NDB

NDB (Non-Directional Beacon) is a ground-based radio transmitter that broadcasts on low/medium frequency (190-535 kHz), providing a signal that aircraft ADF equipment can tune to determine bearing to the station.

NDB approaches are classified as non-precision approaches. While NDBs are being progressively decommissioned as GPS becomes the primary navigation standard, they remain operational in many parts of the world, particularly at smaller airports and in remote areas.