Glossary of Airline Terminology

Automatic Dependent Surveillance-Broadcast (ADS-B)

An aircraft-based surveillance service capable of replacing today’s ground-based radar system. With ADS-B, the aircraft GPS determines aircraft location. ADS-B then broadcasts that position, via a radio transmission, approximately once-per-second, to controllers on the ground and other aircraft. ADS-B would give controllers and other traffic a more precise location for each aircraft. By doing this, a portion of the current infrastructure is, in essence, being shifted to the aircraft. Two major elements of ADS-B comprise the total system. ADS-B Out refers to messages transmitted to ground stations and other aircraft through an onboard transmitter known as a transponder. These messages, using a GPS-derived position, contain information regarding accuracy and position-reliability information. This ensures that the transmitted position meets the requirements necessary for an aircraft to utilize certain airspace or advanced procedures. A robust ground-based system then receives, processes and displays this information for use by air traffic control facilities. ADS-B In refers to the aircraft and ground software and hardware that unlock the potential for greatly advanced air-traffic procedures. Several applications, currently under development, leverage the foundational elements created by the ADS-B Out rule and the associated ground infrastructure. Much greater safety, efficiency, environmental benefits and capacity will be available, compared to the current dated system of ground-based radars and voice communications.

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