Air Traffic Control Systems and Procedures Practice Test

The squawk is how ATC identifies and tracks your aircraft on radar. In an IFR clearance, you’re assigned a discrete four-digit code, and you set that code on the transponder. When your transponder replies with that code, your target on the controller’s radar display is uniquely linked to your aircraft, allowing ATC to monitor its position and altitude and to provide radar-based separation and proper sequencing or handoffs. This identification function is why the squawk code exists. It isn’t used to relay weather, it doesn’t set autopilot, and it isn’t used to store your flight plan.