What is one main reason secondary radar is used in air traffic control?

• A. It provides live video feeds from the aircraft
• B. It allows for ground-based tracking only
• C. It enhances tracking capability when equipped with transponders
• D. It requires no onboard aircraft equipment

Answer: (C)

Secondary radar is essential in air traffic control primarily because it enhances tracking capability when equipped with transponders. This technology allows for more detailed and accurate information about an aircraft's position, altitude, and velocity.

In secondary radar systems, the ground station sends out a signal that prompts the aircraft's transponder to reply with its identification and altitude information. This two-way communication enables air traffic controllers to gather reliable data from the aircraft, which helps in monitoring traffic more efficiently, especially in busy airspace. The use of transponders means that the information provided can be much more precise and timely compared to primary radar systems, which only reflect the physical presence of the aircraft without providing detailed data.

Other options do not accurately describe the benefits of secondary radar. It does not provide live video feeds, nor is it limited to ground-based tracking. Additionally, while secondary radar systems do require equipment on board the aircraft (the transponder), this is not the main reason for their effectiveness; rather, it is their ability to enhance tracking through real-time data exchange.