PAPI usage
 

Hi Folks,

Can anybody direct me as where to find the reference untill what altitude/height we can use the PAPI. Close to touchdown there can be a big difference between a B747 and a C172 on the visual segment just before touchdown.

Thanks!

PAPI usage
 

Makes no active difference. Of course you are right that the system is designed to a mean eye height above the wheels, but if you're still fixated on them for the last hundred or so feet, I'd suggest you need to go back and revise your basic flying skills.

PAPI is an aid to get you from an NPA to the visual segment, after this we use the aiming point (big white markers) for the last bit.

In theory there is no minimum height due to the way that the visual beam is created; it is projected via a focussing lens.

Visual segment is defined by the glare-shield cut-off angle, aircraft attitude, and slant visibility; perhaps this isn’t the term you require.

The important difference, as above, is in the wheel-to-eye height which determines the wheel-height over the threshold. At some major airports, there is a second set of PAPIs installed further into the runway for long body aircraft, following these better optimises the threshold crossing height.

Better question would be not until when, but FROM WHEN can we use them?

It's been discussed before in here somewhere, but makes for ever so interesting reading,:8

hi

I just read this somewhere recently...the reason vasi was abandoned and papi was started.

seems to me that 50' was when papi gives out for practical use

try looking up the US Aeronautical Information Manual online and then looking up airport lighting.

you could also look up PAPI in google

I offer this only from memory, as someone who flys should actually take the time to look it up himself.

some papis have limits placed upon them for specific airports due to terrain near by. I"ve seen one as four miles.


good luck, and learn to find your spot

oh, ok, read about it here and why VASI was done away with

Precision approach path indicator - Wikipedia, the free encyclopedia

Apologies to you Air Engineer, and the other blokes genuinely trying to help you with your post.....

You ask an innocent enough question, and the first reply (#2.....from the Minister in charge of all things aviation...in Vienna) offers no helpful information at all, tells you what you already know, and concludes with an insult regarding your general abilities in an aeroplane.

This, unfortunately, is what you tend to get from PPrune these days.

From the A330 FCOM, Supplementary procedures, Navigation:

Approach on PAPI or TVASI

Eye to wheel height on approach is 32ft and minimum recommended wheel clearance over the
threshold is 20ft. Do not follow Precision Approach Path Indicator (PAPI) or “T”- Visual Approach Slope Indicator (TVASI) guidance below 200ft when PAPI or TVASI Minimum Eye Height over Threshold (MEHT) is less than 52ft.

PAPI is a guide, not a requirement - as such you may use it to guide your actions any time you can see it.

As any guide, you don't use it exclusively - so you don't allow it's errors or limitations to affect your safe landing.

Usually from people who don't know the answer to the question.....

I recall that the DCA Flying Unit in the old days tested the T-VASIS for flyability down to 200 feet. It was assumed that no pilot would want to follow the lights any lower since it was a visual guide not a category 2 or 3 ILS.

For the same reason you should never consider switching from the ILS at Cat 1 height of 200 ft to the PAPI since the electronic glide slope is already there to give guidance.

OP is quite right to ask in my opinion.
I can't answer your question with any wisdom but I can tell you that a hull loss occurred because of precisely this. In the picture below, look at the difference in wheel heights between the 2 bizjets for the same pilot eye heights.
My company operate jet charters to main intl airports as standard, but also occasionally to small airfields where PAPIs have been setup for smaller aircraft. The example below is always brought up during our recurrents.

Go easy on me please!


http://www.tsb.gc.ca/eng/medias-medi...34_photo_5.jpg

Anyone interested, accident report here: Transportation Safety Board of Canada - Aviation Investigation Report A07A0134

Hi Air Engineer, I think it all depends upon what you are flying and at which airfield.

If for instance you are flying a Husky from Doncaster, you have enough room for... A Take-Off,,, Practice EFATO,,, Touch and Go,,, and still have runway left over.
The PAPIs are mostly aligned for CAT landing well into the runway, and most GA aircraft want to be on the ground well before that.

Gliders in particular, practice landing as close to the Threshold Hedge as possible as they are often faced with land-outs in some very small fields. The aiming point is often in the field before the landing field, with the flare occurring just over the hedge.

The geometric PAPI 3 degree glideslope obviously terminates at the PAPI installation. For a CAT airplane the height of the Pilot's eye-line is many feet above his wheels, so the wheels can touch down many metres short of the PAPIs. That is why the PAPIs are several hundred metres up the runway from the threshold.

From flarepilot's wiki link - PAPI to flare (usually 50' ).

VASI designed for use down to 200' (but they worked much lower).

Amazing how often the PAPI's aren't aligned to the glideslope or vice versa... Makes you realise very quickly that they are a reference guide. I was always told not below 200ft in the jet

From the FAA AIM Chapter 2. Aeronautical Lighting and Other Airport Visual Aids

b. Precision Approach Path Indicator (PAPI). The precision approach path indicator (PAPI) uses light units similar to the VASI but are installed in a single row of either two or four light units. These lights are visible from about 5 miles during the day and up to 20 miles at night. The visual glide path of the PAPI typically provides safe obstruction clearance within plus or minus 10 degrees of the extended runway centerline and to 4 SM from the runway threshold.

EDIT: from different source... The VASI only provided guidance down to heights of 60 metres (200 ft) whereas PAPI provides guidance down to flare initiation (typically 15 metres, or 50 ft).

So that looks like it covers both parts of the question, as others stated, down to 50 ft and out to 4nm...

This diagram from a design manual may be helpul as to why there are differences.

http://i43.tinypic.com/2laq3rn.jpg

distances:
http://i40.tinypic.com/dpkaro.jpg

I can't believe a pilot would link to that wikipedia page. I tend to look a long time for more reputable sources before checking wikipedia but even I'm surprised at that entry. I'm guessing the entry was done as a junior high project.

I can't believe that Canada didn't have LLWS alert system

I offered the wiki link as a quick answer to the question, I also indicated that checking the AIM would be a good idea too.