Which system provides both lateral and vertical guidance during an instrument approach?

• A. Doppler Radar
• B. VOR/DME
• C. Primary Surveillance Radar
• D. Instrument Landing System

Answer: (D)

Instrument approaches require both lateral guidance to stay on the runway centerline and vertical guidance to manage descent. The Instrument Landing System provides both. The localizer delivers precise horizontal guidance, keeping you aligned with the runway, while the glide slope gives vertical guidance for the descent path. Together, they form a precision approach with low minimums.

Doppler radar is mainly used for measuring velocity and detecting movement or weather, not for guiding a fixed descent path. VOR/DME offers azimuth guidance and distance information but no vertical guidance. Primary Surveillance Radar tracks aircraft for ATC without providing an approach path or descent guidance.