To what distance does the Localizer signal provide guidance?

The Localizer signal is a crucial component of an Instrument Landing System (ILS), providing lateral guidance to aircraft during the approach phase of landing. It is specifically designed to help pilots align the aircraft with the centerline of the runway.

The correct answer, which is 18 nautical miles, reflects the standard range for typical Localizer systems under specific conditions, usually when the aircraft is at a height above the ground at the final approach stage. Thus, when a pilot receives the Localizer signal, they can rely on it to navigate accurately towards the runway for a safe landing.

The other distances are less commonly associated with the effective range of Localizer guidance for precision approaches; typically, a signal range of 10 nm is generally too short for landing purposes, while 15 nm and 20 nm may not be as widely applicable within standard ILS operational parameters for Localizer systems.