Cleared to Explainan air traffic controller explains Decode your screen

Squawk 7700: what it means when a flight shows an emergency

You saw a plane flash red on a flight tracker. Here's what squawk 7700 means, why pilots set it and why it's usually less dramatic than it looks.

By an air traffic controller 1 min read

The short answer

7700 is the transponder code for a general emergency. Setting it raises an alert on every radar screen that can see the aircraft, so controllers can give it priority. Most 7700 flights land normally: it's often a precaution, such as a sick passenger or a technical warning.

Every airliner carries a transponder: a box that answers radar with a four-digit code, known as a squawk. Controllers give each flight its own code so it shows up with the right label on the screen.

A few codes are reserved for trouble. 7700 is the one for a general emergency.

What happens when a crew sets 7700

The code triggers an alarm or special symbol at every radar position that can see the aircraft. That means a controller notices straight away, even if the radio is busy.

From there:

  1. The crew tells ATC what’s going on, as soon as they can.
  2. Controllers give the flight priority: direct routes, a clear runway, other traffic moved aside.
  3. Fire and rescue services at the landing airport are put on standby.

Why you see it on Flightradar24

Flight trackers pick up the same transponder signal, so a 7700 shows up for anyone watching. It looks dramatic. It usually isn’t.

Crews set 7700 for many reasons: a medical emergency on board, a warning light, a pressurisation problem, or simply to get priority while they sort something out. Most of these flights land normally.

The other two emergency codes

CodeMeaning
7700General emergency
7600Radio failure: the crew can’t talk to ATC
7500Unlawful interference (hijack)

If you see a 7600, the aircraft is fine. It just can’t hear us. There are agreed procedures for exactly that, so everyone knows what it will do next.

Official sources

  1. FAA, Aeronautical Information Manual, 6-2: Emergency services available to pilots
  2. ICAO Doc 4444, Procedures for Air Navigation Services: Air Traffic Management