Definition
A secondary set of communication radios installed at an Air Route Traffic Control Center (ARTCC) sector position that takes over air-to-ground voice communications if the primary radio equipment fails. The backup system uses separate transmitters, receivers, and often separate transmission lines so that controllers can continue talking to aircraft during a primary radio outage.
Plain English
A second, independent set of radios that controllers switch to if their main radios stop working, so they can keep talking to aircraft.
Context Anchor
Seen in discussions of air route traffic control center radio frequency outages, when a center frequency may stop working and alternate communication equipment is used.
Derivation
Backup comes from the idea of something standing behind the main item to support it if needed. Receiver means equipment that takes in radio signals, and transmitter means equipment that sends radio signals. Together, the phrase points to spare equipment that can both hear and talk.
Why Pilots Care
Preserves two-way ATC communication so pilots can continue receiving clearances and traffic advisories without interruption.
Grounding Statement
If the main controller radio quits, the backup radio receiver and transmitter system is the alternate equipment used to keep voice communication going.
Intuition Check
Backup does not mean optional or unimportant here. It means a secondary system intended to take over when the primary radio system is unavailable.
Example Sentence 1
When the primary frequency went silent, the controller activated the backup radio receiver and transmitter system and re-established contact with all aircraft on the sector.
Example Sentence 2
The controller directed traffic to the backup radio receiver and transmitter system until the primary frequency was restored.