When is ADS-C required?

When is ADS-C required?

• A. Over the ocean.
• B. In domestic airspace only
• C. In uncontrolled airspace
• D. Only during night flights

Answer: (A)

ADS-C is used where radar surveillance isn’t available, which is primarily over the ocean. In oceanic and remote airspace, there's no ground radar to continuously monitor an aircraft’s position, so ADS-C provides automatic position reports to air traffic control via a contract-based downlink (often as part of FANS systems). This lets controllers track progress, speeds, altitudes, and routes even when satellites or long-range communications are needed. In domestic or controlled airspace where radar or ADS‑B coverage exists, ADS-C isn’t typically required, and night versus day doesn’t change that. So the situations that necessitate ADS-C are those over the ocean, where radar isn’t reachable.

ADS-C is used where radar surveillance isn’t available, which is primarily over the ocean. In oceanic and remote airspace, there's no ground radar to continuously monitor an aircraft’s position, so ADS-C provides automatic position reports to air traffic control via a contract-based downlink (often as part of FANS systems). This lets controllers track progress, speeds, altitudes, and routes even when satellites or long-range communications are needed.

In domestic or controlled airspace where radar or ADS‑B coverage exists, ADS-C isn’t typically required, and night versus day doesn’t change that. So the situations that necessitate ADS-C are those over the ocean, where radar isn’t reachable.