What three colors of lights indicate a PAPI system?

The Precision Approach Path Indicator (PAPI) system uses a combination of lights to provide visual guidance to pilots during their approach to landing. The correct answer lists the colors as white high, red, and white, which corresponds to how the lighting system indicates whether the aircraft is on the correct glide path.

Specifically, the PAPI will show two white lights and two red lights when the aircraft is above the ideal glide slope, indicating a need to descend. When the aircraft is on the correct glide slope, typically displayed as one white light and one red light, it ensures the pilot is perfectly aligned for a safe touchdown. If the aircraft is below the glide path, it will show two red lights, prompting the pilot to climb to regain the correct approach angle.

This systematic color coding helps pilots quickly and effectively identify their position relative to the glide path, enhancing safety during landing.