Questions tagged [papi]

Papi is the short for "Precision approach path indicator". It's a visual aid providing guidance information to help a pilot acquire and maintain the correct approach.

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30 votes
2 answers
104k views

What's the functional difference between PAPI and VASI?

PAPI and VASI seem to be very similar in the the information they provide - i.e. are you on the glide slope or off it. Is there a functional difference between the two? If there is a difference, and ...
Jeff B's user avatar
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9 votes
2 answers
10k views

What determines the positioning of PAPI lights from the runway threshold?

Why are PAPI lights installed 300m from the threshold? What are the conditions that define the position of the PAPI lights from threshold?
mrinal anurag's user avatar
41 votes
4 answers
37k views

How do PAPI lights work?

Usually, there are four lights at the sides of runways which show airplanes' altitude status: four red lights: too low two red, two white: appropriate altitude four white lights: too high. If two ...
Super Hornet's user avatar
11 votes
2 answers
4k views

How to decide on which side of the runway the approach path indicator (VASI, PAPI) are placed?

This answer provides pictures and drawing of implementation of both PAPI and VASI. In all pictures I found, I cannot figure if there is a rule to put those lights on the right, on the left, or on both ...
Manu H's user avatar
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3 votes
1 answer
3k views

What is the average deviation from the PAPI glide slope at the threshold?

If one approaches with three red and one white light what will be the average deviation from the standard threshold height of 50 feet?
Art Buenaventura's user avatar