ALSF-1 and ALSF-2 configurations are examples of what system?

• A. Approach Lighting System.
• B. Runway End Identifier Lights.
• C. Localizer.
• D. Glide slope.

Answer: (A)

Approach lighting helps pilots transition from instrument procedures to a visual landing by providing a path of lights extending outward from the runway threshold. ALSF-1 and ALSF-2 are two configurations of that system, specifically the Approach Lighting System with Sequenced Flashing Lights. These setups place a sequence of lights along and near the approach path to give strong visual cues, especially in low visibility, with ALSF-2 typically offering a more extended or enhanced arrangement than ALSF-1 to support precision approaches.

This is different from Runway End Identifier Lights, which are a pair of flashing lights at the runway threshold used to identify the runway end; Localizer, which provides horizontal guidance for the ILS, and Glide slope, which provides vertical guidance.