What squawk 7700 means
7700 is the transponder code associated with a general emergency. The code alone does not identify the problem or establish that an accident has happened.
Practise at MadridA code, not a diagnosis
A transponder helps identify an aircraft through its assigned code. Squawk 7700 signals an emergency, but does not encode its cause. Understanding a particular flight requires more information. Seeing 7700 on a flight-tracking app is not enough to determine what happened.
What it means in ATC7700
The game takes its name from this code. During a shift, an emergency arrival may appear, marked in red with the text 7700. The radio announces the situation and the radar helps you locate the flight. It is a simulated game event, not an alert about a real aircraft.
Handling it in the game
Find the aircraft and check its runway, heading, altitude and speed. Arrange the other traffic to make room, maintain separation and prepare the arrival. An emergency does not remove clearance steps or make an occupied runway available. Pause if you need time to review the situation.
Start with a normal arrival
You do not need to wait for an emergency: open Madrid and practise a normal arrival with the tutorial. Reading aircraft targets and checking runway availability helps when traffic demands more attention. Positions are simulated and procedures are simplified.
Source for the real-world code: FAA Aeronautical Information Manual, Emergency Services Available to Pilots.