Aviation Maintenance Terms beginning with A

ADS-B Traffic Advisory System (ATAS)

An ADS-B In application that augments flight crew traffic situation awareness in support of the see-and-avoid responsibility by providing alerts of traffic that are detected in conflict with ownship. This application is named Traffic Situation Awareness with Alerts (TSAA) in RTCA DO-317B.

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Advisory

The level or category of alert for conditions that require flight crew awareness and may require subsequent flight crew response.

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Aircraft Surveillance Application (ASA)

An application that uses aircraft surveillance data to provide benefits to the flight crew (refer to Table 1).

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Aircraft Surveillance Applications System (ASAS)

An aircraft system based on airborne surveillance that provides assistance to the flight crew in operating their aircraft relative to other aircraft. Airborne Surveillance and Separation Assurance Processing (ASSAP). The processing subsystem that accepts surveillance inputs (e.g., ADS-B reports), performs surveillance processing to provide reports and tracks, and performs application-specific processing. Surveillance reports, tracks, and any application-specific alerts or guidance are output by ASSAP to the CDTI function. ASSAP surveillance processing consists of track processing and correlation of ADS-B, TIS-B, ADS-R and TCAS reports.

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Alert

A general term that applies to all advisories, cautions, and warning information; can include visual, aural, tactile, or other attention-getting methods.

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Antenna Offset Parameter

The distance from the nose of the aircraft to the GPS antenna. For large aircraft, this offset is important in accurately placing the aircraft symbol on the airport map.

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Application

The function(s) for which the ASA system is used.

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Area Navigation (RNAV)

A method of navigation that permits aircraft operation on any desired flight path within the coverage of station-referenced navigation aids or within the limits of the capability of self-contained aids, or a combination of these.

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Automatic Dependent Surveillance - Rebroadcast (ADS-R)

Retransmission of UAT ADS-B messages from aircraft on the 1090ES link and 1090ES messages on the UAT link. ADS-R ensures aircraft equipped with different links can receive messages from one another when equipped with ADS-B IN.

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Automatic Dependent Surveillance Broadcast (ADS-B)

An advanced surveillance technology where ADS-B OUT equipped aircraft share position, altitude, velocity, and other information with ATC and other appropriately equipped aircraft.

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Automatic Dependent Surveillance-Broadcast (ADS-B)

A function on an aircraft or surface vehicle operating within the surface movement area that periodically broadcasts its state vector (horizontal and vertical position, horizontal and vertical velocity) and other information. ADS-B is automatic because no external stimulus is required to elicit a transmission. It is dependent because it relies on on-board navigation sources and on-board broadcast transmission systems to provide surveillance information to other users.

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Automatic Dependent Surveillance-Rebroadcast (ADS-R)

A service of the ground system that rebroadcasts ADS-B messages from one link technology onto another. For example, the SBS ground system provides ADS-R service to rebroadcast UAT messages on 1090 MHz and vice versa.

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Availability

An indication of the ability of a system or subsystem to provide usable service. Availability is expressed in terms of the probability of the system or subsystem being available at the beginning of an intended operation.

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