What information does Secondary Radar Mode C provide to air traffic controllers?

Secondary Radar Mode C provides height information and aircraft callsign in label form, which is crucial for air traffic controllers. In Mode C, the transponder on the aircraft emits altitude information, allowing controllers to accurately determine the aircraft's vertical position relative to mean sea level. This data is displayed alongside the aircraft's unique identification or callsign on radar screens, enabling controllers to easily identify and track multiple aircraft simultaneously.

This combination of altitude and identification enhances situational awareness for controllers, facilitating safer and more efficient air traffic management. Height information is particularly important in preventing collisions and ensuring appropriate separation between aircraft at different altitudes. The callsign helps air traffic controllers communicate with the specific aircraft, ensuring clear and accurate communication regarding routing, altitude changes, and other instructions.