Editing Visual approach slope indicator (section)

{{Short description|Runway light set}}
{{redirect|VASI|other uses|Vasi (disambiguation){{!}}Vasi}}
The '''visual approach slope indicator''' ('''VASI''') is a system of [[Electric light|lights]] on the side of an airport [[runway]] threshold that provides visual [[descent (aircraft)|descent]] guidance information during [[final approach]]. These lights may be visible from up to {{convert|8|km|mi}} during the day and up to {{convert|32|km|mi}} or more at night.