Definition
An unstaffed VHF/UHF radio transmitter and receiver site, located away from the air route traffic control center it serves, that extends the controller's voice radio coverage to aircraft flying en route at higher altitudes. RCAG sites are linked back to the controlling ARTCC by landline or microwave, allowing controllers to talk to aircraft far beyond the range of any single antenna at the center itself.
Plain English
A remote radio site that lets en route controllers talk to aircraft that are too far away from the control center to be reached directly. The controller sits at the center; the antenna sits out where the aircraft are.
Context Anchor
You may see RCAG in FAA glossary material, facility descriptions, or communications discussions involving Center or other air traffic control radio coverage.
Derivation
Remote = located away from the main facility. Communications Air/Ground = two-way radio between aircraft (Air) and controllers on the ground (Ground). The name simply describes what the site does: a remote radio relay for air-to-ground talk.
Why Pilots Care
Ensures reliable contact with air traffic control in areas without direct coverage, reducing the chance of lost communications and supporting safer flight through difficult terrain.
Intuition Check
Do not think of an RCAG as a separate controller or a separate control facility. It is a remote radio site used by the controller to reach aircraft by radio.
Example Sentence 1
Center's clear reception at FL350 over remote terrain is made possible by a network of RCAG sites tied back to the ARTCC.
Example Sentence 2
Controllers use the RCAG site to maintain voice contact with aircraft over remote wilderness areas.