What is a "squawk" code in aviation?

A "squawk" code refers specifically to a transponder code assigned by air traffic control. When an aircraft is in flight, its transponder broadcasts information about the aircraft's identity, altitude, and location through a unique code known as a squawk code. This code helps air traffic controllers to identify and keep track of individual aircraft on radar, facilitating safe and efficient air traffic management.

The squawk code is typically a four-digit number that pilots set on their transponder as per instructions from air traffic control. This code can denote various situations, such as signals for normal operation or specific requests, but fundamentally, it serves to identify the aircraft uniquely on radar systems, ensuring effective communication and coordination within controlled airspace.

Understanding the function of squawk codes is crucial for pilots, as correctly responding to ATC instructions may involve changing the squawk code during flight operations, especially when entering different airspace sectors or in emergency situations, which helps maintain safety in aviation.