Definition
An instrument approach procedure that uses a Non-Directional Beacon (NDB) for course guidance combined with Distance Measuring Equipment (DME) for along-track distance information. The NDB provides bearing to or from the station via the aircraft's Automatic Direction Finder (ADF), and DME supplies slant-range distance from a paired DME station, allowing the pilot to identify fixes, step-downs, and the missed approach point by distance rather than by timing or by crossing a second navaid.
Plain English
An instrument approach where the pilot follows a radio beacon for direction and uses a distance readout to know how far they are from a fixed point on the field. The beacon tells you which way; the distance tells you how far.
Context Anchor
Seen on instrument approach charts and in instrument clearances when an airport has an NDB-based approach that also requires DME distance information.
Derivation
Nondirectional beacon means the ground beacon sends its signal out in all directions rather than along one narrow path. Distance measuring equipment means the aircraft equipment shows distance from a ground station. Together, NDB/DME tells you that this approach uses both direction-to-the-beacon information and measured distance.
Why Pilots Care
Allows safe descent and alignment to the runway at airports lacking more precise navigation aids such as ILS or RNAV.
Intuition Check
Do not read “approach” as simply getting close to the airport. Here it means a published instrument procedure with required equipment, distances, altitudes, and a missed approach path.
Example Sentence 1
Cleared for the NDB/DME Runway 14 approach, the pilot tracked inbound on the bearing while using the DME readout to identify the final approach fix.
Example Sentence 2
During the briefing, the crew confirmed the NDB/DME approach minimums and noted the DME distances for each altitude step.