Plain English Meaning

The radio link between a high-altitude air traffic control center and an aircraft has stopped working on the frequency being used. Controllers and pilots then try other ways to talk to each other, such as switching to a different frequency or routing the message through another station.

Full Definition

A loss of two-way radio communication between an aircraft and an Air Route Traffic Control Center (ARTCC), where the controller's transmitter, receiver, or assigned frequency becomes unusable. When this occurs, ARTCC controllers follow established procedures to re-establish , including requesting try another assigned frequency, contact a nearby , or use a different 's voice capability to .