What system relies on an aircraft periodically broadcasting its GPS-derived position?

The system that relies on an aircraft periodically broadcasting its GPS-derived position is Automatic Dependent Surveillance–Broadcast, commonly known as ADS-B. This technology enhances situational awareness by providing both air traffic controllers and other aircraft with real-time information about an aircraft’s position, velocity, and intent, all derived from the aircraft's onboard GPS data.

ADS-B operates independently of ground-based radar, making it particularly effective and reliable in areas where traditional radar coverage may be limited or non-existent, such as over oceans or remote regions. The broadcast nature of ADS-B allows multiple receiving stations and nearby aircraft to receive this information simultaneously, facilitating improved air traffic management and safety.

In contrast, primary radar utilizes reflected radio waves to detect targets and does not rely on information from the aircraft itself, while secondary radar involves transponders that respond to ground signals by providing altitude and identity, lacking the continuous position updates that ADS-B provides. A transponder system operates as part of secondary radar and is commonly used, but it does not inherently broadcast position data based on GPS without ADS-B. Therefore, the emphasis on periodic GPS-derived broadcasting characterizes ADS-B as the correct answer.