Definition
An aircraft radio navigation receiver that automatically points to the bearing of a selected ground-based non-directional beacon (NDB). The cockpit indicator needle rotates to show the direction from the aircraft to the tuned station, allowing the pilot to track to or from that station.
Plain English
A receiver in the aircraft that picks up the signal from a chosen ground radio beacon and swings a needle on the cockpit display to point at it. Whichever way the needle points, that's the direction of the station from the aircraft.
Context Anchor
Seen in older radio navigation, instrument panels, navigation checks, and procedures that use a non-directional beacon.
Derivation
Automatic — the needle finds the station on its own once tuned, without the pilot rotating anything. Direction Finder — equipment that finds the direction of a radio source. The name describes exactly what it does: automatically finds the direction to a beacon.
Why Pilots Care
Supplies a simple, reliable direction reference to a radio station when other navigation aids are unavailable or during basic instrument training.
Intuition Check
Do not assume an ADF tells you how far away the station is. It points toward the selected radio beacon; distance must come from another source or procedure.
Example Sentence 1
After tuning the NDB frequency, the pilot watched the ADF needle settle and then turned the aircraft to keep it pointing straight ahead, tracking directly to the station.
Example Sentence 2
After passing the station the needle reversed, showing the pilot had flown directly over the radio source.