What is being replaced by Distance Measuring Equipment (DME)?

Distance Measuring Equipment (DME) is designed to provide pilots with precise information regarding their distance from a specific navigational aid, typically a VOR (VHF Omnidirectional Range) station. One of the key elements it has replaced in modern navigation systems is the traditional outer, middle, and inner markers used in the Instrument Landing System (ILS).

The outer, middle, and inner markers served as reference points during the approach phase of flight, providing information about the aircraft's position along the ILS approach. However, they are limited in terms of range and provide less precise data compared to the capabilities of DME. DME technology allows for continuous distance monitoring regardless of altitude or position relative to the airport, thereby enhancing situational awareness and contributing to more efficient and safer approaches.

The other options—approach lights, runway markings, and traffic advisories—serve different functions in aviation and are not directly replaced by DME. Approach lights assist pilots in visualizing the runway during the final phases of approach, runway markings provide essential information regarding the runway's layout, and traffic advisories are issued to ensure safe separation between aircraft. Each of these components continues to play an important role in aviation safety and navigation, unlike the more outdated and limited function of