What statement is true regarding Automatic Dependent Surveillance-Broadcast (ADS-B)?

The correct understanding of Automatic Dependent Surveillance-Broadcast (ADS-B) highlights that ADS-B Out transmits line-of-sight signals to Air Traffic Control (ATC) ground receivers and other aircraft. This system operates by automatically broadcasting an aircraft's precise location information, derived from its GPS position, at regular intervals. Consequently, ATC and other equipped aircraft can receive this information in real-time, enhancing situational awareness and safety in the skies.

This technology plays a critical role in modern air traffic management and is a key component of the Next Generation Air Transportation System (NextGen), helping to streamline operations and improve efficiency in controlled airspace. The communication is indeed based on line-of-sight, making it essential for monitoring and coordinating air traffic effectively.

Understanding why this answer is correct also sheds light on the nature of the other options: ADS-B is not optional for all aircraft flying in controlled airspace where the regulations require its use; it operates independently of manual pilot input for transmitting location data; and it specifically targets ATC and other aircraft rather than just military radar installations.