What is the primary purpose of using DME in instrument approaches?

What is the primary purpose of using DME in instrument approaches?

• A. To determine distance to the VOR/DME station
• B. To provide weather information for the approach
• C. To display airport service availability
• D. To measure wind direction

Answer: (A)

Distance measuring equipment gives you the distance from your aircraft to the VOR/DME station, and that distance is what you rely on on an instrument approach to know where you are along the approach path. By measuring slant-range distance in nautical miles, you can identify fixes that are defined by a specific radial and a DME distance, helping you descend and align with the runway accurately. The system works by the aircraft sending a signal to the ground station and receiving a reply, with the time difference converted into distance. This distance information is essential for situational awareness and for executing step-down fixes and the final approach segment. Weather information comes from METAR/TAF or radar, not DME; wind direction is measured by onboard instruments and weather data, not DME; and DME isn’t used to display airport service availability.

Distance measuring equipment gives you the distance from your aircraft to the VOR/DME station, and that distance is what you rely on on an instrument approach to know where you are along the approach path. By measuring slant-range distance in nautical miles, you can identify fixes that are defined by a specific radial and a DME distance, helping you descend and align with the runway accurately. The system works by the aircraft sending a signal to the ground station and receiving a reply, with the time difference converted into distance. This distance information is essential for situational awareness and for executing step-down fixes and the final approach segment. Weather information comes from METAR/TAF or radar, not DME; wind direction is measured by onboard instruments and weather data, not DME; and DME isn’t used to display airport service availability.