Which lighting system begins at the landing threshold and extends into the approach area?

• A. PAPI
• B. Approach Light System (ALS)
• C. REIL
• D. VASI

Answer: (B)

The main idea here is about which lighting system provides a path from the runway threshold outward into the approach area. The approach lighting system is designed to start at the threshold and extend along the approach path, giving pilots visual cues to transition from instrument flight to a visual approach and to judge distance and alignment as they get closer to the runway. It typically includes a series of lights along the extended centerline that may extend out a significant distance, sometimes with crossbars or sequenced flashers.

PAPI and VASI are single-point visual glide-slope indicators located near the runway threshold to help maintain the proper descent angle once established on final, but they don’t extend into the approach area. REIL marks the threshold to help identify the runway, not to guide the approach path. Therefore, the lighting system that begins at the landing threshold and extends into the approach area is the approach lighting system.