What is the function of a precision approach path indicator (PAPI) and how should pilots interpret its colors?

What is the function of a precision approach path indicator (PAPI) and how should pilots interpret its colors?

• A. To provide a visual glide slope cue; red and white lights indicate if aircraft is too high or too low, guiding a proper approach.
• B. To indicate landing clearance by flashing lights.
• C. To measure airspeed using color indicators.
• D. To announce weather via color-coded signals.

Answer: (C)

PAPI provides a visual glide slope cue on final approach. The four lights show white or red to indicate your vertical position relative to the desired glide path. When you’re on the proper glide slope, you typically see two white and two red lights. If more lights are white, you’re high and need to descend; if more lights are red, you’re low and need to raise the nose to come down to the path. This helps you stay on the correct descent angle without relying on cockpit instruments alone. It’s not used to measure airspeed (that’s the airspeed indicator), nor to grant landing clearance or convey weather information.

PAPI provides a visual glide slope cue on final approach. The four lights show white or red to indicate your vertical position relative to the desired glide path. When you’re on the proper glide slope, you typically see two white and two red lights. If more lights are white, you’re high and need to descend; if more lights are red, you’re low and need to raise the nose to come down to the path. This helps you stay on the correct descent angle without relying on cockpit instruments alone. It’s not used to measure airspeed (that’s the airspeed indicator), nor to grant landing clearance or convey weather information.