AF 447 Thread No. 6
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Originally Posted by DozyWannabe
Because the red trace is masked it's hard to tell, but it could equally be the lumps and bumps you'd associate with turbulence.
The regular periodicity and constant amplitude of the 'zipper' trace shows it is not a real world effect. Some sort of quantisation effect surely. Although the graph shows segmented vertical traces that may be limitations of the printer producing the graph. Is it every other recorded/printed sample ? Notice that in CONF iture's post the red trace in the bottom graph sows three similar similar blip and again it happens to align upwards/downwards to one of the major y axis grid lines. Suspect the plotting software myself.
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If procedures had been followed, the F/Ds should have been switched off until the problem was solved.
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It is a strong guess that they never switched of Flight Directors, otherwise you would hear a remark of the two operating pilots on the tape.
Le pilote de gauche : «Remonte ..remonte…. remonte…. Remonte !!!».
Le pilote de droite : «Mais je suis à fond à cabrer depuis tout à l'heure».
Le commandant de bord : «Non non… non… ne remonte pas.. non.. non..».
Le pilote de droite : «Alors descends».
Le pilote de gauche : «Putain… on va taper. C'est pas vrai !»
Le pilote de droite : «Mais qu'est-ce qui se passe ?
Le pilote de droite : «Mais je suis à fond à cabrer depuis tout à l'heure».
Le commandant de bord : «Non non… non… ne remonte pas.. non.. non..».
Le pilote de droite : «Alors descends».
Le pilote de gauche : «Putain… on va taper. C'est pas vrai !»
Le pilote de droite : «Mais qu'est-ce qui se passe ?
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AlphaZuluRomeo
I'm not sure the BEA is right on this one
Or you release all or you release nothing
Releasing fragments is bad than better ( the evidence is here before our eyes .. with all imaginable scenarios and speculations that the few lines of the CVR have induced in the endless posts) .. if transparency and credibility is the BEA (new?) politic
The families of passengers need also respect and have right to know even if this will hurt the crew families (when their relatives have failed on duty)
Releasing fragments of information is a lack of respect for the victims families
Victims families need the same respect as the families of the pilots
Release of entire CVR is not only when heroes are in the pointing end (Sully and al) .. it's also for those who fail ....
Life is not a bed of roses
The truth is sometimes hard to hear
Note that the BEA is right when it wrote:
"This transcription mentions personal conversations between the crew members that have no bearing on the event, which shows a lack of respect for the memory of the late crew members."
"This transcription mentions personal conversations between the crew members that have no bearing on the event, which shows a lack of respect for the memory of the late crew members."
Or you release all or you release nothing
Releasing fragments is bad than better ( the evidence is here before our eyes .. with all imaginable scenarios and speculations that the few lines of the CVR have induced in the endless posts) .. if transparency and credibility is the BEA (new?) politic
The families of passengers need also respect and have right to know even if this will hurt the crew families (when their relatives have failed on duty)
Releasing fragments of information is a lack of respect for the victims families
Victims families need the same respect as the families of the pilots
Release of entire CVR is not only when heroes are in the pointing end (Sully and al) .. it's also for those who fail ....
Life is not a bed of roses
The truth is sometimes hard to hear
Last edited by jcjeant; 14th Oct 2011 at 04:19.
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Hi Dani,
It's more than a strong guess - it's reported on page 74:
"The Flight Directors were not disengaged by the crew, but the crossbars disappeared."
If I was flying at 02:00 and with all the other noises and attention getters going off whilst keeping the wings level in ALT Law, I also may have forgotten to ask for the FDs to be turned off - simply because they had already disappeared from view.
They seem to have simply remembered their previous training (further down on P74)
"The two copilots had only been trained for the emergency manoeuvre at lower levels, in the course of which the pitch attitude to adopt is 10° or 15°."
It is a strong guess that they never switched of Flight Directors, otherwise you would hear a remark of the two operating pilots on the tape.
"The Flight Directors were not disengaged by the crew, but the crossbars disappeared."
If I was flying at 02:00 and with all the other noises and attention getters going off whilst keeping the wings level in ALT Law, I also may have forgotten to ask for the FDs to be turned off - simply because they had already disappeared from view.
They seem to have simply remembered their previous training (further down on P74)
"The two copilots had only been trained for the emergency manoeuvre at lower levels, in the course of which the pitch attitude to adopt is 10° or 15°."
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jcjeant,
I disagree. I'm OK with the BEA policy, here.
If a full transcription was officially released, the "doubters" would then ask for the audio. If the audio was released, the "serious doubters" would then ask if the audio hasn't been modified...
That's a confidence issue. If you don't trust the BEA (or the NTSB, which does just the same (*)), then you won't thrust anything it releases...
(*) expect UA93, but that's another story, with FBI implicated
"The families of passengers need also respect and have right to know" => I agree with that.
"Releasing fragments of information is a lack of respect for the victims families" => define "fragments of information", please.
To my eyes, informations which explain the accident is enough (and whole, once the final report is done). And it's not fragmental, regarding the inquiry/accident. Calling it so is not really "fair"...
I disagree. I'm OK with the BEA policy, here.
If a full transcription was officially released, the "doubters" would then ask for the audio. If the audio was released, the "serious doubters" would then ask if the audio hasn't been modified...
That's a confidence issue. If you don't trust the BEA (or the NTSB, which does just the same (*)), then you won't thrust anything it releases...
(*) expect UA93, but that's another story, with FBI implicated
"The families of passengers need also respect and have right to know" => I agree with that.
"Releasing fragments of information is a lack of respect for the victims families" => define "fragments of information", please.
To my eyes, informations which explain the accident is enough (and whole, once the final report is done). And it's not fragmental, regarding the inquiry/accident. Calling it so is not really "fair"...
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- not clear call of the procedure
- the said procedure asks for pitch 10/15° and power TOGA when low level, the crew initially just adapted pitch (and thrust to CLB)
I've read another hypothesis about "why did they pull". Don't have it saved here (@ work), will post it later (from home) but basically the hypothesis was they did try and follow the bird, which was erroneous due to UAS.
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How could they have "followed the bird" from the start ?
BEA page 75 :
FWIS, there was no attempt to use the bird before captain's suggestion :
BEA page 76
.
Hence the messages :
BEA page 75 :
At 2 h 10 min 47...... The Flight Directors not having been disengaged, the cross bars disappeared and reappeared several times without it being possible, at this stageof the investigation, to know what orders they may have indicated nor to establish if these orders influenced the actions of the PF.
BEA page 76
around 2 h 11 min 42.....the Captain said several times “take that”, doubtless speaking of the FPV
Hence the messages :
02:11:00 - .1/WRN/WN0906010210 228300106FLAG ON CAPT PFD FD
02:11:15 - .1/WRN/WN0906010210 228301106FLAG ON F/O PFD FD
02:12:10 - .1/WRN/WN0906010211 341200106FLAG ON CAPT PFD FPV
02:12:16 - .1/WRN/WN0906010211 341201106FLAG ON F/O PFD FPV
02:11:15 - .1/WRN/WN0906010210 228301106FLAG ON F/O PFD FD
02:12:10 - .1/WRN/WN0906010211 341200106FLAG ON CAPT PFD FPV
02:12:16 - .1/WRN/WN0906010211 341201106FLAG ON F/O PFD FPV
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GerardC,
The thing is, the hypothesis was the first I read & think "hey, I see the logic".
I didn't had time to check all that (besides not being knowledgeable enough to have all answers), and remember having been confused when checking the BEA text (your quote & other §) vs the FDR traces... Will check what I can & post later.
The thing is, the hypothesis was the first I read & think "hey, I see the logic".
I didn't had time to check all that (besides not being knowledgeable enough to have all answers), and remember having been confused when checking the BEA text (your quote & other §) vs the FDR traces... Will check what I can & post later.
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Originally Posted by AZR
... the hypothesis was they did try and follow the bird, which was erroneous due to UAS.
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I don't think it was "erroneous", so much as the FPA "bird" appears and disappears with the F/D, which itself is supposed to be disabled in the case of UAS. Possibly something Airbus could look into changing.
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It is strongly recommended that you never use the bird in case of unreliable instruments. You don't know which part of the instruments, ADR, IRS is not working. FPV is generated in the IR part of the ADIRS (the combined computers, 3 on board). Only by positively identifying a working ADIRS, you could use it. But the AF447 crew never got out of state of confusion, they never started real trouble shooting.
QRH 34.07A:
QRH 34.07A:
- If remaining altitude indication is unreliable:
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OK, digged out a bit, here is the hypothesis (in french) the source being a comment on HMC's blog.
Rough translation
I haven't had time to cross-check with the report if such a scenario is possible, given the known facts (but I got doubts following CONF iture's last post).
If someone want to cross check and/or react to this hypothesis, feel free.
I thought it was interesting in that if could explain the initial pitch up reaction better than with saying the pilot followed (but only partially) the UAS procedure (memory items) for low level flights.
Durant le givrage des sondes pitot les vitesses dégringolent et l'altimètre perd 400' ( mais c'est une fausse indication ) On est donc dans le cas ou le bird, le vecteur vitesse, le FPV n'est pas valide comme indiqué partout dans la doc et tout particulièrement celle d'Air France et même son beau FCTM Airbus customizé AF......
Bref le PF voit le bird tout en bas de l'horizon, il cabre pour tenter de le remonter, perdant complètement de vue l'instrument de pilotage normal qu'est l'assiette. Il est obsédé par le bird qui ne veut pas venir vers le haut, et donc il tire il tire il tire......
Au bout de cinquante secondes, l'avion atteint les 37 500' et son énergie potentielle en a pris un sacré coup, mais les vitesses redeviennent normales et le bird est alors sur l'horizon . Fantastique ! les PNT de l'AF 447 ont donc mis l'avion en palier avec le bird sur l'horizon, mais avec une assiette = incidence = 16° situation qui ne peut perdurer mais qui explique l'action continue à cabrer, car le bird s'effondre, la pente passe harmonieusement de zéro à -25 . L'alarme STALL hurle toujours dans le cockpit et la vitesse passe alors sous soixante kts. L'alarme Stall s'arrête alors, car l'incidence n'est plus considérée comme valide, et le bird disparaît car plus valide non plus. C'est le moment ou le message FPV est envoyé par l'ACARS.
Ensuite plus de bird, et une bande rouge noir et blanc ( black and red Barber Pole ) est visible sur toute l'échelle des vitesse.
Mais ce n'est pas la black and red barber pole de VMO /MMO, c'est la bande basse vitesse c'est à dire la black and amber barber pole de la Loi Normale, qui est remplacée par une black and red barber pole de l'alternate law...
Alors évidemment le PF se croit en survitesse .... , car tout est rouge et noir.......
Bref le PF voit le bird tout en bas de l'horizon, il cabre pour tenter de le remonter, perdant complètement de vue l'instrument de pilotage normal qu'est l'assiette. Il est obsédé par le bird qui ne veut pas venir vers le haut, et donc il tire il tire il tire......
Au bout de cinquante secondes, l'avion atteint les 37 500' et son énergie potentielle en a pris un sacré coup, mais les vitesses redeviennent normales et le bird est alors sur l'horizon . Fantastique ! les PNT de l'AF 447 ont donc mis l'avion en palier avec le bird sur l'horizon, mais avec une assiette = incidence = 16° situation qui ne peut perdurer mais qui explique l'action continue à cabrer, car le bird s'effondre, la pente passe harmonieusement de zéro à -25 . L'alarme STALL hurle toujours dans le cockpit et la vitesse passe alors sous soixante kts. L'alarme Stall s'arrête alors, car l'incidence n'est plus considérée comme valide, et le bird disparaît car plus valide non plus. C'est le moment ou le message FPV est envoyé par l'ACARS.
Ensuite plus de bird, et une bande rouge noir et blanc ( black and red Barber Pole ) est visible sur toute l'échelle des vitesse.
Mais ce n'est pas la black and red barber pole de VMO /MMO, c'est la bande basse vitesse c'est à dire la black and amber barber pole de la Loi Normale, qui est remplacée par une black and red barber pole de l'alternate law...
Alors évidemment le PF se croit en survitesse .... , car tout est rouge et noir.......
During the probe pitot icing, speeds decay and the altimeter loses 400ft (but it is a false indication). Therefore the bird (velocity vector / FPV) is not valid as shown throughout the doc and especially that of Air France - even AF's customized FCTM......
In short, the PF sees the bird at the bottom of the ADI, he pitched up in an attempt to "raise" the bird, completely forgetting the pitch angle which is the basic indication. He is obsessed with the bird that won't come up, so he pulls, pulls, pulls on his stick.....
After fifty seconds, the aircraft reaches 37,500ft and its potential energy has taken a big hit, but the speeds are back to normal and the bird is then on the horizon. Fantastic! AF 447 crews have therefore the aircraft level with the bird on the horizon, but with a pitch = incidence = 16°.
This situation cannot be maintained but explains the pull-up action.
Then the bird collapses, the slope goes smoothly from zero to -25. The alarm still screams 'STALL' in the cockpit and then the speed passes under sixty knots. Stall alarm then stops, because the incidence is no longer considered valid, and the bird disappears as no longer valid either. This is the time the "FPV" related messages are sent by ACARS.
After that, no more bird available, but a red black and white ("black and red Barber Pole") is visible over the entire speed scale.
But this is not the black and red barber pole VMO / MMO, it is the low speed band that is the black and amber barber pole when in Normal Law, which is replaced by a black and red barber pole in Alternate Law ...
So obviously the PF believes he's overspeeding .... Because everything is red and black .......
In short, the PF sees the bird at the bottom of the ADI, he pitched up in an attempt to "raise" the bird, completely forgetting the pitch angle which is the basic indication. He is obsessed with the bird that won't come up, so he pulls, pulls, pulls on his stick.....
After fifty seconds, the aircraft reaches 37,500ft and its potential energy has taken a big hit, but the speeds are back to normal and the bird is then on the horizon. Fantastic! AF 447 crews have therefore the aircraft level with the bird on the horizon, but with a pitch = incidence = 16°.
This situation cannot be maintained but explains the pull-up action.
Then the bird collapses, the slope goes smoothly from zero to -25. The alarm still screams 'STALL' in the cockpit and then the speed passes under sixty knots. Stall alarm then stops, because the incidence is no longer considered valid, and the bird disappears as no longer valid either. This is the time the "FPV" related messages are sent by ACARS.
After that, no more bird available, but a red black and white ("black and red Barber Pole") is visible over the entire speed scale.
But this is not the black and red barber pole VMO / MMO, it is the low speed band that is the black and amber barber pole when in Normal Law, which is replaced by a black and red barber pole in Alternate Law ...
So obviously the PF believes he's overspeeding .... Because everything is red and black .......
If someone want to cross check and/or react to this hypothesis, feel free.
I thought it was interesting in that if could explain the initial pitch up reaction better than with saying the pilot followed (but only partially) the UAS procedure (memory items) for low level flights.
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What is it that convinces people that the PF sussed UAS when the a/p quit? Why is he expected, here, to instantly apply procedures to a mode that is not known? He has been in turbulence, experienced variations (if ONLY VS), that may have him thinking: A/P LIMIT.
In which case: NORMAL LAW retains. He is also committed to control the aircraft, how is he to know there is A/L in his near future?
In the BEA there is PNF mention of the loss of speeds, and reversion of LAW, but ELEVEN seconds LATER.
So prove, regardless of bias, that the PF was not flying NORMAL LAW up to eleven seconds post a/p drop?
Besides, in A/L, he has PITCH protection, so his focus even after he sussed A/L would quite naturally be on ROLL, perhaps at the expense of PITCH.
Not what he "SHOULD" have been flying, but what was possible.
Throughout, and including the prior 32 episodes, where is the instantaneous recognition of UAS by the PF? Yet "Do Nothing", "Wait", are the demands of the ex post brigade here, who would have immediately sussed UAS and been the hero.
cart/horse
In which case: NORMAL LAW retains. He is also committed to control the aircraft, how is he to know there is A/L in his near future?
In the BEA there is PNF mention of the loss of speeds, and reversion of LAW, but ELEVEN seconds LATER.
So prove, regardless of bias, that the PF was not flying NORMAL LAW up to eleven seconds post a/p drop?
Besides, in A/L, he has PITCH protection, so his focus even after he sussed A/L would quite naturally be on ROLL, perhaps at the expense of PITCH.
Not what he "SHOULD" have been flying, but what was possible.
Throughout, and including the prior 32 episodes, where is the instantaneous recognition of UAS by the PF? Yet "Do Nothing", "Wait", are the demands of the ex post brigade here, who would have immediately sussed UAS and been the hero.
cart/horse
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The "Initial PITCH UP reaction" was a response to nose low. That tells us the PF was manually controlling the a/c.
Yet, HERE, it is known 'instantly' that UAS is the PROBLEM. I say, Why? Who among the 32 crews and the myriad sim brigade post UAS/447 debrief acted according to the existing briefing of the pilots of 447?
UAS at the time was criminally unaddressed, as was the re-select of a/p if it obtained, "The A/C may PITCH UP". STALL? Might be Bogus, OR NOT...
Yet here, after two years on, we know UAS was immediately the problem, and the pilot PITCHED UP into STALL that was annunciated once, as bogus, and a second time, as legit?
I am not singling anyone out. I merely note the certitude around a situation about which the manufacturer was blissfully unaware, yet pilots here know precisely what to do. Of course, but a bit late, No?
The a/c, prior to loss of a/p a/t, experienced some vertical turbulence. Was it in excess of the a/p limit to control? By rate or attitude? Is the zipper an attempt to control the a/c in the last seconds of autopilot, and the drop out was an innocent loss of autoflight due MET? UAS followed,
as the a/c reacted to turbulence?
Where is the useful CVR data between a/p drop and STALL? Why is it the dramatic and sad exchanges are included, but evidence of handling attitude and cueing are not?
Yet, HERE, it is known 'instantly' that UAS is the PROBLEM. I say, Why? Who among the 32 crews and the myriad sim brigade post UAS/447 debrief acted according to the existing briefing of the pilots of 447?
UAS at the time was criminally unaddressed, as was the re-select of a/p if it obtained, "The A/C may PITCH UP". STALL? Might be Bogus, OR NOT...
Yet here, after two years on, we know UAS was immediately the problem, and the pilot PITCHED UP into STALL that was annunciated once, as bogus, and a second time, as legit?
I am not singling anyone out. I merely note the certitude around a situation about which the manufacturer was blissfully unaware, yet pilots here know precisely what to do. Of course, but a bit late, No?
The a/c, prior to loss of a/p a/t, experienced some vertical turbulence. Was it in excess of the a/p limit to control? By rate or attitude? Is the zipper an attempt to control the a/c in the last seconds of autopilot, and the drop out was an innocent loss of autoflight due MET? UAS followed,
as the a/c reacted to turbulence?
Where is the useful CVR data between a/p drop and STALL? Why is it the dramatic and sad exchanges are included, but evidence of handling attitude and cueing are not?
Last edited by Lyman; 14th Oct 2011 at 16:05.
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What part of the graph above (FPV off) do you not understand? I don't see why everyone is focussing on the bird now (also in the other thread). This way of discussion leads nowhere. The bird was not on, the FPV not and the FPD not.
If they would have selected something on the FD, you would hear it on the CVR. He would say "let's switch off the FD" or PNF says "switch off the FD". If you don't have any of the two, only one person would have switched it off. They were not able to simultanously coordinate a switching in both seats without telling each other.
If they would have selected something on the FD, you would hear it on the CVR. He would say "let's switch off the FD" or PNF says "switch off the FD". If you don't have any of the two, only one person would have switched it off. They were not able to simultanously coordinate a switching in both seats without telling each other.
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Dani. A very strong point to be made. Why are we missing the Pilots' side of things? The a/c is shown, yet the Pilot data is not.
Much of "UAS Procedure" (such as it was at the time), is missing, so observed and oriented or no, the pilot's did not act on UAS, seemingly. What was it they thought was going on?
In the absence of the record, to accuse them is illogical.
Much of "UAS Procedure" (such as it was at the time), is missing, so observed and oriented or no, the pilot's did not act on UAS, seemingly. What was it they thought was going on?
In the absence of the record, to accuse them is illogical.