How does a transponder assist air traffic control?

• A. It helps identify and track the airplane's location and altitude on radar
• B. It improves weather reporting
• C. It provides autopilot control
• D. It communicates fuel status

Answer: (A)

The main idea is that a transponder lets air traffic control identify and locate an aircraft on the radar display by responding to ground radar interrogations with a unique code and altitude information. While primary radar shows blips, it doesn’t tell controllers who the airplane is or how high it’s flying. The transponder, when asked, replies with a code (and, with Mode C, the aircraft’s altitude), enabling controllers to identify each aircraft and accurately track its position and vertical level to maintain safe separation. The other options describe functions not provided by the transponder.