At what altitude is DME required?

DME, or Distance Measuring Equipment, is a navigational tool used to determine the distance between an aircraft and a ground-based radio station. Its use is mandated above certain altitudes to ensure that pilots can navigate safely and maintain situational awareness, particularly in controlled airspace and during instrument flight rules (IFR).

The requirement for DME becomes crucial above FL 240 (24,000 feet) since this is where aircraft operate in the more congested airspace, including en route and terminal operations. The higher altitude, combined with the speed of aircraft at these levels, necessitates accurate distance information to manage separation and navigation effectively.

DME is typically used in conjunction with VOR (VHF Omnidirectional Range) systems, and its requirement at FL 240 helps ensure that pilots have reliable information to conduct approaches and navigate through regions where radar coverage may be limited or nonexistent. Ensuring accurate navigation at these altitudes is critical for flight safety, making DME a requirement for operations above FL 240.