What is the role of a transponder in aircraft operations?

The transponder plays a crucial role in identifying an aircraft to air traffic control (ATC). When an aircraft is equipped with a transponder, it sends out a unique identification code, along with altitude information, in response to interrogations from ground radar systems. This coded response allows ATC to distinguish between different aircraft on their radar displays, improving situational awareness and helping to ensure safe and efficient air traffic management. The transponder thus serves as a key piece of equipment that enhances the ability of air traffic controllers to track and communicate with aircraft in their airspace.

In the context of the other choices, while measuring fuel consumption and enhancing navigational accuracy are important aspects of aircraft operation, they are not functions of the transponder. Similarly, while communication between aircraft is critical, it is typically achieved through different communication systems rather than the transponder itself. The primary function of the transponder is clearly centered around identifying the aircraft to ATC, making this answer the most accurate in describing its role.