ADF refers to which type of equipment and NDB refers to the associated equipment located where?

ADF stands for Automatic Direction Finder, which is an airborne navigation aid that helps pilots determine their aircraft's direction relative to a Non-Directional Beacon (NDB). The ADF uses signals from the NDB to provide heading information, enabling pilots to navigate effectively even when visibility is poor.

The NDB is the ground-based counterpart that emits non-directional radio signals. It serves as a reference point for the ADF in the aircraft. The correct pairing indicates that the ADF is installed in the aircraft, while the NDB is situated on the ground. This relationship highlights the functionality of the ADF as a navigation tool that relies on the signal from the NDB to guide the aircraft's course.