What do 2 white/2 red lights on the PAPI indicate on approach to a runway?

Two white lights and two red lights on the Precision Approach Path Indicator (PAPI) indicate that the aircraft is on a proper glide slope during its approach to a runway. The PAPI system is designed to provide visual guidance to pilots, helping them maintain the correct descent path. When the lights are divided evenly between white and red, it signifies that the aircraft is neither too low nor too high, and is aligned with the ideal approach angle.

The proper combination of lights allows pilots to confidently descend into the runway, ensuring safety and efficiency in landing procedures. A consistent indication of two white and two red lights serves as a clear signal that the aircraft is operating within the acceptable criteria for a safe landing approach.