Certified Flight Instructor - Flight Instructor Airplane Practice Exam

Which statement is true concerning the operation of DME?

1. DME operates in the VHF frequency band.

2. Distance information received from DME is the actual horizontal distance from the station.

3. DME coded identification is transmitted once for each three or four times that the VOR coded identification is transmitted.

4. DME provides vertical distance measurements from the station.

The correct answer is: DME coded identification is transmitted once for each three or four times that the VOR coded identification is transmitted.

The correct statement regarding the operation of DME (Distance Measuring Equipment) is that DME coded identification is transmitted once for each three or four times that the VOR coded identification is transmitted. This is important because DME and VOR (VHF Omnidirectional Range) are often paired together in navigation systems. The DME provides distance information while the VOR provides directional information. The identification broadcast frequency helps pilots distinguish between different navigational aids, ensuring they are using the correct reference for navigation. When utilizing DME in conjunction with VOR, the identification for DME is typically less frequent. This ensures that while pilots are primarily focused on locating their positional bearings using VOR, they still receive periodic updates from the DME to ascertain their distance from the station without overwhelming them with constant signals from both systems. The other statements do not correctly represent how DME operates. For example, DME does not operate in the VHF frequency band; it works on a UHF frequency range. Additionally, the distance information provided by DME is slant range distance, which is not strictly horizontal distance as it measures the actual distance from the aircraft to the DME transmitter, taking altitude into account. Lastly, DME does not provide vertical distance measurements