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Airbus Within 6ft of the Ground nearly 1 mile Short of Runway

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Airbus Within 6ft of the Ground nearly 1 mile Short of Runway

Old 16th Jul 2022, 14:04
  #141 (permalink)  

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I strongly suspect what was installed at production was only updated to the minimum regulatory standard by the operator.

Our fleet of 36 planes has only 2x T2CAS and 3x T3CAS. The oldest is 9 years junior to the GetJet ship.

​​​​​​BTW: I can only check the charted values against the altimeter: if it was over reading I will be low despite all the best efforts and DME fixes?
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Old 16th Jul 2022, 14:37
  #142 (permalink)  
 
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Originally Posted by alf5071h View Post
The error appears to be incorrect QNH, which results in erroneous indicated altitude - what the pilots see.

An altitude - range table, based on threshold distance, relates the altitude which should be seen at a specific distance, thus a check of the displayed altitude at x nm would identify an indicated value which was below the required chart altitude - below flight path.

The critical points here are (1) having a chart and (2) an appropriate reference position for distance - ideally the threshold. So with an adequate distance reference, the low altitude / below flight path could be identified (but not necessarily the wrong QNH).

I think the point that quite a few people on this thread have been making is that, no, you can’t do a meaningful range/altitude check on a Baro-VNAV approach because it will always appear correct: the navigation computers are following a profile based on altitude, which is determined from static pressure and QNH. Get the QNH wrong and the flightpath will be above/below what it should be but the indications will be right, i.e. if the procedure says 3,000’ at 8DME, that’s what you’ll see, even if you’re actually at 2,500’ or 3,500’ at that point.

The only way to cross-check would be to utilise another, independent source, e.g. RAD ALT or GPS. On the charts I have (Lido) there isn’t really enough information in terms of terrain elevation along the approach track to catch any but the grossest of errors. Hence the need to be vigilant over pressure settings.
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Old 16th Jul 2022, 15:59
  #143 (permalink)  
 
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GPS dist to threshold and a dist / alt from there to reflect where the profile is ?
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Old 16th Jul 2022, 16:17
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Interesting thread, especially being CDG-based and having operated in and out of it 865 times over the past 15 years. Language is a contributing factor here, if only for the ATCO mis-translating "mille un" by "one zero one one". I remember from Human Performance and R/T lessons that mixing up figures including only ones and zeros is fairly common in English (such as FL100 for FL110, which is why we are supposed to say "Flight Level One Hundred" instead of "Flight Level One Zero Zero", for instance).

However, for those who believe that using a single language would mean that everyone is on the same hymn sheet and that as a result no confusion could occur, check out this past accident: https://aviation-safety.net/database...?id=19890219-0 (Sorry, can't find the official report now!)

I cannot comment on technical specifics as I am not A320 type-rated, but as mentioned in previous posts, I cannot figure out why the crew would accept (and read back) a QNH 10Hp higher than the one broadcast on ATIS. Even with rainshowers going through, a 10Hp difference between the time the ATIS was picked up and the approach time is at best improbable in temperate climes such as CDG's. (I sometimes question on frequency a difference of 1-2Hp). Getting the QNH right is simply paramount on 2-D non-precision approaches.

Oh, and btw... whatever happened to going around at MDA (+50 ft) if not visual?

Cheers

Last edited by FougaMagister; 16th Jul 2022 at 16:57.
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Old 16th Jul 2022, 16:52
  #145 (permalink)  
 
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Thanks for the EGPWS info, alf5071h
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Old 16th Jul 2022, 19:41
  #146 (permalink)  
 
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With my previous airline, when ever a GPS approach was carried out, as soon as you approached the FAF equivalent you would report established and ask ATC to confirm the QNH. Anyway, flying into CDG requires all pilots to to exercise threat error management briefing.
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Old 16th Jul 2022, 20:19
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Originally Posted by Youmightsaythat View Post
And as the correct QNH was given in French, and read back in French, two further opportunities for the crew, to pick up on the error. I will remind those who claim two languages are not an issue when the next collision occurs. tick tock tick tock.
I'm more interested in knowing how you propose to overcome this issue. As a linguist, I'm far from convinced that imposing a single language would solve more problems than it might create.
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Old 16th Jul 2022, 21:24
  #148 (permalink)  
 
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Originally Posted by 8314 View Post
Dear fellow pilots!
You have to be vigilant flying in France. They do funny things!
Be safe.
The reason why I never, ever, ever intend to fly in or out of CDG ever again.

The most dangerous airport that I have flown in and out of.

Reading all of this had just reconfirmed that sentiment.
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Old 16th Jul 2022, 21:25
  #149 (permalink)  
 
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FullWings, #142

“… you can’t do a meaningful range/altitude check on a Baro-VNAV approach“.

You are correct.

Some of my previous points were made as a generic guide applying to NPAs without FMS, this does not apply in this specific Baro-VNAV approach.

However, having an appropriately modified EGPWS using geometric altitude could detect an incorrect QNH. Then again, as above, does this aircraft have EGPWS, or some other system, and would that system have alerted the crew; assuming the system was working.

Last edited by alf5071h; 16th Jul 2022 at 21:37.
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Old 16th Jul 2022, 21:37
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Doesn't every A320 pilot set QNH on his altimeter in the cruise when the ATIS is received, before reverting straight back to STD? Then when ATC later tells you to go QNH, the correct value should already be displayed?
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Old 16th Jul 2022, 23:17
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Certainly should do, and this sort of thing should be caught.

See post #5
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Old 17th Jul 2022, 04:55
  #152 (permalink)  
 
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Originally Posted by KAPAC
GPS dist to threshold and a dist / alt from there to reflect where the profile is ?
Already published on the chart, but obviously will be in error if the QNH is set incorrectly.
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Old 17th Jul 2022, 04:58
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Originally Posted by ZeBedie View Post
Doesn't every A320 pilot set QNH on his altimeter in the cruise when the ATIS is received, before reverting straight back to STD? Then when ATC later tells you to go QNH, the correct value should already be displayed?
I always do that exactly to avoid this kind of potential serious incidents..
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Old 17th Jul 2022, 08:13
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Doesn't every A320 pilot set QNH on his altimeter in the cruise when the ATIS is received, before reverting straight back to STD? Then when ATC later tells you to go QNH, the correct value should already be displayed?
I have looked but I can't find the FCOM reference for that procedure.
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Old 17th Jul 2022, 08:18
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Originally Posted by Lookleft View Post
I have looked but I can't find the FCOM reference for that procedure.
Airmanship isnít in the FCOM.
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Old 17th Jul 2022, 08:40
  #156 (permalink)  
 
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Looking back on my own airline career that began mid 1960s Being English, a working knowledge of core aviation French and Portuguese was protective. French perhaps easier for British with closer links to France than Portuguese for operating into Brazil - especially GIG....!
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Old 17th Jul 2022, 09:05
  #157 (permalink)  
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Originally Posted by ZeBedie View Post
Doesn't every A320 pilot set QNH on his altimeter in the cruise when the ATIS is received, before reverting straight back to STD? Then when ATC later tells you to go QNH, the correct value should already be displayed?
Some companies, mine for instance, requires us to set 1013mb before pulling standard passing transition altitude. This is to prevent the wrong level being transmitted to ATC.

We then set QNH when told to descend to an altitude or transition level according to whats been provided by ATC at that time. There is a blunder check where we are supposed to cross check what we've heard with whats on PERF page QNH
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Old 17th Jul 2022, 09:57
  #158 (permalink)  

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Originally Posted by SW1 View Post
set 1013mb before pulling standard passing transition altitude. This is to prevent the wrong level being transmitted to ATC.
Understood, the OIT behind this made it to PPRuNe as well. Do you have any knowledge if the issue actually causes problems in your operating region? Within the range of EU seems it does not, despite some zealot calls we managed to survive without it. As someone said - it's not in the FCOM (OEB) and then fortunately there were no complaints.
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Old 17th Jul 2022, 10:41
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Originally Posted by SW1 View Post
Some companies, mine for instance, requires us to set 1013mb before pulling standard passing transition altitude. This is to prevent the wrong level being transmitted to ATC.
AFAIK, the altitude that ATC see on Mode C/Mode S isn't affected by your altimeter setting - it's always based on a 1013 hPa datum.
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Old 17th Jul 2022, 10:59
  #160 (permalink)  
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Originally Posted by FlightDetent View Post
Understood, the OIT behind this made it to PPRuNe as well. Do you have any knowledge if the issue actually causes problems in your operating region? Within the range of EU seems it does not, despite some zealot calls we managed to survive without it. As someone said - it's not in the FCOM (OEB) and then fortunately there were no complaints.
Ive only been back in Europe less than a year after being in Asia over 9 years so haven't seen if there are any problems if you leave QNH value and just pull standard when passing transition. We never did that in previous companies but at my present European mob flying MSN 2000s its SOP to set 1013 before pulling standard. No info in FCOM either as to why, just in layer 2 of normal procedures,and a mention in a company KORA slide about not transmittjng the wrong level for level bust prevention. My reply was just in response thats its not as simple as just push QNH and hey presto the correct value from ATIS, METAR etc is already there.
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