What is the Instrument Landing System primarily used to provide?

• A. Vertical guidance only.
• B. Horizontal guidance only.
• C. Both horizontal and vertical guidance to a runway.
• D. Ground based enroute navigation.

Answer: (C)

The Instrument Landing System is designed to deliver both lateral and vertical guidance for a precision approach to a runway. The localizer provides horizontal guidance, keeping you centered on the runway centerline as you approach. The glide slope provides vertical guidance, guiding your descent along a predefined glide path to the runway threshold. Used together, they give a precise path from the final approach just above the runway to touchdown, which is crucial in low visibility. This system is ground-based and specifically intended to guide you to the runway, not for general enroute navigation. So the best description is that it provides both horizontal and vertical guidance to a runway.