Definition of Precision Approach Path Indicator (PAPI)
A Precision Approach Path Indicator (PAPI) is an airport lighting system that provides pilots with a visual glide path during the landing approach. It consists of one row of either two or four lights that are positioned perpendicular to the runway. The system employs a symmetric display of lights, with the red light closest to the runway and the white light further away.
The PAPI is similar to the Visual Approach Slope Indicator (VASI) system, but differs in that it relies on a row of lights instead of individual lights. When a pilot is on the correct glide slope, they will see two white lights and two red lights, indicating that they are “on path”. If they are too low, they will see more red lights, whereas, if they are too high, they will see more white lights.
The PAPI system provides crucial information to pilots, allowing them to make adjustments to their landing approach and ensure a safe landing. It is an important tool for air traffic control and helps improve airport efficiency and safety.
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