aeronautical decision-making Holding. A predetermined maneuver that keeps aircraft attitudes that may contribute to poor pilot judgment: anti- within a specified airspace while awaiting further clearance authority, impulsivity, invulnerability, machismo, and from ATC.

resignation.

Holding pattern. A racetrack pattern, involving two turns Hazardous Inflight Weather Advisory Service (HIWAS).

and two legs, used to keep an aircraft within a prescribed An en route FSS service providing continuously updated airspace with respect to a geographic fix. A standard pattern automated of hazardous weather within 150 nautical miles of uses right turns; nonstandard patterns use left turns.

selected VORs, available only in the conterminous 48 states.

Homing. Flying the aircraft on any heading required to keep Head-up display (HUD). A special type of flight viewing the needle pointing to the 0° relative bearing position.

screen that allows the pilot to watch the flight instruments and other data while looking through the windshield of the Horizontal situation indicator (HSI). A flight navigation aircraft for other traffic, the approach lights, or the runway.

instrument that combines the heading indicator with a CDI, in order to provide the pilot with better situational awareness Heading. The direction in which the nose of the aircraft is of location with respect to the courseline.

pointing during flight.

Horsepower. The term, originated by inventor James Watt, Heading indicator. An instrument which senses airplane means the amount of work a horse could do in one second.

movement and displays heading based on a 360° azimuth, One horsepower equals 550 foot-pounds per second, or with the final zero omitted. The heading indicator, also called 33,000 foot-pounds per minute.

a directional gyro (DG), is fundamentally a mechanical instrument designed to facilitate the use of the magnetic Hot start. In gas turbine engines, a start which occurs with compass. The heading indicator is not affected by the forces normal engine rotation, but exhaust temperature exceeds that make the magnetic compass difficult to interpret.

prescribed limits. This is usually caused by an excessively rich mixture in the combustor. The fuel to the engine must Headwork. Required to accomplish a conscious, rational be terminated immediately to prevent engine damage.

thought process when making decisions. Good decision- making involves risk identification and assessment, HSI. See horizontal situation indicator.

information processing, and problem solving.

HUD. See head-up display.

Height above airport (HAA). The height of the MDA above the published airport elevation.

G-14 Human factors. A multidisciplinary field encompassing the Ident. Air Traffic Control request for a pilot to push behavioral and social sciences, engineering, and physiology, the button on the transponder to identify return on the to consider the variables that influence individual and controller’s scope.

crew performance for the purpose of optimizing human performance and reducing errors. IFR. See instrument flight rules.

Hung start. In gas turbine engines, a condition of normal ILS. See instrument landing system.

light off but with rpm remaining at some low value rather than increasing to the normal idle rpm. This is often the result of ILS categories. Categories of instrument approach insufficient power to the engine from the starter. In the event procedures allowed at airports equipped with the following of a hung start, the engine should be shut down. types of instrument landing systems: ILS Category I: Provides for approach to a height Hydroplaning. A condition that exists when landing on a above touchdown of not less than 200 feet, and with surface with standing water deeper than the tread depth of runway visual range of not less than 1,800 feet.

the tires. When the brakes are applied, there is a possibility ILS Category II: Provides for approach to a height that the brake will lock up and the tire will ride on the above touchdown of not less than 100 feet and with surface of the water, much like a water ski. When the tires runway visual range of not less than 1,200 feet.

are hydroplaning, directional control and braking action are virtually impossible. An effective anti-skid system can ILS Category IIIA: Provides for approach without minimize the effects of hydroplaning.

a decision height minimum and with runway visual range of not less than 700 feet.

Hypemic hypoxia. A type of hypoxia that is a result of ILS Category IIIB: Provides for approach without oxygen deficiency in the blood, rather than a lack of inhaled a decision height minimum and with runway visual oxygen. It can be caused by a variety of factors. Hypemic range of not less than 150 feet.

means “not enough blood.” ILS Category IIIC: Provides for approach without a decision height minimum and without runway visual Hyperventilation. Occurs when an individual is experiencing range minimum.

emotional stress, fright, or pain, and the breathing rate and depth increase, although the carbon dioxide level in the IMC. See instrument meteorological conditions.

blood is already at a reduced level. The result is an excessive loss of carbon dioxide from the body, which can lead to Inclinometer. An instrument consisting of a curved glass unconsciousness due to the respiratory system’s overriding tube, housing a glass ball, and damped with a fluid similar mechanism to regain control of breathing.

to kerosene. It may be used to indicate inclination, as a level, or, as used in the turn indicators, to show the relationship Hypoxia. A state of oxygen deficiency in the body sufficient between gravity and centrifugal force in a turn.

to impair functions of the brain and other organs.

Indicated airspeed (IAS). Shown on the dial of the Hypoxic hypoxia. This type of hypoxia is a result of instrument airspeed indicator on an aircraft. Indicated insufficient oxygen available to the lungs. A decrease of airspeed (IAS) is the airspeed indicator reading uncorrected oxygen molecules at sufficient pressure can lead to hypoxic for instrument, position, and other errors. Indicated airspeed hypoxia.

means the speed of an aircraft as shown on its pitot static airspeed indicator calibrated to reflect standard atmosphere I adiabatic compressible flow at sea level uncorrected for IAF. See initial approach fix.

airspeed system errors. Calibrated airspeed (CAS) is IAS corrected for instrument errors, position error (due to IAP. See instrument approach procedures.

incorrect pressure at the static port) and installation errors.

IAS. See indicated airspeed.

Indicated altitude. The altitude read directly from the altimeter (uncorrected) when it is set to the current altimeter ICAO. See International Civil Aviation Organization.

setting.

G-15 Indirect indication. A reflection of aircraft pitch-and-bank Instrument meteorological conditions (IMC).

attitude by instruments other than the attitude indicator. Meteorological conditions expressed in terms of visibility, distance from clouds, and ceiling less than the minimums Induced drag. Drag caused by the same factors that produce specified for visual meteorological conditions, requiring lift; its amount varies inversely with airspeed. As airspeed operations to be conducted under IFR.

decreases, the angle of attack must increase, in turn increasing induced drag. Instrument takeoff. Using the instruments rather than outside visual cues to maintain runway heading and execute Induction icing. A type of ice in the induction system that a safe takeoff.

reduces the amount of air available for combustion. The most commonly found induction icing is carburetor icing. Intercooler. A device used to reduce the temperatures of the compressed air before it enters the fuel metering device. The Inertial navigation system (INS). A computer-based resulting cooler air has a higher density, which permits the navigation system that tracks the movement of an aircraft engine to be operated with a higher power setting.

via signals produced by onboard accelerometers. The initial location of the aircraft is entered into the computer, and all Interference drag. Drag generated by the collision of subsequent movement of the aircraft is sensed and used to airstreams creating eddy currents, turbulence, or restrictions keep the position updated. An INS does not require any inputs to smooth flow.

from outside signals.

International Civil Aviation Organization (ICAO). The Initial approach fix (IAF). The fix depicted on IAP charts United Nations agency for developing the principles and where the instrument approach procedure (IAP) begins unless techniques of international air navigation, and fostering otherwise authorized by ATC. planning and development of international civil air transport.

Inoperative components. Higher minimums are prescribed International standard atmosphere (IAS). A model of when the specified visual aids are not functioning; this standard variation of pressure and temperature.

information is listed in the Inoperative Components Table found in the United States Terminal Procedures Publications. Interpolation. The estimation of an intermediate value of a quantity that falls between marked values in a series.

INS. See inertial navigation system. Example: In a measurement of length, with a rule that is marked in eighths of an inch, the value falls between 3/8 Instantaneous vertical speed indicator (IVSI). Assists in inch and 1/2 inch. The estimated (interpolated) value might interpretation by instantaneously indicating the rate of climb then be said to be 7/16 inch.

or descent at a given moment with little or no lag as displayed in a vertical speed indicator (VSI). Inversion. An increase in temperature with altitude.

Instrument approach procedures (IAP). A series of Inversion illusion. The feeling that the aircraft is tumbling predetermined maneuvers for the orderly transfer of an backwards, caused by an abrupt change from climb to straight aircraft under IFR from the beginning of the initial approach and-level flight while in situations lacking visual reference.

to a landing or to a point from which a landing may be made visually. Inverter. A solid-state electronic device that converts D.C.

into A.C. current of the proper voltage and frequency to Instrument flight rules (IFR). Rules and regulations operate A.C. gyro instruments.

established by the Federal Aviation Administration to govern flight under conditions in which flight by outside visual Isobars. Lines which connect points of equal barometric reference is not safe. IFR flight depends upon flying by pressure.

reference to instruments in the flight deck, and navigation is accomplished by reference to electronic signals. Isogonic lines. Lines drawn across aeronautical charts to connect points having the same magnetic variation.

Instrument landing system (ILS). An electronic system that provides both horizontal and vertical guidance to a IVSI. See instantaneous vertical speed indicator.

specific runway, used to execute a precision instrument approach procedure.

G-16 Lateral stability (rolling). The stability about the J longitudinal axis of an aircraft. Rolling stability or the ability Jet route. A route designated to serve flight operations from of an airplane to return to level flight due to a disturbance 18,000 feet MSL up to and including FL 450.

that causes one of the wings to drop.

Jet stream. A high-velocity narrow stream of winds, usually Latitude. Measurement north or south of the equator in found near the upper limit of the troposphere, which flows degrees, minutes, and seconds. Lines of latitude are also generally from west to east.

referred to as parallels.

Judgment. The mental process of recognizing and analyzing LDA. See localizer-type directional aid.

all pertinent information in a particular situation, a rational evaluation of alternative actions in response to it, and a timely Lead radial. The radial at which the turn from the DME arc decision on which action to take.

to the inbound course is started.

K Leading edge. The part of an airfoil that meets the airflow first.

KIAS. Knots indicated airspeed.

Leading edge devices. High lift devices which are found Knot. The knot is a unit of speed equal to one nautical mile on the leading edge of the airfoil. The most common types (1.852 km) per hour, approximately 1.151 mph.

are fixed slots, movable slats, and leading edge flaps.

Kollsman window. A barometric scale window of a Leading-edge flap. A portion of the leading edge of an sensitive altimeter used to adjust the altitude for the airplane wing that folds downward to increase the camber, altimeter setting.

lift, and drag of the wing. The leading-edge flaps are extended for takeoffs and landings to increase the amount L of aerodynamic lift that is produced at any given airspeed.

LAAS. See local area augmentation system.

Leans, the. A physical sensation caused by an abrupt correction of a banked attitude entered too slowly to stimulate the motion Lag. The delay that occurs before an instrument needle attains sensing system in the inner ear. The abrupt correction can a stable indication.

create the illusion of banking in the opposite direction.

Land breeze. A coastal breeze flowing from land to sea Licensed empty weight. The empty weight that consists caused by temperature differences when the sea surface is of the airframe, engine(s), unusable fuel, and undrainable warmer than the adjacent land. The land breeze usually occurs oil plus standard and optional equipment as specified in the at night and alternates with the sea breeze that blows in the equipment list. Some manufacturers used this term prior to opposite direction by day.

GAMA standardization.

Land as soon as possible. Land without delay at the nearest Lift. A component of the total aerodynamic force on an airfoil suitable area, such as an open field, at which a safe approach and acts perpendicular to the relative wind.

and landing is assured.

Limit load factor. Amount of stress, or load factor, that an Land as soon as practical. The landing site and duration of aircraft can withstand before structural damage or failure flight are at the discretion of the pilot. Extended flight beyond occurs.

the nearest approved landing area is not recommended.

Lines of flux. Invisible lines of magnetic force passing Land immediately. The urgency of the landing is paramount.

between the poles of a magnet.

The primary consideration is to ensure the survival of the occupants. Landing in trees, water, or other unsafe areas L/MF. See low or medium frequency.

should be considered only as a last resort.

LMM. See locator middle marker.

Lateral axis. An imaginary line passing through the center of gravity of an airplane and extending across the airplane from wingtip to wingtip.

G-17 Load factor. The ratio of a specified load to the total weight Low or medium frequency. A frequency range between of the aircraft. The specified load is expressed in terms of 190 and 535 kHz with the medium frequency above 300 any of the following: aerodynamic forces, inertial forces, or kHz. Generally associated with nondirectional beacons ground or water reactions. transmitting a continuous carrier with either a 400 or 1,020 Hz modulation.

Loadmeter. A type of ammeter installed between the generator output and the main bus in an aircraft electrical system. Lubber line. The reference line used in a magnetic compass or heading indicator.

LOC. See localizer.

M Local area augmentation system (LAAS). A differential MAA. See maximum authorized altitude.

global positioning system (DGPS) that improves the accuracy of the system by determining position error from the GPS MAC. See mean aerodynamic chord.

satellites, then transmitting the error, or corrective factors, to the airborne GPS receiver.

Mach number. The ratio of the true airspeed of the aircraft to the speed of sound in the same atmospheric conditions, Localizer (LOC). The portion of an ILS that gives left/right named in honor of Ernst Mach, late 19th century physicist.

guidance information down the centerline of the instrument runway for final approach.

Mach meter. The instrument that displays the ratio of the speed of sound to the true airspeed an aircraft is flying.

Localizer-type directional aid (LDA). A NAVAID used for nonprecision instrument approaches with utility and Magnetic bearing (MB). The direction to or from a radio accuracy comparable to a localizer but which is not a part transmitting station measured relative to magnetic north.

of a complete ILS and is not aligned with the runway. Some LDAs are equipped with a glideslope.

Magnetic compass. A device for determining direction measured from magnetic north.

Locator middle marker (LMM). Nondirectional radio beacon (NDB) compass locator, collocated with a middle Magnetic dip. A vertical attraction between a compass marker (MM).

needle and the magnetic poles. The closer the aircraft is to a pole, the more severe the effect.

Locator outer marker (LOM). NDB compass locator, collocated with an outer marker (OM).

Magnetic heading (MH). The direction an aircraft is pointed with respect to magnetic north.

LOM. See locator outer marker.

Magneto. A self-contained, engine-driven unit that supplies Longitude. Measurement east or west of the Prime Meridian electrical current to the spark plugs; completely independent in degrees, minutes, and seconds. The Prime Meridian is 0° of the airplane’s electrical system. Normally there are two longitude and runs through Greenwich, England. Lines of magnetos per engine.

longitude are also referred to as meridians.

Magnus effect. Lifting force produced when a rotating Longitudinal axis. An imaginary line through an aircraft cylinder produces a pressure differential. This is the same from nose to tail, passing through its center of gravity. The effect that makes a baseball curve or a golf ball slice.

longitudinal axis is also called the roll axis of the aircraft.

Movement of the ailerons rotates an airplane about its Mandatory altitude. An altitude depicted on an instrument longitudinal axis.

approach chart with the altitude value both underscored and overscored. Aircraft are required to maintain altitude at the Longitudinal stability (pitching). Stability about the lateral depicted value.

axis. A desirable characteristic of an airplane whereby it tends to return to its trimmed angle of attack after displacement.

Mandatory block altitude. An altitude depicted on an instrument approach chart with two underscored and overscored altitude values between which aircraft are required to maintain altitude.

G-18 Maneuverability. Ability of an aircraft to change directions MB. See magnetic bearing.

along a flight path and withstand the stresses imposed upon it.

MCA. See minimum crossing altitude.

Maneuvering speed (V ). The design maneuvering speed.

A Operating at or below design maneuvering speed does not MDA. See minimum descent altitude.

provide structural protection against multiple full control inputs in one axis or full control inputs in more than one MEA. See minimum en route altitude.

axis at the same time.

Mean aerodynamic chord (MAC). The average distance Manifold absolute pressure. The absolute pressure of the from the leading edge to the trailing edge of the wing.

fuel/air mixture within the intake manifold, usually indicated in inches of mercury. Mean sea level. The average height of the surface of the sea at a particular location for all stages of the tide over a MAP. See missed approach point. 19-year period.

Margin identification. The top and bottom areas on an MEL. See minimum equipment list.

instrument approach chart that depict information about the procedure, including airport location and procedure Meridians. Lines of longitude.

identification.

Mesophere. A layer of the atmosphere directly above the Marker beacon. A low-powered transmitter that directs its stratosphere.

signal upward in a small, fan-shaped pattern. Used along the flight path when approaching an airport for landing, marker METAR. See Aviation Routine Weather Report.

beacons indicate both aurally and visually when the aircraft is directly over the facility. MFD. See multi-function display.

Mass. The amount of matter in a body. MH. See magnetic heading.

Maximum altitude. An altitude depicted on an instrument MHz. Megahertz.

approach chart with overscored altitude value at which or below aircraft are required to maintain altitude. Microburts. A strong downdraft which normally occurs over horizontal distances of 1 NM or less and vertical Maximum authorized altitude (MAA). A published altitude distances of less than 1,000 feet. In spite of its small representing the maximum usable altitude or flight level for horizontal scale, an intense microburst could induce an airspace structure or route segment. windspeeds greater than 100 knots and downdrafts as strong as 6,000 feet per minute.

Maximum landing weight. The greatest weight that an airplane normally is allowed to have at landing. Microwave landing system (MLS). A precision instrument approach system operating in the microwave spectrum which Maximum ramp weight. The total weight of a loaded aircraft, normally consists of an azimuth station, elevation station, including all fuel. It is greater than the takeoff weight due to the and precision distance measuring equipment.

fuel that will be burned during the taxi and runup operations.

Ramp weight may also be referred to as taxi weight. Mileage breakdown. A fix indicating a course change that appears on the chart as an “x” at a break between two Maximum takeoff weight. The maximum allowable weight segments of a federal airway.

for takeoff.

Military operations area (MOA). Airspace established for Maximum weight. The maximum authorized weight of the purpose of separating certain military training activities the aircraft and all of its equipment as specified in the Type from IFR traffic.

Certificate Data Sheets (TCDS) for the aircraft.

Maximum zero fuel weight (GAMA). The maximum weight, exclusive of usable fuel.

G-19 Military training route (MTR). Airspace of defined vertical Minimums section. The area on an IAP chart that displays the and lateral dimensions established for the conduct of military lowest altitude and visibility requirements for the approach.

training at airspeeds in excess of 250 knots indicated airspeed (KIAS). Missed approach. A maneuver conducted by a pilot when an instrument approach cannot be completed to a landing.

Minimum altitude. An altitude depicted on an instrument approach chart with the altitude value underscored. Aircraft Missed approach point (MAP). A point prescribed in each are required to maintain altitude at or above the depicted value. instrument approach at which a missed approach procedure shall be executed if the required visual reference has not Minimum crossing altitude (MCA). The lowest allowed been established.

altitude at certain fixes an aircraft must cross when proceeding in the direction of a higher minimum en route altitude (MEA). Mixed ice. A mixture of clear ice and rime ice.

Minimum descent altitude (MDA). The lowest altitude (in MLS. See microwave landing system.

feet MSL) to which descent is authorized on final approach, or during circle-to-land maneuvering in execution of a MM. Middle marker.

nonprecision approach.

MOA. See military operations area.

Minimum drag. The point on the total drag curve where the lift-to-drag ratio is the greatest. At this speed, total drag MOCA. See minimum obstruction clearance altitude.

is minimized.

Mode C. Altitude reporting transponder mode.

Minimum en route altitude (MEA). The lowest published altitude between radio fixes that ensures acceptable Moment. The product of the weight of an item multiplied navigational signal coverage and meets obstacle clearance by its arm. Moments are expressed in pound-inches (lb-in).

requirements between those fixes. Total moment is the weight of the airplane multiplied by the distance between the datum and the CG.

Minimum equipment list (MEL). A list developed for larger aircraft that outlines equipment that can be inoperative for Moment arm. The distance from a datum to the applied force.

various types of flight including IFR and icing conditions. This list is based on the master minimum equipment list (MMEL) Moment index (or index). A moment divided by a constant developed by the FAA and must be approved by the FAA for such as 100, 1,000, or 10,000. The purpose of using a moment use. It is specific to an individual aircraft make and model. index is to simplify weight and balance computations of airplanes where heavy items and long arms result in large, Minimum obstruction clearance altitude (MOCA). The unmanageable numbers.

lowest published altitude in effect between radio fixes on VOR airways, off-airway routes, or route segments, which meets Monocoque. A shell-like fuselage design in which the obstacle clearance requirements for the entire route segment stressed outer skin is used to support the majority of imposed and which ensures acceptable navigational signal coverage stresses. Monocoque fuselage design may include bulkheads only within 25 statute (22 nautical) miles of a VOR. but not stringers.

Minimum reception altitude (MRA). The lowest altitude Monoplanes. Airplanes with a single set of wings.

at which an airway intersection can be determined.

Movable slat. A movable auxiliary airfoil on the leading edge Minimum safe altitude (MSA). The minimum altitude of a wing. It is closed in normal flight but extends at high depicted on approach charts which provides at least 1,000 feet angles of attack. This allows air to continue flowing over the of obstacle clearance for emergency use within a specified top of the wing and delays airflow separation.

distance from the listed navigation facility.

MRA. See minimum reception altitude.

Minimum vectoring altitude (MVA). An IFR altitude lower than the minimum en route altitude (MEA) that provides MSA. See minimum safe altitude.

terrain and obstacle clearance.

MSL. See mean sea level.

G-20 MTR. See military training route. National Transportation Safety Board (NTSB). A United States Government independent organization responsible for Multi-function display (MFD). Small screen (CRT or LCD) investigations of accidents involving aviation, highways, in an aircraft that can be used to display information to the waterways, pipelines, and railroads in the United States.

pilot in numerous configurable ways. Often an MFD will be NTSB is charged by congress to investigate every civil used in concert with a primary flight display. aviation accident in the United States.

MVA. See minimum vectoring altitude.

NAVAID. Navigational aid.

N NAV/COM. Navigation and communication radio.

N . Rotational speed of the low pressure compressor in a turbine engine.

NDB. See nondirectional radio beacon.

N . Rotational speed of the high pressure compressor in a Negative static stability. The initial tendency of an aircraft turbine engine.

to continue away from the original state of equilibrium after being disturbed.

Nacelle. A streamlined enclosure on an aircraft in which an engine is mounted. On multiengine propeller-driven Neutral static stability. The initial tendency of an aircraft airplanes, the nacelle is normally mounted on the leading to remain in a new condition after its equilibrium has been edge of the wing.

disturbed.

NACG. See National Aeronautical Charting Group.

NM. Nautical mile.

NAS. See National Airspace System.

NOAA. National Oceanic and Atmospheric Administration.

National Airspace System (NAS). The common network of No-gyro approach. A radar approach that may be used in United States airspace—air navigation facilities, equipment case of a malfunctioning gyro-compass or directional gyro.

and services, airports or landing areas; aeronautical charts, Instead of providing the pilot with headings to be flown, information and services; rules, regulations and procedures, the controller observes the radar track and issues control technical information; and manpower and material.

instructions “turn right/left” or “stop turn,” as appropriate.

National Aeronautical Charting Group (NACG). A Nondirectional radio beacon (NDB). A ground-based radio Federal agency operating under the FAA, responsible for transmitter that transmits radio energy in all directions.

publishing charts such as the terminal procedures and en route charts.

Nonprecision approach. A standard instrument approach procedure in which only horizontal guidance is provided.

National Route Program (NRP). A set of rules and procedures designed to increase the flexibility of user flight No procedure turn (NoPT). Term used with the appropriate planning within published guidelines.

course and altitude to denote that the procedure turn is not required.

National Security Area (NSA). Areas consisting of airspace of defined vertical and lateral dimensions established at locations NoPT. See no procedure turn.

where there is a requirement for increased security and safety of ground facilities. Pilots are requested to voluntarily avoid NOTAM. See Notice to Airmen.

flying through the depicted NSA. When it is necessary to provide a greater level of security and safety, flight in NSAs Notice to Airmen (NOTAM). A notice filed with an aviation may be temporarily prohibited. Regulatory prohibitions are authority to alert aircraft pilots of any hazards en route or at disseminated via NOTAMs.

a specific location. The authority in turn provides means of disseminating relevant NOTAMs to pilots.

G-21 NRP. See National Route Program. Outside air temperature (OAT). The measured or indicated air temperature (IAT) corrected for compression and friction NSA. See National Security Area. heating. Also referred to as true air temperature.

NTSB. See National Transportation Safety Board. Overcontrolling. Using more movement in the control column than is necessary to achieve the desired pitch-and NWS. National Weather Service. bank condition.

Overboost. A condition in which a reciprocating engine O has exceeded the maximum manifold pressure allowed by the manufacturer. Can cause damage to engine components.

Obstacle departure procedures (ODP). A preplanned instrument flight rule (IFR) departure procedure printed for Overpower. To use more power than required for the purpose pilot use in textual or graphic form to provide obstruction of achieving a faster rate of airspeed change.

clearance via the least onerous route from the terminal area to the appropriate en route structure. ODPs are recommended P for obstruction clearance and may be flown without ATC clearance unless an alternate departure procedure (SID or P-static. See precipitation static.

radar vector) has been specifically assigned by ATC.

PAPI. See precision approach path indicator.

Obstruction lights. Lights that can be found both on and off an airport to identify obstructions. PAR. See precision approach radar.

Occluded front. A frontal occlusion occurs when a fast- Parallels. Lines of latitude.

moving cold front catches up with a slow moving warm front.

The difference in temperature within each frontal system is Parasite drag. Drag caused by the friction of air moving a major factor in determining whether a cold or warm front over the aircraft structure; its amount varies directly with occlusion occurs. the airspeed.

ODP. See obstacle departure procedures. Payload (GAMA). The weight of occupants, cargo, and baggage.

OM. Outer marker.

Personality. The embodiment of personal traits and Omission error. The failure to anticipate significant characteristics of an individual that are set at a very early instrument indications following attitude changes; for age and extremely resistant to change.

example, concentrating on pitch control while forgetting about heading or roll information, resulting in erratic control P-factor. A tendency for an aircraft to yaw to the left due to of heading and bank. the descending propeller blade on the right producing more thrust than the ascending blade on the left. This occurs when Optical illusion. A misleading visual image. For the the aircraft’s longitudinal axis is in a climbing attitude in purpose of this handbook, the term refers to the brain’s relation to the relative wind. The P-factor would be to the misinterpretation of features on the ground associated right if the aircraft had a counterclockwise rotating propeller.

with landing, which causes a pilot to misread the spatial relationships between the aircraft and the runway. PFD. See primary flight display.

Orientation. Awareness of the position of the aircraft and of Phugoid oscillations. Long-period oscillations of an oneself in relation to a specific reference point. aircraft around its lateral axis. It is a slow change in pitch accompanied by equally slow changes in airspeed. Angle Otolith organ. An inner ear organ that detects linear of attack remains constant, and the pilot often corrects for acceleration and gravity orientation. phugoid oscillations without even being aware of them.

Outer marker. A marker beacon at or near the glideslope PIC. See pilot in command.

intercept altitude of an ILS approach. It is normally located four to seven miles from the runway threshold on the Pilotage. Navigation by visual reference to landmarks.

extended centerline of the runway.

G-22 Pilot in command (PIC). The pilot responsible for the Power. Implies work rate or units of work per unit of time, operation and safety of an aircraft. and as such, it is a function of the speed at which the force is developed. The term “power required” is generally associated Pilot report (PIREP). Report of meteorological phenomena with reciprocating engines.

encountered by aircraft.

Powerplant. A complete engine and propeller combination Pilot’s Operating Handbook/Airplane Flight Manual with accessories.

(POH/AFM). FAA-approved documents published by the airframe manufacturer that list the operating conditions for Precession. The characteristic of a gyroscope that causes an a particular model of aircraft. applied force to be felt, not at the point of application, but 90° from that point in the direction of rotation.

PIREP. See pilot report.

Precipitation. Any or all forms of water particles (rain, Pitot pressure. Ram air pressure used to measure airspeed. sleet, hail, or snow) that fall from the atmosphere and reach the surface.

Pitot-static head. A combination pickup used to sample pitot pressure and static air pressure. Precipitation static (P-static). A form of radio interference caused by rain, snow, or dust particles hitting the antenna and Plan view. The overhead view of an approach procedure on inducing a small radio-frequency voltage into it.

an instrument approach chart. The plan view depicts the routes that guide the pilot from the en route segments to the IAF. Precision approach. A standard instrument approach procedure in which both vertical and horizontal guidance Planform. The shape or form of a wing as viewed from is provided.

above. It may be long and tapered, short and rectangular, or various other shapes. Precision approach path indicator (PAPI). A system of lights similar to the VASI, but consisting of one row of lights Pneumatic. Operation by the use of compressed air. in two- or four-light systems. A pilot on the correct glideslope will see two white lights and two red lights. See VASI.

POH/AFM. See Pilot’s Operating Handbook/Airplane Flight Manual. Precision approach radar (PAR). A type of radar used at an airport to guide an aircraft through the final stages of Point-in-space approach. A type of helicopter instrument landing, providing horizontal and vertical guidance. The approach procedure to a missed approach point more than radar operator directs the pilot to change heading or adjust 2,600 feet from an associated helicopter landing area. the descent rate to keep the aircraft on a path that allows it to touch down at the correct spot on the runway.

Poor judgment chain. A series of mistakes that may lead to an accident or incident. Two basic principles generally Precision runway monitor (PRM). System allows associated with the creation of a poor judgment chain are: simultaneous, independent instrument flight rules (IFR) (1) one bad decision often leads to another; and (2) as a approaches at airports with closely spaced parallel runways.

string of bad decisions grows, it reduces the number of subsequent alternatives for continued safe flight. ADM is Preferred IFR routes. Routes established in the major intended to break the poor judgment chain before it can terminal and en route environments to increase system cause an accident or incident. efficiency and capacity. IFR clearances are issued based on these routes, listed in the Chart Supplement U.S. except Position error. Error in the indication of the altimeter, ASI, when severe weather avoidance procedures or other factors and VSI caused by the air at the static system entrance not dictate otherwise.

being absolutely still.

Preignition. Ignition occurring in the cylinder before the time Position report. A report over a known location as of normal ignition. Preignition is often caused by a local hot transmitted by an aircraft to ATC. spot in the combustion chamber igniting the fuel-air mixture.

Positive static stability. The initial tendency to return to a Pressure altitude. Altitude above the standard 29.92 "Hg state of equilibrium when disturbed from that state. plane.

G-23 Pressure demand oxygen system. A demand oxygen system R that supplies 100 percent oxygen at sufficient pressure above Rabbit, the. High-intensity flasher system installed at many the altitude where normal breathing is adequate. Also referred large airports. The flashers consist of a series of brilliant to as a pressure breathing system.

blue-white bursts of light flashing in sequence along the approach lights, giving the effect of a ball of light traveling Prevailing visibility. The greatest horizontal visibility toward the runway.

equaled or exceeded throughout at least half the horizon circle (which is not necessarily continuous).

Radar. A system that uses electromagnetic waves to identify the range, altitude, direction, or speed of both moving and Preventive maintenance. Simple or minor preservative fixed objects such as aircraft, weather formations, and terrain.

operations and the replacement of small standard parts The term RADAR was coined in 1941 as an acronym for not involving complex assembly operation as listed in 14 Radio Detection and Ranging. The term has since entered CFR part 43, appendix A. Certificated pilots may perform the English language as a standard word, radar, losing the preventive maintenance on any aircraft that is owned or capitalization in the process.

operated by them provided that the aircraft is not used in air carrier service.

Radar approach. The controller provides vectors while monitoring the progress of the flight with radar, guiding Primary and supporting. A method of attitude instrument the pilot through the descent to the airport/heliport or to a flying using the instrument that provides the most direct specific runway.

indication of attitude and performance.

Radar services. Radar is a method whereby radio waves are Primary flight display (PFD). A display that provides transmitted into the air and are then received when they have increased situational awareness to the pilot by replacing the been reflected by an object in the path of the beam. Range is traditional six instruments used for instrument flight with determined by measuring the time it takes (at the speed of light) an easy-to-scan display that provides the horizon, airspeed, for the radio wave to go out to the object and then return to the altitude, vertical speed, trend, trim, and rate of turn among receiving antenna. The direction of a detected object from a other key relevant indications.

radar site is determined by the position of the rotating antenna when the reflected portion of the radio wave is received.

PRM. See precision runway monitor.

Radar summary chart. A weather product derived from the Procedure turn. A maneuver prescribed when it is necessary national radar network that graphically displays a summary to reverse direction to establish an aircraft on the intermediate of radar weather reports.

approach segment or final approach course.

Radar weather report (SD). A report issued by radar Profile view. Side view of an IAP chart illustrating the vertical stations at 35 minutes after the hour, and special reports approach path altitudes, headings, distances, and fixes.

as needed. Provides information on the type, intensity, and location of the echo tops of the precipitation.

Prohibited area. Designated airspace within which flight of aircraft is prohibited.

Radials. The courses oriented from a station.

Propeller. A device for propelling an aircraft that, when Radio or radar altimeter. An electronic altimeter that rotated, produces by its action on the air, a thrust approximately determines the height of an aircraft above the terrain by perpendicular to its plane of rotation. It includes the control measuring the time needed for a pulse of radio-frequency components normally supplied by its manufacturer.

energy to travel from the aircraft to the ground and return.

Propeller/rotor modulation error. Certain propeller Radio frequency (RF). A term that refers to alternating rpm settings or helicopter rotor speeds can cause the VOR current (AC) having characteristics such that, if the current is course deviation indicator (CDI) to fluctuate as much as input to antenna, an electromagnetic (EM) field is generated ±6°. Slight changes to the rpm setting will normally smooth suitable for wireless broadcasting and/or communications.

out this roughness.

G-24 Radio magnetic indicator (RMI). An electronic navigation Reduced vertical separation minimum (RVSM). Reduces instrument that combines a magnetic compass with an ADF or the vertical separation between flight levels (FL) 290 and 410 VOR. The card of the RMI acts as a gyro-stabilized magnetic from 2,000 feet to 1,000 feet, and makes six additional FLs compass, and shows the magnetic heading the aircraft is flying. available for operation. Also see DRVSM.

Reference circle (also, distance circle). The circle depicted Radiosonde. A weather instrument that observes and reports in the plan view of an IAP chart that typically has a 10 NM meteorological conditions from the upper atmosphere. This radius, within which chart the elements are drawn to scale.

instrument is typically carried into the atmosphere by some form of weather balloon. Regions of command. The “regions of normal and reversed command” refers to the relationship between speed and the Radio wave. An electromagnetic (EM) wave with frequency power required to maintain or change that speed in flight.

characteristics useful for radio transmission.

Region of reverse command. Flight regime in which flight RAIM. See receiver autonomous integrity monitoring. at a higher airspeed requires a lower power setting and a lower airspeed requires a higher power setting in order to RAM recovery. The increase in thrust as a result of ram air maintain altitude.

pressures and density on the front of the engine caused by air velocity. REIL. See runway end identifier lights.

Random RNAV routes. Direct routes, based on area Relative bearing (RB). The angular difference between the navigation capability, between waypoints defined in terms aircraft heading and the direction to the station, measured of latitude/longitude coordinates, degree-distance fixes, or clockwise from the nose of the aircraft.

offsets from established routes/airways at a specified distance and direction. Relative bearing indicator (RBI). Also known as the fixed- card ADF, zero is always indicated at the top of the instrument Ranging signals. Transmitted from the GPS satellite, signals and the needle indicates the relative bearing to the station.

allowing the aircraft’s receiver to determine range (distance) from each satellite. Relative humidity. The ratio of the existing amount of water vapor in the air at a given temperature to the maximum Rapid decompression. The almost instantaneous loss of amount that could exist at that temperature; usually expressed cabin pressure in aircraft with a pressurized cockpit or cabin. in percent.

RB. See relative bearing. Relative wind. Direction of the airflow produced by an object moving through the air. The relative wind for an airplane in RBI. See relative bearing indicator. flight flows in a direction parallel with and opposite to the direction of flight; therefore, the actual flight path of the RCO. See remote communications outlet. airplane determines the direction of the relative wind.

Receiver autonomous integrity monitoring (RAIM). A Remote communications outlet (RCO). An unmanned system used to verify the usability of the received GPS signals communications facility that is remotely controlled by air and warns the pilot of any malfunction in the navigation traffic personnel.

system. This system is required for IFR-certified GPS units.

Required navigation performance (RNP). A specified level Recommended altitude. An altitude depicted on an instrument of accuracy defined by a lateral area of confined airspace in approach chart with the altitude value neither underscored nor which an RNP-certified aircraft operates.

overscored. The depicted value is an advisory value.

Restricted area. Airspace designated under 14 CFR part Receiver-transmitter (RT). A system that receives and 73 within which the flight of aircraft, while not wholly transmits a signal and an indicator. prohibited, is subject to restriction.

Reverse sensing. The VOR needle appearing to indicate the reverse of normal operation.

G-25 RF. Radio frequency. Runway edge lights. A component of the runway lighting system that is used to outline the edges of runways at night Rhodopsin. The photosensitive pigments that initiate the or during low visibility conditions. These lights are classified visual response in the rods of the eye. according to the intensity they are capable of producing.

Rigging. The final adjustment and alignment of an aircraft Runway end identifier lights (REIL). A pair of synchronized and its flight control system that provides the proper flashing lights, located laterally on each side of the runway aerodynamic characteristics. threshold, providing rapid and positive identification of the approach end of a runway.

Rigidity. The characteristic of a gyroscope that prevents its axis of rotation tilting as the Earth rotates. Runway visibility value (RVV). The visibility determined for a particular runway by a transmissometer.

Rigidity in space. The principle that a wheel with a heavily Runway visual range (RVR). The instrumentally derived weighted rim spinning rapidly will remain in a fixed position horizontal distance a pilot should be able to see down the in the plane in which it is spinning. runway from the approach end, based on either the sighting of high-intensity runway lights, or the visual contrast of Rime ice. Rough, milky, opaque ice formed by the other objects.

instantaneous freezing of small supercooled water droplets.

RVR. See runway visual range.

Risk. The future impact of a hazard that is not eliminated or controlled. RVV. See runway visibility value.

S Risk elements. There are four fundamental risk elements in aviation: the pilot, the aircraft, the environment, and the SA. See selective availability.

type of operation that comprise any given aviation situation.

St. Elmo’s Fire. A corona discharge which lights up the Risk management. The part of the decision-making aircraft surface areas where maximum static discharge occurs.

process which relies on situational awareness, problem recognition, and good judgment to reduce risks associated Satellite ephemeris data. Data broadcast by the GPS with each flight.

satellite containing very accurate orbital data for that satellite, atmospheric propagation data, and satellite clock error data.

RMI. See radio magnetic indicator.

Sea breeze. A coastal breeze blowing from sea to land RNAV. See area navigation.

caused by the temperature difference when the land surface is warmer than the sea surface. The sea breeze usually occurs RNP. See required navigation performance.

during the day and alternates with the land breeze that blows in the opposite direction at night.

RT. See receiver-transmitter.

Sea level engine. A reciprocating aircraft engine having a Rudder. The movable primary control surface mounted on rated takeoff power that is producible only at sea level.

the trailing edge of the vertical fin of an airplane. Movement of the rudder rotates the airplane about its vertical axis.

Scan. The first fundamental skill of instrument flight, also known as “cross-check;” the continuous and logical Ruddervator. A pair of control surfaces on the tail of an observation of instruments for attitude and performance aircraft arranged in the form of a V. These surfaces, when information.

moved together by the control wheel, serve as elevators, and when moved differentially by the rudder pedals, serve Sectional aeronautical charts. Designed for visual as a rudder.

navigation of slow- or medium-speed aircraft. Topographic information on these charts features the portrayal of relief, Runway centerline lights. Runway lighting which consists and a judicious selection of visual check points for VFR of flush centerline lights spaced at 50-foot intervals beginning flight. Aeronautical information includes visual and radio 75 feet from the landing threshold.

aids to navigation, airports, controlled airspace, restricted areas, obstructions and related data.

G-26 SDF. See simplified directional facility. Simplified directional facility (SDF). A NAVAID used for nonprecision instrument approaches. The final approach Selective availability (SA). A satellite technology permitting course is similar to that of an ILS localizer; however, the the Department of Defense (DOD) to create, in the interest SDF course may be offset from the runway, generally not of national security, a significant clock and ephemeris error more than 3°, and the course may be wider than the localizer, in the satellites, resulting in a navigation error. resulting in a lower degree of accuracy.

Semicircular canal. An inner ear organ that detects angular Single-pilot resource management (SRM). The ability acceleration of the body. for a pilot to manage all resources effectively to ensure the outcome of the flight is successful.

Semimonocoque. A fuselage design that includes a substructure of bulkheads and/or formers, along with stringers, Situational awareness. Pilot knowledge of where the aircraft to support flight loads and stresses imposed on the fuselage. is in regard to location, air traffic control, weather, regulations, aircraft status, and other factors that may affect flight.

Sensitive altimeter. A form of multipointer pneumatic altimeter with an adjustable barometric scale that allows the Skidding turn. An uncoordinated turn in which the rate of reference pressure to be set to any desired level. turn is too great for the angle of bank, pulling the aircraft to the outside of the turn.

Service ceiling. The maximum density altitude where the best rate-of-climb airspeed will produce a 100-feet-per-minute Skills and procedures. The procedural, psychomotor, and climb at maximum weight while in a clean configuration perceptual skills used to control a specific aircraft or its with maximum continuous power. systems. They are the airmanship abilities that are gained through conventional training, are perfected, and become Servo. A motor or other form of actuator which receives a almost automatic through experience.

small signal from the control device and exerts a large force to accomplish the desired work. Skin friction drag. Drag generated between air molecules and the solid surface of the aircraft.

Servo tab. An auxiliary control mounted on a primary control surface, which automatically moves in the direction opposite Slant range. The horizontal distance from the aircraft antenna the primary control to provide an aerodynamic assist in the to the ground station, due to line-of-sight transmission of the movement of the control. DME signal.

SIDS. See standard instrument departure procedures. Slaved compass. A system whereby the heading gyro is “slaved to,” or continuously corrected to bring its direction SIGMET. The acronym for Significant Meteorological readings into agreement with a remotely located magnetic information. A weather advisory in abbreviated plain direction sensing device (usually a flux valve or flux gate language concerning the occurrence or expected occurrence compass).

of potentially hazardous en route weather phenomena that may affect the safety of aircraft operations. SIGMET is warning Slipping turn. An uncoordinated turn in which the aircraft information, hence it is of highest priority among other types is banked too much for the rate of turn, so the horizontal lift of meteorological information provided to the aviation users. component is greater than the centrifugal force, pulling the aircraft toward the inside of the turn.

Signal-to-noise ratio. An indication of signal strength received compared to background noise, which is a measure Small airplane. An airplane of 12,500 pounds or less of the adequacy of the received signal. maximum certificated takeoff weight.

Significant weather prognostic. Presents four panels Somatogravic illusion. The misperception of being showing forecast significant weather. in a nose-up or nose-down attitude, caused by a rapid acceleration or deceleration while in flight situations that Simplex. Transmission and reception on the same frequency. lack visual reference.

G-27 Spatial disorientation. The state of confusion due to Stability. The inherent quality of an airplane to correct for misleading information being sent to the brain from various conditions that may disturb its equilibrium, and to return sensory organs, resulting in a lack of awareness of the aircraft or to continue on the original flight path. It is primarily an position in relation to a specific reference point. airplane design characteristic.

Special flight permit. A flight permit issued to an aircraft Stagnant hypoxia. A type of hypoxia that results when the that does not meet airworthiness requirements but is capable oxygen-rich blood in the lungs is not moving to the tissues of safe flight. A special flight permit can be issued to move that need it.

an aircraft for the purposes of maintenance or repair, buyer delivery, manufacturer flight tests, evacuation from danger, Stall. A rapid decrease in lift caused by the separation of or customer demonstration. Also referred to as a ferry permit. airflow from the wing’s surface, brought on by exceeding the critical angle of attack. A stall can occur at any pitch Special use airspace. Airspace in which flight activities are attitude or airspeed.

subject to restrictions that can create limitations on the mixed use of airspace. Consists of prohibited, restricted, warning, Standard atmosphere. At sea level, the standard atmosphere military operations, and alert areas. consists of a barometric pressure of 29.92 inches of mercury ("Hg) or 1013.2 millibars, and a temperature of 15 °C (59 Special fuel consumption. The amount of fuel in pounds °F). Pressure and temperature normally decrease as altitude per hour consumed or required by an engine per brake increases. The standard lapse rate in the lower atmosphere for horsepower or per pound of thrust. each 1,000 feet of altitude is approximately 1 "Hg and 2 °C (3.5 °F). For example, the standard pressure and temperature Speed. The distance traveled in a given time. at 3,000 feet mean sea level (MSL) are 26.92 "Hg (29.92 "Hg – 3 "Hg) and 9 °C (15 °C – 6 °C).

Spin. An aggravated stall that results in an airplane descending in a helical, or corkscrew path. Standard empty weight (GAMA). This weight consists of the airframe, engines, and all items of operating equipment Spiral instability. A condition that exists when the static that have fixed locations and are permanently installed in the directional stability of the airplane is very strong as compared airplane including fixed ballast, hydraulic fluid, unusable to the effect of its dihedral in maintaining lateral equilibrium. fuel, and full engine oil.

Spiraling slipstream. The slipstream of a propeller-driven Standard holding pattern. A holding pattern in which all airplane rotates around the airplane. This slipstream strikes turns are made to the right.

the left side of the vertical fin, causing the aircraft to yaw slightly. Rudder offset is sometimes used by aircraft designers Standard instrument departure procedures (SIDS).

to counteract this tendency. Published procedures to expedite clearance delivery and to facilitate transition between takeoff and en route operations.

Spoilers. High-drag devices that can be raised into the air flowing over an airfoil, reducing lift and increasing drag. Standard rate turn. A turn in which an aircraft changes its Spoilers are used for roll control on some aircraft. Deploying direction at a rate of 3° per second (360° in 2 minutes) for spoilers on both wings at the same time allows the aircraft low- or medium-speed aircraft. For high-speed aircraft, the to descend without gaining speed. Spoilers are also used to standard rate turn is 1½° per second (360° in 4 minutes).

shorten the ground roll after landing.

Standard service volume (SSV). Defines the limits of the SRM. See single-pilot resource management. volume of airspace which the VOR serves.

SSR. See secondary surveillance radar. Standard terminal arrival route (STAR). A preplanned IFR ATC arrival procedure published for pilot use in graphic SSV. See standard service volume. and/or textual form.

Stabilator. A single-piece horizontal tail surface on an Standard weights. Weights established for numerous items airplane that pivots around a central hinge point. A stabilator involved in weight and balance computations. These weights serves the purposes of both the horizontal stabilizer and the should not be used if actual weights are available.

elevators.

G-28 STAR. See standard terminal arrival route. Supercooled water droplets. Water droplets that have been cooled below the freezing point, but are still in a liquid state.

Static longitudinal stability. The aerodynamic pitching moments required to return the aircraft to the equilibrium Surface analysis chart. A report that depicts an analysis of angle of attack. the current surface weather. Shows the areas of high and low pressure, fronts, temperatures, dewpoints, wind directions Static pressure. Pressure of air that is still or not moving, and speeds, local weather, and visual obstructions.

measured perpendicular to the surface of the aircraft.

Synchro. A device used to transmit indications of angular Static stability. The initial tendency an aircraft displays movement or position from one location to another.

when disturbed from a state of equilibrium.

Synthetic vision. A realistic display depiction of the aircraft Station. A location in the airplane that is identified by a in relation to terrain and flight path.

number designating its distance in inches from the datum.

The datum is, therefore, identified as station zero. An item T located at station +50 would have an arm of 50 inches.

TAA. See terminal arrival area.

Stationary front. A front that is moving at a speed of less TACAN. See tactical air navigation.

than 5 knots.

Tactical air navigation (TACAN). An electronic navigation Steep turns. In instrument flight, any turn greater than standard system used by military aircraft, providing both distance and rate; in visual flight, anything greater than a 45° bank.

direction information.

Stepdown fix. The point after which additional descent is Takeoff decision speed (V ). Per 14 CFR section 23.51: permitted within a segment of an IAP.

“the calibrated airspeed on the ground at which, as a result of engine failure or other reasons, the pilot assumed to have Strapdown system. An INS in which the accelerometers made a decision to continue or discontinue the takeoff.” and gyros are permanently “strapped down” or aligned with the three axes of the aircraft.

Takeoff distance. The distance required to complete an all-engines operative takeoff to the 35-foot height. It must Stratoshere. A layer of the atmosphere above the tropopause be at least 15 percent less than the distance required for a extending to a height of approximately 160,000 feet.

one-engine inoperative engine takeoff. This distance is not normally a limiting factor as it is usually less than the one- Stress. The body’s response to demands placed upon it.

engine inoperative takeoff distance.

Stress management. The personal analysis of the kinds of Takeoff safety speed (V ). Per 14 CFR part 1: “A referenced stress experienced while flying, the application of appropriate airspeed obtained after lift-off at which the required one stress assessment tools, and other coping mechanisms.

engine-inoperative climb performance can be achieved.” Structural icing. The accumulation of ice on the exterior TAWS. See terrain awareness and warning system.

of the aircraft.

Taxiway lights. Omnidirectional lights that outline the edges Sublimation. Process by which a solid is changed to a gas of the taxiway and are blue in color.

without going through the liquid state.

Taxiway turnoff lights. Lights that are flush with the runway Suction relief valve. A relief valve in an instrument vacuum which emit a steady green color.

system required to maintain the correct low pressure inside the instrument case for the proper operation of the gyros.

TCAS. See traffic alert collision avoidance system.

Supercharger. An engine- or exhaust-driven air compressor TCH. See threshold crossing height.

used to provide additional pressure to the induction air so the engine can produce additional power.

TDZE. See touchdown zone elevation.

G-29 TEC. See Tower En Route Control. Terrain awareness and warning system (TAWS). A timed-based system that provides information concerning Technique. The manner in which procedures are executed. potential hazards with fixed objects by using GPS positioning and a database of terrain and obstructions to provide true Telephone information briefing service (TIBS). An FSS predictability of the upcoming terrain and obstacles.

service providing continuously updated automated telephone recordings of area and/or route weather, airspace procedures, TFR. See temporary flight restriction.

and special aviation-oriented announcements.

Thermosphere. The last layer of the atmosphere that begins Temporary flight restriction (TFR). Restriction to flight above the mesosphere and gradually fades away into space.

imposed in order to: Threshold crossing height (TCH). The theoretical height 1. Protect persons and property in the air or on the surface above the runway threshold at which the aircraft’s glideslope from an existing or imminent flight associated hazard; antenna would be if the aircraft maintained the trajectory 2. Provide a safe environment for the operation of established by the mean ILS glideslope or MLS glidepath.

disaster relief aircraft; Thrust. The force which imparts a change in the velocity of a 3. Prevent an unsafe congestion of sightseeing aircraft mass. This force is measured in pounds but has no element of above an incident; time or rate. The term “thrust required” is generally associated 4. Protect the President, Vice President, or other public with jet engines. A forward force which propels the airplane figures; and, through the air.

5. Provide a safe environment for space agency operations.

Thrust (aerodynamic force). The forward aerodynamic Pilots are expected to check appropriate NOTAMs during force produced by a propeller, fan, or turbojet engine as it flight planning when conducting flight in an area where a forces a mass of air to the rear, behind the aircraft.

temporary flight restriction is in effect.

Thrust line. An imaginary line passing through the center of Tension. Maintaining an excessively strong grip on the control the propeller hub, perpendicular to the plane of the propeller column, usually resulting in an overcontrolled situation.

rotation.

Terminal aerodrome forecast (TAF). A report established Time and speed table. A table depicted on an instrument for the 5 statute mile radius around an airport. Utilizes the approach procedure chart that identifies the distance from the same descriptors and abbreviations as the METAR report.

FAF to the MAP, and provides the time required to transit that distance based on various groundspeeds.

Terminal arrival area (TAA). A procedure to provide a new transition method for arriving aircraft equipped with Timed turn. A turn in which the clock and the turn FMS and/or GPS navigational equipment. The TAA contains coordinator are used to change heading a definite number a “T” structure that normally provides a NoPT for aircraft of degrees in a given time.

using the approach.

TIS. See traffic information service.

Terminal instrument approach procedure (TERP).

Prescribes standardized methods for use in designing Title 14 of the Code of Federal Regulations (14 CFR).

instrument flight procedures.

Includes the federal aviation regulations governing the operation of aircraft, airways, and airmen.

TERP. See terminal instrument approach procedure.

Torque. (1) A resistance to turning or twisting. (2) Forces that Terminal radar service areas (TRSA). Areas where produce a twisting or rotating motion. (3) In an airplane, the participating pilots can receive additional radar services. The tendency of the aircraft to turn (roll) in the opposite direction purpose of the service is to provide separation between all of rotation of the engine and propeller. (4) In helicopters with IFR operations and participating VFR aircraft.

a single, main rotor system, the tendency of the helicopter to turn in the opposite direction of the main rotor rotation.

G-30 Torquemeter. An instrument used with some of the larger Transponder code. One of 4,096 four-digit discrete codes reciprocating engines and turboprop or turboshaft engines to ATC assigns to distinguish between aircraft.

measure the reaction between the propeller reduction gears and the engine case. Trend. Immediate indication of the direction of aircraft movement, as shown on instruments.

Total drag. The sum of the parasite drag and induced drag.

Tricycle gear. Landing gear employing a third wheel located Touchdown zone elevation (TDZE). The highest elevation on the nose of the aircraft.

in the first 3,000 feet of the landing surface, TDZE is indicated on the instrument approach procedure chart when Trim. To adjust the aerodynamic forces on the control straight-in landing minimums are authorized. surfaces so that the aircraft maintains the set attitude without any control input.

Touchdown zone lights. Two rows of transverse light bars disposed symmetrically about the runway centerline in the Trim tab. A small auxiliary hinged portion of a movable runway touchdown zone. control surface that can be adjusted during flight to a position resulting in a balance of control forces.

Tower En Route Control (TEC). The control of IFR en route traffic within delegated airspace between two Tropopause. The boundary layer between the troposphere or more adjacent approach control facilities, designed to and the stratosphere which acts as a lid to confine most of the expedite traffic and reduce control and pilot communication water vapor, and the associated weather, to the troposphere.

requirements.

Troposphere. The layer of the atmosphere extending from TPP. See United States Terminal Procedures Publication. the surface to a height of 20,000 to 60,000 feet, depending on latitude.

Track. The actual path made over the ground in flight.

True airspeed. Actual airspeed, determined by applying a Tracking. Flying a heading that will maintain the desired correction for pressure altitude and temperature to the CAS.

track to or from the station regardless of crosswind conditions.

True altitude. The vertical distance of the airplane above Traffic Alert Collision Avoidance System (TCAS). sea level—the actual altitude. It is often expressed as feet An airborne system developed by the FAA that operates above mean sea level (MSL). Airport, terrain, and obstacle independently from the ground-based Air Traffic Control elevations on aeronautical charts are true altitudes.

system. Designed to increase flight deck awareness of proximate aircraft and to serve as a “last line of defense” for Truss. A fuselage design made up of supporting structural the prevention of midair collisions. members that resist deformation by applied loads. The truss- type fuselage is constructed of steel or aluminum tubing.

Traffic information service (TIS). A ground-based service Strength and rigidity is achieved by welding the tubing providing information to the flight deck via data link using together into a series of triangular shapes, called trusses.

the S-mode transponder and altitude encoder to improve the safety and efficiency of “see and avoid” flight through an T-tail. An aircraft with the horizontal stabilizer mounted on automatic display that informs the pilot of nearby traffic. the top of the vertical stabilizer, forming a T.

Trailing edge. The portion of the airfoil where the airflow Turbine discharge pressure. The total pressure at the over the upper surface rejoins the lower surface airflow. discharge of the low-pressure turbine in a dual-turbine axial- flow engine.

Transcribed Weather Broadcast (TWEB). An FSS service, available in Alaska only, providing continuously updated Turbine engine. An aircraft engine which consists of an automated broadcast of meteorological and aeronautical data air compressor, a combustion section, and a turbine. Thrust over selected L/MF and VOR NAVAIDs. is produced by increasing the velocity of the air flowing through the engine.

Transponder. The airborne portion of the ATC radar beacon system.

G-31 Turbocharger. An air compressor driven by exhaust gases, Underpower. Using less power than required for the purpose which increases the pressure of the air going into the engine of achieving a faster rate of airspeed change.

through the carburetor or fuel injection system.

United States Terminal Procedures Publication (TPP).

Turbofan engine. A fanlike turbojet engine designed to Booklets published in regional format by FAA Aeronautical create additional thrust by diverting a secondary airflow Navigation Products (AeroNav Products) that include DPs, around the combustion chamber. STARs, IAPs, and other information pertinent to IFR flight.

Turbojet engine. A turbine engine which produces its thrust Unusual attitude. An unintentional, unanticipated, or entirely by accelerating the air through the engine. extreme aircraft attitude.

Turboprop engine. A turbine engine which drives a Useful load. The weight of the pilot, copilot, passengers, propeller through a reduction gearing arrangement. Most of baggage, usable fuel, and drainable oil. It is the basic empty the energy in the exhaust gases is converted into torque, rather weight subtracted from the maximum allowable gross weight.

than using its acceleration to drive the aircraft. This term applies to general aviation aircraft only.

Turboshaft engine. A gas turbine engine that delivers power User-defined waypoints. Waypoint location and other data through a shaft to operate something other than a propeller. which may be input by the user, this is the only GPS database information that may be altered (edited) by the user.

Turn-and-slip indicator. A flight instrument consisting V of a rate gyro to indicate the rate of yaw and a curved glass inclinometer to indicate the relationship between gravity and V . See takeoff decision speed.

centrifugal force. The turn-and-slip indicator indicates the relationship between angle of bank and rate of yaw. Also V2. See takeoff safety speed.

called a turn-and-bank indicator.

VA . See maneuvering speed.

Turn coordinator. A rate gyro that senses both roll and yaw due to the gimbal being canted. Has largely replaced Vapor lock. A problem that mostly affects gasoline-fuelled the turn-and-slip indicator in modern aircraft.

internal combustion engines. It occurs when the liquid fuel changes state from liquid to gas while still in the fuel delivery TWEB. See Transcribed Weather Broadcast.

system. This disrupts the operation of the fuel pump, causing loss of feed pressure to the carburetor or fuel injection system, U resulting in transient loss of power or complete stalling.

UHF. See ultra-high frequency. Restarting the engine from this state may be difficult. The fuel can vaporize due to being heated by the engine, by the Ultra-high frequency (UHF). The range of electromagnetic local climate or due to a lower boiling point at high altitude.

frequencies between 300 MHz and 3,000 MHz.

Variation. Compass error caused by the difference in the physical locations of the magnetic north pole and the Ulitimate load factor. In stress analysis, the load that causes physical breakdown in an aircraft or aircraft geographic north pole.

component during a strength test, or the load that according to computations, should cause such a breakdown. VASI. See visual approach slope indicator.

Uncaging. Unlocking the gimbals of a gyroscopic instrument, VDP. See visual descent point.

making it susceptible to damage by abrupt flight maneuvers or rough handling. Vector. A force vector is a graphic representation of a force and shows both the magnitude and direction of the force.

Uncontrolled airspace. Class G airspace that has not been Vectoring. Navigational guidance by assigning headings.

designated as Class A, B, C, D, or E. It is airspace in which air traffic control has no authority or responsibility to control VEF. Calibrated airspeed at which the critical engine of a air traffic; however, pilots should remember there are VFR minimums which apply to this airspace. multi-engine aircraft is assumed to fail.

G-32 Velocity. The speed or rate of movement in a certain V-G diagram. A chart that relates velocity to load factor. It direction. is valid only for a specific weight, configuration and altitude and shows the maximum amount of positive or negative lift Venturi tube. A specially shaped tube attached to the outside the airplane is capable of generating at a given speed. Also of an aircraft to produce suction to allow proper operation shows the safe load factor limits and the load factor that the of gyro instruments. aircraft can sustain at various speeds.

Vertical axis. An imaginary line passing vertically through Victor airways. Airways based on a centerline that extends the center of gravity of an aircraft. The vertical axis is called from one VOR or VORTAC navigation aid or intersection, the z-axis or the yaw axis. to another navigation aid (or through several navigation aids or intersections); used to establish a known route for en route Vertical card compass. A magnetic compass that consists of procedures between terminal areas.

an azimuth on a vertical card, resembling a heading indicator with a fixed miniature airplane to accurately present the Visual approach slope indicator (VASI). A visual aid of heading of the aircraft. The design uses eddy current damping lights arranged to provide descent guidance information to minimize lead and lag during turns. during the approach to the runway. A pilot on the correct glideslope will see red lights over white lights.

Vertical speed indicator (VSI). A rate-of-pressure change instrument that gives an indication of any deviation from a Visual descent point (VDP). A defined point on the final constant pressure level. approach course of a nonprecision straight-in approach procedure from which normal descent from the MDA to the Vertical stability. Stability about an aircraft’s vertical axis. runway touchdown point may be commenced, provided the Also called yawing or directional stability. runway environment is clearly visible to the pilot.

Very-high frequency (VHF). A band of radio frequencies Visual flight rules (VFR). Flight rules adopted by the falling between 30 and 300 MHz. FAA governing aircraft flight using visual references. VFR operations specify the amount of ceiling and the visibility the Very-high frequency omnidirectional range (VOR). pilot must have in order to operate according to these rules.

Electronic navigation equipment in which the flight deck When the weather conditions are such that the pilot cannot instrument identifies the radial or line from the VOR station, operate according to VFR, he or she must use instrument measured in degrees clockwise from magnetic north, along flight rules (IFR).

which the aircraft is located.

Visual meteorological conditions (VMC). Meteorological Vestibule. The central cavity of the bony labyrinth of the conditions expressed in terms of visibility, distance from ear, or the parts of the membranous labyrinth that it contains. cloud, and ceiling meeting or exceeding the minimums specified for VFR.

V . The maximum speed with the flaps extended. The upper FE limit of the white arc. V . Landing gear extended speed. The maximum speed at LE which an airplane can be safely flown with the landing gear VFR. See visual flight rules. extended.

VFR on top. ATC authorization for an IFR aircraft to operate V . Landing gear operating speed. The maximum speed for LO in VFR conditions at any appropriate VFR altitude. extending or retracting the landing gear if using an airplane equipped with retractable landing gear.

VFR over the top. A VFR operation in which an aircraft operates in VFR conditions on top of an undercast. V . Minimum control airspeed. This is the minimum MC flight speed at which a light, twin-engine airplane can be VFR terminal area chart. At a scale of 1:250,000, a chart satisfactorily controlled when an engine suddenly becomes that depicts Class B airspace, which provides for the control inoperative and the remaining engine is at takeoff power.

or segregation of all the aircraft within the Class B airspace.

The chart depicts topographic information and aeronautical VMC. See visual meteorological conditions.

information including visual and radio aids to navigation, airports, controlled airspace, restricted areas, obstructions, and related data.

G-33 V . The never-exceed speed. Operating above this speed is NE W prohibited since it may result in damage or structural failure.

WAAS. See wide area augmentation system.

The red line on the airspeed indicator.

Wake turbulence. Wingtip vortices that are created when V . The maximum structural cruising speed. Do not NO an airplane generates lift. When an airplane generates lift, exceed this speed except in smooth air. The upper limit of air spills over the wingtips from the high pressure areas the green arc.

below the wings to the low pressure areas above them. This flow causes rapidly rotating whirlpools of air called wingtip VOR. See very-high frequency omnidirectional range.

vortices or wake turbulence.

VORTAC. A facility consisting of two components, VOR Warm front. The boundary area formed when a warm air and TACAN, which provides three individual services: VOR mass contacts and flows over a colder air mass. Warm fronts azimuth, TACAN azimuth, and TACAN distance (DME) cause low ceilings and rain.

at one site.

Warning area. An area containing hazards to any aircraft VOR test facility (VOT). A ground facility which emits a not participating in the activities being conducted in the test signal to check VOR receiver accuracy. Some VOTs are area. Warning areas may contain intensive military training, available to the user while airborne, while others are limited gunnery exercises, or special weapons testing.

to ground use only.

WARP. See weather and radar processing.

VOT. See VOR test facility.

Waste gate. A controllable valve in the tailpipe of an aircraft VSI. See vertical speed indicator.

reciprocating engine equipped with a turbocharger. The valve is controlled to vary the amount of exhaust gases forced V . The stalling speed or the minimum steady flight speed S0 through the turbocharger turbine.

in the landing configuration. In small airplanes, this is the power-off stall speed at the maximum landing weight in the Waypoint. A designated geographical location used for route landing configuration (gear and flaps down). The lower limit definition or progress-reporting purposes and is defined in of the white arc.

terms of latitude/longitude coordinates.

V . The stalling speed or the minimum steady flight speed S1 WCA. See wind correction angle.

obtained in a specified configuration. For most airplanes, this is the power-off stall speed at the maximum takeoff weight Weather and radar processor (WARP). A device that in the clean configuration (gear up, if retractable, and flaps provides real-time, accurate, predictive, and strategic weather up). The lower limit of the green arc.

information presented in an integrated manner in the National Airspace System (NAS).

V-tail. A design which utilizes two slanted tail surfaces to perform the same functions as the surfaces of a conventional Weather depiction chart. Details surface conditions as elevator and rudder configuration. The fixed surfaces act as derived from METAR and other surface observations.

both horizontal and vertical stabilizers.

Weight. The force exerted by an aircraft from the pull of V . Best angle-of-climb speed. The airspeed at which an X gravity.

airplane gains the greatest amount of altitude in a given distance. It is used during a short-field takeoff to clear an Wide area augmentation system (WAAS). A differential obstacle.

global positioning system (DGPS) that improves the accuracy of the system by determining position error from the GPS V . Best rate-of-climb speed. This airspeed provides the Y satellites, then transmitting the error, or corrective factors, most altitude gain in a given period of time.

to the airborne GPS receiver.

V . Best rate-of-climb speed with one engine inoperative.

YSE Wind correction angle (WCA). The angle between the This airspeed provides the most altitude gain in a given desired track and the heading of the aircraft necessary to period of time in a light, twin-engine airplane following an keep the aircraft tracking over the desired track.

engine failure.

G-34 Wind direction indicators. Indicators that include a Z wind sock, wind tee, or tetrahedron. Visual reference will Zone of confusion. Volume of space above the station where determine wind direction and runway in use.

a lack of adequate navigation signal directly above the VOR station causes the needle to deviate.

Wind shear. A sudden, drastic shift in windspeed, direction, or both that may occur in the horizontal or vertical plane.

Zulu time. A term used in aviation for coordinated universal time (UTC) which places the entire world on one time standard.

Winds and temperature aloft forecast (FB). A twice daily forecast that provides wind and temperature forecasts for specific locations in the contiguous United States.

Wing area. The total surface of the wing (in square feet), which includes control surfaces and may include wing area covered by the fuselage (main body of the airplane), and engine nacelles.

Wings. Airfoils attached to each side of the fuselage and are the main lifting surfaces that support the airplane in flight.

Wing root. The wing root is the part of the wing on a fixed- wing aircraft that is closest to the fuselage. Wing roots usually bear the highest bending forces in flight and during landing, and they often have fairings to reduce interference drag between the wing and the fuselage. The opposite end of a wing from the wing root is the wing tip.

Wing span. The maximum distance from wingtip to wingtip.

Wingtip vortices. The rapidly rotating air that spills over an airplane’s wings during flight. The intensity of the turbulence depends on the airplane’s weight, speed, and configuration.

Also referred to as wake turbulence. Vortices from heavy aircraft may be extremely hazardous to small aircraft.

Wing twist. A design feature incorporated into some wings to improve aileron control effectiveness at high angles of attack during an approach to a stall.

Work. A measurement of force used to produce movement.

World Aeronautical Charts (WAC). A standard series of aeronautical charts covering land areas of the world at a size and scale convenient for navigation (1:1,000,000) by moderate speed aircraft. Topographic information includes cities and towns, principal roads, railroads, distinctive landmarks, drainage, and relief. Aeronautical information includes visual and radio aids to navigation, airports, airways, restricted areas, obstructions and other pertinent data.

G-35 G-36

Index

Other markings ....................................................... 14-15 A Runway markings ..................................................... 14-5 Adjustable stabilizer ..................................................... 6-12 Taxiway markings .................................................. 14-11 Adverse balance ........................................................... 10-3 Airports ........................................................................ 14-2 Adverse conditions ....................................................... 13-5 Civil airports ............................................................. 14-2 Adverse yaw ................................................................... 6-3 Military/federal government airports ....................... 14-2 Advisory circular (AC) ................................................ 1-10 Private airports ......................................................... 14-2 Aeromedical factors ..................................................... 17-1 Towered .................................................................... 14-2 Aeronautical charts ............................................ 14-3, 16-2 Nontowered .............................................................. 14-2 Aeronautical decision-making ....................................... 2-1 Airport signs ............................................................... 14-15 History of ADM ......................................................... 2-2 Destination signs ........................................ 14-12, 14-16 Aeronautical Information Manual (AIM) ...................... 1-9 Direction signs ........................................................ 14-16 After-landing..............................................................14-34 Information signs .................................................... 14-16 Ailerons .......................................................................... 6-3 Location signs ........................................................ 14-15 Coupled ailerons ......................................................... 6-4 Mandatory instruction signs ................................... 14-15 Differential ailerons .................................................... 6-4 Runway distance remaining signs .......................... 14-16 Frise-type ailerons ...................................................... 6-4 Airport surveillance radar ............................................ 13-4 Airborne radar .............................................................. 13-4 Air Route surveillance radar (ARSR) .......................... 13-2 Aircraft documents ......................................................... 9-6 Air Route traffic control center (ARTCC) ................... 13-2 Aircraft engine ............................................................... 7-1 Airship .......................................................................... 1-15 Aircraft inspections ........................................................ 9-8 Airspace ....................................................................... 15-1 100-hour Inspection .................................................... 9-8 Airspeed ............................................................. 9-2, 16-10 Altimeter system inspection ....................................... 9-9 Airspeed indicator (ASI) .............................................. 11-2 Annual inspection ....................................................... 9-8 Airspeed indicator markings .......................................... 8-9 Preflight inspections ................................................... 9-9 Airspeed limitations ....................................................... 8-9 Transponder inspection .............................................. 9-9 Airspeed tape ............................................................... 8-12 Aircraft maintenance ...................................................... 9-8 Air traffic control (ATC) ................................. 14-24, 15-7 Aircraft owner/operator responsibilities ...................... 9-13 Airworthiness certificate ................................................ 9-7 Aircraft Owners and Pilots Association (AOPA) ........ 3-13 Airworthiness directives (ADs) ................................... 9-12 Aircraft types and categories ....................................... 1-15 Alcohol ....................................................................... 17-15 Air data computer (ADC) ............................................ 8-14 Alert areas .................................................................... 15-4 Airfoil ..................................................................... 4-6, 4-7 Alternator ..................................................................... 7-30 Leading edge .............................................................. 4-6 Altimeter .............................................................. 8-3, 8-13 Trailing edge ............................................................... 4-6 Setting the altimeter .................................................... 8-5 Airframe systems ......................................................... 7-25 Altimeter operation ........................................................ 8-6 Airline Deregulation Act of 1978 .................................. 1-7 Altitude ................................................................ 8-6, 12-6 Air masses..................................................................12-17 Absolute altitude ......................................................... 8-7 Air navigation .............................................................. 16-1 Density altitude ........................................................... 8-7 Airplane ........................................................................ 1-15 Indicated altitude ........................................................ 8-6 Airplane flight manuals (AFM) ......................... 9-1, 16-17 Pressure altitude ......................................................... 8-7 Airport beacon ........................................................... 14-16 True altitude ............................................................... 8-6 Airport lighting .......................................................... 14-18 Altitude-induced decompression sickness (DCS)......17-18 Airport markings .......................................................... 14-5 I-1 Ammeter ...................................................................... 7-31 Wind ...................................................................... 13-6 Aneroid barometer ....................................................... 12-5 Zulu time ............................................................... 13-7 Aneroid wafer ................................................................ 8-3 Pilot weather reports (PIREPs) ................................. 13-8 Angle of attack (AOA) ................................................... 6-4 Axes of an aircraft ........................................................ 5-12 Anti-ice ........................................................................ 7-40 Axes of rotation .............................................................. 6-3 Antiservo tab ........................................................ 3-6, 6-11 Approach light systems .............................................. 14-16 B Arm .............................................................................. 10-4 Balance ......................................................................... 10-2 Assembling necessary material .................................. 16-17 Balance tabs ................................................................. 6-11 ATC Automation ........................................................... 1-6 Balloon ......................................................................... 1-15 ATC delays .................................................................. 13-5 Barbs .......................................................................... 12-12 ATC radar beacon system (ATCRBS) ....................... 14-24 Basic aerodynamics ....................................................... 3-2 ATC radar weather displays ....................................... 13-16 Drag ............................................................................ 3-2 Atmosphere ................................................. 4-1, 11-2, 12-2 Lift .............................................................................. 3-2 Atmospheric circulation ............................................... 12-3 Thrust ......................................................................... 3-2 Atmospheric pressure ........................................... 4-3, 11-2 Weight ........................................................................ 3-2 Atmospheric stability ................................................. 12-12 Basic empty weight ...................................................... 10-4 Attitude indicator ............................................... 8-13, 8-18 Bernoulli, Daniel ............................................................ 4-6 Autokinesis ................................................................ 17-26 Bernoulli’s Principle of Differential Pressure ................ 4-6 Automatic decision-making ......................................... 2-21 Best angle-of-climb speed (V ) ................................... 8-10 X Operational pitfalls ................................................... 2-21 Best rate-of-climb speed (V ) ...................................... 8-10 Y Automatic direction finder (ADF) ............................. 16-29 Binocular cues ............................................................ 17-26 Automation .................................................................. 2-25 Blade angle ................................................................... 5-28 Automation management ............................................. 2-31 Bleed air heating systems ............................................. 7-30 Autopilot ...................................................................... 6-12 Blocked pitot system .................................................... 8-10 Autopilot systems ......................................................... 2-27 Blocked static system ................................................... 8-11 Aviation forecasts ........................................................ 13-9 Boundary layer ..................................................... 5-6, 5-46 Area forecasts (FA) ...................................... 13-9, 13-10 Brake horsepower (BHP) ..................................... 7-6, 7-24 Terminal aerodrome forecasts (TAF) ....................... 13-9 Brakes .......................................................................... 7-34 Forecast change group ......................................... 13-9 Bus bar ......................................................................... 7-31 Forecast significant weather ................................ 13-9 Forecast sky condition .......................................... 13-9 C Forecast visibility ................................................. 13-9 Cabin pressure control system ..................................... 7-35 Forecast wind ....................................................... 13-9 Cabin pressurization system ........................................ 7-35 ICAO station identifier ......................................... 13-9 Calibrated airspeed (CAS) ................................. 8-9, 11-18 Probability forecast .............................................. 13-9 Canard ............................................................................ 6-7 Type of report ....................................................... 13-9 Carbon monoxide (CO) poisoning.............................17-12 Aviation medical examiner (AME) ............................. 17-2 Carburetor air temperature gauge ................................ 7-11 Aviation routine weather report (METAR) ............... 12-17 Carburetor heat ............................................................. 7-10 Aviation safety inspector (ASI) ..................................... 1-9 Carburetor icing ............................................................. 7-9 Aviation weather reports .............................................. 13-5 Carburetor systems ......................................................... 7-8 Aviation routine weather report (METAR) Float-type carburetor .................................................. 7-8 Altimeter setting .................................................... 13-7 Pressure-type carburetor ............................................. 7-9 Modifier ................................................................ 13-6 Ceiling........................................................................12-17 Remarks ................................................................ 13-7 Center of gravity (CG) ....................................... 10-2, 10-4 Sky condition ......................................................... 13-7 CG limits .................................................................. 10-5 Station identifier ................................................... 13-6 CG range ................................................................... 10-5 Temperature and dew point .................................. 13-7 Central blind spot ....................................................... 17-21 Type of report ....................................................... 13-6 Certificated flight instructor (CFI) ..................... 1-19, 1-23 Visibility ................................................................ 13-6 Certificate of aircraft registration ................................... 9-6 Weather ................................................................. 13-6 I-2 Chandelles .................................................................... 5-36 Course deviation indicator (CDI) ............................... 16-23 Chart Supplement U.S. .............................................. 16-17 Course intercept ......................................................... 16-27 Clearing procedures ................................................... 14-28 Angle of intercept ................................................... 16-27 Before takeoff ......................................................... 14-28 Rate of intercept ..................................................... 16-27 Climbs and descents ............................................... 14-28 Cross-country flying .................................................... 16-1 Straight and Level .................................................. 14-28 Crosswind and headwind component chart ............... 11-25 Traffic at VOR sites ............................................... 14-28 Current conditions ........................................................ 13-5 Traffic patterns ....................................................... 14-28 Training operations ................................................. 14-28 D Climb performance ...................................................... 11-6 Dark adaptation .......................................................... 17-23 Angle of climb (AOC) .............................................. 11-7 Datum ........................................................................... 10-5 Climb Performance Factors ...................................... 11-8 Data link weather ....................................................... 13-21 Rate of climb (ROC) ................................................ 11-7 Data link weather products ........................................ 13-23 Clouds ........................................................................ 12-15 Flight information service-broadcast (FIS-B) ........ 13-23 Cloud classification ................................................ 12-17 Daylight saving time .................................................... 16-5 Alto ...................................................................... 12-17 Dead reckoning .......................................................... 16-13 Castellanus ......................................................... 12-17 DECIDE model ............................................................ 2-18 Cirrus .................................................................. 12-17 Choose (a course of action) ...................................... 2-20 Cumulus .............................................................. 12-17 Detect (the problem) ................................................. 2-20 Fracto ................................................................. 12-17 Do (the necessary actions) ........................................ 2-20 Lenticularus ........................................................ 12-17 Estimate (the need to react) ...................................... 2-20 Nimbus ................................................................ 12-17 Evaluate (the effect of the action) ............................ 2-20 Stratus ................................................................. 12-17 Identify (solutions) ................................................... 2-20 Code of Federal Regulations (CFR) .............................. 1-7 Decision-making in a dynamic environment ............... 2-21 Collision avoidance....................................................14-28 Use of resources ....................................................... 2-21 Combustion .................................................................. 7-18 External resources ................................................ 2-23 Combustion heater systems .......................................... 7-29 Internal resources ................................................. 2-23 Compass heading ....................................................... 16-16 Decision-making process ............................................. 2-12 Composite materials in aircraft ...................................... 3-9 Dehydration ................................................................ 17-14 Composites ..................................................................... 3-9 Deice system ................................................................ 7-40 Compressor stalls ......................................................... 7-23 Delta ............................................................................. 10-5 Control ......................................................................... 10-3 Density altitude .............................................................. 4-4 Control instruments ...................................................... 3-13 Density altitude charts................................................11-20 Controllability .................................................... 5-15, 5-42 Density altitude (DA) ................................................... 12-5 Controlled airport ......................................................... 14-2 Department of transportation (DOT) ............................. 1-6 Controlled airspace ...................................................... 15-2 Deposition ..................................................................12-15 Class A airspace ....................................................... 15-2 Designated pilot examiner ........................................... 1-24 Class B airspace ........................................................ 15-2 Design maneuvering speed (V ) .................................. 8-10 A Class C airspace ........................................................ 15-2 Destination forecast ..................................................... 13-5 Class D airspace ....................................................... 15-2 Determining loaded weight and CG ............................ 10-7 Class E airspace ........................................................ 15-2 Deviation .......................................................... 16-8, 16-16 Controlled firing areas (CFAs) .................................... 15-4 Dew point ....................................................... 12-13, 13-13 Convective currents ..................................................... 12-7 Distance measuring equipment (DME) ..................... 16-27 Convective significant meteorological Doppler radar ............................................................... 13-3 information (WST) ..................................................... 13-12 Drag ........................................................................ 5-1, 5-6 Converting KTS to MPH ........................................... 16-11 Form drag ................................................................... 5-6 Converting minutes to equivalent hours .................... 16-11 Induced drag ....................................................... 5-6, 5-7 Cooling ........................................................................... 7-1 Interference drag ......................................................... 5-6 Coriolis force ............................................................... 12-3 Parasite drag ............................................................... 5-6 Corkscrew effect .......................................................... 5-31 Skin friction drag ........................................................ 5-6 Course ........................................................................ 16-10 I-3 Drift angle ..................................................................16-10 Filing a VFR flight plan.............................................16-21 Drugs..........................................................................17-16 Flameout ......................................................................7-24 Dutch roll .....................................................................5-20 Flaperons........................................................................6-5 Dynamic hydroplaning...............................................11-13 Flaps...............................................................................6-8 Fowler flaps................................................................6-9 Plain flap ....................................................................6-8 E Split flap .....................................................................6-8 Eddy current damping..................................................8-27 Flicker vertigo............................................................17-27 Electrical ........................................................................7-1 Flight ..............................................................................1-2 Electrical system ..........................................................7-30 Flight computers ........................................................16-12 Electronic flight display (EFD)............... 3-12, 8-12, 13-18 Flight controls ................................................................6-2 Elevator .................................................................. 3-6, 6-5 Flight control systems ....................................................6-1 Emergency locator transmitter (ELT)............................9-9 Flight diversion ..........................................................16-34 Empennage............................................................. 3-3, 3-6 Flight limits....................................................................9-4 Empty-field myopia ...................................................17-22 Flight maneuvers..........................................................5-36 Engine ............................................................................7-1 Flight planning ...........................................................16-17 Engine cooling systems................................................7-17 Flight school.................................................................1-18 Engineered materials arresting systems (EMAS) ......14-35 Flight service station ....................................................13-4 Engine pressure ratio (EPR).........................................7-22 Flight Standards District Office (FSDO) .......................1-9 Engine temperature limitations ....................................7-23 Flight Standards Service (AFS) .....................................1-8 Enhanced flight vision system ...................................17-28 Floor load limit ............................................................10-5 Enhanced night vision systems ..................................17-27 Flux gate compass system............................................8-20 Enhanced situational awareness...................................2-30 Fog ................................................................. 12-15, 17-10 Enhanced taxiway centerline markings .....................14-12 Advection fog.........................................................12-15 En route forecast ..........................................................13-5 Ice fog.....................................................................12-15 Environmental control systems......................................7-1 Radiation fog ..........................................................12-15 Equipment use..............................................................2-27 Sea smoke...............................................................12-15 Equivalent airspeed (EAS).........................................11-18 Steam fog................................................................12-15 Equivalent shaft horsepower (ESHP) ..........................7-24 Upslope fog ............................................................12-15 Estimated time en route (ETE) ..................................16-17 Forces in climbs ...........................................................5-23 Exhaust gas temperature (EGT)...................................7-22 Forces in descents ........................................................5-24 Exhaust gas temperature (EGT) gauge ..........................7-9 Forces in turns..............................................................5-22 Exhaust heating systems ..............................................7-29 Foreign object damage (FOD) .....................................7-23 Exhaust systems ...........................................................7-18 Free directional oscillations .........................................5-20 Explosive decompression.............................................7-36 Free-stream velocity.......................................................5-6 Exposure to chemicals ...............................................17-13 Friction...........................................................................4-2 Engine oil ...............................................................17-14 Fronts .........................................................................12-18 Fuel.........................................................................17-14 Cold front ...............................................................12-20 Hydraulic fluid .......................................................17-13 Fast-moving cold front .......................................12-20 Occluded front........................................................12-21 F Warm front .............................................................12-18 Fairings ..........................................................................5-6 Fuel ................................................................................7-1 False horizon..............................................................17-26 Fuel consumption.......................................................16-11 Fascination (fixation) .................................................17-27 Fuel contamination.......................................................7-27 Fatigue........................................................................17-13 Fuel fired geaters..........................................................7-29 FDC NOTAMs.............................................................1-13 Fuel gauges ..................................................................7-26 Featureless terrain illusion .........................................17-10 Fuel grades ...................................................................7-27 Federal Aviation Administration (FAA)........................1-3 Aviation gasoline (AVGAS) ....................................7-27 Federal certification of pilots and mechanics ................1-4 Supplemental type certificate (STC) ........................7-27 Federal Communications Commission (FCC). 9-13, 14-22 Fuel injection system ...................................................7-11 Field offices ...................................................................1-8 Fuel load.......................................................................10-5 I-4 Fuel primer...................................................................7-25 Hydraulic systems........................................................7-31 Fuel rate .....................................................................16-17 Hydromechanical ...........................................................6-2 Fuel selectors ...............................................................7-26 Hyperventilation ..........................................................17-4 Fuel systems.................................................................7-25 Hypoxia........................................................................17-3 Fuel-pump system ....................................................7-25 Histotoxic hypoxia ...................................................17-4 Gravity-feed system .................................................7-25 Hypemic hypoxia .....................................................17-3 Fuel tanks .....................................................................7-25 Hypoxic hypoxia ......................................................17-3 Full authority digital engine control (FADEC)............7-20 Stagnant hypoxia ......................................................17-3 Fuselage .........................................................................3-3 I G Ice.................................................................................5-26 General Aviation Manufacturers Icing ...........................................................................12-24 Association (GAMA).....................................................9-2 Ignition...........................................................................7-1 Generator......................................................................7-30 Ignition system.............................................................7-15 Glider ...........................................................................1-15 Illusions........................................................................17-6 Global positioning system (GPS)..................... 3-13, 16-30 Impact pressure chamber and lines ................................8-2 RAIM capability.....................................................16-32 Inches of mercury ........................................................12-4 Selective availability ..............................................16-31 Inclinometer .................................................................8-18 VFR use of GPS .....................................................16-32 Indicated airspeed (IAS) .................................... 8-8, 11-18 Graphical METARs ...................................................13-21 Induction ........................................................................7-1 Ground adjustable tabs.................................................6-11 Induction system ............................................................7-7 Ground lighting illusions ...........................................17-10 In-flight weather advisories .......................................13-11 Ground power unit (GPU) ...........................................7-30 AIRMET.................................................................13-11 Groundspeed (GS) .................................. 8-9, 16-10, 16-17 SIGMET .................................................................13-12 Gyroscopic action ..................................... 5-31, 5-32, 8-15 In-runway lighting .....................................................14-18 Precession.................................................................8-15 Instrument landing system (ILS) .................................3-13 Rigidity in space.......................................................8-15 Intelligent flight control systems (IFCS) .......................6-2 Gyroscopic attitude indicators .....................................6-12 International Civil Aviation Organization Gyroscopic flight instruments......................................8-15 (ICAO) ............................................................... 4-3, 14-22 Gyroscopic principles ..................................................8-15 International Standard Atmosphere (ISA) .. 4-3, 11-2, 12-5 Inversion ....................................................................12-13 Isobars ........................................................................12-12 H Hazard ............................................................................2-4 J Hazardous attitudes........................................................2-5 Hazardous in-flight weather advisory (HIWAS) .........13-4 Jet-fueled piston engine .................................................7-4 Haze ...........................................................................17-10 Heading ......................................................................16-10 K Heading indicator............................................... 8-13, 8-19 Knowledge examination ..............................................1-21 Heatstroke ..................................................................17-14 High speed flight..........................................................5-44 L Hypersonic................................................................5-45 Lags..............................................................................8-27 Subsonic flow................................................. 5-44, 5-45 Land and hold short lights..........................................14-18 Supersonic flow........................................................5-44 Landing ......................................................................14-34 Transonic..................................................................5-45 Landing charts............................................................11-26 High speed flight controls............................................5-49 Landing gear ..........................................3-3, 3-7, 7-1, 7-33 High speed stalls ..........................................................5-36 Landing gear extended speed (V ) .............................8-10 Horizontal situation indicator ....................................16-24 LE Landing gear operating speed (V ) ............................8-10 Human behavior...........................................................2-11 LO Landing performance .................................................11-16 Humidity ............................................................ 4-5, 12-13 Landing strip indicators .............................................14-20 Relative humidity ...................................................12-13 I-5 Lattitude ....................................................................... 16-3 Medical certification requirements .............................. 1-20 Lazy eights ................................................................... 5-36 Meridians ..................................................................... 16-3 Leading edge device ...................................................... 6-9 Mesopic vision ........................................................... 17-21 Leading edge cuffs ................................................... 6-10 Mesosphere .................................................................. 12-3 Leading edge flaps .................................................... 6-10 Meteorologists .............................................................. 13-1 Leads ............................................................................ 8-27 Microjets ...................................................................... 7-20 Licensed empty weight ................................................ 10-5 Middle ear .................................................................... 17-5 Lift .................................................................................. 5-1 Military operation areas (MOAs) ................................. 15-4 Lift/drag ratio ................................................................. 5-5 Military training routes (MTRs) .................................. 15-6 Lighter-than-air aircraft ............................................... 1-15 Minimum control speed (VMC) .................................. 8-10 Lightning .................................................................... 12-25 Minimum equipment lists (MEL) .................................. 9-9 Lightning strike protection ........................................... 3-11 Mixture control .............................................................. 7-9 Likelihood of an event ................................................... 2-6 Moisture .....................................................................12-13 Improbable .................................................................. 2-6 Moment ........................................................................ 10-5 Occasional .................................................................. 2-6 Moment arm ....................................................... 10-4, 5-13 Probable ...................................................................... 2-6 Moment index .............................................................. 10-5 Remote ....................................................................... 2-6 Monocoque ............................................................ 3-3, 3-8 Load distribution .......................................................... 5-43 Motion sickness .........................................................17-12 Loadmeter .................................................................... 7-31 Multi-function display (MFD) ......................... 3-12, 13-18 Local airport advisory .................................................. 15-6 Longitude ..................................................................... 16-3 N Lost procedures .......................................................... 16-34 N indicator .................................................................. 7-23 Lubrication ..................................................................... 7-1 N indicator .................................................................. 7-23 National Aeronautics and Space Administration M (NASA) ................................................................ 6-2, 3-13 National airspace system .............................................. 15-7 Mach buffet .................................................................. 5-49 National Oceanic and Atmospheric Administration Mach number ............................................................... 5-45 (NOAA) ......................................................................... 4-5 Magnetic compass ........................................................ 8-23 National security areas (NSAs) .................................... 15-7 Induced errors ........................................................... 8-24 National weather service (NWS) ................................. 13-1 Acceleration error ................................................ 8-26 Navigation instruments ................................................ 3-13 Deviation ............................................................... 8-24 Negative arm .............................................................. 10-10 Dip errors ............................................................. 8-25 Negative dynamic stability .......................................... 5-15 Northerly turning errors ....................................... 8-26 Negative static stability ................................................ 5-14 Oscillation error ................................................... 8-27 Net thrust ...................................................................... 7-24 Southerly turning errors ....................................... 8-26 Neutral dynamic stability ............................................. 5-15 Variation ............................................................... 8-24 Neutral static stability .................................................. 5-14 Magnetic compasses .................................................... 6-12 Newton’s Basic Laws of Motion ................................... 4-5 Magnetic heading ....................................................... 16-16 Newton’s First Law ........................................................ 4-5 Magnus effect ................................................................. 4-6 Newton’s First Law of Motion .................................... 5-22 Maintenance entries ..................................................... 9-10 Newton’s Second Law ................................................... 4-5 Managing aircraft automation ...................................... 2-29 Newton’s Third Law ...................................................... 4-6 Maneuverability ........................................................... 5-15 Newton’s Third Law of Physics .................................. 5-31 Manifold absolute pressure (MAP) ................................ 7-6 Next generation weather radar system Maximum landing weight ............................................ 10-5 (NEXRAD) ................................................................ 13-18 Maximum ramp weight ................................................ 10-5 Abnormalities ......................................................... 13-21 Maximum takeoff weight ............................................. 10-5 Limitations ............................................................. 13-21 Maximum weight ......................................................... 10-5 Night blind spot .......................................................... 17-22 Maximum zero fuel weight .......................................... 10-5 Night landing illusions ............................................... 17-27 Mean aerodynamic chord (MAC) ...................... 5-13, 10-5 Night vision ................................................................ 17-22 Measurement of direction ............................................ 16-5 Night vision illusions ................................................. 17-26 Medical certificate ....................................................... 17-2 I-6 Night vision protection .............................................. 17-23 Pitch ............................................................................. 5-13 Nondirectional beacon (NDB) ..................................... 3-13 Pitching ........................................................................ 5-15 Notices to Airmen (NOTAM) ...................................... 13-5 Pitot-static flight instruments ......................................... 8-1 FDC NOTAMs ......................................................... 1-12 Placards .......................................................................... 9-4 NOTAM composition .............................................. 1-13 Plotter.........................................................................16-12 NOTAM (D) information ......................................... 1-12 Positive dynamic stability ............................................ 5-15 Positive static stability ................................................. 5-14 Postural considerations ................................................ 17-8 O Powered-lift .................................................................. 1-15 Obstruction lights ....................................................... 14-19 Powered parachute ....................................................... 1-15 Dual lighting ........................................................... 14-19 Powerplant ...............................................3-3, 3-7, 7-1, 9-3 High intensity white obstruction lights .................. 14-19 Practical test ................................................................. 1-22 Red obstruction lights ............................................. 14-19 Precipitation ............................................................... 12-17 Obstructions on wind ................................................... 12-8 Precision approach path indicator (PAPI) .................. 14-16 Oil Systems .................................................................. 7-16 Pre-landing ................................................................. 14-34 Operational incidents (OI) ......................................... 14-31 Pressure .......................................................................... 4-3 Optical illusions ......................................................... 17-10 Pressure altimeter ........................................................... 8-3 Original equipment manufacturer (OEM) ..................... 7-4 Pressure altitude ................................................... 4-4, 11-3 Outside air temperature (OAT) gauge ............... 7-11, 8-28 Pressurized aircraft ....................................................... 7-34 Oxygen masks .............................................................. 7-38 Preventive maintenance ............................................... 9-10 Oxygen systems ........................................................... 7-37 Primary flight controls ................................................... 6-2 Continuous-flow oxygen system .............................. 7-38 Primary flight display .................................................. 3-12 Diluter-demand oxygen systems .............................. 7-38 Primary locations of the FAA Electrical pulse-demand oxygen system .................. 7-38 Field offices Pressure-demand oxygen systems ............................ 7-38 Flight Standards District Office (FSDO) ............... 1-9 Flight Standards Service (AFS) .............................. 1-8 P Primary radar .............................................................14-24 Parachute jump aircraft operations .............................. 15-6 Procedures, vortex avoidance ....................................14-28 Parachute jumps ......................................................... 15-11 Professional Air Traffic Controllers Organization Parallels ........................................................................ 16-3 (PATCO) strike .............................................................. 1-6 PAVE checklist .............................................................. 2-8 Prohibited areas ............................................................ 15-3 Payload ......................................................................... 10-5 Propeller .......................................................... 3-7, 7-1, 7-4 Pennants ..................................................................... 12-12 Adjustable-pitch propeller .......................................... 7-6 Perceive, Process, Perform (3P) ................................... 2-15 Fixed-pitch propeller .................................................. 7-5 Forming good safety habits ...................................... 2-18 Propeller anti-ice .......................................................... 7-41 Performance ................................................................. 11-5 Propeller blade ............................................................. 5-28 Performance charts ..................................................... 11-19 Propeller principles ...................................................... 5-28 Performance data ......................................................... 11-1 Published VFR routes .................................................. 15-6 Performance instruments ............................................. 3-12 Pulse oximeters ............................................................ 7-39 P factor ............................................................... 5-30, 5-32 Photopic vision ........................................................... 17-20 R Pilotage ...................................................................... 16-12 Radar observations ....................................................... 13-3 Pilot certifications ........................................................ 1-16 Radar traffic advisories .............................................. 14-26 Airline transport pilot ............................................... 1-18 Radio communications ............................................... 14-22 Commercial pilot ...................................................... 1-18 Radio equipment ........................................................ 14-22 Private pilot .............................................................. 1-17 Radio magnetic indicator (RMI) ................................ 16-24 Recreational pilot ..................................................... 1-17 Radio navigation ........................................................ 16-22 Sport pilot ................................................................. 1-16 Radius of turn ............................................................... 5-39 Pilot deviations ........................................................... 14-31 Range performance ...................................................... 11-9 Pilot’s operating handbook (POH) ..................... 9-1, 16-17 I-7 Rapid decompression ................................................... 7-36 Severity of an event ....................................................... 2-6 Reciprocating engines .................................................... 7-2 Catastrophic ................................................................ 2-6 Four-stroke engines .................................................... 7-3 Critical ........................................................................ 2-6 Horizontally-opposed engine ..................................... 7-2 Marginal ..................................................................... 2-6 In-line engines ............................................................ 7-2 Negligible ................................................................... 2-6 Radial engines ............................................................ 7-2 Shock waves ................................................................. 5-46 Two-stroke engine ...................................................... 7-3 Significant Meteorological Information (SIGMET) .. 13-12 Reference datum .......................................................... 10-5 Single-engine best rate-of-climb (V ) ....................... 8-10 YSE Refueling procedures ................................................... 7-29 Single-pilot resource management ................................. 2-4 Region of reversed command .................................... 11-11 Sinus problems ............................................................. 17-5 Repairs and alterations ................................................. 9-12 Situational awareness ................................................... 2-24 Respect for onboard systems ....................................... 2-29 Obstacles to maintaining situational awareness ....... 2-24 Restricted areas ............................................................ 15-3 Size-distance illusion ................................................. 17-27 Retractable landing gear .............................................. 7-34 Skidding turn ................................................................ 5-23 Reversible perspective illusion .................................. 17-26 Slipping turn ................................................................. 5-23 Risk ........................................................................ 2-4, 2-6 Slip/skid indicator ........................................................ 8-13 Mitigating risk ............................................................ 2-8 Slotted flap ..................................................................... 6-8 Risk management ........................................................... 2-3 Spatial disorientation ................................................... 17-6 Rocket .......................................................................... 1-15 Special airworthiness certificate .................................... 9-8 Roll ............................................................................... 5-13 Special flight permits ................................................... 9-12 Rolling .......................................................................... 5-17 Special use airspace ..................................................... 15-3 Rotorcraft ..................................................................... 1-15 Spins ............................................................................. 5-36 Gyroplane ................................................................. 1-15 Spiral instability ........................................................... 5-20 Helicopter ................................................................. 1-15 Spoilers ........................................................................ 6-10 Rough air ...................................................................... 5-37 Squall line .................................................................. 12-23 Rudder .................................................................... 3-6, 6-4 SRM and the 5P check ................................................. 2-13 Ruddervators .................................................................. 6-8 Passengers ................................................................ 2-14 Runway and terrain slopes illusion ............................17-10 Pilot .......................................................................... 2-14 Runway approach area holding position signs and Plan ........................................................................... 2-14 markings.....................................................................14-14 Plane ......................................................................... 2-14 Runway centerline lighting system (RCLS) ..............14-18 Programming ............................................................ 2-15 Runway confusion .....................................................14-31 Stabilator ........................................................................ 6-7 Runway end identifier lights (REIL) .........................14-17 Stability ............................................5-14, 5-42, 10-2, 10-3 Runway holding position marking ............................... 14-8 Dynamic stability ..................................................... 5-14 Runway holding position sign ..................................... 14-6 Lateral stability ......................................................... 5-17 Runway incursion avoidance ..................................... 14-30 Dihedral ................................................................ 5-18 Runway lighting ......................................................... 14-17 Sweepback and wing location ............................... 5-18 Runway surface and gradient ..................................... 11-12 Keel effect and weight distribution ....................... 5-18 Runway width illusion ............................................... 17-10 Longitudinal stability ............................................... 5-15 Static stability ........................................................... 5-14 Vertical stability ....................................................... 5-19 S Stalls ................................................................... 5-25, 5-36 Safety program airmen notification system Stall speed performance charts .................................. 11-27 (SPANS) ...................................................................... 1-14 Standard airworthiness certificate .................................. 9-7 Satellite ........................................................................ 13-4 Standard datum plane (SDP) ........................................ 11-3 Scanning techniques ................................................... 17-23 Standard empty weight ................................................ 10-5 Scotopic vision ........................................................... 17-21 Standard temperature lapse rate ................................... 11-2 Sectional charts ............................................................ 16-2 Standard weights .......................................................... 10-5 Segmented circle visual indicator system .................. 14-20 Starting system ............................................................. 7-18 Self-Imposed stress .................................................... 17-25 Static pressure chamber and lines .................................. 8-2 Semimonocoque ..................................................... 3-3, 3-8 Station .......................................................................... 10-5 Servicing of oxygen systems ....................................... 7-39 I-8 Straight and Level ............................................ 11-5, 14-28 Transcribed weather broadcast (TWEB) (Alaska only)................................................................13-4 Stratosphere..................................................................12-3 Transponder ...............................................................14-25 Stress ..........................................................................17-12 Trend vectors ...............................................................8-14 Stress management.......................................................2-21 Tricycle landing gear airplanes....................................7-33 Student pilot .................................................................1-20 Trim systems................................................................6-10 Student pilot solo requirements ...................................1-21 Trim tabs .............................................................. 3-6, 6-10 Subcomponents of an airplane .......................................3-8 Tropopause...................................................................12-3 Airframe .....................................................................3-8 Troposphere .................................................................12-2 Brakes.........................................................................3-8 True airspeed (TAS) .......................................... 8-9, 11-18 Electrical system.........................................................3-8 True course.................................................................16-16 Flight controls ............................................................3-8 True heading ..............................................................16-16 Sublimation ................................................................12-15 Truss structure................................................................3-8 Sumps...........................................................................7-27 T-tail configuration ........................................................6-6 Superchargers...............................................................7-12 Turbine engines............................................................7-20 Surface aviation weather observations (METARs) .....13-2 Turbofan ...................................................................7-21 Sweepback ...................................................................5-48 Turbojet ....................................................................7-20 Synopsis .......................................................................13-5 Turboprop.................................................................7-21 Synthetic vision system..............................................17-28 Turboshaft ................................................................7-21 Turbosuperchargers............................................ 7-12, 7-13 T Turbulence .................................................................12-24 Tachometer ..................................................................8-13 Turn indicators ................................................... 8-13, 8-16 Tailwheel landing gear airplanes .................................7-33 Turn-and-slip indicator.............................................8-16 Takeoff charts ............................................................11-20 Turn rate indicator........................................................8-13 Takeoff performance..................................................11-14 Taxiway centerline lead-on lights..............................14-18 U Taxiways, marking and lighting of permanently Closed runways..........................................................14-14 Ultralight vehicle .........................................................1-14 Temperature ................................................... 12-13, 13-13 Uncontrolled airspace ..................................................15-3 Temporary flight restrictions (TFR) ............................15-6 Class G airspace .......................................................15-3 Terminal doppler weather radar (TDWR) ...................13-4 Universal coordinated time (UTC) ..............................16-5 Terminal radar service area (TRSA)................ 14-26, 15-7 Unmanned free balloons ............................................15-11 Tetrahedron ................................................................14-20 Upper air observations .................................................13-2 Thermosphere ..............................................................12-3 Useful load ...................................................................10-5 Thielert, Frank................................................................7-4 Three-color visual approach path...............................14-17 V Thrust ..................................................................... 5-1, 5-2 V ...............................................................................11-18 A Thrust horsepower (THP) .................................... 7-6, 7-24 Variable inlet guide vane (VIGV)................................7-24 Thunderstorms ...........................................................12-22 Variation .......................................................... 16-6, 16-16 Time and distance check from a station.....................16-26 Vector analysis...........................................................16-13 Time Zones ..................................................................16-3 Vehicle (driver) deviations ........................................14-31 Central standard time................................................16-5 Vertical card magnetic compass ..................................8-27 Eastern standard time ...............................................16-5 Vertical speed indicator (VSI) ............................. 8-7, 8-13 Mountain standard time............................................16-5 Very high frequency (VHF).......................................16-22 Pacific standard time ................................................16-5 Very high frequency (VHF) omni-directional Tornadoes...................................................................12-23 radio range (VOR) ........................................... 3-13, 16-22 Torque ..........................................................................5-30 Very light jets (VLJs)...................................................7-20 Torquemeter.................................................................7-22 Vestibular illusions Total distance .............................................................16-17 Coriolis illusion ........................................................17-7 Touchdown zone lights (TDZL) ................................14-18 Elevator illusion .......................................................17-8 Track ..........................................................................16-10 Graveyard spiral .......................................................17-7 Transcontinental air mail route ......................................1-4 I-9 Somatogravic illusion...............................................17-7 Wind....................................................................13-13 The leans...................................................................17-7 Weather depiction chart..........................................13-15 vestibular system..........................................................17-6 Weather check............................................................16-17 V ..............................................................................11-18 Weather products age and expiration.........................13-18 FE VFR terminal area charts .............................................16-2 Weight.......................................... 5-1, 5-2, 5-8, 5-40, 10-2 VFR waypoints ..........................................................16-33 Weight and balance............................................ 5-40, 10-4 Vg diagram...................................................................5-37 Weight and balance computations............................10-5 Viscosity ........................................................................4-2 Weight and balance restrictions ...............................10-6 Visibility ....................................................................12-17 Weight and loading distribution.....................................9-3 Vision in flight ...........................................................17-19 Weight control .............................................................10-1 Visual approach slope indicator (VASI)....................14-16 Weight-shift-control.....................................................1-15 visual flight rules (VFR) ..............................................16-1 Wind correction angle (WCA)...................................16-16 Visual glide slope indicators......................................14-16 Wind direction indicators...........................................14-20 Visual illusions.............................................................17-8 Wind patterns ...............................................................12-7 Autokinesis...............................................................17-8 Winds and temperature aloft forecast (FB)................13-13 False horizon ............................................................17-8 Winds and temperatures aloft ......................................13-5 V ..............................................................................11-18 Wind shear LE V ..............................................................................11-18 Low-level wind shear .............................................12-11 LO V ..............................................................................11-19 Wind shifts .................................................................12-21 NE V .............................................................................11-19 Wind sock ..................................................................14-20 NO VOR/DME RNAV.....................................................16-28 Wind triangle .............................................................16-13 Vortex avoidance procedures.....................................14-28 Winglets .........................................................................4-9 Vortex behavior .........................................................14-27 Wings .............................................................................3-3 Vortex generation.......................................................14-26 Wingtip vortices.............................................................5-8 Vortex strength...........................................................14-27 World aeronautical charts ............................................16-2 V ..............................................................................11-18 WSR-88D NEXRAD radar..........................................13-3 S0 V ..............................................................................11-18 S1 V-Tail.............................................................................6-8 Y V ...............................................................................11-18 X Yaw ..............................................................................5-13 V ...............................................................................11-18 Y Yawing.........................................................................5-19 Yaw String ...................................................................8-18 W Wake turbulence ................................................ 5-9, 14-26 Z Warning areas ..............................................................15-4 Zero fuel weight.........................................................10-10 Water refraction .........................................................17-10 WCA ..........................................................................16-10 Weather ........................................................................12-1 Weather avoidance assistance....................................13-18 Weather briefings.........................................................13-5 Abbreviated briefing.................................................13-5 Outlook briefing .......................................................13-5 Standard briefing ......................................................13-5 Weather charts ...........................................................13-13 Significant weather prognostic charts ....................13-15 Surface analysis chart.............................................13-13 Dew point............................................................13-13 Present weather ..................................................13-13 Pressure change/tendency ..................................13-13 Sea level pressure ...............................................13-13 Sky cover.............................................................13-13 Temperature........................................................13-13 I-10