What is a squawk code?

A squawk code refers to a four-digit number assigned to an aircraft for identification by radar, specifically when the aircraft is being monitored by air traffic control. This code is entered into the aircraft's transponder, allowing controllers to uniquely identify and track the aircraft on radar displays. Each aircraft is assigned a distinct squawk code, which helps to avoid confusion and ensures safety in the busy skies.

The use of squawk codes is critical for managing air traffic, as they provide essential information, including the aircraft's location and altitude. Air traffic controllers can instruct pilots to change their squawk code in various situations, such as when entering a controlled airspace or in response to an emergency situation. This system enhances situational awareness and safety for both pilots and air traffic personnel.

In contrast, other answers refer to unrelated concepts that do not align with the established use of squawk codes in aviation. For instance, identification numbers for passengers, flight destinations, and emergency status signals do not pertain to the specific function and identification process enabled by squawk codes in radar systems.