What squawking is
Every airliner and most other aircraft carry a transponder: a radio that answers radar and broadcasts the aircraft’s position (ADS-B, the signal Bogey reads). Air traffic control gives each flight a four-digit code, and “squawk four two one seven” means “set your transponder to 4217.” “Squawk ident” asks the pilot to press a button that makes the aircraft stand out on the controller’s screen.
The special codes
- 7700: emergency. A pilot in distress or urgency “should squawk Mode 3/A, Code 7700/Emergency” (FAA). It “normally triggers an alarm or special indicator at all control positions.” More in what does squawk 7700 mean.
- 7600: radio failure. If an aircraft loses two-way radio, the pilot sets 7600 so controllers know it can’t hear them, and everyone follows the lost-radio procedures.
- 7500: unlawful interference. It tells controllers an aircraft has been hijacked. The FAA notes it “will never be assigned by ATC without prior notification from the pilot.” It is very rarely seen; most real-world 7500s turn out to be mistakes that get corrected in seconds.
- 1200: VFR in the US. Pilots flying on their own under visual rules, not talking to controllers, set 1200. Europe and the UK use 7000 for the same job, and 2000 for aircraft entering their airspace without an assigned code.
Pilots changing codes are told to avoid passing through 7500, 7600 or 7700, which would set off “momentary false alarms.”
Squawks in Bogey
When an aircraft near you sets 7700, Bogey can push an alert, and it shows up on the live SITREP board and in red on the map. Most emergencies end with a safe landing; catching one makes for a memorable card.
