I am trying to compare a VASI-4 light system with a PAPI lights. I know that 2White-2Red is the pattern that indicates that the aircraft is on the glideslope; more reds mean lower and more white means higher than the desired glideslope height. With relations to that, how should the VASI lights be on a correct/incorrect approach?

P.S. My question is specific to VASI-4 light system aka 2-bar VASI.

UPDATE I found this from FAA that may very well be the answer, but an explanation would be great.

  • $\begingroup$ @FreeMan I didn't ask for how they work. I don't see this as a duplicate. I asked for the sources that confirms what the correct indication for 2-bar VASIs should be $\endgroup$ – hagubear Mar 17 '15 at 12:43
  • 1
    $\begingroup$ The sources are contained in the answers of the other question. $\endgroup$ – Federico Mar 17 '15 at 12:50

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