Squawk 7600

The transponder code for radio communication failure. It tells every controller who sees you on radar that you can no longer talk to them, so they can keep traffic clear and expect you to follow the published radio-failure procedure.

Keep transmitting blind in case your transmitter still works and keep listening on the frequency. A VFR flight continues in visual conditions and lands at the nearest suitable aerodrome. Memory aid: “seven-six, radio fix”.