Which system is referred to by the acronym PAPI?

The term PAPI stands for Precision Approach Path Indicator. This system is critical for pilots during the approach and landing phases of flight, providing visual guidance on the proper glide slope angle to ensure a safe arrival at the runway.

PAPI consists of a series of lights located beside the runway that change colors based on the aircraft's altitude in relation to the desired approach path. When the lights appear white, it indicates that the aircraft is above the glide slope; when they are red, it shows that the aircraft is below. The correct configuration, which is a mix of white and red lights, signals that the aircraft is on the ideal approach path.

This system is designed to enhance safety and prevent accidents associated with improper approach angles, especially in low visibility conditions. Its importance in aviation safety standards is recognized internationally, making it a fundamental component of modern runway approach systems.