4 red but on glide slope
Thread Starter
Join Date: Jan 2018
Location: London
Posts: 85
Likes: 0
Received 0 Likes
on
0 Posts
PelicanSquawk , IMO you have been unjustly criticised. We need some more info though.
- You say "the chart says MEHt 738 61ft". What chart was this? If it is an official, state chart, I'm surprised it says 738. MEHT for a PAPI/VASI is not contingent on an aircraft type. The PAPI will merely place the eyeballs of who is looking at it at 61ft over the threshold, nothing more. It doesn't matter if it is a Concorde or a Cessna 172.
- What does your ops manual say about transferring to the Visual Aim Point off an ILS? Any mention of transitioning to the PAPI? Mind you, such a thing is, IMO, a stupid idea because it would severely destabilise your approach below the ILS DA. Can your instructor imagine you hauling back on the stick at 200ft AGL to correct the 4 reds you saw?
- What's your stabilised approach criteria? Does it mention that the PAPI overrides the ILS GS?
- What airport was this at? Perhaps the "61ft" is incorrect. It is quite easy to use Google Earth to verify the MEHt if the PAPI can be seen.
- In any case, if the FDAP shows you were on the GS the whole way down, anybody who criticises you or worse, marks you down, is on shaky ground, in my view.
Flight Detent , I don't expect the Yanks to have ICAO markings but the runway above, 05L, has got incorrect markings as well. There should be markings at 150m, 300m then the aiming point markings at 400m. Where is that airport?
- You say "the chart says MEHt 738 61ft". What chart was this? If it is an official, state chart, I'm surprised it says 738. MEHT for a PAPI/VASI is not contingent on an aircraft type. The PAPI will merely place the eyeballs of who is looking at it at 61ft over the threshold, nothing more. It doesn't matter if it is a Concorde or a Cessna 172.
- What does your ops manual say about transferring to the Visual Aim Point off an ILS? Any mention of transitioning to the PAPI? Mind you, such a thing is, IMO, a stupid idea because it would severely destabilise your approach below the ILS DA. Can your instructor imagine you hauling back on the stick at 200ft AGL to correct the 4 reds you saw?
- What's your stabilised approach criteria? Does it mention that the PAPI overrides the ILS GS?
- What airport was this at? Perhaps the "61ft" is incorrect. It is quite easy to use Google Earth to verify the MEHt if the PAPI can be seen.
- In any case, if the FDAP shows you were on the GS the whole way down, anybody who criticises you or worse, marks you down, is on shaky ground, in my view.
Flight Detent , I don't expect the Yanks to have ICAO markings but the runway above, 05L, has got incorrect markings as well. There should be markings at 150m, 300m then the aiming point markings at 400m. Where is that airport?
tbh it was a case of me really focussing on nailing the GS because I was getting a bit of criticism before for not maintaining in the last 300ft or so the glide path…but in this case it resulted in 4 reds…I must admit I was much more focused inside and not enough outside…but I feel at a bit of a loss because all the data suggests I couldn’t have maintained the path better, but I’ve been written up as getting low on 4 reds. I really don’t want to have this situation again…and I don’t want to make a big deal of one approach with my instructor because I should just move on.
The chart is navtech and it definitely says 61ft and then a note saying that it’s the MEHT for B738.
Without wishing to plough through all of the very learned data on this thread, PAPIs are only as good as their last flight check, and that is a very variable standard! As pointed out previously, they are unreliable, at best, below CAT 1 minima, and also depend upon which Aircraft Cat they are calibrated. For instance, NCE 04L is set for Cat D, presumably to prevent them digging their tail into the Med. On my Cat C aircraft, the GS equates to 3 red/1 white.
Originally Posted by PelicanSquawk
but I feel at a bit of a loss because all the data suggests I couldn’t have maintained the path better, but I’ve been written up as getting low on 4 reds. I really don’t want to have this situation again…and I don’t want to make a big deal of one approach with my instructor because I should just move on.
Thread Starter
Join Date: Jan 2018
Location: London
Posts: 85
Likes: 0
Received 0 Likes
on
0 Posts
any way thanks all for your input and thoughts…I guess I just need to scan better outside if that’s available.
This is a bit of a bęte noir of mine.
My company was training newbies to fly PAPIs to touchdown-and then wondering why we had so many long landings! Hardly surprising when so much of the TDZ was being wasted.
As mentioned, screen height at the beginning of the TDZ is 50 feet AGL, which in my cat C aircraft pretty much means that when the white line passes directly beneath my gonads (other genital organs are available), the RadAlt should be saying ‘50….’. Usually, at this point the PAPIs show three reds if set to 3 degrees.
So, as Capt Bloggs says, your trainer is erroneous in his assessment if you were in the correct position. I would clarify prior to your next training flight precisely how the trainer expects you to approach this.
My company was training newbies to fly PAPIs to touchdown-and then wondering why we had so many long landings! Hardly surprising when so much of the TDZ was being wasted.
As mentioned, screen height at the beginning of the TDZ is 50 feet AGL, which in my cat C aircraft pretty much means that when the white line passes directly beneath my gonads (other genital organs are available), the RadAlt should be saying ‘50….’. Usually, at this point the PAPIs show three reds if set to 3 degrees.
So, as Capt Bloggs says, your trainer is erroneous in his assessment if you were in the correct position. I would clarify prior to your next training flight precisely how the trainer expects you to approach this.
Policy at every airline I have been at is to transition to visual aids when visual. No one needs to be looking in the cockpit at 61 feet or 5 seconds to touchdown other than a peak at airspeed entering the flare.
Only half a speed-brake
#21 shows it's been recently re-painted - wait for it - from the FAA to the ICAO standard? Hahaha. Just look at the picture. PAPI at 400 m and GS antenna at 330.
With 4 reds, the OP was below glide. That is not a good thing and was called properly, only using the wrong scale.
Being correct and 4 reds happens only on PAPI <> GP 150 m difference (had it on my last flight which we discussed, hence the keen interest today) and this was only 70 m.
Here:
(time stamp 2:50)
With 4 reds, the OP was below glide. That is not a good thing and was called properly, only using the wrong scale.
Being correct and 4 reds happens only on PAPI <> GP 150 m difference (had it on my last flight which we discussed, hence the keen interest today) and this was only 70 m.
Here:
Last edited by FlightDetent; 26th Jul 2022 at 17:48.
Only half a speed-brake
Comes from a country which learned their aviation from the nice coherent FAA regulatory set but then recent years saw a drive of super-aligning with ICAO. Consequently, some runways (all 3000+) are marked with APMs at 300 mtrs, some at 400 mtrs and some even at 450 mtrs. Kid you not, during today's reading I found an airport that has all three choices and the last remaining runway's threshold is yet different as it is displaced by 600 m
.They do keep the PAPI aligned with the markers though. The duality of these being either 300 or 400/450 is nothing new for an 'ICAO' pilot who faces the same two options depending on runway length (2400+ / <
.)When I looked at LAX to see an 'FAA runway' in actual FAA land, markings were as expected. The heart-break moment was seeing the PAPI not aligned with the 305 m/ 1000 ft APM but rather way beyond at 440.
The explanation for this is a) the FAA never said they need to align b) it is provided for large airplanes. I still understand the big jets of Airbus are uniqe to have the GP antenna at cockpit station. Hence my comment the A380 looks specifically designed to exactly match the standard PAPI<>GP offset (as per your drawing).
Not just the big airbus jets, FD-the 320 has a 6 foot displacement between pilot and antenna…
Thread Starter
Join Date: Jan 2018
Location: London
Posts: 85
Likes: 0
Received 0 Likes
on
0 Posts
There is a strong correlation of posts saying the instructor has a wrong idea what needs to be done.
Need the location for AIP charts to prove it.
Yes, the GP can be off. 94% chance this is a case of normal GP and short aim, resulting at 4 reds where 3 reds were geometrically correct. 2W2R for flare would also wrong.
Need the location for AIP charts to prove it.
Yes, the GP can be off. 94% chance this is a case of normal GP and short aim, resulting at 4 reds where 3 reds were geometrically correct. 2W2R for flare would also wrong.
I am a much simpler man than some of the evidently big brains who have posted already so despite my experience and age I've found this thread educational but in a way a little inconclusive.
I have been often baffled by the desire of other pilots (usually with little experience on type) to try and hand fly the jet on the glideslope when visual sometimes below minima. Surely it is easier to look out? I note from other posts that the PAPIs aren't terribly accurate and will likely be set to result in touchdown further down the runway than the G/S but I would advocate having an aiming point on the runway which should not move up or down the windshield, isn't that one purpose of the runway markings also discussed above?
In sympathy with the OP's Trainer, maybe (s)he was concerned that once you get to 4 reds and maybe aren't looking at the G/S anymore, then how do you know how much below the 3deg slope you are? I'd be doubtful too about the accuracy of data monitoring information the OP has referred to. What is the sample rate apart from anything else? The trainer has at least succeeded in getting you to think about your technique.
Standing by to be torn apart.
I have been often baffled by the desire of other pilots (usually with little experience on type) to try and hand fly the jet on the glideslope when visual sometimes below minima. Surely it is easier to look out? I note from other posts that the PAPIs aren't terribly accurate and will likely be set to result in touchdown further down the runway than the G/S but I would advocate having an aiming point on the runway which should not move up or down the windshield, isn't that one purpose of the runway markings also discussed above?
In sympathy with the OP's Trainer, maybe (s)he was concerned that once you get to 4 reds and maybe aren't looking at the G/S anymore, then how do you know how much below the 3deg slope you are? I'd be doubtful too about the accuracy of data monitoring information the OP has referred to. What is the sample rate apart from anything else? The trainer has at least succeeded in getting you to think about your technique.
Standing by to be torn apart.
Have to agree with Alfaalfa.
It was depressing to watch newbies ruin a perfectly good approach below 200ft by looking out of the window and flying the aircraft to what would have been a good landing until they glanced at the needles then either, mainly dived, or climbed to regain the ILS.
When asked why they said it was how they were trained!
It was depressing to watch newbies ruin a perfectly good approach below 200ft by looking out of the window and flying the aircraft to what would have been a good landing until they glanced at the needles then either, mainly dived, or climbed to regain the ILS.
When asked why they said it was how they were trained!
Only half a speed-brake
The conclusive and geometrically correct way out of this is
a) figure out the distance of a 3 deg aiming point (300 m or my type)
b) learn to read the different markers and standards to identify the physical location
===== the result just cannot get any easier =====
Field guide A320:
Fly the plane at the front edge of the 2nd marker.
Field guide A330/340
Fly the plane at the far edge of the 2nd marker.
===== if your antenna is within 3 m from pilot eye, use the same ======
(note the absence of any reference to PAPI or GS, FAA or ICAO or other's regulatory reference and runway length considerations).
a) figure out the distance of a 3 deg aiming point (300 m or my type)
b) learn to read the different markers and standards to identify the physical location
===== the result just cannot get any easier =====
Field guide A320:
Fly the plane at the front edge of the 2nd marker.
Field guide A330/340
Fly the plane at the far edge of the 2nd marker.
===== if your antenna is within 3 m from pilot eye, use the same ======
(note the absence of any reference to PAPI or GS, FAA or ICAO or other's regulatory reference and runway length considerations).
Last edited by FlightDetent; 26th Jul 2022 at 19:48.
Thread Starter
Join Date: Jan 2018
Location: London
Posts: 85
Likes: 0
Received 0 Likes
on
0 Posts
I am a much simpler man than some of the evidently big brains who have posted already so despite my experience and age I've found this thread educational but in a way a little inconclusive.
I have been often baffled by the desire of other pilots (usually with little experience on type) to try and hand fly the jet on the glideslope when visual sometimes below minima. Surely it is easier to look out? I note from other posts that the PAPIs aren't terribly accurate and will likely be set to result in touchdown further down the runway than the G/S but I would advocate having an aiming point on the runway which should not move up or down the windshield, isn't that one purpose of the runway markings also discussed above?
In sympathy with the OP's Trainer, maybe (s)he was concerned that once you get to 4 reds and maybe aren't looking at the G/S anymore, then how do you know how much below the 3deg slope you are? I'd be doubtful too about the accuracy of data monitoring information the OP has referred to. What is the sample rate apart from anything else? The trainer has at least succeeded in getting you to think about your technique.
Standing by to be torn apart.
I have been often baffled by the desire of other pilots (usually with little experience on type) to try and hand fly the jet on the glideslope when visual sometimes below minima. Surely it is easier to look out? I note from other posts that the PAPIs aren't terribly accurate and will likely be set to result in touchdown further down the runway than the G/S but I would advocate having an aiming point on the runway which should not move up or down the windshield, isn't that one purpose of the runway markings also discussed above?
In sympathy with the OP's Trainer, maybe (s)he was concerned that once you get to 4 reds and maybe aren't looking at the G/S anymore, then how do you know how much below the 3deg slope you are? I'd be doubtful too about the accuracy of data monitoring information the OP has referred to. What is the sample rate apart from anything else? The trainer has at least succeeded in getting you to think about your technique.
Standing by to be torn apart.
I think this was my issue, basically too much inside on the instruments, and then baffled by what was written because I was too busy not looking outside. I suppose whatever I saw on the instruments isn’t that relevant if I was low just by reference to looking outside…my confusion is how both could have been true. At another runway I guess it would have worked out 2w2r but for whatever reason not at this one…
An interesting sim exercise we did a few years ago was to set up a generic runway in CAVOK with all the electronic and visual aids available (ILS, DME, VNAV, PAPI, etc.), then keep repositioning onto short finals, failing them one by one until there was nothing but concrete left. This forced people to use a visual aiming point and to refresh the skills that were required on light aircraft, but had fallen into semi-disuse over thousands of hours of precision approaches into major airports.
The whole point of any approach aids, excepting CAT III NDH, is to get you to a position where you can continue visually using an appropriate reference on the runway itself.
It does make me wonder, in the situation that the OP describes, if the PAPIs had been U/S, would his approach and landing been commented upon adversely?
The whole point of any approach aids, excepting CAT III NDH, is to get you to a position where you can continue visually using an appropriate reference on the runway itself.
It does make me wonder, in the situation that the OP describes, if the PAPIs had been U/S, would his approach and landing been commented upon adversely?
Join Date: Jan 2014
Location: N5109.2W10.5
Posts: 720
Likes: 0
Received 0 Likes
on
0 Posts
Due to different wheel to eye heights on different types, there will always be a mismatch between ILS glide slope indications and VASI indications when very close to the runway - but you should never see 4 reds without comment.
Originally Posted by Fullwings
It does make me wonder, in the situation that the OP describes, if the PAPIs had been U/S, would his approach and landing been commented upon adversely?
Pilots should not be jumping from one reference to the other below 200ft.