Definition
A function on an aircraft that automatically broadcasts the aircraft's GPS-derived position, altitude, velocity, identification, and other status information once per second over a digital data link. This signal is received by air traffic control ground stations and by other suitably equipped aircraft, and is the primary means by which controllers and nearby traffic see the aircraft in modern surveillance airspace.
Plain English
It is a system that constantly tells everyone — controllers and other aircraft — exactly where you are, how high you are, how fast you are going, and who you are, without anyone having to ask.
Context Anchor
Pilots encounter ADS-B Out when checking aircraft equipment, planning flights into airspace where it is required, and using traffic information provided by air traffic control or cockpit displays.
Derivation
Each word carries weight. Automatic — the aircraft sends the data on its own, with no pilot action required. Dependent — the accuracy depends on the aircraft's own navigation source (GPS), not on a ground radar. Surveillance — it allows others to watch the aircraft's position. Broadcast — the signal goes out to everyone in range, not to a single receiver. Out — refers to information leaving the aircraft, as opposed to ADS-B In, which is information received by the aircraft.
Why Pilots Care
ADS-B Out is required for operations in most U.S. controlled airspace; it improves traffic awareness and safety while replacing older radar-based surveillance.
Intuition Check
Do not read “Out” as meaning “outside the aircraft.” Here, “Out” means the aircraft is sending its position and identity information outward to receivers.
Example Sentence 1
Before entering the Class B airspace, the pilot confirmed the ADS-B Out was transmitting correctly.
Example Sentence 2
An inoperative ADS-B Out unit required the pilot to obtain a deviation authorization for the flight.