What does PAPI provide to pilots, and how is glide slope indicated?

• A. A 2-light array indicating distance to runway via color codes.
• B. Provides a 4-light array providing visual glide slope guidance; color combinations indicate if on, above, or below slope.
• C. An array of 6 lights indicating lateral alignment only.
• D. A single white light indicating optimal approach angle.

Answer: (B)

PAPI uses a four-light visual array to give pilots a quick sense of their vertical path during approach. Each light can be red or white, and when you’re on the correct glide slope you should see two red and two white lights. If more lights are white, you’re above the glide slope; if more lights are red, you’re below it. This provides an immediate, intuitive cue for maintaining the proper descent angle alongside other instruments.