Aircraft Weight and Balance Control

Table 3-2. Standard Crewmember Weights ............................................................................. 3-5 Table 3-3. Minimum Sample Sizes .......................................................................................... 3-7 Table C-1. Calculation of Zone 1 Centroid.............................................................................. C-2 Table C-2. Calculation of Zone 2 Centroid.............................................................................. C-2 Table C-3. Calculation of Zone 3 Centroid.............................................................................. C-2 Table C-4. Moments Resulting From the Zone Centroid Assumption for Zone 1 .................. C-3 Table C-5. Moments Resulting From the Window-Aisle-Remaining Assumption for Zone 1 ............................................................................................................... C-3 Table C-6. Comparison of Moments for Zone 1 ...................................................................... C-3 Table C-7. Moments Resulting From the Zone Centroid Assumption for Zone 2 .................. C-4 Table C-8. Moments Resulting From the Window-Aisle-Remaining Assumption for Zone 2 ............................................................................................................... C-5 Table C-9. Comparison of Moments for Zone 2 ...................................................................... C-5 Table C-10. Moments Resulting From the Zone Centroid Assumption for Zone 3 .................. C-6 5/6/19 AC 120-27F iv List of Tables (Continued) Table C-11. Moments Resulting From the Window-Aisle-Remaining Assumption for Zone 3 ............................................................................................................... C-6 Table C-12. Comparison of Moments for Zone 3 ...................................................................... C-6 Table D-1. Row Factor ............................................................................................................. D-1 Table D-2. Sample Curtailment Due to Variations in Passenger Weight and Male/Female Ratio Using Window-Aisle Method ...................................................................... D-2 Table D-3. Sample Curtailment Due to Variations in Passenger Weight and Male/Female Ratio Using Row Count Method............................................................................ D-4 5/6/19 AC 120-27F 1-1 CHAPTER 1. GENERAL 1.1 Purpose of This Advisory Circular (AC). 1.1.1 This AC provides operators with guidance on how to develop and receive approval for a Weight and Balance (W&B) control program for aircraft operated under Title 14 of the Code of Federal Regulations (14 CFR) part 91 subpart K (part 91K), and parts 121, 125, and 135. 1.1.2 This AC presents recommendations for an acceptable means, but not the only means, to develop and receive approval for a W&B control program, and includes guidance for using average and estimated weights in accordance with part 121, § 121.153(b) and other applicable sections of parts 91K, 121, 125, and 135. This AC contains guidance that is not legally binding in its own right and will not be relied upon by the Department of Transportation (DOT) or the Federal Aviation Administration (FAA) as a separate basis for affirmative enforcement action or other administrative penalty. Moreover, conformity with this guidance document (as distinct from existing statutes and regulations) is voluntary only, and nonconformity will not affect rights and obligations under existing statutes and regulations. Note: Per part 125, § 125.91(b), no person may operate an airplane in a part 125 operation unless the current empty weight and center of gravity (CG) are calculated from the values established by an actual weighing of the airplane within the preceding 36 calendar-months. 1.1.3 If an operator adopts the suggestions contained in this AC, the operator must ensure that, when appropriate, it replaces discretionary language such as “should” and “may” with mandatory language in relevant manuals, operations specifications (OpSpecs), or management specifications (MSpecs). 1.1.4 Each W&B program for a part 121 operator should include risk management processes (RMP) and safety attributes from the current edition of AC 120-92, Safety Management Systems for Aviation Service Providers. If the operator has an approved Safety Risk Management (SRM) process, the change will run through the operator’s program as designed. 1.2 Who Should Use This AC? 1.2.1 This document provides guidance to operators that are either required to have an approved W&B control program under parts 121 and 125 or that choose to use actual or average aircraft, passenger, or baggage weights when operating under part 91K or part 135. The guidance in this AC is useful for anyone involved in developing or revising a W&B control program. Note: Operators using an approved carry-on baggage program should refer to the current edition of AC 121-29, Carry-On Baggage, for more information regarding carry-on baggage. 5/6/19 AC 120-27F 1-2 1.2.2 As shown in Table 1-1, Aircraft Cabin Size, the FAA has divided aircraft into three categories for this AC to provide guidance appropriate to the size of the aircraft. Table 1-1. Aircraft Cabin Size For this AC, an aircraft originally certificated with— Is considered— 71 or more passenger seats A large cabin aircraft 30 to 70 passenger seats A medium cabin aircraft 5 to 29 passenger seats A small cabin aircraft Note: Aircraft with fewer than five passenger seats must use actual passenger and baggage weights. 1.3 Where You Can Find This AC. You can find this AC on the FAA’s website at http://www.faa.gov/regulations_policies/advisory_circulars. 1.4 What This AC Cancels. AC 120-27E, Aircraft Weight and Balance Control, dated June 10, 2005, is cancelled. 1.5 How is This AC Organized? This AC has four main chapters and six appendices. Chapter 2 addresses aircraft weighing and loading schedules. Chapter 3 describes different methods to determine the weight of passengers and bags. Chapter 4 addresses the operator’s reporting systems and the FAA’s initial and continuing approval and oversight of an operator’s W&B control program. Finally, Appendices A through F contain technical information such as definitions, sources of data used in the AC, a sample loading envelope, an additional curtailment for passenger weight variation, suggestions to improve accuracy, and a checklist for operators. 1.6 What Should an Operator Consider While Reading This AC? 1.6.1 Accurately calculating an aircraft’s weight and CG before flight is essential to comply with the certification limits established for the aircraft. These limits include both weight and CG limits. The operator must comply with §§ 91.9, 121.141, 125.75, and 135.23, as applicable, and all operating limitations as specified in the Airplane Flight Manual (AFM) or Rotorcraft Flight Manual (RFM) Weight and Balance Manuals (WBM) and related supplements, and Supplemental Type Certificates (STC). The objective is to calculate the takeoff weight and CG of an aircraft as accurately as possible. Typically, an operator calculates takeoff weight by adding the Basic Empty Weight (BEW) of the aircraft, the weight of the passengers, cargo payload, and the weight of fuel. 1.6.2 When using average weights for passengers and bags, the operator must be vigilant to ensure that the W&B control program reflects the reality of actual aircraft loading (considering operation, markets served, and passenger mix and frequency of flights of particular routes). The FAA will periodically review the guidance in this AC and update it if regulatory requirements change. Ultimately, the operator is responsible for determining whether the procedures described in this AC are appropriate for use in its type(s) of operation. 5/6/19 AC 120-27F 1-3 1.6.3 Weight should be a consistent measure in either pounds or kilograms. If both pounds and kilograms are used, procedures must include a method of conversion to ensure accurate weights and measures are used in the calculation of aircraft W&B. 1.7 Who Can Use Standard Average Weights? 1.7.1 Standard Average Weights. Use of standard average weights is limited to operators of multiengine turbine-powered aircraft that have a passenger-seat configuration of five or more passenger seats who hold a Letter of Authorization (LOA), OpSpecs, or MSpecs, as applicable, and were certificated under 14 CFR part 25, 29, or part 23 normal category; or the operator and manufacturer are able to prove that the aircraft can meet the performance requirements prescribed by part 23 normal category aircraft. Single-engine and multiengine turbine helicopter air ambulance (HAA) operators may also use standard average weights for emergency medical service (EMS) operations, provided they have received an LOA. 1.7.2 Use of Standard Average Weights. The FAA’s recommendations and advice on the safe use of standard average weights are contained in this document. In the FAA’s view, it would be unsafe for an aircraft operator to use standard average weights in any of the following aircraft: 1. All single-engine piston-powered aircraft. 2. All multiengine piston-powered aircraft. 3. All turbine-powered single-engine aircraft. Note: All multiengine turbine-powered aircraft certificated under part 23, except for normal category aircraft, may only use an actual weight. Normal category aircraft per part 23, § 23.2005 may use standard average weights and should see paragraph 3.1.1.6 for further guidance. 1.8 AC Feedback Form. For your convenience, the AC Feedback Form is the last page of this AC. Note any deficiencies found, clarifications needed, or suggested improvements regarding the contents of this AC on the Feedback Form. 5/6/19 AC 120-27F 2-1 CHAPTER 2. AIRCRAFT WEIGHTS AND LOADING SCHEDULES 2.1 Establishing Aircraft Weight. 2.1.1 How Does an Operator Establish the Initial Weight of an Aircraft? Prior to being placed into service, each aircraft is weighed and the empty weight and center of gravity (CG) location are established. New aircraft are normally weighed at the factory and are eligible to be placed into operation without reweighing as long as the W&B records were adjusted for any alterations and modifications to the aircraft. Some modifications to aircraft, however, warrant reweighing. See paragraph 2.1.4.3 for a discussion of when it might be unsafe to fail to reweigh an aircraft after it has undergone modification(s). Aircraft that transfer from one operator to another that has an approved program do not need to be reweighed prior to use by the receiving operator unless: (1) more than 36 calendar-months have elapsed since last individual or fleet weighing or (2) some other modification to the aircraft warrants that the aircraft be weighed (e.g., paragraph 2.1.4.3). Aircraft transferred, purchased, or leased from an operator without an approved W&B program and that have been unmodified or only minimally modified can be placed into service without being reweighed if the last weighing was accomplished by an acceptable method within the last 12 calendar-months and a W&B change record was maintained by the operator. Examples of such an acceptable method are methods consistent with the manufacturer’s instructions or that adhere to the current edition of Advisory Circular (AC) 43.13-1, Acceptable Methods, Techniques, and Practices—Aircraft Inspection and Repair. 2.1.2 How Does an Operator Document Changes to an Aircraft’s W&B? The W&B system should include methods, such as a log, ledger, or other equivalent electronic means, by which the operator will maintain a complete, current, and continuous record of the Basic Empty Weight (BEW) and CG of each aircraft. Alterations and changes affecting the W&B of the aircraft should be recorded in this log. Changes in the amount of weight or in the location of weight in or on the aircraft should be recorded whenever the weight change is at or exceeds the weights listed in Table 2-1, Incremental Weight Changes That Should Be Recorded in a Weight and Balance Change Record. Table 2-1. Incremental Weight Changes That Should Be Recorded in a Weight and Balance Change Record In the weight change record of a— An operator should record any weight changes of— Large cabin aircraft +/- 10 lb or greater Medium cabin aircraft +/- 5 lb or greater Small cabin aircraft +/- 1 lb or greater 2.1.3 How Does the Operator Maintain the BEW? The loading schedule may utilize the individual weight of the aircraft in computing operational W&B or the operator may choose to establish fleet empty weights for a fleet or group of aircraft. 5/6/19 AC 120-27F 2-2 2.1.3.1 Reestablishment of BEW. The BEW and CG position of each aircraft should be reestablished at the reweighing periods discussed in paragraph 2.1.4. In addition, it should be reestablished through calculation whenever the cumulative change to the W&B log is more than plus or minus one-half of 1 percent (0.5 percent) of the maximum landing weight or whenever the cumulative change in the CG position exceeds one-half of 1 percent (0.5 percent) of the mean aerodynamic chord (MAC). In the case of helicopters and airplanes that do not have a MAC-based CG envelope (e.g., canard-equipped airplane), whenever the cumulative change in the CG position exceeds one-half of 1 percent (0.5 percent) of the total CG range, the W&B should be reestablished. Note: When reestablishing the aircraft BEW between reweighing periods, the weight changes may be computed provided the weight and CG location of the modifications are known; otherwise the aircraft must be reweighed. 2.1.3.2 Fleet Operating Empty Weights (FOEW). An operator may choose to use one weight for a fleet or group of aircraft if the weight and CG of each aircraft is within the limits stated above in paragraph 2.1.3.1 for establishment of BEW. When the cumulative changes to an aircraft W&B log exceed the weight or CG limits for the established fleet weight, the empty weight for that aircraft should be reestablished. This may be done by moving the aircraft to another group or by reestablishing new FOEWs. 2.1.4 How Often are Aircraft Weighed? 2.1.4.1 Individual Aircraft Weighing Program. Aircraft are normally weighed at intervals of 36 calendar-months. An operator may extend this weighing period for a particular model aircraft when pertinent records of actual routine weighing during the preceding period of operation show that W&B records accurately reflect aircraft weights and CG positions are within the cumulative limits specified for establishment of BEW (see paragraph 2.1.3.1). Under an individual aircraft weighing program, an increase should not be granted that would permit any aircraft to exceed 48 calendar-months since its last weighing, including when an aircraft is transferred from one operator to another. In the case of helicopters, increases should not exceed the time that is equivalent to the aircraft overhaul period. Note: Per § 125.91(b), no person may operate an airplane in a part 125 operation unless the current empty weight and CG are calculated from the values established by an actual weighing of the airplane within the preceding 36 calendar-months. 2.1.4.2 Fleet Weighing. An operator may choose to weigh only a portion of the fleet every 36 months and apply the weight and moment change determined by these sample weighings to the remainder of the fleet. For each aircraft 5/6/19 AC 120-27F 2-3 weighed, the new aircraft empty weight and moment is determined by the weighing and entered in the aircraft weight log. The difference between this new aircraft weight and moment and the previous aircraft weight and moment shown in the log is the weight and moment change. The average of the weight and moment changes for the aircraft weighed as part of this fleet weighing is then entered as an adjustment to the aircraft weight logs for each of the aircraft in the fleet that were not weighed. 2.1.4.2.1 A fleet is composed of a number of aircraft of the same type. (For example, B747-200s in a passenger configuration and B747-200 freighters should be considered different fleets. Likewise, B757-200s and B757-300s should be considered different fleets.) The primary purpose of defining a fleet is to determine how many aircraft should be weighed in each weighing cycle. A fleet may be further divided into groups to establish FOEWs. Table 2-2. Number of Aircraft to Weigh in a Fleet For fleets of— An operator must weigh (at minimum)— 1 to 3 aircraft All aircraft 4 to 9 aircraft 3 aircraft, plus at least 50 percent of the number of aircraft greater than 3 More than 9 aircraft 6 aircraft, plus at least 10 percent of the number of aircraft greater than 9 2.1.4.2.2 In choosing the aircraft to be weighed, the aircraft in the fleet having the most hours flown since last weighing should be selected. 2.1.4.2.3 An operator should establish a time limit such that all aircraft in a fleet are eventually weighed. Based on the length of time that a fleet of aircraft typically remains in service with an operator, the time limit should not exceed 18 years (six 3-year weighing cycles). It is not intended that an operator be required to weigh any remaining aircraft in the event that business conditions result in retirement of a fleet before all aircraft have been weighed. 2.1.4.3 Weighing Aircraft—Modifications. For most aircraft modifications, a mathematical calculation of the W&B change is practical. For some modifications, such as interior reconfigurations, the large number of parts removed, replaced, and installed may make an accurate determination of the W&B change by computation impractical. 2.1.4.3.1 When the accuracy of the calculation is questionable, the weight and moment change estimate should be verified by reweighing the aircraft. The operator should weigh two or more aircraft to confirm the computed weight change estimate. The operator may choose to weigh the aircraft before and after the modification, or just after the modification. If the weighings are inconsistent with the computed weight change estimate, then additional aircraft should be weighed as prescribed in Table 2-2, based on the size of the fleet. 5/6/19 AC 120-27F 2-4 2.1.4.3.2 The operator may choose not to calculate the weight change but to reestablish the aircraft W&B by reweighing the aircraft prior to subsequent revenue operation. An operator using an individual aircraft weighing program would weigh each aircraft modified, and an operator using a fleet weighing program would weigh the number of aircraft as prescribed in Table 2-2, based on the size of the fleet. 2.1.5 What Procedures Should Be Used to Weigh an Aircraft? 2.1.5.1 An operator should take precautions to ensure that it weighs an aircraft as accurately as possible. These precautions include checking to ensure that all required items are aboard the aircraft and the quantity of all fluids aboard the aircraft is considered. An operator should weigh the aircraft in still air. 2.1.5.2 An operator should establish and follow instructions for weighing the aircraft that are consistent with the recommendations of the aircraft manufacturer and scale manufacturer. The operator should ensure that all scales are certified and calibrated by the manufacturer or a certified laboratory, such as a civil department of weights and measures, or the operator may calibrate the scale under an approved calibration program. The operator should also ensure that the scale is calibrated within the manufacturer’s recommended time, or time periods, as specified in the operator’s approved calibration program. Note: If manufacturer’s data is not available, the operator is responsible for developing appropriate weighing instructions for its particular aircraft. 2.2 Aircraft Loading Schedules. 2.2.1 What is a Loading Schedule? 2.2.1.1 The loading schedule is used to document compliance with the certificated W&B limitations contained in the manufacturer’s Airplane Flight Manual (AFM) or Rotorcraft Flight Manual (RFM), Type Certificate Data Sheet (TCDS), and Weight and Balance Manual (WBM). 2.2.1.2 The loading schedule is developed by the operator based on its specific loading calculation procedures and provides the operational limits for use with the operator’s W&B program approved under this AC. These approved operational limits are typically more restrictive and may not exceed the manufacturer’s certificated limits. This is because the loading schedule is generally designed to check only specific conditions (e.g., takeoff and zero fuel) known prior to takeoff, and must account for variations in W&B in flight. Loading the aircraft so that the calculated W&B is within the approved operational limits will maintain the actual W&B within the certificated limits throughout the flight. 5/6/19 AC 120-27F 2-5 2.2.1.3 Development of a loading schedule represents a trade-off between ease of use and loading flexibility. A schedule can provide more loading flexibility by requiring more detailed inputs, or it can be made easier to use by adjusting the operational limits to account for the uncertainty caused by the less detailed inputs. 2.2.1.4 Several types of loading schedules are commonly used, including computer programs as well as “paper” schedules, which can be graphical, such as an alignment (“chase around chart”) system, slide rule, or numerical, such as an adjusted weight or index system. 2.2.1.5 It is often more convenient to compute the balance effects of combined loads and to display the results by using “balance units” or “index units.” This is done by adding the respective moments (weight times arm) of each item. Graphing the moments’ results in a “fan grid” where lines of constant balance arms (BA) or percent MAC are closer together at lower weights and further apart at higher weights. Direct graphical or numerical addition of the balance effects are possible using these moment values. 2.2.1.6 To make the magnitude of the numbers more manageable, moments can be converted to an index unit. For example: Note: Where datum is the reference BA that will plot as a vertical line on the fan grid, M and K are constants that are selected by the operator. M is used to scale the index values, and K is used to set the index value of the reference BA. 2.2.2 How Should an Operator Determine the Weight of Each Fluid Used Aboard the Aircraft? An operator should use one of the following: 1. The actual weight of each fluid, 2. A standard volume conversion for each fluid, or 3. A volume conversion that includes a correction factor for temperature. 2.3 Constructing a Loading Envelope. 2.3.1 What Should an Operator Consider when Constructing a Loading Envelope? Each operator complying with this AC must construct a loading envelope applicable to each aircraft being operated. The envelope will include all relevant W&B limitations. It will be used to ensure that the aircraft is always operated within appropriate W&B limitations, and will include provisions to account for the loading of passengers, fuel, and cargo; the in-flight movement of passengers, aircraft components, and other loaded items; and the usage or transfer of fuel and other consumables. The operator must be able to 5/6/19 AC 120-27F 2-6 demonstrate that the aircraft is being operated within its certificated W&B limitations using reasonable assumptions that are clearly stated. 2.3.2 What Information from the Aircraft Manufacturer Should an Operator Use? The construction of the loading envelope will begin with the W&B limitations provided by the aircraft manufacturer in the WBM, TCDS, or similar approved document as required by part 91, § 91.9 and §§ 121.141, 125.75, 125.91, and 135.23(b). These limitations will include, at minimum, the following items, as applicable: 1. Maximum zero fuel weight. 2. Maximum takeoff weight. 3. Maximum taxi weight. 4. Takeoff and landing CG limitations. 5. In-flight CG limitations. 6. Maximum floor loadings—including both running and per square foot limitations. 7. Maximum compartment weights. 8. Fuselage shear limitations. 9. Any other limitations provided by the manufacturer. 2.3.3 What Should the Operator Consider When Curtailing the Manufacturer’s Loading Envelope? 2.3.3.1 The operator should curtail the manufacturer’s loading limitations to account for loading variations and in-flight movement that are encountered in normal operations. For example, if passengers are expected to move about the cabin in flight, the operator must curtail the manufacturer’s CG envelope by an amount necessary to ensure that movement of passengers does not take the aircraft outside its certified envelope. If the aircraft is loaded within the new, curtailed envelope, it will always be operated within the manufacturer’s envelope, even though some of the loading parameters, such as passenger seating location, are not precisely known. 2.3.3.2 In some cases, an aircraft may have more than one loading envelope for preflight planning and loading. Each envelope must have the appropriate curtailments applied for those variables that are expected to be relevant for that envelope. For example, an aircraft might have separate takeoff, in-flight, and landing envelopes. Passengers are expected to remain seated in the cabin during takeoff or landing. Therefore, the takeoff and landing envelope does not need to be curtailed for passenger movement. 2.3.3.3 Upon determination of the curtailed version of each envelope, the most restrictive points (for each condition the operator’s program will check) generated by an “overlay” of the envelopes will form the aircraft “operational 5/6/19 AC 120-27F 2-7 envelopes.” Operators must adhere to the limitations relevant to such envelopes. By restricting operation to these operational envelopes, compliance with the manufacturer’s certified envelope will be ensured in all phases of flight, based upon the assumptions within the curtailment process. An operator may choose to not combine the envelopes but observe each envelope independently. However, due to calculation complexity, this is typically only possible through automation of the W&B calculation. 2.3.3.4 An operator could make an allowance for curtailment of the aircraft loading envelope to account for minor errors in bag counts and documentation, provided the operator provides valid survey data to ensure the accuracy of the baggage weight. The survey data should show the average variance an operator experiences in bag counts and include calculations for these variances to demonstrate that no limitations were exceeded. The operator should include the average variance in their loading schedule developed in paragraph 2.3.3.3. Note: For acceptable methods used in surveying weights, see paragraph 3.3. 2.3.3.5 The specific amount of weight added to the Basic Operating Weight (BOW) would be based on the operator conducting a survey of their bag count and documentation errors and providing the appropriate amount of curtailment to ensure the aircraft remains within the CG envelope. This could be in the form of a minor tolerance specific to their approved program, rather than a broadly applicable allowance for all operators. 2.3.4 What are Some Examples of Common Curtailments to the Manufacturer’s Loading Envelope? The following paragraphs provide examples of common loading curtailments. Appendix C, Sample Operational Loading Envelope, also provides an example of how operators may calculate these curtailments. Operators must include curtailments appropriate to the operations being conducted. Each of the items mentioned below is a single curtailment factor. The total curtailment of the manufacturer’s envelope is computed by combining the curtailments resulting from each of these factors. 2.3.4.1 Passenger Distribution. The operator must account for the seating of passengers in the cabin. The loading envelope does not need to be curtailed if the actual seating location of each passenger is known. If assigned seating is used to determine passenger location, the operator must implement procedures to ensure that the assignment of passenger seating is incorporated into the loading procedure. Operator procedures should take into account the possibility that passengers may not sit in their assigned seat and how this may affect CG during takeoff and landing. 2.3.4.1.1 If the actual seating location of each passenger is not known, the operator may assume that all passengers are seated uniformly throughout the cabin or a specified subsection of the cabin. If this assumption is made, the operator 5/6/19 AC 120-27F 2-8 must curtail the loading envelope to account for the fact that the passenger loading may not be uniform. The curtailment may make reasonable assumptions about the manner in which people distribute themselves throughout the cabin. For example, the operator may assume that window seats are occupied first, followed by aisle seats, followed by the remaining seats (window-aisle-remaining seating). Both forward and rear loading conditions should be considered. That is, the passengers may fill up the window, aisle, and remaining seats from the front of the aircraft to the back, or the back to the front. 2.3.4.1.2 If necessary, the operator may divide the passenger cabin into subsections or “zones” and manage the loading of each zone individually. It can be assumed that passengers will be sitting uniformly throughout each zone, as long as the curtailments described in the previous paragraph are put in place. 2.3.4.1.3 All such assumptions should be adequately documented. 2.3.4.2 Fuel. The operator’s curtailed loading envelope must account for the effects of fuel. The following are examples of several types of fuel-related curtailments: 2.3.4.2.1 Fuel Density. A certain fuel density may be assumed and a curtailment included accounting for the possibility of different fuel density values. Fuel density curtailments only pertain to differences in fuel moment caused by varying fuel volumes, not to differences in total fuel weight. The fuel gauges in most transport category aircraft measure weight, not volume. Therefore, the indicated weight of the fuel load can be assumed accurate. 2.3.4.2.2 Fuel Movement. The movement or transfer of fuel in flight. 2.3.4.2.3 Fuel Usage In Flight. The burning of fuel may cause the CG of the fuel load to change. The effect of fuel burning down to the required reserve fuel or to an acceptable fuel amount established by the operator should be accounted for. A curtailment may be included to ensure that this change does not cause the CG of the aircraft to move outside of the acceptable envelope. 2.3.4.3 Fluids. The operator’s curtailed CG envelope must account for the effects of galley and lavatory fluids. These factors include such things as: 1. Use of potable water in flight. 2. Movement of water or lavatory fluids. 2.3.4.4 In-Flight Movement of Passenger and Crew. The operational envelope must account for the in-flight movement of passengers, crew, and equipment. This may be done by including a curtailment equal to the moment change caused by the motion being considered. It may be assumed that all passengers, crew, and equipment are secured when the aircraft is in the takeoff or landing 5/6/19 AC 120-27F 2-9 configuration. Standard operational procedures may be taken into account. Examples of items that can move during flight are: 2.3.4.4.1 Flight Deck Crewmembers Moving to the Lavatory. Flight deck crewmembers may move to the most forward lavatory in accordance with the security procedures prescribed for crews leaving the cockpit. An offsetting credit may be taken if another crewmember moves to the flight deck during a lavatory trip. 2.3.4.4.2 Flight Attendants (F/A) Moving Throughout the Cabin. Operators should take their standard operating procedures into account. If procedures do not dictate otherwise, it should be assumed that the F/As can travel anywhere within the compartment to which they are assigned. 2.3.4.4.3 Service Carts Moving Throughout the Cabin. Operators should consider their standard operating procedures. If procedures do not dictate otherwise, it should be assumed that the service carts can travel anywhere within the compartment to which they are assigned. If multiple carts are in a given compartment and no restrictions are placed on their movement, then the maximum number of carts, moving the maximum distance, must be considered. The weight of the number of F/As assigned to each cart must also be considered. The assumed weight of each cart may be the maximum anticipated cartload or the maximum design load, as appropriate for the operator’s procedures. 2.3.4.4.4 Passengers Moving Throughout the Cabin. Allowances should be made for the possibility that passengers may move about the cabin in flight. The most common would be movement to the lavatory, described below. If a lounge or other passenger gathering area is provided, the operator should assume that passengers move there from the centroid of the passenger cabin(s). The maximum capacity of the lounge should be taken into account. 2.3.4.4.5 Passengers Moving to the Lavatory. Operators should account for the CG change caused by passengers moving to the lavatory. Operators should develop reasonable scenarios for the movement of passengers in their cabins and consider the CG shifts that can be expected to occur. Generally, operators may assume that passengers move to the lavatories closest to their seats. In aircraft with a single lavatory, operators should consider movement from the “most adverse” seat. Operators may make assumptions that reflect operator lavatory and seating policies. For example, operators may assume that coach passengers may only use the lavatories in the coach cabin, if that is the operator’s normal policy. 2.3.4.5 Movement of Flaps and Landing Gear. If the manufacturer has not already done so, the operator must account for the movement of landing gear, flaps, wing leading edge devices, or any other moveable components of the 5/6/19 AC 120-27F 2-10 aircraft. Devices deployed only while in contact with the ground, such as ground spoilers or thrust reversers, may be excluded from such curtailments. 2.3.4.6 Baggage and Freight. It can be assumed that baggage and freight may be loaded at the centroid of each baggage compartment. Operators do not need to include a curtailment if procedures are used to ensure the cargo is loaded uniformly and physically restrained (secured) to prevent the contents from becoming a hazard by shifting between zones or compartments. 2.4 Onboard W&B Systems. 2.4.1 How Does an Onboard W&B System Compare to a Conventional Weight Buildup Method? 2.4.1.1 An operator may use an onboard W&B system to measure an aircraft’s W&B as a primary means to dispatch an aircraft, provided the FAA has certified the system and approved the system for use in an operator’s W&B control program. This paragraph discusses the differences an operator should consider when using an onboard W&B system compared to a conventional weight buildup method. This paragraph addresses only the operational considerations related to the use of an FAA-approved onboard W&B system. 2.4.1.2 Like operators using a conventional weight buildup method to calculate W&B, an operator using an onboard W&B system as a primary W&B control system should curtail the manufacturer’s loading envelope to ensure the aircraft does not exceed the manufacturer’s certificated weight and CG limits. However, an operator using an onboard W&B system would not need to curtail the loading envelope for assumptions about passenger and bag weight or distribution. 2.4.1.3 Because an onboard W&B system measures the actual weight and CG location of an aircraft, an operator may not need to include certain curtailments to the loading envelope to account for variables such as passenger seating variation or variation in passenger weight. However, an operator should curtail the loading envelope for any system tolerances that may result in CG errors. Using an onboard W&B system does not relieve an operator from the requirement to complete and maintain a load manifest. 2.4.2 What Measures Should an Operator Take to Obtain Operational Approval for an Onboard W&B System? 2.4.2.1 System Calibration. An operator should develop procedures to calibrate its onboard W&B system equipment periodically in accordance with the manufacturer’s instructions. An operator may calibrate its system with operational items or fuel aboard the aircraft to test the system at a representative operational weight. However, an operator may not use an onboard W&B system in place of procedures described in paragraph 2.1 for weighing the aircraft to establish BEW or CG location. 5/6/19 AC 120-27F 2-11 2.4.2.2 Demonstration of System Accuracy. As part of the approval process, an operator should demonstrate that the onboard W&B system maintains its certificated accuracy. An operator should only have to conduct this demonstration once for each type aircraft with a similarly installed onboard W&B system. For the demonstration, the operator should use the accuracy demonstration test provided in the maintenance manual portion of the Supplemental Type Certificate (STC) or type certificate (TC) of the onboard W&B system. 2.4.3 What Operational Considerations Should an Operator Take into Account when Using an Onboard W&B System? 2.4.3.1 Certification Limits. An operator using an onboard W&B system as its primary means of calculating W&B should have procedures in place to ensure that the system is operated within the limits established during the system’s certification process. 2.4.3.2 Environmental Considerations. An operator using an onboard W&B system should ensure that it uses the system within the environmental limits established by the manufacturer. Environmental conditions that may affect the performance of an onboard W&B system include temperature, barometric pressure, wind, ramp slope, rain, snow, ice, frost, dew, and deicing fluid. 2.4.3.3 Aircraft Considerations. An operator using an onboard W&B system should ensure the weight and CG measured by the system are not affected by the aircraft configuration, such as the movement of flaps, stabilizers, doors, stairways or jetways, or any connections to ground service equipment. Other factors that an operator should consider include engine thrust, oleo strut extension, and aircraft taxi movement. 2.4.3.4 Takeoff Trim Settings. If the aircraft manufacturer provides trim settings for takeoff based on the aircraft’s CG location, an operator using an onboard W&B system should ensure that the onboard W&B system provides flightcrew members with adequate information to determine the appropriate trim setting. 2.4.3.5 Operational Envelope. The operational envelope for onboard W&B systems should be developed using the same procedures described in other parts of this AC, with the exception that the operational envelope does not need to be curtailed for passenger random seating and passenger weight variance. Also, note that the fuel load is subtracted from the measured takeoff weight to determine the zero fuel weight and CG, instead of being added to the zero fuel weight as part of the load buildup. In addition, an operator should curtail the CG envelope for any system CG tolerance. 5/6/19 AC 120-27F 2-12 2.4.3.6 Complying with Compartment or Unit Load Device (ULD) Load Limits. When using an onboard W&B system, an operator should develop in its W&B control program a method to ensure that it does not exceed the floor, linear or running loading limits specified for a compartment or ULD. If an operator develops appropriate procedures, an operator may request approval to exclude bag counts from its load manifest. The following are two examples of acceptable means to demonstrate compliance with compartment load limits. 2.4.3.6.1 An operator may assign a standard average weight to bags. Operators should see paragraphs 3.3 and 3.4 for baggage. Based on that standard average weight, the operator may place a placard in each compartment stating the maximum number of bags permitted. An operator may also create a table that lists the total weight associated with a given number of bags to ensure the operator does not exceed the load limit of a compartment or ULD. 2.4.3.6.2 By conducting sample loadings, an operator may demonstrate that the average density of the bags it places in a compartment or ULD would not allow it to exceed the compartment or ULD load limits inadvertently. 2.4.4 May an Operator Use the Information in this AC to Develop a Backup System? An operator using an onboard W&B system as its primary means of measuring W&B may use the guidance in this AC to develop a backup system based on a conventional weight buildup provided that the backup system has been approved by the Certificate Management Office (CMO)/Flight Standards District Office (FSDO). Should the primary onboard W&B system become inoperative, the operator should have provisions for deferring the inoperative equipment until repairs can be made prior to further operations. The FAA may grant relief for an onboard W&B system through the minimum equipment list (MEL). An operator using an onboard W&B system should not use the backup system unless: 1. The onboard system is inoperative; 2. The onboard system has been deferred in accordance with the aircraft MEL; and 3. The operator has been approved to use average weights or conventional weight buildup. 5/6/19 AC 120-27F 3-1 CHAPTER 3. METHODS TO DETERMINE THE WEIGHT OF PASSENGERS 3.1 Choosing the Appropriate Method. 3.1.1 What Should an Operator Consider when Choosing the Appropriate Method? 3.1.1.1 Using Average Weights. For many years, operators of transport category aircraft have used average weights for passengers and bags to calculate an aircraft’s W&B, in accordance with standards and recommended practices. This method eliminates many potential sources of error associated with accounting for a large number of relatively lightweights. However, differences between the actual weight of passengers and bags and the average weight of passengers and bags can occur when using average weights. 3.1.1.2 Using Standard Average Passenger Weights. Statistical probability dictates that the smaller the sample size (i.e., cabin size), the more the average of the sample will deviate from the average of the larger universe. Because of this, the use of standard average passenger weights in W&B programs for small and medium cabin aircraft should be examined in greater detail. 3.1.1.3 Determining Passenger and Bag Weight. Three methods are available to operators to determine passenger and bag weight. These methods include standard average weights, as described in paragraph 3.2; average weights based on survey results, as described in paragraph 3.3; and actual weights, as described in paragraph 3.4. An operator should review the following discussion and consult Table 3-1, Example of Standard Average Passenger Weights, to determine which methods are appropriate to its type of operation. Operators should see paragraphs 3.3 and 3.4 for determining baggage weights. 3.1.1.4 Large Cabin Aircraft. Operators of large cabin aircraft may use the standard average weights for passengers. If an operator determines the standard average weights are not representative of its operation for certain route or regions, the operator should conduct a survey as detailed in paragraph 3.3 to establish more appropriate average weights for its operation. Operators of large cabin aircraft should conduct a baggage survey as detailed in paragraph 3.3 to establish standard average baggage weights for their operation. Large cabin operators also have the option of using actual baggage weights as described in paragraph 3.4. Operators should have procedures along with controls for identifying situations that would require the use of nonstandard weight groups or actual weights. 3.1.1.5 Medium Cabin Aircraft. 3.1.1.5.1 Evaluation Criteria for Medium Cabin Aircraft. Operators should evaluate medium cabin aircraft to determine whether to treat the aircraft as a large or small cabin aircraft. For the FAA to recommend that medium cabin aircraft be treated as a large cabin aircraft, the aircraft must meet either: 5/6/19 AC 120-27F 3-2 1. Loadability criteria, or 2. The loading schedule criteria. 3.1.1.5.2 Evaluation Criteria for Small Cabin Aircraft. If the aircraft does not meet either the loadability or loading schedule criteria, then the FAA does not recommend that the operator use large cabin aircraft procedures. Instead, the aircraft should be subject to the small cabin aircraft methods outlined in paragraph 3.1.1.6. 3.1.1.5.3 Loadability Criteria. • The center of gravity (CG) of the Basic Empty Weight (BEW) is within the manufacturer’s loading envelope. • The CG of the zero fuel weight is within the manufacturer’s loading envelope when loaded with a full load of passengers and all cargo compartments are filled with a density of 10 pounds per cubic foot. 3.1.1.5.4 Loading Schedule Criteria. • The operator must use a loading schedule based upon zones. • The aircraft cabin may have no more than four rows of seats per zone with not less than four zones. 3.1.1.6 Small Cabin Aircraft. Operators of small cabin aircraft may request approval to use any one of the following methods when calculating the aircraft W&B. 1. Actual passenger and bag weights, or 2. Standard average passenger and standard average by surveying bag weights prescribed for large cabin aircraft or average weights based on an FAA-accepted survey if: • The aircraft was certificated under part 23 normal category, part 25, or part 29 (or is able to prove the aircraft has equivalent part 23 normal category or part 29 performance data); and • When using the Window-Aisle-Remaining (Zone) Method, the operator applies the additional curtailments as prescribed in Appendix D, Additional Curtailment to CG Envelopes for Passenger Weight Variations in Small Cabin Aircraft. 5/6/19 AC 120-27F 3-3 3.2 Standard Average Weights. 3.2.1 What Standard Average Passenger Weights Should an Operator Use? 3.2.1.1 The standard average passenger weights are based on data from U.S. Government health agency surveys. An operator may use the example table in Table 3-1 in association with the Centers for Disease Control (CDC) weights to establish their standard average weights. The first column in Table 3-1 are CDC/National Health and Nutrition Examination Survey (NHANES) weights without summer or winter clothing weights. For more background information on the source of these weights, refer to Appendix B, Source of Standard Average Weights. 3.2.1.2 The operator will use the third column labeled “Standard Average Weight” in Table 3-1 to enter in their standard average weight per passenger based on seasonal clothing variance. The standard average weight is calculated by adding the CDC/NHANES weights in the first column and the clothing weights located the middle column. The clothing weights are 5 pounds for summer clothing, and 10 pounds for winter clothing. Where no gender is given, the standard average passenger weights are based on the assumption that 50 percent of passengers are male and 50 percent of passengers are female. Table 3-1. Example of Standard Average Passenger Weights CDC/NHANES Weights Average Clothing Weight Standard Average Weight Summer Weights Summer Weights lbs Average passenger weight (5 lbs) lbs lbs Average male passenger weight (5 lbs) lbs lbs Average female passenger weight (5 lbs) lbs lbs Child weight (2 years to less than 13 years of age) (5 lbs) lbs Winter Weights Winter Weights lbs Average passenger weight (10 lbs) lbs lbs Average male passenger weight (10 lbs) lbs lbs Average female passenger weight (10 lbs) lbs lbs Child weight (2 years to less than 13 years of age) (10 lbs) lbs 5/6/19 AC 120-27F 3-4 3.2.1.3 An operator may use summer weights from May 1 to October 31, and winter weights from November 1 to April 30. However, these dates may not be appropriate for all routes or operators. For routes with no seasonal variation, an operator may use the average weights appropriate to the climate. Use of year-round average weights for operators with seasonal variation should avoid using an average weight that falls between the summer and winter average weights. Operators with seasonal variation that elect to use a year-round average weight should use the winter average weight. The FAA must approve use of seasonal dates, other than those listed above. 3.2.1.4 The standard average weights listed in Table 3-1 will not take into consideration a carry-on bag program. Operators should see paragraphs 3.3 and 3.4 for baggage weights. Note: The weight of children under the age of 2 must be accounted for by using the current edition of CDC Anthropometric Reference Data for Children and Adults. The carrier may either: 1) use the mean of both male and female weights under the age of 2; or 2) provide the Administrator with survey data to support how many children under the age of 2 should be calculated along with the adult passenger weights. 3.2.1.5 The standard average passenger weights established by the operator will be provided to the FAA for review and approval, and entered into the operator’s operations specifications (OpSpecs), management specifications (MSpecs), or Letter of Authorization (LOA), as applicable. 3.2.2 What Are the Standard Average Weights for Crewmembers? 3.2.2.1 An operator may choose to use one of the following for crewmember weights: CDC/NHANES weights for F/As and Civil Aerospace Medical Institute (CAMI) first- and second-class medical certificate weights to establish their standard crewmember weights. The operator also has the option to conduct a survey as described in paragraph 3.3, or use actual weights as described in paragraph 3.4 to establish average crewmember weights appropriate for its operation. 5/6/19 AC 120-27F 3-5 Table 3-2. Standard Crewmember Weights Crewmember CAMI Medical Certificate Average Weights CDC/ NHANES Average Weight Uniform Weights Crewmember Average Weights with Uniform Crewmember Average Weight with Uniform & Bags Male flightcrew member lbs lbs lbs lbs lbs Female flightcrew member lbs lbs lbs lbs lbs Flight attendant NA lbs lbs lbs lbs Male flight attendant NA lbs lbs lbs lbs Female flight attendant NA lbs lbs lbs lbs Crewmember Bag Weights Crewmember roller bag lbs Pilot flight bag lbs Flight attendant kit lbs 3.2.2.2 The operator should use Table 3-2, Standard Crewmember Weights to establish their standard crewmember weights. The operator must either use survey weights or actual weights for crewmember uniforms, bags, pilot flight bags, and F/A kit(s) as described in paragraphs 3.3 and 3.4. The operator will add CDC/NHANES weights to the table as described in paragraph 3.2.1, and Appendix B. 3.2.2.3 If the operator opts to use first- and second-class medical weights provided by CAMI, the operator must use the most current Aerospace Medical Certification Statistical Handbook report. The first-and second-class medical mean weight from the report should be placed in the second column titled “CAMI Medical Certificate Average Weights” of Table 3-2. (For additional information on CAMI, see Appendix B.) 3.2.2.4 The F/A weights with bags assume that each F/A has one crewmember roller bag and one F/A kit. 3.2.2.5 An operator may include the weight of crewmembers in an aircraft’s BEW or add the weight to the load manifest prepared for each flight. 5/6/19 AC 120-27F 3-6 3.2.2.6 The standard average crewmember weights established by the operator will be provided to the FAA for review and approval and issued through the operator’s OpSpecs, MSpecs, or LOA, as applicable. 3.2.3 What Weights May Be Used for Company Materials (COMAT), Freight, and Mail? 3.2.3.1 COMAT and Freight. An operator should use actual weights for company materials, aircraft parts, and freight carried aboard an aircraft. 3.2.3.2 Mail. An operator should use the weights provided with manifested mail shipments to account for the weight of the mail. If an operator has to separate a shipment of mail, the operator may make actual estimates about the weight of the individual pieces, provided the sum of the estimated weights is equal to the actual manifested weight of the entire shipment. Note: Operators must ensure when using manifested mail shipments to account for weight, the operator must have procedures to ensure the weights provided are verified. 3.2.4 What are the Standard Average Weights for Special Passenger Groups that Do Not Fit an Operator’s Standard Average Weight Profile? 3.2.4.1 Actual passenger weights should be used for nonstandard weight groups (e.g., sports teams) unless average weights have been established for such groups by conducting a survey in accordance with the procedures established in paragraph 3.1. When such groups form only a part of the total passenger load, actual weights, or established average weights for the nonstandard group, should be used for such exception groups and average weights used for the balance of the passenger load. In such instances, a notation should be made in the load manifest indicating the number of persons in the special group and identifying the group (e.g., football squad). 3.2.4.2 Roster weights may be used for determining the actual passenger weight. 3.2.4.3 Actual baggage weights must be used in cases where the carry-on bags are not representative of the operator’s profile. 3.2.4.4 Groups that are predominantly male or female should use the standard average weights for males or females provided in Table 3-1. 3.2.4.5 For military groups, the Department of Defense (DOD) requires actual passenger and cargo weights be used in computing the aircraft W&B for all DOD charter missions. This requirement is specified in DOD Commercial Air Carrier Quality and Safety requirements (refer to Title 32 of the Code of Federal Regulations part 861, § 861.4(e)(3)(ix)). FAA-approved air carrier W&B control programs may be used to account for carry-on/personal items for mixed loads of military and their dependents (such as channel missions). For combat-equipped troop charters, the Air Mobility Command (AMC) will 5/6/19 AC 120-27F 3-7 provide guidance to account for the additional weight. If aircraft operators perceive that the weights provided are understated, they should seek confirmation of the actual weights and should make reasonable upward estimations and adjustments to those passenger and/or bag weights. 3.3 Average Weights Based on Survey Results. 3.3.1 What Should an Operator Consider when Designing a Survey? 3.3.1.1 This paragraph provides operators with an acceptable survey method to use in determining average weights for a W&B control program. This paragraph also describes how an operator can conduct a survey to count personal items, carry-on bags, and checked bags to determine an appropriate allowance for those items. In addition, an operator may use the methods described in this paragraph to conduct a survey to determine the percentage of male and female passengers and to calculate an average passenger weight. 3.3.1.2 Surveys conducted correctly allow an operator to draw reliable inferences about large populations based on relatively small sample sizes. In designing a survey, an operator should consider: 1. The sample size required to achieve the desired reliability, 2. The sample selection process, and 3. The type of survey (average weights or a count of items). 3.3.2 What Sample Sizes Should an Operator Use? Several factors must be considered when determining an adequate sample size. The more varied the population, the larger the sample size required to obtain a reliable estimate. Paragraph 3.3.3 provides a formula to derive the absolute minimum sample size to achieve a 95 percent confidence level. Table 3-3, Minimum Sample Sizes, has been provided for those operators that wish to use calculations other than those listed in paragraph 3.3.3. Table 3-3 provides the operator with an acceptable number of samples that may be collected to obtain a 95 percent confidence level and lists the tolerable error associated with each category. Table 3-3. Minimum Sample Sizes Survey Subject Minimum Sample Size Tolerable Error Adult (standard adult/male/female) 2,700 1% Child 1,400 2% Checked bags 1,400 2% Heavy bag 1,400 2% Planeside loaded bags 1,400 2% Personal items and carry-on bags 1,400 2% Personal items only (for operators with a no carry-on bag program) 1,400 2% 5/6/19 AC 120-27F 3-8 3.3.3 When Conducting a Survey, Can an Operator Collect a Smaller Sample Size than That Published in Table 3-3? If the operator has chosen to use a sample size that is smaller than that provided in Table 3-3, the operator should collect a sufficient number of samples to satisfy the following formulas: 3.3.4 What Sampling Method Should an Operator Use? 3.3.4.1 Random Sampling. An operator conducting a survey must employ random sampling techniques. Random sampling means that every member of a group has an equal chance of being selected for inclusion in the sample. If an operator conducts a survey that does not employ random sampling, the characteristics of the selected sample may not be indicative of the larger group as a whole. Because of this, any conclusions drawn from such a survey may not be valid. 3.3.4.2 Random Sampling Methods. The following are two examples of random sampling methods that an operator may find appropriate for the type of survey conducted. An operator may also consult a basic publication on statistics to determine whether a different random sampling method is more appropriate. 3.3.4.2.1 Simple Random Selection. An operator should assign a sequential number to each item in a group (such as passengers waiting on a line or bag claim tickets). Then the operator randomly selects numbers and includes the item corresponding with the number in the sample. The operator repeats this process until it has obtained the minimum sample size. 3.3.4.2.2 Systematic Random Selection. An operator should randomly select an item in sequence to begin the process of obtaining samples. The operator should then use a predetermined, systematic process to select the remaining samples 5/6/19 AC 120-27F 3-9 following the first sample. For example, an operator selects the third person in line to participate in the survey. The operator then selects every fifth person after that to participate in the survey. The operator continues selecting items to include in the sample until it has obtained the minimum sample size. 3.3.4.3 Elective Passenger Participation. Regardless of the sampling method used, an operator has the option of surveying each passenger and bag aboard the aircraft and should give a passenger the right to decline to participate in any passenger or bag weight survey. If a passenger declines to participate, the operator should select the next passenger based on the operator’s random selection method rather than select the next passenger in a line. If a passenger declines to participate, an operator should not attempt to estimate data for inclusion in the survey. 3.3.5 What Should an Operator Consider when Developing a Survey Plan and Submitting it to the FAA? 3.3.5.1 Developing a Survey Plan. Before conducting a survey, an operator should develop a survey plan. The plan should describe the dates, times, and locations the survey will take place. In developing a survey plan, the operator should consider its type of operation, hours of operation, markets served, passenger mix, and frequency of flights on particular routes. In general, an operator should avoid conducting surveys on holidays or other dates that are not representative of normal operations. 3.3.5.2 Submitting the Survey Plan to the FAA. An operator should submit its survey plan to the FAA at least 30 calendar-days before the operator expects to begin the survey. Before the survey begins, the operator’s principal inspector (PI) will review the plan and work with the operator to develop a mutually acceptable plan. During the survey, the PI will oversee the survey process to validate the execution of the survey plan. After the survey is complete, the PI will review the survey results and issue the appropriate OpSpecs or MSpecs. Once a survey begins, the operator should continue the survey until complete, even if the initial survey data indicates that the average weights are lighter or heavier than expected. 3.3.6 What General Survey Procedures Should an Operator Use? 3.3.6.1 Survey Locations. An operator should accomplish a survey at one or more airports that represent at least 15 percent of an operator’s daily departures. To provide connecting passengers with an equal chance of being selected in the survey, an operator should conduct its survey within the secure area of the airport. An operator should select locations to conduct its survey that would provide a sample that is random and representative of its operations. For example, an operator should not conduct a survey at a gate used by shuttle operations unless the operator is conducting a survey specific to that route or the operator only conducts shuttle operations. 5/6/19 AC 120-27F 3-10 3.3.6.2 Weighing Passengers. An operator that chooses to weigh passengers as part of a survey should take care to protect the privacy of passengers. The scale readout should remain hidden from public view. An operator should ensure that any passenger weight data collected remains confidential. 3.3.6.3 Weighing Bags. When weighing bags, the operator should account for all items taken aboard the aircraft as well as checked-in items. In addition, the operator should ensure a proper accounting for all planeside loaded items, and have procedures on how to handle these items. Note: The operator should ensure that all scales are certified and calibrated by the manufacturer or a certified laboratory, such as a civil department of weights and measures, or the operator may calibrate the scale under an approved calibration program. The operator should also ensure that the scale is calibrated within the manufacturer’s recommended time, or time periods, as specified in the operator’s approved calibration program. 3.3.6.4 Rounding in Survey Collection. When collecting survey data, values should be recorded to the same precision as the accuracy of the collection method, including considerations such as any calibration tolerance or estimation on analog scales. For example, when using scales calibrated to the nearest pound, it is just as incorrect to record values at the tenth of a pound as it is to round to the nearest 10 pounds. 3.3.6.5 Surveys for Particular Routes. An operator may conduct a survey for a particular route if the operator believes that the average weights on that route may differ from those in the rest of its operations. To establish a standard average passenger weight along the route, an operator may survey passengers at only one location. However, an operator should conduct surveys of personal items and bags at both the departure and arrival locations of the route, unless the operator can substantiate there is no significant difference in the weight and number of bags in either direction along the route. 3.3.7 What Information Might an Operator Gain From Conducting a Count Survey? An operator may conduct a survey to count certain items without determining the weight of those items. For example, an operator may determine that the standard average weights for male and female passengers are appropriate for its operations, but on some routes, the passengers are predominantly male or female. In such a case, an operator should conduct a survey to determine the percentage of male and female passengers. The operator could use the results of the survey to justify a weight other than the standard weights, which assume a 50 percent male and 50 percent female mix of passengers. 3.3.8 When Should an Operator Conduct Another Survey to Revalidate the Data From an Earlier Survey? In order for survey-derived average weights to be effective, an operator’s W&B control program should include a safety risk assessment and safety management principles from Safety Management Systems (SMS). The operator’s periodic assessment 5/6/19 AC 120-27F 3-11 should include a method to review its underlying program that considers any survey of passengers or bags. The FAA recommends operators accomplish such a review every 36 calendar-months, as well as when the operator obtains data suggesting a possible change affecting the program. Examples of such changes include the operator changing carry-on bag or checked bag policies, charges for carry-on or checked baggage, and route changes where seasonal variances may not be appropriate. If such an assessment determines that any assumption or behavior has changed, the operator should consider providing notice of a change within 90 days of completing the safety risk assessment and submit mitigating action(s), if necessary. Mitigating actions might include making changes to the program, revalidating survey data, or updating the OpSpecs described in paragraph 4.2.2. 3.3.9 What Standard Average Weights Should an Operator Use for their Baggage Weights? An operator will use the survey methods described above to determine their standard average baggage weight. Once the operator has completed the survey, the operator will update their OpSpecs with the appropriate weights as well as update their manuals reflecting their standard baggage weights. 3.3.9.1 If an operator chooses not to survey their bags, the operator has the option of using actual weights as described in paragraph 3.4. 3.3.10 What is a Heavy Bag? A heavy bag is considered any bag that weighs more than 50 pounds but less than 100 pounds. An operator should account for a heavy bag by using one of the following weights: 1. An average weight based on the results of a survey of heavy bags, or 2. The actual weight of the heavy bag. 3.3.11 What is a Non-Luggage/Non-Standard Bag? A non-luggage/non-standard bag is any bag that does not meet the normal criteria for luggage or a bag as described in the operator’s W&B program. Examples include golf bags, fishing equipment packages, wheelchairs, strollers in their shipping configuration, windsurfing kits, and boxed bicycles. For non-luggage/non-standard bags, operators may use any appropriate combination of actual weights and average weights based on survey results. Operators that wish to establish an average weight for a particular type of non-luggage/non-standard bag, such as a golf bag, must conduct a survey in accordance with the procedures established in this chapter. Operators should also establish a method to calculate the effect on CG of a non-luggage/non-standard bag that may occupy more than one compartment on the aircraft. 3.3.12 Planeside Loaded and Checked Bags. Operators using their standard average survey bag weights should consider all bags not stored in the cabin as checked bags. However, operators might develop procedures for identifying bags that would typically be considered carry-on and/or planeside loaded baggage and incorporate such average weights into their approved carry-on and W&B control program. When an operator develops such procedures, the operator may use the standard average weights they determined by survey, specified for carry-on, planeside loaded, and checked baggage. 5/6/19 AC 120-27F 3-12 Operators conducting flights in which all passenger bags are typically loaded planeside, or all bags are carried into the cabin for further storage, should develop guidelines to inform pilots when it is appropriate to use the heavier standard average checked bag weights, heavy bag weights, or actual weights. Note: If an operator discovers that a planeside loaded bag should have been treated as a checked bag, the operator should account for that bag at the standard average weight by survey for a checked bag. 3.4 Actual Weight Programs. 3.4.1 If the Operator Decides to Use an Actual Weight Program, How Might it Determine the Actual Weight of Passengers? An operator may determine the actual weight of passengers by: 1. Weighing each passenger on a scale before boarding the aircraft (types of weight scales and scale tolerances will be defined in the operator’s approved W&B control program); or 2. Asking each passenger his or her weight. An operator should add to this asked (volunteered) weight at least 10 pounds to account for clothing. An operator should increase this allowance for clothing on certain routes or during certain seasons, if appropriate. Note: If an operator believes that the weight volunteered by a passenger is understated, the operator should make a reasonable estimate of the passenger’s actual weight and add 10 pounds. 3.4.2 If the Operator Decides to Use an Actual Weight Program, How Should it Determine the Actual Weights of Personal Items and Bags? To determine the actual weight of a personal item, carry-on bag, checked bag, planeside loaded bag, or a heavy bag, an operator should weigh the item on a scale. Note: The operator should ensure that all scales are certified and calibrated by the manufacturer or a certified laboratory, such as a civil department of weights and measures, or the operator may calibrate the scale under an approved calibration program. The operator should also ensure that the scale is calibrated within the manufacturer’s recommended time, or time periods, as specified in the operator’s approved calibration program. 3.4.3 What Approach Should an Operator Use to Record Actual Weights? An operator using actual weights should record all weights used in the load calculation. 5/6/19 AC 120-27F 4-1 CHAPTER 4. OPERATOR REPORTING SYSTEMS AND FAA OVERSIGHT 4.1 Pilot and Agent Reporting Systems. 4.1.1 What are the Pilot’s and Operator’s Responsibilities in Reporting Aircraft Loading and Manifest Preparation Discrepancies? Each operator should develop a reporting system and encourage employees to report any discrepancies in aircraft loading or manifest preparation. These discrepancies may include errors in documentation or calculation, or issues with aircraft performance and handling qualities that indicate the aircraft weight or balance is not accurate. Operators should determine the cause of each discrepancy and take appropriate corrective action. This would include a load audit on affected flights or conducting a passenger or bag weight survey in accordance with this advisory circular (AC) if trends indicate it is warranted. Note 1: Section 121.665 states, “each certificate holder is responsible for the preparation and accuracy of a load manifest form before each takeoff.” The FAA, however, encourages operators to develop a reporting system in order to account for any discrepancies or errors in documentation and to determine the cause of each discrepancy, in the interest of reducing the likelihood that load manifests contain incorrect information. Note 2: While accountability for compliance with § 121.665 must be based on the original manifest, an operator is not barred from taking any corrective action determined by their safety management system (SMS) to have a positive impact on the safety of any continuing flight. For example, an operator may prepare a separate, amended manifest if the flightcrew might unknowingly exceed the maximum certified landing weight or other safety limitation without the amendment. 4.2 FAA Oversight. 4.2.1 Which FAA Inspectors are Responsible for Approving and Oversight of an Operator’s W&B Program? The FAA has divided the responsibility of approving and oversight of an operator’s W&B control program between the operator’s principal inspectors (PI) in the certificate management office (CMO) or Flight Standards District Office (FSDO). An operator that wishes to change aspects of its W&B control program, including average weights, should submit all applicable supporting data (part 121 operators) to include a safety risk assessment to the PIs and for approval. If the FAA approves the changes, the FAA will issue revised operations specifications (OpSpecs), management specifications (MSpecs), or Letter of Authorization (LOA), as appropriate. 4.2.2 Which Portions of OpSpecs or MSpecs are Relevant to an Operator’s W&B Program? This AC details methods to develop a W&B control program with greater accuracy and increased flexibility. By changing its OpSpecs or MSpecs, an operator may alter the weights used in its W&B control program to include appropriate combinations of standard average weights, average weights based on survey results, or actual weights. 5/6/19 AC 120-27F 4-2 4.2.2.1 OpSpec or MSpec Parts A and E will address: 1. Average passenger and average bag weights by survey; 2. Situations when the use of average weights is inappropriate; 3. The treatment of charter flights or special groups, if applicable; 4. The type of loading schedule and instructions for its use; 5. Aircraft weighing schedules; and 6. Other procedures that the operator may require to assure accuracy of their control of W&B program. 4.2.2.2 OpSpec or MSpec E096, Aircraft Weighing, is issued to an operator with an approved aircraft weight program. The FAA issues this paragraph after reviewing and approving the operator’s aircraft W&B control procedures in their entirety. 4.2.2.3 OpSpec or MSpec A011, Approved Carry-On Baggage Program, is issued to an operator with an approved carry-on bag program. This paragraph provides details about the operator’s approved carry-on bag program and states whether the operator has a carry-on bag program or a no-carry-on bag program. The FAA will issue this paragraph after reviewing the operator’s carry-on baggage program in its entirety. 4.2.2.4 If an operator chooses to use standard average passenger weights as outlined in this AC, the FAA will document that decision by issuing one or more of the following OpSpecs or MSpecs. If an operator proposes to use weights other than the standard average weights, and if the FAA concurs with the statistically valid data provided by the operator to support such average weights, the weights will be documented in the following OpSpecs or MSpecs. Although the following OpSpecs and MSpecs authorize an operator to use average weights, an operator may use actual weights at any time once issued these paragraphs. 1. OpSpec/MSpec A097, Small Cabin Aircraft Passenger and Baggage Weight Program. 2. OpSpec/MSpec A098, Medium Cabin Aircraft Passenger and Baggage Weight Program. 3. OpSpec/MSpec A099, Large Cabin Aircraft Passenger and Baggage Weight Program. Note: If an operator does not provide the FAA with adequate information to justify the issuance of one of the above paragraphs that documents the use of standard average, survey-derived average, the FAA may issue OpSpec/MSpec A096, Actual Passenger and Baggage 5/6/19 AC 120-27F 4-3 Weight Program for All Aircraft, which authorizes the operator to use only actual passenger and bag weights. 4.2.2.5 If an operator chooses to develop a W&B control program using only actual weights for all the aircraft it operates, the FAA will issue OpSpec/MSpec A096. The FAA will not issue OpSpec/MSpec A097, A098, or A099 to operators with a W&B control program that uses only actual weights. The FAA will only issue OpSpecs/MSpecs A096, A097, A098, and/or A099 after reviewing the operator’s actual or average weight program. 4.2.2.6 An operator that receives approval to use survey-derived (nonstandard) average weights should document and make available, upon request, the data and methodology used to derive those weights. An operator’s documentation should be sufficiently comprehensive to allow the FAA to reproduce the same results during an audit. An operator should retain this documentation for as long as the operator uses the survey-derived average weights in its W&B control program. See paragraph 3.3.8 for when to revalidate survey-derived (nonstandard) average weights. 4.2.2.7 If an operator chooses to conduct a survey, the operator will use the results of the survey to establish a revised average weight and must curtail the loading envelope as necessary. Once approved by the FAA, the appropriate OpSpecs, MSpecs, or LOA will be issued. 4.2.2.8 For operators using an onboard W&B system to determine the W&B of the aircraft, the FAA will issue OpSpec or MSpec A096. OpSpec/MSpec A096 documents the use of actual weights and the use of its onboard W&B system. For an operator that chooses to use standard average weights as a backup system, the FAA will issue OpSpec/MSpec A097, A098, or A099, as appropriate. By authorizing the use of average weights, the operator may elect to use actual weights derived from its onboard W&B system, and may use average weights as an alternative should the system be inoperative. 4.2.2.9 For operators conducting all-cargo operations, the FAA will issue OpSpec A096. OpSpec/MSpec A096 documents the use of actual weights, with the exception of flightcrew and the weights of flightcrew bags. These weights may be accounted for using the standard average weights described in Table 3-2. 5/6/19 AC 120-27F Appendix A A-1 APPENDIX A. DEFINITIONS A.1 Balance Arm (BA). The horizontal distance from the reference datum to the CG of an item. A.2 Basic Empty Weight (BEW). The aircraft empty weight, adjusted for variations in standard items. A.3 Basic Operating Weight (BOW). The empty weight of the aircraft plus the weight of the required crew, their baggage, and other standard items such as meals and potable water. A.4 Cargo. As used in this advisory circular (AC), any property carried on an aircraft other than mail, stores, and accompanied or mishandled baggage. A.5 Carry-On Bag. A bag that the operator allows the passenger to carry on board. It should be of a size and shape that will allow it to be stowed under the passenger seat or in a storage compartment. The operator establishes the exact dimensional limits based on the particular aircraft stowage limits. A.6 Certificated Weight and Center of Gravity (CG) Limits. Weight and CG limits are established at the time of aircraft certification. They are specified in the applicable Airplane Flight Manual (AFM), Rotorcraft Flight Manual (RFM), or Weight and Balance Manual (WBM) as provided by the manufacturer. A.7 Checked Bags. Checked bags are those bags placed in the cargo compartment of the aircraft. This includes bags that are too large to be placed in the cabin of the aircraft or those bags that are required to be carried in the cargo compartment by regulation, security program, or company policy. For bags checked planeside, see the definition for planeside loaded bags. A.8 Curtailment. Creating an operational loading envelope that is more restrictive than the manufacturer’s CG envelope, to assure the aircraft will be operated within limits during all phases of flight. Curtailment typically accounts for, but is not limited to, in-flight movement, gear and flap movement, cargo variation, fuel density, fuel burn-off, and seating variation. A.9 Datum. An imaginary vertical plane from which all horizontal distances are measured for balance purpose. A.10 Fleet Operating Empty Weight (FOEW). Average operational empty weight (OEW) used for a fleet or group of aircraft of the same model and configuration. A.11 Heavy Bags. Heavy bags are considered any bag that weighs more than 50 pounds but less than 100 pounds. Bags that are 100 pounds or more are considered cargo. A.12 Large Cabin Aircraft. Aircraft originally certificated with a maximum seating capacity of 71 or more passenger seats. 5/6/19 AC 120-27F Appendix A A-2 A.13 Loading Envelope. Weight and CG envelope used in a loading schedule. Loading the aircraft within the loading envelope will maintain the aircraft weight and CG throughout the flight within the limits established by the type certificate (TC) or Supplemental Type Certificate (STC) that applies to the aircraft. A.14 Loading Schedule. Method for calculating and documenting aircraft Weight and Balance (W&B) prior to taxiing, to ensure the aircraft will remain within all required W&B limitations throughout the flight. A.15 Maximum Landing Weight. The maximum weight at which the aircraft may normally be landed. A.16 Maximum Takeoff Weight (MTOW). The maximum allowable aircraft weight at the start of the takeoff run. A.17 Maximum Taxi Weight. The maximum allowable aircraft weight for taxiing. A.18 Maximum Zero Fuel Weight (MZFW). The maximum permissible weight of an aircraft with no disposable fuel and oil. A.19 Mean Aerodynamic Chord (MAC). The MAC is established by the manufacturer, which defines its leading edge and its trailing edge in terms of distance (usually inches) from the datum. The CG location and various limits are then expressed in percentages of the chord. The location and dimensions of the MAC can be found in the aircraft specifications, the type certificate data sheet (TCDS), the AFM, RFM, or the aircraft WBM. A.20 Medium Cabin Aircraft. Aircraft originally certificated with a maximum seating capacity between 70 and 30 passenger seats, inclusive. A.21 Moment. The moment is the product of a weight multiplied by its arm. The moment of an item about the datum is obtained by multiplying the weight of the item by its horizontal distance from the datum. A.22 Onboard Weight and Balance (W&B) System. A system that weighs an aircraft and payload, then computes the CG using equipment onboard the aircraft. A.23 Operational Items. Personnel, equipment, and supplies necessary for a particular operation but not included in BEW. These items may vary for a particular aircraft and may include, but are not limited to, the following: 1. Crewmembers and bags; 2. Manuals and navigation equipment; 3. Passenger service equipment, including pillows, blankets, and magazines; 4. Removable service equipment for cabin, galley, and bar; 5. Food and beverage, including liquor; 5/6/19 AC 120-27F Appendix A A-3 6. Usable fluids, other than those in useful load; 7. Required emergency equipment for all flights; 8. Life rafts, life vests, and emergency transmitters; 9. Potable water; 10. Drainable unusable fuel; 11. Spare parts normally carried aboard and not accounted for as cargo; and 12. All other equipment considered standard by the operator. A.24 Passenger Assist/Comfort Animals and Devices. These include, but are not limited to, canes, crutches, walkers, wheelchairs, and service animals. A.25 Passenger Weight. Passenger weight is the actual weight or the approved average weight of the passenger. 1. An adult is defined as an individual 13 years or older. 2. A child is defined as an individual aged 2 to less than 13 years of age. 3. Infants are children who have not yet reached their second birthday and are considered part of the adult standard average passenger weight. A.26 Personal Item. Items the operator may allow a passenger to carry on board, in addition to a carry-on bag. Typically, an operator may allow one personal item such as a purse, briefcase, computer and case, camera and case, diaper bag, or an item of similar size. Other items, such as coats, umbrellas, reading material, food for immediate consumption, child restraint systems, and service animals, are allowed to be carried on the aircraft and are not counted against the personal item allowance. A.27 Planeside Loaded Bag. Any bag or item that is placed at the door or steps of an aircraft and subsequently placed in the aircraft cargo compartment or cargo bin. A.28 Roster Weight. The listing of a group of passengers specifically by name and weight. A.29 Small Cabin Aircraft. Aircraft originally certificated with a maximum seating capacity between 5 and 29 passenger seats, inclusive. A.30 Standard Deviation. One of several indexes of variability used to characterize dispersion among measures in a given population. A.31 Standard Items. Equipment and fluids not considered an integral part of a particular aircraft and not a variation for the same type of aircraft. These items may include, but are not limited to, the following: 1. Unusable fuel and other unusable fluids; 2. Engine oil; 5/6/19 AC 120-27F Appendix A A-4 3. Toilet fluid and chemical; 4. Fire extinguishers, pyrotechnics, and emergency oxygen equipment; 5. Structure in galley, buffet, and bar; and 6. Supplementary electronic equipment. A.32 Type Certificate Data Sheet (TCDS). An FAA document that records the type certification data of a product (such as a control surface movement limits, operating limitations, placards, and W&B) that may also be available in the flight manual or maintenance manual in accordance with the current edition of FAA Order 8110.4, Type Certification. The TCDS is part of the TC, per 14 CFR part 21, § 21.41. A.33 Useful Load. Difference between takeoff weight and BEW. It includes payload, usable fuel, and other usable fluids not included as operational items. 5/6/19 AC 120-27F Appendix B B-1 APPENDIX B. SOURCE OF STANDARD AVERAGE WEIGHTS B.1 Standard Average Passenger Weights. B.1.1 The Federal Aviation Administration (FAA) examined data from several large-scale, national health studies conducted by U.S. Government health agencies. The FAA found that the National Health and Nutrition Examination Survey (NHANES), conducted by the Centers for Disease Control (CDC), provided the most comprehensive and appropriate data. The data in NHANES cover a broad spectrum of the general population, are based on a large sample size, and are not restricted geographically to a particular area. B.1.2 The CDC collects NHANES data annually by conducting an actual scale weighing of approximately 9,000 subjects in a clinical setting. The CDC normally publishes results every 4 years. Additional information on NHANES and the data points used to derive average weights are found at the following websites: 1. General information: http://www.cdc.gov/nchs/nhanes.htm. 2. CDC body measurements for men and women 20 years and over: http://www.cdc.gov/nchs/fastats/body-measurements.htm. B.2 Standard Average Crewmember Weights. B.2.1 The FAA Civil Aerospace Medical Institute (CAMI) publishes annually the Aerospace Medical Certification Statistical Handbook, which contains descriptive characteristics of all active U.S. civil aviation airmen. An operator’s use of reports from CAMI ensures the operator is using the most current version of the Handbook. The operator will use the proper medical class and establish a crewmember mean weight respective to their operation. These reports are found at: http://www.faa.gov/data_research/research/med_hu manfacs/oamtechreports/2010s/. 5/6/19 AC 120-27F Appendix C C-1 APPENDIX C. SAMPLE OPERATIONAL LOADING ENVELOPE C.1 Introduction. The following is an example of how to develop an operational loading envelope. For this example, a hypothetical 19-seat normal category aircraft is used. Although this example uses inches to measure fuselage station, an operator may choose to use an index system for convenience. C.2 Assumptions for This Example. C.2.1 Passenger Weight. Because the aircraft is certificated under the normal category of 14 CFR part 23, and because it is originally type certificated (TC) for five or more passenger seats, it would be appropriate in this example to use the weights derived in Chapter 3, Methods to Determine the Weight of Passengers, paragraph 3.2. For this example, it is assumed that the operator has a no-carry-on baggage program; therefore, it is also assumed the operator should use a standard average passenger weight of 189 pounds in winter and 184 pounds in summer. For this example, a standard average passenger weight of 189 pounds is used. The operator also assumes that passengers are distributed throughout the cabin in accordance with the window-aisle-remaining method. Note that because this aircraft has only two window seats per row, the operator may reasonably assume that passengers begin seating themselves in the front of the cabin and select the most forward seat available. C.2.2 Bag Weights. For this example, the operator assumes that a checked bag weighs 30 pounds and a planeside loaded bag weighs 20 pounds, based on the operator’s survey. C.2.3 Interior Seating. For this example, consider a normal category 19-seat aircraft with the interior seating diagram shown in Figure C-1, Sample Aircraft Interior Seating Diagram. For this example, the fuselage station (F.S.) of each seat row is the seated passenger centroid. (For other diagrams, this may not be true.) Figure C-1. Sample Aircraft Interior Seating Diagram 5/6/19 AC 120-27F Appendix C C-2 C.3 Curtailments for Passenger Seating Variation. C.3.1 Establishing Zones. The operator elects to separate the passenger cabin into three zones. Zone 1 will contain rows 1 to 3, zone 2 will contain rows 4 to 6, and zone 3 will contain rows 7 to 9. C.3.2 Determining the Centroid of Each Zone. When using cabin zones, an operator assumes that all passengers are sitting at the centroid of their zone. To find the centroid of each zone: 1. Multiply the number of seats in each row of the zone by the location of the row, 2. Add each number calculated in step 1, and 3. Divide the number in step 2 by the total number of seats in the zone. Note: For this sample aircraft, see Tables C-1 through C-3 below. Table C-1. Calculation of Zone 1 Centroid Row No. No. of Seats Row Location No. of Seats x Row Location 1 2 198 in 396 in 2 2 228 in 456 in 3 2 258 in 516 in TOTAL 6 NA 1,368 in 1,368 in / 6 seats = 228 in Table C-2. Calculation of Zone 2 Centroid Row No. No. of Seats Row Location No. of Seats x Row Location 4 2 289 in 578 in 5 2 318 in 636 in 6 2 347 in 694 in TOTAL 6 NA 1,908 in 1,908 in / 6 seats = 318 in Table C-3. Calculation of Zone 3 Centroid Row No. No. of Seats Row Location No. of Seats x Row Location 7 2 377 in 754 in 8 2 407 in 814 in 9 3 436 in 1,308 in TOTAL 7 NA 2,876 in 2,876 in / 7 seats = 411 in 5/6/19 AC 120-27F Appendix C C-3 C.3.3 Comparing Loading Assumptions. To determine the appropriate amount of curtailment, the operator should compare aircraft loading based on the window-aisle-remaining assumption with aircraft loaded based on the assumption that passengers are sitting at the centroid of their respective zones. An operator may determine the appropriate curtailment by comparing the moments resulting from these assumptions and identifying the loading scenarios that result in the most forward or aft center of gravity (CG) location. See Tables C-4 through C-12 below. C.3.3.1 Curtailment Calculation for Zone 1. Table C-4. Moments Resulting From the Zone Centroid Assumption for Zone 1 Passenger No. Assumed Weight Assumed Arm Moment Cumulative Moment 1 189 lb 228 in 43,092 in-lb 43,092 in-lb 2 189 lb 228 in 43,092 in-lb 86,184 in-lb 3 189 lb 228 in 43,092 in-lb 129,276 in-lb 4 189 lb 228 in 43,092 in-lb 172,368 in-lb 5 189 lb 228 in 43,092 in-lb 215,460 in-lb 6 189 lb 228 in 43,092 in-lb 258,552 in-lb Table C-5. Moments Resulting From the Window-Aisle-Remaining Assumption for Zone 1 Passenger No. Assumed Row Assumed Weight Assumed Arm Moment Cumulative Moment 1 1 189 lb 198 in 37,422 in-lb 37,422 in-lb 2 1 189 lb 198 in 37,422 in-lb 74,844 in-lb 3 2 189 lb 228 in 43,092 in-lb 117,936 in-lb 4 2 189 lb 228 in 43,092 in-lb 161,028 in-lb 5 3 189 lb 258 in 48,762 in-lb 209,790 in-lb 6 3 189 lb 258 in 48,762 in-lb 258,552 in-lb Table C-6. Comparison of Moments for Zone 1 Passenger No. Cumulative Moment from the Zone Centroid Assumption Cumulative Moment From the Window-Aisle-Remaining Assumption Difference 1 43,092 in-lb 37,422 in-lb -5,670 in-lb 2 86,184 in-lb 74,844 in-lb -11,340 in-lb 3 129,276 in-lb 117,936 in-lb -11,340 in-lb 4 172,368 in-lb 161,028 in-lb -11,340 in-lb 5 215,460 in-lb 209,790 in-lb -5,670 in-lb 6 258,552 in-lb 258,552 in-lb 0 in-lb 5/6/19 AC 120-27F Appendix C C-4 Figure C-2. Sample Passenger Seating Moment (Zone 1) C.3.3.2 Curtailment Calculation for Zone 2. Table C-7. Moments Resulting From the Zone Centroid Assumption for Zone 2 Passenger No. Assumed Weight Assumed Arm Moment Cumulative Moment 7 189 lb 318 in 60,102 in-lb 60,102 in-lb 8 189 lb 318 in 60,102 in-lb 120,204 in-lb 9 189 lb 318 in 60,102 in-lb 180,306 in-lb 10 189 lb 318 in 60,102 in-lb 240,408 in-lb 11 189 lb 318 in 60,102 in-lb 300,510 in-lb 12 189 lb 318 in 60,102 in-lb 360,612 in-lb 5/6/19 AC 120-27F Appendix C C-5 Table C-8. Moments Resulting From the Window-Aisle-Remaining Assumption for Zone 2 Passenger No. Assumed Row Assumed Weight Assumed Arm Moment Cumulative Moment 7 4 189 lb 289 in 54,621 in-lb