What is a squawk code?

A squawk code is a four-digit code assigned by air traffic control that allows individual aircraft to be identified on radar. This code is entered into the aircraft's transponder, which communicates with radar systems and helps air traffic controllers track and manage traffic in the skies. Each aircraft is assigned a unique squawk code that helps prevent confusion and ensures that controllers can accurately identify and communicate with specific aircraft.

The transponder's response, which includes the squawk code, enables air traffic controllers to differentiate between numerous aircraft in proximity to one another. This is an essential part of maintaining safety and efficient operations in controlled airspace. The use of squawk codes is part of the broader system of surveillance and alerting that supports situational awareness for both pilots and air traffic controllers.