Non-Directional Beacon (NDB)

A non-directional beacon is a radio transmitter located in a known place, used as an aid to air or maritime navigation as a radio beacon.

NDBs consist of two parts: the Automatic Direction Finder (ADF) equipment on the aircraft that detects the signal from an NDB, and the transmitting NDB.

They have continued to provide a critical and reliable means of aircraft navigation despite the advent of GNSS and modern ground-based systems. However, there are still operational teams that require revision.