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Pilot/Controller Glossary 

9/5/24 

AUTOMATIC DEPENDENT SURVEILLANCE

BROADCAST IN (ADS

B In)

 Aircraft avionics capable 

of receiving ADS

B Out transmissions directly from other aircraft, as well as traffic or weather information 

transmitted from ground stations. 

(See AUTOMATIC DEPENDENT SURVEILLANCE

BROADCAST OUT.) 

(See AUTOMATIC DEPENDENT SURVEILLANCE

REBROADCAST.) 

(See FLIGHT INFORMATION SERVICE

BROADCAST.) 

(See TRAFFIC INFORMATION SERVICE

BROADCAST.) 

AUTOMATIC DEPENDENT SURVEILLANCE

BROADCAST OUT (ADS

B Out)

 The transmitter 

onboard an aircraft or ground vehicle that periodically broadcasts its GNSS

derived position along with other 

required information, such as identity, altitude, and velocity. 

(See AUTOMATIC DEPENDENT SURVEILLANCE

BROADCAST.) 

(See AUTOMATIC DEPENDENT SURVEILLANCE

BROADCAST IN.) 

AUTOMATIC DEPENDENT SURVEILLANCE

CONTRACT (ADS

C)

 A data link position reporting 

system, controlled by a ground station, that establishes contracts with an aircraft’s avionics that occur 

automatically whenever specific events occur, or specific time intervals are reached. 
AUTOMATIC DEPENDENT SURVEILLANCE- REBROADCAST (ADS-R)

 A datalink translation function 

of the ADS

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

1090 MHz). The ADS

B system receives the ADS

B messages transmitted on one frequency and ADS

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

B In 

equipped aircraft to see nearby ADS

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

operating on the same ADS

B frequency exchange information directly and do not require the ADS

translation function. 
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 ONLY

 The continuous 

broadcast of recorded non

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

 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]

 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

 A rotorcraft flight condition in which the lifting rotor is driven entirely by action of the air 

when the rotorcraft is in motion. 

PCG A

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