Which system is particularly useful for determining distance from a navigational aid?

The Distance Measuring Equipment (DME) is specifically designed to determine the distance between an aircraft and a navigational aid, typically a VOR station or a TACAN. DME operates by sending a signal from the aircraft to the ground station, which then responds with a return signal. The onboard equipment calculates the time taken for this round trip and converts it into a distance measurement, which is presented to the pilot.

This capability to provide precise distance information is crucial for navigating accurately, especially when approaching or departing from an airport or during instrument flight rules (IFR) operations. The DME can give pilots a reliable indication of how far they are from a specific navigational point, allowing for better situational awareness and improved flight planning.

In contrast, while GPS can also determine position and distance, its function extends beyond just measuring distance to a navigational aid, encompassing broader applications such as route planning and waypoint navigation. Similarly, VOR and NDB systems primarily provide directional information rather than direct distance measurements. Thus, DME is distinctly recognized for its specialized role in providing accurate distance information from navigational aids.