Plain English Meaning

A special number a pilot dials into the transponder to tell air traffic control, without using the radio, that the radio has stopped working. Once it's set, controllers can see on their screens that this specific aircraft has lost radio contact.

Full Definition

The four-digit transponder code (7600) set by a pilot to indicate to air traffic control that the aircraft has experienced a loss of two-way radio communication. When selected on the transponder, this code highlights the aircraft's radar return on ATC displays and alerts controllers that normal voice communication is not possible.

Context Anchor

Used during communication-failure procedures, especially when flying under air traffic control or in instrument flying.