What type of guidance does a Localizer provide in an Instrument Landing System (ILS)?

A Localizer in an Instrument Landing System (ILS) provides lateral guidance. It assists pilots in aligning the aircraft with the runway centerline during the final approach segment of a landing. The Localizer transmits guided signals that define the precise horizontal path the aircraft should follow to ensure a correct approach. This capability is crucial for maintaining the aircraft's proper track during low visibility conditions or at night, where visual cues are limited.

In contrast, other guidance systems play different roles. For instance, vertical guidance is typically provided by the Glide Slope component of the ILS, which instructs pilots on the appropriate vertical descent angle. Distance measuring refers to a system that provides information on how far the aircraft is from the runway threshold, which is not within the Localizer's function. Approach path guidance is more broadly related to ensuring the correct descent profile, which involves both horizontal and vertical components, but the Localizer specifically focuses only on lateral alignment. Thus, the Localizer’s role is vital for achieving accurate lateral positioning on approach, confirming that B is indeed the appropriate response.