What signals does the Distance Measuring Equipment (DME) send?

Distance Measuring Equipment (DME) is a critical component in aviation navigation systems that specifically measures the distance between an aircraft and a ground-based station. It operates by sending a signal from the aircraft to the ground station, which then responds with a signal back to the aircraft. The time it takes for this round-trip signal to occur is used to calculate the distance, allowing pilots and air traffic controllers to determine how far the aircraft is from the DME station.

Thus, the option highlighting the measurement of distance between the aircraft and the ground station accurately captures the primary function of DME. This capability is essential for pilots to maintain situational awareness regarding their position relative to navigational aids, which directly supports safe and efficient flight operations.