Definition
The four-digit transponder code (7600) that a pilot selects to alert air traffic control that the aircraft has lost two-way radio communication. When squawked, it causes the aircraft's radar return to be flagged on ATC displays as a communication failure.
Plain English
A special number you put into your transponder to tell controllers, on their radar screens, that your radio has stopped working.
Context Anchor
Used in lost-communications procedures, especially during instrument flight when a pilot cannot talk with air traffic control by radio.
Why Pilots Care
ATC provides priority handling and separation services assuming you cannot hear instructions.
Grounding Statement
When normal radio contact is lost, code 7600 is the aircraft’s radar-visible way of signaling the problem.
Intuition Check
Do not treat code 7600 as a radio frequency or a spoken call. It is a transponder setting that air traffic control sees on radar.
Example Sentence 1
When the radios went silent and resetting them didn't help, the pilot squawked 7600 and continued the flight under lost-communication procedures.
Example Sentence 2
ATC noticed the aircraft squawking code 7600 and issued vectors without expecting a reply.