Plain English Meaning

A system where the aircraft automatically reports its position to controllers at agreed times or events, instead of being tracked by radar. It is mainly used over oceans and remote areas where radar cannot reach.

Full Definition

A surveillance system in which an aircraft automatically transmits position, altitude, and other flight data to an air traffic control facility under the terms of a pre-arranged agreement, or 'contract,' between the aircraft's avionics and the ATC ground system. The contract specifies what data is sent and when — for example, at fixed time intervals, when the aircraft passes a waypoint, or when a deviation from the planned occurs. ADS-C is primarily used in oceanic and remote where conventional is unavailable.