Document
7/9/26 Pilot/Controller Glossary
PILOT/CONTROLLER
GLOSSARY
PURPOSE a. This Glossary was compiled to promote a common understanding of the terms used in the Air Traffic Control system. It includes those terms which are intended for pilot/controller communications. Those terms most frequently used in pilot/controller communications are printed in bold italics . The definitions are primarily defined in an operational sense applicable to both users and operators of the National Airspace System. Use of the Glossary will preclude any misunderstandings concerning the system’s design, function, and purpose.
b. Because of the international nature of flying, terms used in the Lexicon, published by the International Civil Aviation Organization (ICAO), are included when they differ from FAA definitions. These terms are followed by “[ICAO].” For the reader’s convenience, there are also cross references to related terms in other parts of the Glossary and to other documents, such as the Code of Federal Regulations (CFR) and the Aeronautical Information Manual (AIM).
c. Terms used in this glossary that apply to flight service station (FSS) roles are included when they differ from air traffic control functions. These terms are followed by “[FSS].” d. This Glossary will be revised, as necessary, to maintain a common understanding of the system.
EXPLANATION OF CHANGES e. Terms Added: COMBINED CONTROL FACILITY (CCF) f. Terms Deleted: COMBINED CENTER − RAPCON (CERAP) g. Terms Modified: REMOTE COMMUNICATIONS AIR/GROUND FACILITY (RCAG) SIMULTANEOUS (PARALLEL) DEPENDENT APPROACHES h. Editorial/format changes were made where necessary. Revision bars were not used due to the insignificant nature of the changes.
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CALCULATED LANDING TIME − A term that may be used in place of tentative or actual calculated landing time, whichever applies.
CALIBRATED AIRSPEED (CAS) – The indicated airspeed of an aircraft, corrected for position and instrument error. Calibrated airspeed is equal to true airspeed in standard atmosphere at sea level.
CALL FOR RELEASE − Wherein the overlying ARTCC requires a terminal facility to initiate verbal coordination to secure ARTCC approval for release of a departure into the en route environment.
CALL UP − Initial voice contact between a facility and an aircraft, using the identification of the unit being called and the unit initiating the call.
(Refer to AIM.)
CANADIAN MINIMUM NAVIGATION PERFORMANCE SPECIFICATION AIRSPACE − That portion of Canadian domestic airspace within which MNPS separation may be applied.
CARDINAL ALTITUDES − “Odd” or “Even” thousand-foot altitudes or flight levels; e.g., 5,000, 6,000, 7,000, FL 250, FL 260, FL 270.
(See ALTITUDE.)
(See FLIGHT LEVEL.)
CARDINAL FLIGHT LEVELS − (See CARDINAL ALTITUDES.)
CAT − (See CLEAR-AIR TURBULENCE.)
CATCH POINT − A fix/waypoint that serves as a transition point from the high altitude waypoint navigation structure to an arrival procedure (STAR) or the low altitude ground − based navigation structure.
CBO − (See COMMUNITY − BASED ORGANIZATION.)
CCF − (See COMBINED CONTROL FACILITY.)
CEILING − The heights above the earth’s surface of the lowest layer of clouds or obscuring phenomena that is reported as “broken,” “overcast,” or “obscuration,” and not classified as “thin” or “partial.” (See ICAO term CEILING.)
CEILING [ICAO] − The height above the ground or water of the base of the lowest layer of cloud below 6,000 meters (20,000 feet) covering more than half the sky.
CENTER − (See AIR ROUTE TRAFFIC CONTROL CENTER.)
CENTER’S AREA − The specified airspace within which an air route traffic control center (ARTCC) provides air traffic control and advisory service.
(See AIR ROUTE TRAFFIC CONTROL CENTER.)
(Refer to AIM.)
PCG C − 1 Pilot/Controller Glossary 2/20/25 Pilot/Controller Glossary 7/9/26 CENTER WEATHER ADVISORY − An unscheduled weather advisory issued by Center Weather Service Unit meteorologists for ATC use to alert pilots of existing or anticipated adverse weather conditions within the next 2 hours. A CWA may modify or redefine a SIGMET.
(See AIRMET.)
(See CONVECTIVE SIGMET.)
(See GRAPHICAL AIRMEN’S METEOROLOGICAL INFORMATION.)
(See SAW.)
(See SIGMET.)
(Refer to AIM.)
CENTRAL EAST PACIFIC − An organized route system between the U.S. West Coast and Hawaii.
CEP − (See CENTRAL EAST PACIFIC.)
CERTIFICATE OF WAIVER OR AUTHORIZATION (COA) − An FAA grant of approval for a specific flight operation or airspace authorization or waiver.
CERTIFIED TOWER RADAR DISPLAY (CTRD) − An FAA radar display certified for use in the NAS.
CFR − (See CALL FOR RELEASE.)
CHA (See CONTINGENCY HAZARD AREA) CHAFF − Thin, narrow metallic reflectors of various lengths and frequency responses, used to reflect radar energy. These reflectors, when dropped from aircraft and allowed to drift downward, result in large targets on the radar display.
CHART SUPPLEMENT − A series of civil/military flight information publications issued by FAA every 56 days consisting of the Chart Supplement U.S., Chart Supplement Alaska, and Chart Supplement Pacific.
CHART SUPPLEMENT ALASKA − A flight information publication designed for use with appropriate IFR or VFR charts which contains data on all airports, seaplane bases, and heliports open to the public including communications data, navigational facilities, airport diagrams, certain special notices, and non − regulatory procedures. Also included in this publication are selected entries needed to support the unique geographical operational conditions of Alaska. This publication is issued in one volume for the state of Alaska.
CHART SUPPLEMENT PACIFIC − A flight information publication designed for use with appropriate IFR or VFR charts which contains data on all airports, seaplane bases, and heliports open to the public including communications data, navigational facilities, airport diagrams, certain special notices, and non − regulatory procedures. Also included in this publication are Instrument Approach Procedures (IAP), Departure Procedures (DP), and Standard Terminal Arrival (STAR) charts, along with selected entries needed to support the unique geographical operational conditions of the Pacific Oceanic region. This publication is issued in one volume for the Hawaiian Islands and other selected Pacific Islands.
CHART SUPPLEMENT U.S. − A flight information publication designed for use with appropriate IFR or VFR charts which contains data on all airports, seaplane bases, and heliports open to the public including communications data, navigational facilities, airport diagrams, certain special notices, and non − regulatory procedures. This publication is issued for the conterminous U.S., Puerto Rico, and the Virgin Islands in seven volumes according to geographical area.
CHARTED VFR FLYWAYS − Charted VFR Flyways are flight paths recommended for use to bypass areas heavily traversed by large turbine-powered aircraft. Pilot compliance with recommended flyways and associated altitudes is strictly voluntary. VFR Flyway Planning charts are published on the back of existing VFR Terminal Area charts.
CHARTED VISUAL FLIGHT PROCEDURE APPROACH − An approach conducted while operating on an instrument flight rules (IFR) flight plan which authorizes the pilot of an aircraft to proceed visually and clear PCG C − 2 Pilot/Controller Glossary 2/20/25 7/9/26 Pilot/Controller Glossary of clouds to the airport via visual landmarks and other information depicted on a charted visual flight procedure.
This approach must be authorized and under the control of the appropriate air traffic control facility. Weather minimums required are depicted on the chart.
CHASE − An aircraft flown in proximity to another aircraft normally to observe its performance during training or testing.
CHASE AIRCRAFT − (See CHASE.)
CHOP − A form of turbulence.
a. Light Chop– Turbulence that causes slight, rapid and somewhat rhythmic bumpiness without appreciable changes in altitude or attitude.
b. Moderate Chop– Turbulence similar to Light Chop but of greater intensity. It causes rapid bumps or jolts without appreciable changes in aircraft altitude or attitude.
(See TURBULENCE.)
CIRCLE-TO-LAND MANEUVER − A maneuver initiated by the pilot to align the aircraft with a runway for landing when a straight-in landing from an instrument approach is not possible or is not desirable. At tower controlled airports, this maneuver is made only after ATC authorization has been obtained and the pilot has established required visual reference to the airport.
(See CIRCLE TO RUNWAY.)
(See LANDING MINIMUMS.)
(Refer to AIM.)
CIRCLE TO RUNWAY (RUNWAY NUMBER) − Used by ATC to inform the pilot that he/she must circle to land because the runway in use is other than the runway aligned with the instrument approach procedure. When the direction of the circling maneuver in relation to the airport/runway is required, the controller will state the direction (eight cardinal compass points) and specify a left or right downwind or base leg as appropriate; e.g., “Cleared VOR Runway Three Six Approach circle to Runway Two Two,” or “Circle northwest of the airport for a right downwind to Runway Two Two.” (See CIRCLE-TO-LAND MANEUVER.)
(See LANDING MINIMUMS.)
(Refer to AIM.)
CIRCLING APPROACH − (See CIRCLE-TO-LAND MANEUVER.)
CIRCLING MANEUVER − (See CIRCLE-TO-LAND MANEUVER.)
CIRCLING MINIMA − (See CONTROLLED AIRSPACE.)
CIVIL AIRCRAFT OPERATION (CAO) − Aircraft operations other than public use.
CLASS A AIRSPACE − (See CONTROLLED AIRSPACE.)
CLASS B AIRSPACE − (See CONTROLLED AIRSPACE.)
CLASS C AIRSPACE − (See CONTROLLED AIRSPACE.)
CLASS D AIRSPACE − (See CONTROLLED AIRSPACE.)
CLASS E AIRSPACE − (See CONTROLLED AIRSPACE.)
PCG C − 3 Pilot/Controller Glossary 2/20/25 Pilot/Controller Glossary 7/9/26 CLASS G AIRSPACE − Airspace that is not designated in 14 CFR part 71 as Class A, Class B, Class C, Class D, or Class E controlled airspace is Class G (uncontrolled) airspace.
(See UNCONTROLLED AIRSPACE.)
CLEAR AIR TURBULENCE (CAT) − Turbulence encountered in air where no clouds are present. This term is commonly applied to high-level turbulence associated with wind shear. CAT is often encountered in the vicinity of the jet stream.
(See WIND SHEAR.)
(See JET STREAM.)
CLEAR OF THE RUNWAY − a. Taxiing aircraft, which is approaching a runway, is clear of the runway when all parts of the aircraft are held short of the applicable runway holding position marking.
b. A pilot or controller may consider an aircraft, which is exiting or crossing a runway, to be clear of the runway when all parts of the aircraft are beyond the runway edge and there are no restrictions to its continued movement beyond the applicable runway holding position marking.
c. Pilots and controllers must exercise good judgment to ensure that adequate separation exists between all aircraft on runways and taxiways at airports with inadequate runway edge lines or holding position markings.
CLEARANCE − (See AIR TRAFFIC CLEARANCE.)
CLEARANCE LIMIT − The fix, point, or location to which an aircraft is cleared when issued an air traffic clearance.
(See ICAO term CLEARANCE LIMIT.)
CLEARANCE LIMIT [ICAO] − The point to which an aircraft is granted an air traffic control clearance.
CLEARANCE VOID IF NOT OFF BY (TIME) − Used by ATC to advise an aircraft that the departure release is automatically canceled if takeoff is not made prior to a specified time. The expiration of a clearance void time does not cancel the departure clearance or IFR flight plan. It withdraws the pilot’s authority to depart IFR until a new departure release/release time has been issued by ATC. Pilots who choose to depart VFR after their clearance void time has expired should not depart using the previously assigned IFR transponder code.
(See ICAO term CLEARANCE VOID TIME.)
CLEARANCE VOID TIME [ICAO] − A time specified by an air traffic control unit at which a clearance ceases to be valid unless the aircraft concerned has already taken action to comply therewith.
CLEARED APPROACH − ATC authorization for an aircraft to execute any standard or special instrument approach procedure for that airport. Normally, an aircraft will be cleared for a specific instrument approach procedure.
(See CLEARED (Type of) APPROACH.)
(See INSTRUMENT APPROACH PROCEDURE.)
(Refer to 14 CFR part 91.)
(Refer to AIM.)
CLEARED (Type of) APPROACH − ATC authorization for an aircraft to execute a specific instrument approach procedure to an airport; e.g., “Cleared ILS Runway Three Six Approach.” (See APPROACH CLEARANCE.)
(See INSTRUMENT APPROACH PROCEDURE.)
(Refer to 14 CFR part 91.)
(Refer to AIM.)
CLEARED AS FILED − Means the aircraft is cleared to proceed in accordance with the route of flight filed in the flight plan. This clearance does not include the altitude, DP, or DP Transition.
(See REQUEST FULL ROUTE CLEARANCE.)
(Refer to AIM.)
PCG C − 4 Pilot/Controller Glossary 2/20/25 7/9/26 Pilot/Controller Glossary CLEARED FOR TAKEOFF − ATC authorization for an aircraft to depart. It is predicated on known traffic and known physical airport conditions.
CLEARED FOR THE OPTION − ATC authorization for an aircraft to make a touch-and-go, low approach, missed approach, stop and go, or full stop landing at the discretion of the pilot. It is normally used in training so that an instructor can evaluate a student’s performance under changing situations. Pilots should advise ATC if they decide to remain on the runway, of any delay in their stop and go, delay clearing the runway, or are unable to comply with the instruction(s).
(See OPTION APPROACH.)
(Refer to AIM.)
CLEARED THROUGH − ATC authorization for an aircraft to make intermediate stops at specified airports without refiling a flight plan while en route to the clearance limit.
CLEARED TO LAND − ATC authorization for an aircraft to land. It is predicated on known traffic and known physical airport conditions.
CLEARWAY − An area beyond the takeoff runway under the control of airport authorities within which terrain or fixed obstacles may not extend above specified limits. These areas may be required for certain turbine-powered operations and the size and upward slope of the clearway will differ depending on when the aircraft was certificated.
(Refer to 14 CFR part 1.)
CLIMB TO VFR − ATC authorization for an aircraft to climb to VFR conditions within Class B, C, D, and E surface areas when the only weather limitation is restricted visibility. The aircraft must remain clear of clouds while climbing to VFR.
(See SPECIAL VFR CONDITIONS.)
(Refer to AIM.)
CLIMBOUT − That portion of flight operation between takeoff and the initial cruising altitude.
CLIMB VIA– An abbreviated ATC clearance that requires compliance with the procedure lateral path, associated speed restrictions, and altitude restrictions along the cleared route or procedure.
CLOSE PARALLEL RUNWAYS − Two parallel runways whose extended centerlines are separated by less than 4,300 feet and at least 3000 feet (750 feet for SOIA operations) for which ATC is authorized to conduct simultaneous independent approach operations. PRM and simultaneous close parallel appear in approach title.
Dual communications, special pilot training, an Attention All Users Page (AAUP), NTZ monitoring by displays that have aural and visual alerting algorithms are required. A high update rate surveillance sensor is required for certain runway or approach course spacing.
CLOSED LOOP CLEARANCE − A vector or reroute clearance that includes a return to route point and updates ERAM to accurately reflect the anticipated route (e.g., a QU route pick that anticipates length of vector and includes the next fix that ties into the route of flight.)
CLOSED RUNWAY − A runway that is unusable for aircraft operations. Only the airport management/military operations office can close a runway.
CLOSED TRAFFIC − Successive operations involving takeoffs and landings or low approaches where the aircraft does not exit the traffic pattern.
CLOUD − A cloud is a visible accumulation of minute water droplets and/or ice particles in the atmosphere above the Earth’s surface. Cloud differs from ground fog, fog, or ice fog only in that the latter are, by definition, in contact with the Earth’s surface.
CLT − (See CALCULATED LANDING TIME.)
PCG C − 5 Pilot/Controller Glossary 2/20/25 Pilot/Controller Glossary 7/9/26 CLUTTER − In radar operations, clutter refers to the reception and visual display of radar returns caused by precipitation, chaff, terrain, numerous aircraft targets, or other phenomena. Such returns may limit or preclude ATC from providing services based on radar.
(See CHAFF.)
(See GROUND CLUTTER.)
(See PRECIPITATION.)
(See TARGET.)
(See ICAO term RADAR CLUTTER.)
CMNPS − (See CANADIAN MINIMUM NAVIGATION PERFORMANCE SPECIFICATION AIRSPACE.)
COA − (See CERTIFICATE OF WAIVER OR AUTHORIZATION.)
COASTAL FIX − A navigation aid or intersection where an aircraft transitions between the domestic route structure and the oceanic route structure.
CODES − The number assigned to a particular multiple pulse reply signal transmitted by a transponder.
(See DISCRETE CODE.)
COLD TEMPERATURE CORRECTION − A correction in feet, based on height above airport and temperature, that is added to the aircraft’s indicated altitude to offset the effect of cold temperature on true altitude.
COLLABORATIVE TRAJECTORY OPTIONS PROGRAM (CTOP) − CTOP is a traffic management program administered by the Air Traffic Control System Command Center (ATCSCC) that manages demand through constrained airspace, while considering operator preference with regard to both route and delay as defined in a Trajectory Options Set (TOS).
COMBINED CONTROL FACILITY (CCF) − An air traffic facility that combines the functions of an ARTCC and a radar approach control facility.
(See AIR ROUTE TRAFFIC CONTROL CENTER.)
(See RADAR APPROACH CONTROL FACILITY.)
COMMON POINT − A significant point over which two or more aircraft will report passing or have reported passing before proceeding on the same or diverging tracks. To establish/maintain longitudinal separation, a controller may determine a common point not originally in the aircraft’s flight plan and then clear the aircraft to fly over the point.
(See SIGNIFICANT POINT.)
COMMON PORTION − (See COMMON ROUTE.)
COMMON ROUTE − That segment of a North American Route between the inland navigation facility and the coastal fix.
OR COMMON ROUTE − (See SEGMENTS OF A SID/STAR) COMMON TRAFFIC ADVISORY FREQUENCY (CTAF) − A frequency designed for the purpose of carrying out airport advisory practices while operating to or from an airport without an operating control tower. The CTAF may be a UNICOM, Multicom, FSS, or tower frequency and is identified in appropriate aeronautical publications.
(See DESIGNATED COMMON TRAFFIC ADVISORY FREQUENCY (CTAF) AREA.)
(Refer to AC 90-66, Non − Towered Airport Flight Operations.)
PCG C − 6 Pilot/Controller Glossary 2/20/25 7/9/26 Pilot/Controller Glossary RANDOM ALTITUDE − An altitude inappropriate for direction of flight and/or not in accordance with FAA Order JO 7110.65, paragraph 4 − 5 − 1, VERTICAL SEPARATION MINIMA.
RANDOM ROUTE − Any route not established or charted/published or not otherwise available to all users.
RC (See RADIO − CONTROLLED.)
RC − (See ROAD RECONNAISSANCE.)
RCAG − (See REMOTE CENTER AIR/GROUND FACILITY.)
RCC − (See RESCUE COORDINATION CENTER.)
RCO − (See REMOTE COMMUNICATIONS OUTLET.)
RCR − (See RUNWAY CONDITION READING.)
READ BACK − Repeat my message back to me.
RECEIVER AUTONOMOUS INTEGRITY MONITORING (RAIM) − A technique whereby a civil GNSS receiver/processor determines the integrity of the GNSS navigation signals without reference to sensors or non-DoD integrity systems other than the receiver itself. This determination is achieved by a consistency check among redundant pseudorange measurements.
RECEIVING CONTROLLER − A controller/facility receiving control of an aircraft from another controller/facility.
RECEIVING FACILITY − (See RECEIVING CONTROLLER.)
RECONFORMANCE − The automated process of bringing an aircraft’s Current Plan Trajectory into conformance with its track.
RECREATIONAL FLYER − Pilot of a UAS who is operating under 49 USC §44809, Exception for Limited Recreational Operations of Unmanned Aircraft.
REDUCE SPEED TO (SPEED) − (See SPEED ADJUSTMENT.)
REDUCED VERTICAL SEPARATION MINIMUM (RVSM) AIRSPACE − RVSM airspace is defined as any airspace between FL 290 and FL 410 inclusive, where eligible aircraft are separated vertically by 1,000 feet.
Authorization guidance for operations in this airspace is provided in Advisory Circular AC 91 − 85.
REFINED HAZARD AREA (RHA) − Used by ATC. Airspace that is defined and distributed after a failure of a launch or reentry operation to provide a more concise depiction of the hazard location than a Contingency Hazard Area.
(See AIRCRAFT HAZARD AREA.)
(See CONTINGENCY HAZARD AREA.)
(See TRANSITIONAL HAZARD AREA.)
REIL − (See RUNWAY END IDENTIFIER LIGHTS.)
RELEASE TIME − A departure time restriction issued to a pilot by ATC (either directly or through an authorized relay) when necessary to separate a departing aircraft from other traffic.
(See ICAO term RELEASE TIME.)
PCG R − 5 Pilot/Controller Glossary 2/20/25 Pilot/Controller Glossary 7/9/26 RELEASE TIME [ICAO] − Time prior to which an aircraft should be given further clearance or prior to which it should not proceed in case of radio failure.
REMOTE AIRPORT INFORMATION SERVICE (RAIS) − A temporary service provided by facilities, which are not located on the landing airport, but have communication capability and automated weather reporting available to the pilot at the landing airport.
REMOTE CENTER AIR/GROUND FACILITY (RCAG) − An unmanned VHF/UHF transmitter/receiver facility which is used to expand ARTCC air/ground communications coverage and to facilitate direct contact between pilots and controllers. RCAG facilities are sometimes not equipped with emergency frequencies 121.5 MHz and 243.0 MHz.
(Refer to AIM.)
REMOTE COMMUNICATIONS OUTLET (RCO) − An unmanned communications facility remotely controlled by air traffic personnel. RCOs serve FSSs. Remote Transmitter/Receivers (RTR) serve terminal ATC facilities. An RCO or RTR may be UHF or VHF and will extend the communication range of the air traffic facility. There are several classes of RCOs and RTRs. The class is determined by the number of transmitters or receivers. Classes A through G are used primarily for air/ground purposes. RCO and RTR class O facilities are nonprotected outlets subject to undetected and prolonged outages. RCO (O’s) and RTR (O’s) were established for the express purpose of providing ground-to-ground communications between air traffic control specialists and pilots located at a satellite airport for delivering en route clearances, issuing departure authorizations, and acknowledging instrument flight rules cancellations or departure/landing times. As a secondary function, they may be used for advisory purposes whenever the aircraft is below the coverage of the primary air/ground frequency.
REMOTE IDENTIFICATION (RID) − A system for electronic identification and secure oversight of UAS.
(See 4 CFR part 89) (See AIM) REMOTE PILOT − Pilot of a UAS who is not operating as a recreational flyer under 49 USC §44809, the Exception for Limited Recreational Operations of Unmanned Aircraft.
REMOTE PILOT IN COMMAND (RPIC) − The RPIC is directly responsible for and is the final authority as to the operation of the unmanned aircraft system.
REMOTE TRANSMITTER/RECEIVER (RTR) − (See REMOTE COMMUNICATIONS OUTLET.)
REPORT − Used to instruct pilots to advise ATC of specified information; e.g., “Report passing Hamilton VOR.” REPORTING POINT − A geographical location in relation to which the position of an aircraft is reported.
(See COMPULSORY REPORTING POINTS.)
(See ICAO term REPORTING POINT.)
(Refer to AIM.)
REPORTING POINT [ICAO] − A specified geographical location in relation to which the position of an aircraft can be reported.
REQUEST FULL ROUTE CLEARANCE − Used by pilots to request that the entire route of flight be read verbatim in an ATC clearance. Such request should be made to preclude receiving an ATC clearance based on the original filed flight plan when a filed IFR flight plan has been revised by the pilot, company, or operations prior to departure.
REQUIRED NAVIGATION PERFORMANCE (RNP)– A statement of the navigational performance necessary for operation within a defined airspace. The following terms are commonly associated with RNP: a. Required Navigation Performance Level or Type (RNP-X). A value, in nautical miles (NM), from the intended horizontal position within which an aircraft would be at least 95-percent of the total flying time.
PCG R − 6 Pilot/Controller Glossary 2/20/25 8/7/25 Pilot/Controller Glossary SIDESTEP MANEUVER − A visual maneuver accomplished by a pilot at the completion of an instrument approach to permit a straight-in landing on a parallel runway not more than 1,200 feet to either side of the runway to which the instrument approach was conducted.
(Refer to AIM.)
SIGMET − A weather advisory issued concerning weather significant to the safety of all aircraft. SIGMET advisories cover severe and extreme turbulence, severe icing, and widespread dust or sandstorms that reduce visibility to less than 3 miles.
(See AIRMET.)
(See CONVECTIVE SIGMET.)
(See CWA.)
(See GRAPHICAL AIRMEN’S METEOROLOGICAL INFORMATION.)
(See ICAO term SIGMET INFORMATION.)
(See SAW.)
(Refer to AIM.)
SIGMET INFORMATION [ICAO] − Information issued by a meteorological watch office concerning the occurrence or expected occurrence of specified en-route weather phenomena which may affect the safety of aircraft operations.
SIGNIFICANT METEOROLOGICAL INFORMATION − (See SIGMET.)
SIGNIFICANT POINT − A point, whether a named intersection, a NAVAID, a fix derived from a NAVAID(s), or geographical coordinate expressed in degrees of latitude and longitude, which is established for the purpose of providing separation, as a reporting point, or to delineate a route of flight.
SIMULATED FLAMEOUT − A practice approach by a jet aircraft (normally military) at idle thrust to a runway.
The approach may start at a runway (high key) and may continue on a relatively high and wide downwind leg with a continuous turn to final. It terminates in landing or low approach. The purpose of this approach is to simulate a flameout.
(See FLAMEOUT.)
SIMULTANEOUS CLOSE PARALLEL APPROACHES − A simultaneous, independent approach operation permitting ILS/RNAV/GLS approaches to airports having parallel runways separated by at least 3,000 feet and less than 4,300 − feet between centerlines. Aircraft are permitted to pass each other during these simultaneous operations. Integral parts of a total system are radar, NTZ monitoring with enhanced FMA color displays that include aural and visual alerts and predictive aircraft position software, communications override, ATC procedures, an Attention All Users Page (AAUP), PRM in the approach name, and appropriate ground based and airborne equipment. High update rate surveillance sensor required for certain runway or approach course separations.
SIMULTANEOUS (CONVERGING) DEPENDENT APPROACHES- An approach operation permitting ILS/RNAV/GLS approaches to runways or missed approach courses that intersect where required minimum spacing between the aircraft on each final approach course is required.
SIMULTANEOUS (CONVERGING) INDEPENDENT APPROACHES- An approach operation permitting ILS/RNAV/GLS approaches to non-parallel runways where approach procedure design maintains the required aircraft spacing throughout the approach and missed approach and hence the operations may be conducted independently.
SIMULTANEOUS ILS APPROACHES − An approach system permitting simultaneous ILS approaches to airports having parallel runways separated by at least 4,300 feet between centerlines. Integral parts of a total system are ILS, radar, communications, ATC procedures, and appropriate airborne equipment.
(See PARALLEL RUNWAYS.)
(Refer to AIM.)
PCG S − 5 Pilot/Controller Glossary 2/20/25 Pilot/Controller Glossary 7/9/26 SIMULTANEOUS OFFSET INSTRUMENT APPROACH (SOIA) − An instrument landing system comprised of an ILS PRM, RNAV PRM or GLS PRM approach to one runway and an offset LDA PRM with glideslope or an RNAV PRM or GLS PRM approach utilizing vertical guidance to another where parallel runway spaced less than 3,000 feet and at least 750 feet apart. The approach courses converge by 2.5 to 3 degrees. Simultaneous close parallel PRM approach procedures apply up to the point where the approach course separation becomes 3,000 feet, at the offset MAP. From the offset MAP to the runway threshold, visual separation by the aircraft conducting the offset approach is utilized.
(Refer to AIM) SIMULTANEOUS (PARALLEL) DEPENDENT APPROACHES- An approach operation permitting approaches to adjacent parallel runways where prescribed diagonal spacing must be maintained. Aircraft are not permitted to pass each other during simultaneous dependent operations.
SINGLE DIRECTION ROUTES − Preferred IFR Routes which are sometimes depicted on high altitude en route charts and which are normally flown in one direction only.
(See PREFERRED IFR ROUTES.)
(Refer to CHART SUPPLEMENT U.S.)
SINGLE FREQUENCY APPROACH − A service provided under a letter of agreement to military single-piloted turbojet aircraft which permits use of a single UHF frequency during approach for landing. Pilots will not normally be required to change frequency from the beginning of the approach to touchdown except that pilots conducting an en route descent are required to change frequency when control is transferred from the air route traffic control center to the terminal facility. The abbreviation “SFA” in the DoD FLIP IFR Supplement under “Communications” indicates this service is available at an aerodrome.
SINGLE-PILOTED AIRCRAFT − A military turbojet aircraft possessing one set of flight controls, tandem cockpits, or two sets of flight controls but operated by one pilot is considered single-piloted by ATC when determining the appropriate air traffic service to be applied.
(See SINGLE FREQUENCY APPROACH.)
SKYSPOTTER − A pilot who has received specialized training in observing and reporting inflight weather phenomena.
SLASH − A radar beacon reply displayed as an elongated target.
SLDI − (See SECTOR LIST DROP INTERVAL.)
SLOW TAXI − To taxi a float plane at low power or low RPM.
SMALL UNMANNED AIRCRAFT SYSTEM (sUAS)– An unmanned aircraft weighing less than 55 pounds on takeoff, including everything that is on board or otherwise attached to the aircraft.
SMAR − (See SPECIAL MILITARY ACTIVITY ROUTE.)
SN − (See SYSTEM STRATEGIC NAVIGATION.)
SPACE − BASED ADS − B (SBA) − A constellation of satellites that receives ADS − B Out broadcasts and relays that information to the appropriate surveillance facility. The currently deployed SBA system is only capable of receiving broadcasts from 1090ES − equipped aircraft, and not from those equipped with only a universal access transceiver (UAT). Also, aircraft with a top − of − fuselage − mounted transponder antenna (required for TCAS II installations) will be better received by SBA, especially at latitudes below 45 degrees.
(See AUTOMATIC DEPENDENT SURVEILLANCE − BROADCAST.)
(See AUTOMATIC DEPENDENT SURVEILLANCE − BROADCAST OUT.)
SPACE LAUNCH AND REENTRY AREA − Locations where commercial space launch and/or reentry operations occur. For pilot awareness, a rocket − shaped symbol is used to depict space launch and reentry areas on sectional aeronautical charts.
PCG S − 6