What is the range of the DME?

The Distance Measuring Equipment (DME) system is designed to provide pilots with the distance from the aircraft to a DME ground station. The correct answer indicates a slant range of 199 nautical miles, which is the maximum effective range at which the DME can accurately provide distance information.

The DME operates by sending out a signal that is then received and processed to calculate the distance based on the time it takes for the signal to travel to the ground station and back. The slant range is the direct line distance from the aircraft to the DME ground station, which means it accounts for the altitude of the aircraft. This is crucial for navigation and instrument approaches, as pilots rely on DME for precise distance information when flying.

The other options present distances that do not accurately reflect the operational capabilities of standard DME systems. While some might suggest slightly longer or shorter distances, 199 nautical miles is established as the maximum operational range under typical conditions for many DME installations. Hence, the provided answer correctly identifies the maximum slant range for DME.