Plain English Meaning

A simple radio station on the ground that sends out a steady signal in every direction. An instrument in the aircraft points toward the station, so the pilot knows which way to fly to reach it.

Full Definition

Ground-based radio transmitters that broadcast a low or medium frequency signal equally in all directions. An aircraft equipped with an automatic direction finder (ADF) receiver uses the signal to determine the bearing from the aircraft to the station, allowing the pilot to navigate to or from the beacon. NDBs may be used as standalone navigation aids, as compass locators associated with an , or as the basis for .