Which navigation aid is used with the ground-based nondirectional beacon (NDB)?

• A. AME
• B. AWOS
• C. ADS-B
• D. ADF

Answer: (D)

When using a ground-based nondirectional beacon for navigation, the instrument you rely on is the Automatic Direction Finder. The NDB simply transmits a nondirectional signal on LF/MF, and the ADF receiver uses its loop antenna (with a sense antenna to resolve ambiguity) to determine the direction to the beacon. The bearing to the station is then shown on an indicator (such as an RMI or HSI paired with the ADF), allowing you to fly toward or away from the beacon or to intercept a course relative to its direction. Other systems like AWOS provide weather information, and ADS-B is used for surveillance and position reporting, not for determining bearing to an NDB. So the ADF is the navigation aid designed to work with an NDB.