Definition
A ground-based radar system used by air traffic control that works in cooperation with a transponder carried in the aircraft. The ground station sends out an interrogation signal; the aircraft's transponder receives it and replies with a coded signal that identifies the aircraft and reports its altitude. The controller's display then shows the aircraft as a distinct, labeled target rather than just a raw radar return.
Plain English
It's the radar setup ATC uses to 'talk to' your transponder. The radar asks, your transponder answers with your code and altitude, and you show up on the controller's screen as an identified aircraft.
Context Anchor
Seen in acronym lists and in discussions of radar, aircraft identification, altitude reporting, and transponder-related equipment.
Derivation
The word 'beacon' originally meant a signal fire or marker used to guide travelers. In radar, a 'beacon' system is one where the target actively replies to a signal, rather than just passively reflecting it. So an ATC radar beacon system is a radar in which each aircraft acts as its own little signaling beacon, answering when the ground station calls.
Why Pilots Care
Enables positive aircraft identification and altitude readout, reducing the risk of misidentification and supporting safe separation in controlled airspace.
Intuition Check
Do not picture a flashing light on the aircraft. Here, “beacon” means an electronic signal that replies to air traffic control radar.
Example Sentence 1
The controller identified the aircraft on radar using the ATCRB return from its transponder.
Example Sentence 2
A malfunctioning transponder prevents the ATCRB from displaying the aircraft on the radar scope.