Precision approach path indicator: Difference between revisions

Revision as of 14:42, 1 March 2023

Revision as of 14:52, 1 March 2023

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[[Image:PAPI M39.jpg|thumb|Individual precision approach path indicator]]

The PAPI is a light array positioned beside the [[runway]]. It normally consists of four equi-spaced light units color-coded to provide a visual indication of an aircraft's position relative to the designated [[glideslope]] for the runway. An abbreviated system (APAPI) consisting of two light units can be used for some categories of aircraft operations. The international standard for PAPI is published by the [[International Civil Aviation Organization]] (ICAO) in ''Aerodromes, Annex 14 to the Convention on International Civil Aviation, Volume 1, Chapter 5''. National regulations generally adopt the standards and recommended practices published by ICAO. An earlier glideslope indicator system, the [[visual approach slope indicator]] (VASI) is now obsolete and was deleted from ''Annex 14'' in 1995. The VASI, only provided guidance down to heights of {{convert|60|m|ft|sigfig=1}} whereas PAPI provides guidance down to flare initiation (typically {{convert|15|m|ft|sigfig=1|disp=x|, or }}).{{cn|date=February 2023}}

PAPIs are calibrated relative to the Minimum Eye Height over Threshold (MEHT). Pilots in certain aircraft may see a "slightly low" indication even though they are on the ILS glideslope, <ref>https://publicapps.caa.co.uk/docs/33/CAP637%20Visual%20Aids%20Handbook.pdf</ref> when pilot eye height is above the ILS receiver antenna.<ref>https://www.airbus.com/sites/g/files/jlcbta136/files/2021-11/Airbus-Aircraft-Data-for-Visual-Aids-Calibration-v5.0.pdf</ref>