Ok Tedi

An NDB-DME places Distance Measuring Equipment alongside a Non-Directional Beacon, so an older beacon can also provide distance. The pilot gets bearing the traditional way — an ADF needle pointing to the NDB in the LF/MF band — and slant-range distance from the paired DME on UHF. Together they yield a rho-theta fix (angle plus distance) using largely legacy equipment.

This combination is far less common than VOR-based navaids and shares the NDB's limitations: shoreline and night effects and thunderstorm interference on the bearing signal, even though the DME distance itself is reliable. NDB-DMEs typically support a specific instrument approach or fix where a VOR was never installed, and like other NDB-based aids they are gradually being retired in favor of GPS.