Precision approach path indicator

Precision Approach Path Indicator (PAPI) -
Required Visual Reference
Runway centerline lights ...

Precision approach path indicator (PAPI). A system of lights similar to the VASI, but consisting of one row of lights in two- or four-light systems. A pilot on the correct glide slope will see two white lights and two red lights. See VASI.

PRECISION APPROACH PATH INDICATOR (PAPI) - An airport lighting facility in the terminal area navigation system used under VFR conditions (see also), through a single row of two to four lights, ...

Precision Approach Path Indicator
A more accurate VASI. This 4-light visual glideslope indicator is calibrated to display smaller deviations than a VASI.
Procedure Turn ...

PAPI - precision approach path indicator, a system of coloured lights installed at the approach end of a runway which provides visual guidance to the correct glidepath. A successor to VASI, below.

See also: Aircraft, Flight, Runway, Power, Landing