An aircraft radio navigation system which senses and indicates the direction to a L/MF nondirectional radio beacon (NDB) ground transmitter. Direction is indicated to the pilot as a magnetic bearing or as a relative bearing to the longitudinal axis of the aircraft depending on the type of indicator installed in the aircraft. In certain applications, such as military, ADF operations may be based on airborne and ground transmitters in the VHF/UHF frequency spectrum.

Listed in the Pilot/Controller Glossary as a cross-reference to AUTOMATIC DIRECTION FINDER, whose text is shown above.

Source FAA Pilot/Controller Glossary↗ · checked 2026-08-25