Which of the following best describes Multilateration (MLAT)?

Multilateration (MLAT) is a method used for determining the position of an aircraft and is fundamentally based on the time difference of arrival (TDOA) of signals emitted from the aircraft's transponders. This technology uses multiple ground stations that listen for the signals from the aircraft's transponder. By measuring the time it takes for the signals to reach the different ground stations, the system can accurately triangulate the aircraft's position.

The reliance on aircraft operating transponders is essential because those transponders send out signals that contain relevant identification and altitude data, which enables the multilateration system to effectively track and determine the location of the aircraft.

Other options do not accurately represent the nature of multilateration. While radar technology can be used for tracking, MLAT specifically does not depend on radar systems but rather on the signals sent from transponders. The assertion that it relies on ground control for surveillance is overly broad, as ground control can engage in various forms of monitoring without being specific about multilateration. Lastly, while GPS data is indeed crucial for navigation, multilateration operates independently of GPS by utilizing its own method of signal triangulation to establish an aircraft's position based on transponder emissions.