What is the primary function of a transponder in aviation?

The primary function of a transponder in aviation is to send aircraft information to Air Traffic Control. Specifically, the transponder responds to signals received from ground-based radar systems by transmitting a signal containing essential data about the aircraft, such as its identity (squawk code), altitude, and sometimes additional information like flight number. This communication allows Air Traffic Control to accurately track and identify aircraft within their airspace, enhancing safety and efficiency.

The capability of the transponder plays a crucial role in maintaining situational awareness for both air traffic controllers and pilots. By providing real-time data, it helps in ensuring proper separation between aircraft and plays a critical role in the overall air traffic management system.

While the other options refer to important functions in aviation, they do not accurately describe the primary role of a transponder. For example, transponders do not monitor engine performance or provide navigational assistance directly; rather, they focus on transmitting crucial identification and altitude data to enhance air traffic visibility.