What capability does an NDB provide?

An NDB, or Non-Directional Beacon, provides indirect navigation support via radio signals. This capability allows pilots to navigate by tuning their aircraft's radio receiver to the specific frequency of the NDB. The NDB transmits signals in all directions, and pilots can locate the NDB using an Automatic Direction Finder (ADF) or similar equipment. The ADF provides the bearing to the NDB, which pilots can use to establish their position relative to the beacon and navigate toward or away from it.

While other options mention different aspects of navigation, they do not accurately represent the primary function of an NDB. For instance, enhancing GPS positioning relates to global navigation systems, while guiding visual flights based on landmarks involves visual VFR navigation rather than radio navigation. Serving as a location marker on sectional charts might be true in a general sense, but it does not capture the primary navigational capability of an NDB, which is the transmission of radio signals that pilots can use for indirect navigation.