What is the primary function of a transponder in aviation?

The primary function of a transponder in aviation is to provide identification and altitude information. Transponders are crucial for aircraft surveillance, as they transmit data in response to ground-based radar signals. When the radar system sends a signal, the transponder responds with information including the aircraft's unique identifier (known as the squawk code) and its altitude. This data is essential for air traffic control, as it allows controllers to accurately track multiple aircraft in the airspace, ensuring safety and efficient management of flights.

The transponder's role primarily revolves around enhancing situational awareness for both pilots and air traffic controllers, assisting in collision avoidance and maintaining safe separations between aircraft. This functionality is particularly critical in busy airspace environments and during instrument flight operations.

Other options, while they relate to various aspects of aviation systems, do not pertain to the transponder's capabilities. For instance, engine temperature regulation and monitoring fuel efficiency are responsibilities that involve different aircraft systems, while streaming video footage is unrelated to transponder technology and does not contribute to the operational requirements of aircraft navigation and safety.