Bloggs, you're like my wife, "You may be right, but that's not what I meant. Show me more."

Not ILS, but RNP, quibble if you like.

http://155.178.201.160/d-tpp/1312/00546RR3R.PDF

RUNWAY 3R
Latitude: 34-38.787753N
Longitude: 112-25.680282W
Elevation: 5027.8 ft.
Gradient: 1.0% UP
Traffic pattern: right
Runway heading: 028 magnetic, 041 true
Displaced threshold: 379 ft.
Declared distances: TORA:7616 TODA:7616 ASDA:7616 LDA:7237
Markings: nonprecision, in good condition
Visual slope indicator: 4-light PAPI on left (4.00 degrees glide path)

Not at all. The claim's been made. I am interested in examples, that's all.

I agree that one is not co-incident, but the discussion's about ILS vs PAPI, OK465.

Still, on that example, I would have thought visual/PAPI slopes would be more accurate than RNP VNAV, so why the steep PAPI, I wonder? Perhaps the 5268 obstacle affects the PAPI tolerances but not the RNP...

Good luck trying to follow, in any meaningful aeroplane, a 4° PAPI at 5000ft AMSL!

I've seen a video clip of that landing. A portion of the fuselage did fall off and skid along on the round.

Here's the video clip:

:confused:

Okay, given that at SFO the ILS GS was out of service, and the plane was far below the PAPI, you're going to have to explain to me how the SFO crash has anything to do with non-coincident gs and PAPI

You are missing the numerous factors involved in the design. There are differences in the assumed eye height vs the antennae height. (Note the EW eye to wheel height vs AW antennae to wheel height factor)

This is from the design manual, so as you can see, there are many factors involved.

EDIT: A squared...I never said it had anything to with the incident, I said it brought the issue of multiple TCH and GPA's to the forefront.

well yes, I suppose that in a broad sense it was a reminder that TCH ought to be a positive number. Other than that, you've still lost me.

That may be the case, but the diagram clearly shows different slopes for the PAPI and the ILS GS. Obviously there are going to be differences in eye heights verses antenna heights; that is not the issue. This issue I have is that "The diagram is coincident, both the ILS and PAPI are set at 3°" is wrong. The slopes are different and the GPIs are different.

:eek: I better quit while I'm ahead! :{

Obviously no FDAP gatekeepers to contend with... :E

For that matter, how about London City Airport with it's 5.5 degree ILS and PAPI? It's my understanding that there's a number of jets operating in there on schedules, as well as all the turboprops.

Bloggs, just for you!

In order for you to see 2 reds and 2 whites on a 3° glideslope...ie to see both the Unit B and Unit C...

(this is the math from the other diagram, they illustrate the same)
Note angle M

http://i44.tinypic.com/e80jl1.jpg

Thanks for the interesting information guys …
 

If I may, the point I was trying to make was that airplane attitude is critically important (all the time, but particularly so just prior to landing) such that if the airplane attitude on very short final is rotated up to something like 20° of pitch, with the stick shaker barking and the throttles against the forward stops … but if the pilot stills see’s “2 whites and 2 reds” out the front window, that isn’t going to mean much other than what may be included in the accident report or chiseled on his tombstone.

Correct, and that is why your original diagram is wonky, because angle C is shown aligned along 3° (same as ILS GS), not above it. The PAPI on-slope angle is between B and C (as shown above). Your original diagram depicts what looks like a PAPI on about 2.8° with the ILS (I assume) on 3°. They not co-incident in either GPI or slope angle, which is what you said they were.

At last, very good, your wife will now be happy. :p

The question is, why would such as situation exist? PAPI put in before the ILS? Surely any terrain limitation would affect the ILS GS tolerances more than a visual PAPI, which can be flown super-accurately where the tolerances between each red/white are very small?

I agree. Worrying about a fraction of a degree of difference between ILS antenna and visual vasi or papi is like admitting you are an automation or visual guidance dependent pilot. All pilots worth anything should be able to judge a 3 degree glide slope with nothing at night just by looking at the angle to the runway out the window. Yes some runways have an upslope or downslope but you already know that if you did any homework.

bubbers44:


True to a point. But, the FAA has gotten a lot more nervous about NPAs at night recently. There are now a lot of notes like the one for KBHM Runway 18.

"woods for the trees." KISS.

One of our pilots took out the fence at the cliff on the north end of TGU Honduras. Probably because he didn't compensate for the upslope runway. He got low and slow. It had no GS guidance but everybody else had no problems. Keeping up basic flying skills unfortunately now days is on the back burner so more of these incidents will happen unless we go back to when we actually made pilots prove they could fly manually. Asiana crash might get the FAA's attention of poor hand flying skills. We will see.