Understanding ADS-B and Emergency Squawk Codes

Modern aircraft are equipped with a technology called Automatic Dependent Surveillance-Broadcast (ADS-B). Unlike traditional radar, which actively pings aircraft to determine their position, ADS-B allows an aircraft to broadcast its own position, enabling it to be easily tracked. This broadcast includes identity, position, altitude, velocity, and other information.

What is a Squawk Code?

A "squawk" code is a four-digit number assigned to an aircraft by air traffic control (ATC). This code is transmitted by the aircraft's transponder and helps ATC identify and track the plane on their radar screens. While most codes are unique and assigned for specific flights, there are several universal codes reserved for special situations.

• 7700: General Emergency. This is the most common emergency code. It signifies that the aircraft is in a state of distress for any reason, such as engine failure, depressurization, or a medical emergency on board. Declaring 7700 alerts all nearby ATC facilities that the flight needs immediate attention and priority.
• 7600: Lost Communications. This code indicates that the aircraft has lost two-way radio communication with ATC. Pilots will follow standard lost-communication procedures, and ATC will clear the airspace along the aircraft's expected flight path to ensure safety.
• 7500: Hijacking. This is the code for an unlawful interference, such as a hijacking.

This website tracks flights that broadcast these critical squawk codes.