Precision approach path indicator: Difference between revisions

Revision as of 07:34, 19 November 2005

Revision as of 07:36, 1 January 2006

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The '''Precision Approach Path Indicator (PAPI)''' is a [[light]] system positioned beside the [[runway]] that consists of two or four boxes of lights that provide a visual indication of an airplane's position on the [[glidepath]] for the associated [[runway]]. The [[Federal Aviation Administration|FAA]] standard for the PAPI is the same as the [[ICAO]]'s standard [[|VASI|Visual Glide Slope Indicator]].

Each box of lights is equipped with an [[optics|optical]] apparatus that splits light output into two segments: red (the lower segment) and white. Depending on the viewing, and thus the descent, angle, a [[aviator|pilot]] will see either the red or the white portion.

A normal glidepath (usually 3%) is indicated by an even split in red and white lights. If an airplane is beneath the glidepath, more red lights are visible to the pilots; if an airplane is above the glidepath, more white lights are visible.

During aircraft [[descent_(aircraft)|descent]], this system, along with other airport lights, may be activated by the [[aviator|pilot]] by keying the airplane [[microphone]] with the airplane's communication radio tuned to the [[CTAF]].

==See also==