Definition
A surveillance technology in which an aircraft automatically broadcasts its identification, position, altitude, velocity, and other data, derived primarily from onboard GPS, at regular intervals. Air traffic control and other suitably equipped aircraft receive these broadcasts directly, without the need for a radar interrogation. ADS-B Out refers to the aircraft transmitting this information; ADS-B In refers to the aircraft receiving ADS-B broadcasts from other aircraft and ground services such as traffic and weather.
Plain English
A system where your aircraft constantly tells everyone nearby — controllers and other pilots — exactly where it is and how it is moving, using GPS. It does this on its own, without anyone asking. If your aircraft can also receive these messages from others, you can see nearby traffic and weather on a display in the cockpit.
Context Anchor
Pilots encounter ADS-B in aircraft equipment requirements, traffic displays, airspace rules, and air traffic control surveillance discussions.
Derivation
The name describes how it works. Automatic — it transmits on its own without being asked. Dependent — it depends on data from onboard systems, mainly GPS, rather than ground radar. Surveillance — it is a way of watching where aircraft are. Broadcast — the signal goes out to anyone listening, not just to one receiver.
Why Pilots Care
Provides real-time traffic awareness, supports more efficient routing, and is required to enter many controlled airspaces.
Intuition Check
ADS-B is not radar. Radar sends out a signal and watches for a return; ADS-B has the aircraft send out its own position and movement information.
Example Sentence 1
The aircraft was equipped with ADS-B Out, so the controller could see its position without using primary radar.
Example Sentence 2
The aircraft was equipped with ADS-B Out to meet the requirements for flying in Class B airspace.