Pilot/Controller Glossary 

3/21/24 

AUTOMATIC DEPENDENT SURVEILLANCE- REBROADCAST (ADS-R)

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 A datalink translation function 

of the ADS

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B ground system required to accommodate the two separate operating frequencies (978 MHz and 

1090 MHz). The ADS

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B system receives the ADS

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B messages transmitted on one frequency and ADS

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R 

translates and reformats the information for rebroadcast and use on the other frequency. This allows ADS

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B In 

equipped aircraft to see nearby ADS

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B Out traffic regardless of the operating link of the other aircraft. Aircraft 

operating on the same ADS

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B frequency exchange information directly and do not require the ADS

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R 

translation function. 
AUTOMATIC DIRECTION FINDER

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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) 

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 ALASKA FSSs ONLY

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 The continuous 

broadcast of recorded non

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control information at airports in Alaska where a FSS provides local airport advisory 

service. The AFIS broadcast automates the repetitive transmission of essential but routine information such as 

weather, wind, altimeter, favored runway, braking action, airport NOTAMs, and other applicable information. 

The information is continuously broadcast over a discrete VHF radio frequency (usually the ASOS/AWOS 

frequency). 
AUTOMATIC TERMINAL INFORMATION SERVICE

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 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 [ICAO]

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 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. 
AUTOROTATION

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 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. 
AVAILABLE LANDING DISTANCE (ALD)

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 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 WATCH NOTIFICATION MESSAGE

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 The Storm Prediction Center (SPC) issues Aviation Watch 

Notification Messages (SAW) to provide an area threat alert for the aviation meteorology community to forecast 

organized severe thunderstorms that may produce tornadoes, large hail, and/or convective damaging winds as 

indicated in Public Watch Notification Messages within the Continental U.S. A SAW message provides a 

description of the type of watch issued by SPC, a valid time, an approximation of the area in a watch, and primary 

hazard(s). 

PCG A

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