ADF stands for which navigation aid?

• A. Attitude Indicator
• B. Automatic Data Filter
• C. Automatic Direction Finder
• D. Air Data Facility

Answer: (C)

ADF stands for Automatic Direction Finder, a radio navigation aid that helps pilots determine the bearing to a ground radio beacon. The system receives signals from a non-directional beacon (NDB) and, using a loop and sense antenna, indicates the aircraft’s bearing to the station on the instrument. By centering the bearing you can fly toward or away from the beacon or intercept a course relative to the beacon. The sense feature helps resolve the front–back ambiguity that can occur with loop antennas.

This is different from an attitude indicator, which shows the aircraft’s orientation in space, or from other items that aren’t cockpit navigation aids, like Automatic Data Filter or Air Data Facility.