Definition
The pointer on an Automatic Direction Finder (ADF) instrument that rotates to indicate the direction of a tuned non-directional radio beacon (NDB) relative to the aircraft. On a fixed-card ADF, the needle points to the relative bearing from the nose; on a movable-card or Radio Magnetic Indicator (RMI), the needle points to the magnetic bearing to the station.
Plain English
The arrow on the ADF gauge that always points toward the radio station the receiver is tuned to. Whichever way the arrow points, that is the direction of the station from the aircraft.
Context Anchor
Seen on ADF cockpit indicators during traditional radio navigation and some instrument approach procedures.
Derivation
ADF means automatic direction finder: the system automatically finds the direction of a selected radio signal. The word “needle” refers to the pointer on the cockpit instrument, like a pointer on a gauge.
Why Pilots Care
It helps determine direction to a beacon for orientation and navigation when other systems are unavailable.
Intuition Check
Do not read the ADF needle as the airplane’s heading. It points toward the selected station; the airplane may be flying in a different direction.
Example Sentence 1
After tuning the NDB frequency and identifying the station, the pilot watched the ADF needle swing around to point off the right wing.
Example Sentence 2
With the ADF needle steady ahead, the plane flew a direct course to the beacon.