What is one characteristic of an NDB?

An NDB, or Non-Directional Beacon, is a radio navigation aid that communicates signals to aircraft, enabling them to determine their bearing relative to the NDB. This means that pilots can use the signals to navigate toward or away from the beacon, making it a vital tool for directional navigation rather than providing a direct approach to an airport. It is particularly valuable in situations where visual references are limited, such as in poor weather or at night.

While it's true that NDB signals help pilots navigate, they do not provide altitude information, which makes that option inaccurate. The NDB is not a visual reference for land navigation; it relies strictly on radio signals, unlike visual aids such as landmarks or lighted beacons. Though NDBs can complement GPS navigation, they are traditionally standalone systems and do not require GPS to function. Thus, the characteristic that identifies NDBs accurately is their role in directing pilots through radio signals.