AUTOMATIC DEPENDENT SURVEILLANCE BROADCAST (ADSB)
A surveillance system in which an aircraft or vehicle to be detected is fitted with cooperative equipment in the form of a data link transmitter. The aircraft or vehicle periodically broadcasts its GPS-derived position and other information such as velocity over the data link, which is received by a ground-based transmitter/receiver (transceiver) for processing and display at an air traffic control facility. (See GLOBAL POSITIONING SYSTEM.) (See GROUND-BASED TRANSCEIVER.)

AUTOMATIC DEPENDENT SURVEILLANCE CONTRACT (ADSC)
A data link position reporting system, controlled by a ground station, that establishes contracts with an aircrafts avionics that occur automatically whenever specific events occur, or specific time intervals are reached.

AUTOMATIC DEPENDENT SURVEILLANCE-BROADCAST (ADS-B)
A device used in aircraft that repeatedly broadcasts a message that includes position (such as latitude, longitude, and altitude), velocity, and possibly other information.

AUTOMATIC DIRECTION FINDER
An aircraft radio navigation system which senses and indicates the direction to a L/MF nondirectional radio beacon (NDB) ground transmitter. Direction is indicated to the pilot as a magnetic bearing or as a relative bearing to the longitudinal axis of the aircraft depending on the type of indicator installed in the aircraft. In certain applications, such as military, ADF operations may be based on airborne and ground transmitters in the VHF/UHF frequency spectrum. (See BEARING.) (See NONDIRECTIONAL BEACON.) AUTOMATIC FLIGHT INFORMATION SERVICE (AFIS) ALASKA FSSs

AUTOMATIC DIRECTION FINDER (ADF)
Electronic navigation equipment that operates in the low- and medium-frequency bands. Used in conjunction with the ground-based non directional beacon (NDB), the instrument displays the number of degrees clockwise from the nose of the aircraft to the station being received.

AUTOMATIC TERMINAL INFORMATION SERVICE
The continuous broadcast of recorded noncontrol information in selected terminal areas. Its purpose is to improve controller effectiveness and to relieve frequency congestion by automating the repetitive transmission of essential but routine information; e.g., “Los Angeles information Alfa. One three zero zero Coordinated Universal Time. Weather, measured ceiling two thousand overcast, visibility three, haze, smoke, temperature seven one, dew point five seven, wind two five zero at five, altimeter two niner niner six. I-L-S Runway Two Five Left approach in use, Runway Two Five Right closed, advise you have Alfa.” (See ICAO term AUTOMATIC TERMINAL INFORMATION SERVICE.) (Refer to AIM.)

AUTOMATIC TERMINAL INFORMATION SERVICE (ATIS)
The continuous broadcast (by radio or telephone) of recorded noncontrol, essential but routine information in selected terminal areas.

AUTOMATIC TERMINAL INFORMATION SERVICE [ICAO]
The provision of current, routine information to arriving and departing aircraft by means of continuous and repetitive broadcasts throughout the day or a specified portion of the day.

AUTOMATIC WEATHER OBSERVING SYSTEM (AWOS)
Continuous broadcast (by radio or telephone) of weather conditions at selected locations.

AUTOPILOT
Those units and components that furnish a means of automatically controlling the aircraft.

AUTOROTATION
A rotorcraft flight condition in which the lifting rotor is driven entirely by action of the air when the rotorcraft is in motion. a. Autorotative Landing/Touchdown Autorotation. Used by a pilot to indicate that the landing will be made without applying power to the rotor. b. Low Level Autorotation. Commences at an altitude well below the traffic pattern, usually below 100 feet AGL and is used primarily for tactical military training. c. 180 degrees Autorotation. Initiated from a downwind heading and is commenced well inside the normal traffic pattern. “Go around” may not be possible during the latter part of this maneuver.

AUXILIARY FIN
An additional vertical stabilizer installed on some float planes to offset the increased surface area of the floats in front of the center of gravity.

AVAILABLE LANDING DISTANCE (ALD)
The portion of a runway available for landing and roll-out for aircraft cleared for LAHSO. This distance is measured from the landing threshold to the hold-short point.

AVIATION MEDICAL EXAMINER (AME)
A medical doctor authorized to perform aviation medical exams for aviators.

AVIATION ROUTINE WEATHER REPORT (METAR)
Observation of current surface weather reported in a standard international format.

AVIATION WEATHER SERVICE
A service provided by the National Weather Service (NWS) and FAA which collects and disseminates pertinent weather information for pilots, aircraft operators, and ATC. Available aviation weather reports and forecasts are displayed at each NWS office and FAA FSS. (See EN ROUTE FLIGHT ADVISORY SERVICE.) (See TRANSCRIBED WEATHER BROADCAST.) (See WEATHER ADVISORY.) (Refer to AIM.)

AWOS
See Automated Weather Observing System.

AWW
(See SEVERE WEATHER FORECAST ALERTS.)

AXES OF AN AIRCRAFT
Three imaginary lines that pass through an aircraft’s center of gravity. The axes can be considered as imaginary axles around which the aircraft rotates. The three axes pass through the center of gravity at 90° angles to each other. The axis from nose to tail is the longitudinal axis (pitch), the axis that passes from wingtip to wingtip is the lateral axis (roll), and the axis that passes vertically through the center of gravity is the vertical axis (yaw).

AXIAL FLOW COMPRESSOR
A type of compressor used in a turbine engine in which the airflow through the compressor is essentially linear. An axial-flow compressor is made up of several stages of alternate rotors and stators. The compressor ratio is determined by the decrease in area of the succeeding stages.

AXIS-OF-ROTATION
The imaginary line about which the rotor rotates. It is represented by a line drawn through the center of, and perpendicular to, the tip-path plane.

AZIMUTH CARD
A card that may be set, gyroscopically controlled, or driven by a remote compass.
FAST FILE
An FSS system whereby a pilot files a flight plan via telephone that is recorded and later transcribed for transmission to the appropriate air traffic facility. (Alaska only.)

FAWP
Final Approach Waypoint

FCLT
(See FREEZE CALCULATED LANDING TIME.)

FDC NOTAM
A NOTAM regulatory in nature, transmitted by USNOF and given system wide dissemination. (See ICAO term NOTAM.)

FEATHERED PROPELLER
A propeller whose blades have been rotated so that the leading and trailing edges are nearly parallel with the aircraft flight path to stop or minimize drag and engine rotation. Normally used to indicate shutdown of a reciprocating or turboprop engine due to malfunction.

FEDERAL AIRWAYS
(See LOW ALTITUDE AIRWAY STRUCTURE.)

FEEDER FIX
The fix depicted on Instrument Approach Procedure Charts which establishes the starting point of the feeder route.

FEEDER ROUTE
A route depicted on instrument approach procedure charts to designate routes for aircraft to proceed from the en route structure to the initial approach fix (IAF). (See INSTRUMENT APPROACH PROCEDURE.)

FIELD ELEVATION
(See AIRPORT ELEVATION.)

FILED
Normally used in conjunction with flight plans, meaning a flight plan has been submitted to

FILED FLIGHT PLAN
The flight plan as filed with an ATS unit by the pilot or his/her designated representative without any subsequent changes or clearances.

FINAL
Commonly used to mean that an aircraft is on the final approach course or is aligned with a landing area. (See FINAL APPROACH COURSE.) (See FINAL APPROACH-IFR.) (See SEGMENTS OF AN INSTRUMENT APPROACH PROCEDURE.)

FINAL APPROACH [ICAO]
That part of an instrument approach procedure which commences at the specified final approach fix or point, or where such a fix or point is not specified. a. At the end of the last procedure turn, base turn or inbound turn of a racetrack procedure, if specified; or b. At the point of interception of the last track specified in the approach procedure; and ends at a point in the vicinity of an aerodrome from which: 1. A landing can be made; or 2. A missed approach procedure is initiated.

FINAL APPROACH COURSE
A bearing/radial/ track of an instrument approach leading to a runway or an extended runway centerline all without regard to distance.

FINAL APPROACH FIX
The fix from which the final approach (IFR) to an airport is executed and which identifies the beginning of the final approach segment. It is designated on Government charts by the Maltese Cross symbol for Nonprecision approaches and the lightning bolt symbol, designating the PFAF, for precision approaches; or Pilot/Controller Glossary 7/24/14

FINAL APPROACH POINT
The point, applicable only to a Nonprecision approach with no depicted FAF (such as an on airport VOR), where the aircraft is established inbound on the final approach course from the procedure turn and where the final approach descent may be commenced. The FAP serves as the FAF and identifies the beginning of the final approach segment. (See FINAL APPROACH FIX.) (See SEGMENTS OF AN INSTRUMENT APPROACH PROCEDURE.)

FINAL APPROACH SEGMENT
(See SEGMENTS OF AN INSTRUMENT APPROACH PROCEDURE.)

FINAL APPROACH SEGMENT [ICAO]
That segment of an instrument approach procedure in which alignment and descent for landing are accomplished.

FINAL APPROACH-IFR
The flight path of an aircraft which is inbound to an airport on a final instrument approach course, beginning at the final approach fix or point and extending to the airport or the point where a circle-to-land maneuver or a missed approach is executed. (See FINAL APPROACH COURSE.) (See FINAL APPROACH FIX.) (See FINAL APPROACH POINT.) (See SEGMENTS OF AN INSTRUMENT APPROACH PROCEDURE.) (See ICAO term FINAL APPROACH.)

FINAL CONTROLLER
The controller providing information and final approach guidance during PAR and ASR approaches utilizing radar equipment. (See RADAR APPROACH.)

FINAL GUARD SERVICE
A value added service provided in conjunction with LAA/RAA only during periods of significant and fast changing weather conditions that may affect landing and takeoff operations.

FINAL MONITOR AID
A high resolution color display that is equipped with the controller alert system hardware/software used to monitor the no transgression zone (NTZ) during simultaneous parallel approach operations. The display includes alert algorithms providing the target predictors, a color change alert when a target penetrates or is predicted to penetrate the no transgression zone (NTZ), synthesized voice alerts, and digital mapping. (See RADAR APPROACH.)

FINAL MONITOR CONTROLLER
Air Traffic Control Specialist assigned to radar monitor the flight path of aircraft during simultaneous parallel (approach courses spaced less than 9000 feet/9200 feet above 5000 feet) and simultaneous close parallel approach operations. Each runway is assigned a final monitor controller during simultaneous parallel and simultaneous close parallel ILS approaches.

FIR
(See FLIGHT INFORMATION REGION.)

FIRST TIER CENTER
The ARTCC immediately adjacent to the impacted center.

FIS
system provides pilots and flight crews of properly equipped aircraft with a cockpit display of certain aviation weather and aeronautical information.

FIX
A geographical position determined by visual reference to the surface, by reference to one or more radio NAVAIDs, by celestial plotting, or by another navigational device.

FIX BALANCING
A process whereby aircraft are evenly distributed over several available arrival fixes reducing delays and controller workload.

FL 600. CONTROLLED AIRSPACE [ICAO]
An airspace of defined dimensions within which air traffic control service is provided to IFR flights and to VFR flights in accordance with the airspace classification. Note: Controlled airspace is a generic term which covers ATS airspace Classes A, B, C, D, and

FLAG
A warning device incorporated in certain airborne navigation and flight instruments indicating that: a. Instruments are inoperative or otherwise not operating satisfactorily, or b. Signal strength or quality of the received signal falls below acceptable values.

FLAG ALARM
(See FLAG.)

FLAMEOUT
An emergency condition caused by a loss of engine power.

FLAMEOUT PATTERN
An approach normally conducted by a single-engine military aircraft experiencing loss or anticipating loss of engine.

FLIGHT CHECK
A call-sign prefix used by FAA aircraft engaged in flight inspection/certification of navigational aids and flight procedures. The word “recorded” may be added as a suffix; e.g., “Flight Check 320 recorded” to indicate that an automated flight inspection is in progress in terminal areas. (See FLIGHT INSPECTION.) (Refer to AIM.)

FLIGHT FOLLOWING
(See TRAFFIC ADVISORIES.)

FLIGHT INFORMATION REGION
An airspace of defined dimensions within which Flight Information Service and Alerting Service are provided. a. Flight Information Service. A service provided for the purpose of giving advice and information useful for the safe and efficient conduct of flights. b. Alerting Service. A service provided to notify appropriate organizations regarding aircraft in need of search and rescue aid and to assist such organizations as required.

FLIGHT INFORMATION SERVICE

A service provided for the purpose of giving advice and information useful for the safe and efficient conduct of flights.

FLIGHT INSPECTION
Inflight investigation and evaluation of a navigational aid to determine whether it meets established tolerances. (See FLIGHT CHECK.) (See NAVIGATIONAL AID.)

FLIGHT LEVEL
A level of constant atmospheric pressure related to a reference datum of 29.92 inches of mercury. Each is stated in three digits that represent hundreds of feet. For example, flight level (FL) 250 represents a barometric altimeter indication of 25,000 feet; FL 255, an indication of 25,500 feet. (See ICAO term FLIGHT LEVEL.)

FLIGHT LEVEL [ICAO]
A surface of constant atmospheric pressure which is related to a specific pressure datum, 1013.2 hPa (1013.2 mb), and is separated from other such surfaces by specific pressure intervals. Note 1: A pressure type altimeter calibrated in accordance with the standard atmosphere: a. When set to a QNH altimeter setting, will indicate altitude; b. When set to a QFE altimeter setting, will indicate height above the QFE reference datum; and c. When set to a pressure of 1013.2 hPa (1013.2 mb), may be used to indicate flight levels. Note 2: The terms ‘height’ and ‘altitude,’ used in Note 1 above, indicate altimetric rather than geometric heights and altitudes.

FLIGHT LINE
A term used to describe the precise movement of a civil photogrammetric aircraft along a predetermined course(s) at a predetermined altitude during the actual photographic run.

FLIGHT MANAGEMENT SYSTEM PROCEDURE
An arrival, departure, or approach procedure developed for use by aircraft with a slant (/) E or slant (/) F equipment suffix.

FLIGHT MANAGEMENT SYSTEMS
A computer system that uses a large data base to allow routes to be preprogrammed and fed into the system by means of a data loader. The system is constantly updated with respect to position accuracy by reference to conventional navigation aids. The sophisticated program and its associated data base ensures that the most appropriate aids are automatically selected during the information update cycle.

FLIGHT PLAN
Specified information relating to the intended flight of an aircraft that is filed orally or in writing with an FSS or an ATC facility. (See FAST FILE.) (See FILED.) (Refer to AIM.)

FLIGHT PLAN AREA (FPA)
The geographical area assigned to a flight service station (FSS) for the purpose of establishing primary responsibility for services that may include search and rescue for VFR aircraft, issuance of NOTAMs, pilot briefings, inflight services, broadcast services, emergency services, flight data processing, international operations, and aviation weather services. Large consolidated FSS facilities may combine FPAs into larger areas of responsibility (AOR). (See FLIGHT SERVICE STATION.) (See TIE-IN FACILITY.)

FLIGHT RECORDER
A general term applied to any instrument or device that records information about the performance of an aircraft in flight or about conditions encountered in flight. Flight recorders may make records of airspeed, outside air temperature, vertical acceleration, engine RPM, manifold pressure, and other pertinent variables for a given flight. (See ICAO term FLIGHT RECORDER.)

FLIGHT STANDARDS DISTRICT OFFICE
An FAA field office serving an assigned geographical area and staffed with Flight Standards personnel who serve the aviation industry and the general public on matters relating to the certification and operation of air carrier and general aviation aircraft. Activities include general surveillance of operational safety, certification of airmen and aircraft, accident prevention, investigation, enforcement, etc.

FLIGHT TEST
A flight for the purpose of: a. Investigating the operation/flight characteristics of an aircraft or aircraft component. b. Evaluating an applicant for a pilot certificate or rating.

FLIGHT VISIBILITY
(See VISIBILITY.)

FLIGHT WATCH
A shortened term for use in air-ground contacts to identify the flight service station providing En Route Flight Advisory Service; e.g., “Oakland Flight Watch.” (See EN ROUTE FLIGHT ADVISORY SERVICE.)
FLIP
(See DOD FLIP.)

FLY HEADING (DEGREES)
Informs the pilot of the heading he/she should fly. The pilot may have to turn to, or continue on, a specific compass direction in order to comply with the instructions. The pilot is expected to turn in the shorter direction to the heading unless otherwise instructed by

FLY VISUAL TO AIRPORT
(See PUBLISHED INSTRUMENT APPROACH PROCEDURE VISUAL SEGMENT.)

FLY-OVER WAYPOINT
A fly-over waypoint precludes any turn until the waypoint is overflown and is followed by an intercept maneuver of the next flight segment.

FMA
(See FINAL MONITOR AID.)

FMSP
(See FLIGHT MANAGEMENT SYSTEM PROCEDURE.)

FORMATION FLIGHT
More than one aircraft which, by prior arrangement between the pilots, operate as a single aircraft with regard to navigation and position reporting. Separation between aircraft within the formation is the responsibility of the flight leader and the pilots of the other aircraft in the flight. This includes transition periods when aircraft within the formation are maneuvering to attain separation from each other to effect individual control and during join-up and breakaway. a. A standard formation is one in which a proximity of no more than 1 mile laterally or longitudinally and within 100 feet vertically from the flight leader is maintained by each wingman. b. Nonstandard formations are those operating under any of the following conditions: 1. When the flight leader has requested and ATC has approved other than standard formation dimensions. 2. When operating within an authorized altitude reservation (ALTRV) or under the provisions of a letter of agreement. 3. When the operations are conducted in airspace specifically designed for a special activity. (See ALTITUDE RESERVATION.) (Refer to 14 CFR Part 91.)

FRC
(See REQUEST FULL ROUTE CLEARANCE.)

FREEZE CALCULATED LANDING TIME
A dynamic parameter number of minutes prior to the meter fix calculated time of arrival for each aircraft when the TCLT is frozen and becomes an ACLT (i.e., the VTA is updated and consequently the TCLT is modified as appropriate until FCLT minutes prior to meter fix calculated time of arrival, at which time updating is suspended and an ACLT and a frozen meter fix crossing time (MFT) is assigned).

FREEZE HORIZON
The time or point at which an aircraft’s STA becomes fixed and no longer fluctuates with each radar update. This setting ensures a constant time for each aircraft, necessary for the metering controller to plan his/her delay technique. This setting can be either in distance from the meter fix or a prescribed flying time to the meter fix.

FREEZE SPEED PARAMETER
A speed adapted for each aircraft to determine fast and slow aircraft. Fast aircraft freeze on parameter FCLT and slow aircraft freeze on parameter

FREEZE/FROZEN
Terms used in referring to arrivals which have been assigned ACLTs and to the lists in which they are displayed.

FSDO
(See FLIGHT STANDARDS DISTRICT OFFICE.)

FSPD
(See FREEZE SPEED PARAMETER.)

FSS
(See FLIGHT SERVICE STATION.)

FSS. RADIO ALTIMETER
Aircraft equipment which makes use of the reflection of radio waves from the ground to determine the height of the aircraft above the surface.

FUEL DUMPING
Airborne release of usable fuel. This does not include the dropping of fuel tanks. (See JETTISONING OF EXTERNAL STORES.)

FUEL REMAINING
A phrase used by either pilots or controllers when relating to the fuel remaining on board until actual fuel exhaustion. When transmitting such information in response to either a controller question or pilot initiated cautionary advisory to air traffic control, pilots will state the APPROXIMATE NUMBER OF MINUTES the flight can continue with the fuel remaining. All reserve fuel SHOULD BE INCLUDED in the time stated, as should an allowance for established fuel gauge system error.

FUEL SIPHONING
Unintentional release of fuel caused by overflow, puncture, loose cap, etc.