What is the primary function of a Non-Directional Beacon (NDB)?

Answer: B — Emits a signal which pilots navigate towards

The primary function of a Non-Directional Beacon (NDB) is to emit a signal that pilots can navigate toward. NDBs transmit a low-frequency radio signal omnidirectionally, allowing aircraft to receive the signal from various directions. Pilots utilize this signal when flying with the ADF (Automatic Direction Finder) equipment on board, helping them determine their bearing to the beacon. This capability is essential for navigation, especially in areas where other navigational aids may not be available or in conditions where visibility is poor. In contrast, other options do not describe functions of an NDB. For instance, while ground vehicles may be guided by other types of navigation systems, NDBs are specifically for aircraft. Weather data is provided by other types of radar and meteorological sources, not NDBs. Similarly, altitude determination during landing is typically handled by other instruments, such as altimeters and ILS (Instrument Landing System), rather than by NDBs.