Glideslope versus Papi??
So if that is true why on earth would folks fly a PAPI showing 3 reds and one white? Wouldn't it mean your aiming point is the same as an on slope indication but you fly a shallower angle to get to it?
Thoughts??
Thoughts??
Yes I would agree!
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Ozexpat: Please expand. No our route guide does not mention them. I'm still curious as to their worth, especially as the ones I've seen are on an ILS RWY, illuminating at the same time as the G/S. Seems like a waste of amps/volts to me.
1. Redundancy; and
2. The previous installation was a T-VASIS.
I favour the redundancy argument, especially at international aerodromes, but this benefit is sometimes negated because both PAPI systems are left on when a faulty one should be turned off. Of course, this makes it a tad difficult for us to figure out which one is giving the right information.
T-VASI has some advantages, see previous thread discussions.
At major commercial airports which operate long body aircraft, the double PAPI installation provides suitable flexibility for a range aircraft types; all in proportion to the runway length etc.
PAPI has an advantage over other systems in that it uses a projected beam of light – a lens / filter system like some old film/slide projectors. This provides a narrower and more powerful beam of light which usually enables an earlier point of contact both in good and poor visibility.
There are many dangers in deliberately flying low (RRR/W). The approach path will be a closer to obstacles or the ground, particularly on short final; the reduced altitude clearance decreases the safety margin in the event of windshear or wake turbulence and will result in a low threshold crossing height with a danger of early touchdown – even in the undershoot. Conversely, flying a shallow slope and then converting to a ‘normal’ threshold crossing height can extend the flare and landing touchdown point with all of the dangers of an overrun particularly on a down-sloping runway where the effects are magnified.
A significant point from the original question is the altitude that any disparity between PAPI and ILS is noticed. In my experience there are few if any mismatches above 100ft; thus a mismatch at 200ft might suggest a PAPI alignment error, an ILS GS transmission error, or that your aircraft has an exceptional eye/ILS aerial height.
At major commercial airports which operate long body aircraft, the double PAPI installation provides suitable flexibility for a range aircraft types; all in proportion to the runway length etc.
PAPI has an advantage over other systems in that it uses a projected beam of light – a lens / filter system like some old film/slide projectors. This provides a narrower and more powerful beam of light which usually enables an earlier point of contact both in good and poor visibility.
There are many dangers in deliberately flying low (RRR/W). The approach path will be a closer to obstacles or the ground, particularly on short final; the reduced altitude clearance decreases the safety margin in the event of windshear or wake turbulence and will result in a low threshold crossing height with a danger of early touchdown – even in the undershoot. Conversely, flying a shallow slope and then converting to a ‘normal’ threshold crossing height can extend the flare and landing touchdown point with all of the dangers of an overrun particularly on a down-sloping runway where the effects are magnified.
A significant point from the original question is the altitude that any disparity between PAPI and ILS is noticed. In my experience there are few if any mismatches above 100ft; thus a mismatch at 200ft might suggest a PAPI alignment error, an ILS GS transmission error, or that your aircraft has an exceptional eye/ILS aerial height.
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Canada AIM 7.6.3
Where Vasi is provided on a prec approach it will be turned off,unless requested,when wx below 500',to avoid contradition between the precision approach and Vasis glidepaths
Where Vasi is provided on a prec approach it will be turned off,unless requested,when wx below 500',to avoid contradition between the precision approach and Vasis glidepaths
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Additional Transport Canada info
You may find some of the additional detail at this site interesting:
http://www.tc.gc.ca/CivilAviation/pu.../5-3.htm#5.3.6
Pardon me if I missed mention of this in a previous reply, but the PAPI and glideslope indications below 200' will only coincide if the aircraft's glideslope antenna and the pilot's line of sight are also aligned when in the normal approach attitude, and then only if the PAPI and glideslope angles and placement are both exactly the same. Given these variables, it is difficult to provide a generic answer for every glideslope / PAPI / aircraft combination. The technical specifications available at the above website will give you an idea of some of the design and installation criteria, if you have the time and inclination to read through them.
Fly safely ...
http://www.tc.gc.ca/CivilAviation/pu.../5-3.htm#5.3.6
Pardon me if I missed mention of this in a previous reply, but the PAPI and glideslope indications below 200' will only coincide if the aircraft's glideslope antenna and the pilot's line of sight are also aligned when in the normal approach attitude, and then only if the PAPI and glideslope angles and placement are both exactly the same. Given these variables, it is difficult to provide a generic answer for every glideslope / PAPI / aircraft combination. The technical specifications available at the above website will give you an idea of some of the design and installation criteria, if you have the time and inclination to read through them.
Fly safely ...
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depends on the one with the ink pen!!!
i was undergoing an evaluation into LFMH (EBU) ILS 18--close in final and the checker in the right seat said, "YOU"RE BELOW THE PAPI!!!!" like all were going to die----
i said, "i'm on the glideslope."
"YOU'RE BELOW THE PAPI!!!!!" even closer to death!!!!
"i'm following the glideslope!" at that point thinking......(can't put it here)---
"YOU'RE BELOW THE PAPI!!!!!" sounding as if his life was passing before him
we somehow made it without any grass stains on the tyres---
so it all depends on what the checker thinks on the day!!
his evaluation of my flying was below par--
i said, "i'm on the glideslope."
"YOU'RE BELOW THE PAPI!!!!!" even closer to death!!!!
"i'm following the glideslope!" at that point thinking......(can't put it here)---
"YOU'RE BELOW THE PAPI!!!!!" sounding as if his life was passing before him
we somehow made it without any grass stains on the tyres---
so it all depends on what the checker thinks on the day!!
his evaluation of my flying was below par--
yyz340c re: eye / GS aerial height. I recall that there are design recommendations which indicate acceptable values for aircraft installations, thus limiting the extent of this error – possible the value was 5 ft in the approach configuration and at the approach speed.
PAPI has a relatively narrow beam as shown in the Canadian diagram; if you wish you can calculate the height difference between the WW/RR changeover points (angular difference and slant range), thus bound the aircraft altitude where the PAPI and GS should (could) agree. However, the most significant difference is that PAPI quickly ‘switches’ between W/R due to its design characteristic (sharp transition), whereas VASI suffers from a large ambiguous zone of ‘pink’; thus the advice to be cautious of VASI.
It is unfortunate that the Canadian section is titled visual approach slope indicator 'VASI' where they are discussing PAPI (APAPI), which is to be their standard.
PAPI has a relatively narrow beam as shown in the Canadian diagram; if you wish you can calculate the height difference between the WW/RR changeover points (angular difference and slant range), thus bound the aircraft altitude where the PAPI and GS should (could) agree. However, the most significant difference is that PAPI quickly ‘switches’ between W/R due to its design characteristic (sharp transition), whereas VASI suffers from a large ambiguous zone of ‘pink’; thus the advice to be cautious of VASI.
It is unfortunate that the Canadian section is titled visual approach slope indicator 'VASI' where they are discussing PAPI (APAPI), which is to be their standard.
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unless low visibility procedures are in progress and the ILS sensitive area is clear How can you be so sure that the GS is all that accurate from 200' to the ground?
if the viz is good use the papi as a guide but don't just blindly follow it or the GS for that matter.
if the viz is good use the papi as a guide but don't just blindly follow it or the GS for that matter.
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Glideslope vs PAPI
PAPI and Localizer Glideslope are not designed to coincide or give the same information. It is rarely possible to compare the visual indication with the Glaidepath when you are established on Glidepath. Even at higher altitudes there are discrepencies. As you descend on the glidepath with the autopilot on you may get a chance to compare the two.
In most cases The PAPI instalation is installed on a Non Precision approach runway for descent information below MDA. In other words it is for a visual approach.
Some airports have PAPI which also coincide with the Precision Runway. This is rare in Canada. You will find PAPI on all Instrument runways in St. John's Itl - CYYT. This is due to moderate to severe turbulence, and windhshear.
The reason they do not comapare is that they are located at a different location. The planned touchdown point is often set up at a different location. They were never intended to be the same.
At lower altitudes the visual (PAPI) and instrument signal (Glidepath) often cross each other.
In most cases The PAPI instalation is installed on a Non Precision approach runway for descent information below MDA. In other words it is for a visual approach.
Some airports have PAPI which also coincide with the Precision Runway. This is rare in Canada. You will find PAPI on all Instrument runways in St. John's Itl - CYYT. This is due to moderate to severe turbulence, and windhshear.
The reason they do not comapare is that they are located at a different location. The planned touchdown point is often set up at a different location. They were never intended to be the same.
At lower altitudes the visual (PAPI) and instrument signal (Glidepath) often cross each other.
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Papi
Aéroport de Nice Cote d'Azur - FAQ, Saleya, PAPI
Nice in south of France is a good example, the Jeppesen plates state the papi is for a cat d aircraft.
Nice in south of France is a good example, the Jeppesen plates state the papi is for a cat d aircraft.
The more enlightened aerodromes put a little note on the Jepps ;words to the effect of -"PAPI indications not useable below 200 feet". Valid on a stabilised approach.
However, on the 744, ground effect at (Cat 1- manual flown) minimums tends to reduce the descent rate and drive you a little high on the slope. Doesn't take much to change from 2W/2Reds to 3W/1Red; not a particular problem, as this is what you expect to see at 50 ft RA as you cross the threshold (on the 74).
Trouble is, pushing the nose down at that height at high landing weights (higher RoD's) to get back on the slope (not!) could possibly generate a "sink rate" warning due to the narrow margins, and (in my outfit at least) a little e-mail from the FDAP monitoring department. On the other hand, watch the PAPI's when the Autoland is at work. Always interesting, because it can be surprising sometimes, depending on individual runway settings, or for whatever other reason. Good old autopilot doesn't care, just sticks to it's job, which is invariably done well and usually far better than Yours Truly.
When manual flying, I like to listen to what the Auto Callout has to say as the threshold passes beneath. "50 feet" suggests all is well.
However, on the 744, ground effect at (Cat 1- manual flown) minimums tends to reduce the descent rate and drive you a little high on the slope. Doesn't take much to change from 2W/2Reds to 3W/1Red; not a particular problem, as this is what you expect to see at 50 ft RA as you cross the threshold (on the 74).
Trouble is, pushing the nose down at that height at high landing weights (higher RoD's) to get back on the slope (not!) could possibly generate a "sink rate" warning due to the narrow margins, and (in my outfit at least) a little e-mail from the FDAP monitoring department. On the other hand, watch the PAPI's when the Autoland is at work. Always interesting, because it can be surprising sometimes, depending on individual runway settings, or for whatever other reason. Good old autopilot doesn't care, just sticks to it's job, which is invariably done well and usually far better than Yours Truly.
When manual flying, I like to listen to what the Auto Callout has to say as the threshold passes beneath. "50 feet" suggests all is well.
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Follow the ILS or VOR,DME,NDB to MDH (MDA) as applicapple. When visual, use the PAPI's as a guide, but remember back to your first lesson as a pilot. If the 'picture' looks right, then it is right, and land. If not, go around.
No need to discuss various glide angles, PAPI 'eye hieghts', aerodromes set for certain aircraft types etc etc.
We are trained to land our aircraft as hands on, eyes out, capable people.
Fly the aircraft, hands on, eyes out, isn't that whats it's all about?
No need to discuss various glide angles, PAPI 'eye hieghts', aerodromes set for certain aircraft types etc etc.
We are trained to land our aircraft as hands on, eyes out, capable people.
Fly the aircraft, hands on, eyes out, isn't that whats it's all about?
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I just 'eye ball' the last 200ft. I will primarily look at and follow the G/S and also use the PAPi for a 'gross error' check, 3 white or 3 red is fine.
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I am sure there are several similar approaches but Quito is a fine one. The G/S is set at at about 6 deg as you fly down a mountain and the PAPI is to be flown after safe ground clearance is obtained. Have landed here a few times on a G/S approach, the aircraft we were operating were not designed for carrier landings.
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Michaleknight
EBCI is probably setup for the millitary fast jets there. It's the same in Eindhoven (EHEH) it's stipulated on the Jeppesens.
Below 200 feet you'll hear people say the PAPI are useless. Only way around it is to fly the aircraft visually and down onto the markers.
Below 200 feet you'll hear people say the PAPI are useless. Only way around it is to fly the aircraft visually and down onto the markers.
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Originally Posted by Airportdata
PAPI and Localizer Glideslope are not designed to coincide or give the same information.
Originally Posted by ICAO Annex XIV
5.3.5.36 When the runway is equipped with an ILS and/or
MLS, the siting and the angle of elevation of the light units
shall be such that the visual approach slope conforms as
closely as possible with the glide path of the ILS and/or the
minimum glide path of the MLS, as appropriate.
MLS, the siting and the angle of elevation of the light units
shall be such that the visual approach slope conforms as
closely as possible with the glide path of the ILS and/or the
minimum glide path of the MLS, as appropriate.
In addition, localizers do not have glide slopes. ILS systems do.
Originally Posted by Airportdata
In most cases The PAPI instalation is installed on a Non Precision approach runway for descent information below MDA. In other words it is for a visual approach.
Originally Posted by ICAO Annex XIV
5.3.5.1 A visual approach slope indicator system shall be
provided to serve the approach to a runway whether or not the
runway is served by other visual approach aids or by nonvisual
aids, where one or more of the following conditions
exist:
a) the runway is used by turbojet or other aeroplanes with
similar approach guidance requirements;
b) the pilot of any type of aeroplane may have difficulty in
judging the approach due to:
1) inadequate visual guidance such as
...
provided to serve the approach to a runway whether or not the
runway is served by other visual approach aids or by nonvisual
aids, where one or more of the following conditions
exist:
a) the runway is used by turbojet or other aeroplanes with
similar approach guidance requirements;
b) the pilot of any type of aeroplane may have difficulty in
judging the approach due to:
1) inadequate visual guidance such as
...
In Oz, most of the PAPIs at the major airports have been set with an eye-height of around 60-70 ft, whereas the ILS has stayed at a Threshold crossing height of 50ft (or thereabouts). The reason I've heard bandied around is to make the PAPI look normal ie 2R/2W when the ILS is flown by a wide/long body (I assume brought about by the intro of the A380). This makes sense, as the eyes in the cockpit and the GS antenna would be more vertically-spaced than for a smaller aircraft.
We brief what we'll see on each approach ie a flyup indication on the PAPI down low (we are required to follow the GS to touchdown if it is available: also stops FOQA events).
We brief what we'll see on each approach ie a flyup indication on the PAPI down low (we are required to follow the GS to touchdown if it is available: also stops FOQA events).
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GS aerial verses MEHT.
At YPPH RW03 the MEHT (pilots eye height) over the threshold is 71ft,the TCH (G/S height) is 50ft.
If the difference between the eyeheight and the G/S aerial on your particular aircraft is 21ft,and assuming a precise coupled approach is flown,both the PAPI and GS indicator will indicate on slope.
I would be interested in seeing the MEHT/GS difference for several Cat C & D aircraft.
If the difference between the eyeheight and the G/S aerial on your particular aircraft is 21ft,and assuming a precise coupled approach is flown,both the PAPI and GS indicator will indicate on slope.
I would be interested in seeing the MEHT/GS difference for several Cat C & D aircraft.
Nice in south of France is a good example, the Jeppesen plates state the papi is for a cat d aircraft.
Its about time that airlines taught visual aiming point as the important criteria below 200 ft as 3 whites/ 1/2 dot high at 200 ft is a small error at this point. I have seen guys completely destabilising approaches at this point for no good reason.