Flyf15 From , joined Dec 1969, posts, RR:
Reply 1, posted (12 years 4 months 2 weeks 6 days 9 hours ago) and read 13262 times:
Much more simple than that.
Each "station"/"light emitter" has a light in a box. There is a metal divider placed in the box that is precisely aligned with what the glideslope should be at that position. Below this metal divider is a red lens. Due to this, if you are above the angle of the metal divider, you see the white light, if you are below it, you see the red light.
Av8trxx From United States of America, joined Nov 2001, 657 posts, RR: 6
Reply 3, posted (12 years 4 months 2 weeks 6 days 9 hours ago) and read 13247 times:
Yes, the PAPI itself does not "identify an aircraft and thus to give them the proper light information", but rather the pilot identifies their position on the glideslope by the colors visible on the PAPI. Perhaps these diagrams & explainations will help: http://www.bayareapilot.com/vasiPAPI.htm