What does PAPI stand for?

PAPI stands for Precision Approach Path Indicator. This is a visual aid used in aviation to provide guidance to pilots on the correct approach path for landing an aircraft. PAPI systems consist of a set of lights, typically arranged in pairs, that indicate whether the aircraft is on the correct glide slope. A combination of white and red lights informs the pilot if they are above or below the ideal approach angle. This system enhances safety and accuracy during landings, especially in environments where visual references may be limited.

The other options represent terms that do not correspond to established aviation terminology. Pilot Activity Performance Indicator and Pressure Altitude Path Indicator do not have recognized meanings in the context of aviation. Similarly, Primary Airspeed Performance Indicator is not a standard tool or reference in pilot training or operations. Therefore, the association of PAPI with precision approach guidance clearly distinguishes it as the correct choice in this context.