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Habsheim

Old 27th Feb 2014, 15:24
  #561 (permalink)  
 
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Originally Posted by roulishollandais View Post
Could Asseline refuse to do that scheduled flight, presold to the Newspapper l'Alsace and their readers, without to be fired by Air France ?
Almost certainly. Asseline wasn't the only senior A320 captain at AF, so it would likely have simply passed to someone else on the duty roster.

Let's not beat about the bush here - Most indications (mainly thinking of the apparent confidence on the CVR) prior to the accident convey that Asseline was more than happy to operate the flight. His later (and IMO correct) view that the preparation was poorly handled seems to be a case of 20/20 hindsight.
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Old 27th Feb 2014, 15:55
  #562 (permalink)  
 
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Originally Posted by Owain Glyndwr
It was of course poor judgement on the part of a pilot that produced the problem in the first place.
We all know that for a while, don't we ?
How does it justify to not look one step further ?
If you want to so speculate feel free....
Why speculation should be your exclusivity ?

Originally Posted by Dozy
In the case of Habsheim, the aircraft was low, slow - and with the engines spooled down until far too late it was continuing to decelerate until possibly a second or so prior to impact. These are pretty much the polar opposite of optimum conditions, and in such events the systems will comply as best they can with what they have to work with.
What would be the point to benefit from alpha max only in case of 'optimum conditions' ?
That's when you're in deep problem you want to rely on it and that's how Airbus is selling it.

Originally Posted by roulishollandais
I wonder why Asseline want to fly his Airbus at "alphamax" and uses that word in his briefing?
Asseline writes on Page 29 :
C'est dans cette ambiance particulière, très différente de celle du travail habituel d'un pilote de ligne, que j'ai reçu la mission de présenter cet avion à Habsheim. Il me semblait indispensable de le faire du mieux possible, en démontrant ses extraordinaires qualités de vol, tant vantées par son constructeur. La seule documentation de vol complète dont nous disposions était celle d'Airbus. Il y était écrit en toutes lettres que, si nous voulions utiliser l'avion en volant aux grandes incidences (c'est-à-dire à très faible vitesse), nous pouvions le faire, la seule condition étant de maintenir le manche à fond en arrière, les ordinateurs assurant la totale sécurité de la manœuvre. Les pilotes d'essai d'Airbus usaient et abusaient de cette caractéristique à chaque sortie publique de l'avion. Les pilotes en entraînement en recevaient la démonstration en tour de piste à Toulouse, au-dessus des agglomérations. Seul cet avion pouvait voler dans ces conditions en toute sécurité, les enseignements des pilotes d'essais nous confortaient dans cette idée. Le Titanic ne pouvait pas couler, l'A 320 ne pouvait pas décrocher (tomber par perte de vitesse).
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Old 27th Feb 2014, 19:43
  #563 (permalink)  
 
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Originally Posted by CONF iture View Post
How does it justify to not look one step further ?
Haven't we all been looking at least one "step further" for nearly 30 pages and nearly 600 posts now?

Why speculation should be your exclusivity ?
That makes no sense - OG's specifically inviting you to speculate there.

What would be the point to benefit from alpha max only in case of 'optimum conditions' ?
That's when you're in deep problem you want to rely on it and that's how Airbus is selling it.
"Optimum conditions" in this case meaning only enough airspeed and time for the systems to stabilise at or as near as possible to 17.5deg AoA. Asseline had neither, largely down to his own decision-making. The systems can't defy the laws of physics.

Airbus promoted the systems as being able to help pilots get themselves out of trouble, and in that respect they do. But by disabling A/THR/Alpha Floor or getting the aircraft so low that Alpha Floor is inhibited, a pilot is going outside of Airbus's recommended operation techniques and will therefore be responsible for the consequences.

Asseline writes on Page 29 :
Apologies for rough Google translation:
It is in this particular atmosphere, very different from the usual work of an airline pilot, I have been tasked to present this aircraft [at] Habsheim.
...
The test drivers were using Airbus and abusing [highlighting?] this feature each public release of the aircraft. Pilots received training in the demonstration lap in Toulouse, above cities.
Such equivocation stands in marked contrast to Asseline's confident attitude during the briefing on the CVR:

Bon alors, décollage, virage à droite, on laisse le volet 1, enfin on fait un décollage normal, on rentre le train et avec les volets 1, tranquillement on va chercher notre truc. Dès qu'on l'a formellement identifié, on sort la tôle jusqu'à volets 3 train sorti, on fait un passage à cent pieds, train sorti et là, tu me laisses faire. Je t'amène en alpha max, je débraye l'alpha floor et à ce moment là, si je te dis que c'est dur, tu m'aides et tu tiens les gaz à vario zéro.

where in response to a query from his F/O as to how to increase thrust and escape:

Tu veux t' faire reluire là-hein ?
he says:

Ben, ça. J' l'ai fait vingt fois, c'lui-là.
Which I believe is along the lines of "I've done this twenty times". If he had indeed done it twenty times over Toulouse, I strongly doubt he'd have been doing it at 100ft.

Note also this phrase in the briefing itself :
...je débraye l'alpha floor et à ce moment là...
Which clearly indicates that his intent *was* to disable Alpha Floor, and it seems he missed it in the event.
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Old 28th Feb 2014, 04:52
  #564 (permalink)  
 
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Originally Posted by Dozy
"Optimum conditions" in this case meaning only enough airspeed and time for the systems to stabilise at or as near as possible to 17.5deg AoA. Asseline had neither, largely down to his own decision-making.
To provide performance is to rapidly deliver alpha max whatever the conditions and to do so, a temporary overshoot of alpha max can naturally be part of the process, as demonstrated by the test pilot in the video.
No PERF when the AoA is restricted between 14 and 15 but should target 17.5 deg instead.
Then you'll need to explain what "enough airspeed" has to do as a criteria to properly stabilize at alpha max ... ??

The systems can't defy the laws of physics.
It does not have to defy any laws of physics to stabilize at alpha max ... what a strange concept you have here ...

Airbus promoted the systems as being able to help pilots get themselves out of trouble, and in that respect they do. But by disabling A/THR/Alpha Floor or getting the aircraft so low that Alpha Floor is inhibited, a pilot is going outside of Airbus's recommended operation techniques and will therefore be responsible for the consequences.
We are instructed to use alpha max and to totally rely on the capacity of the system to deliver alpha max when needed. That's how the protected aircraft is able to outperform the non protected one.
That you disable alpha floor has nothing to do with the capacity to deliver alpha max.

Which clearly indicates that his intent *was* to disable Alpha Floor, and it seems he missed it in the event.
Nothing new here ... but he did not miss anything - They just came in too fast, and TOGA was selected before the alpha for an eventual alpha floor activation was reached anyway.

For the rest of your partial translations, sorry, but it is very unclear to me what your points are ... ?
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Old 28th Feb 2014, 09:07
  #565 (permalink)  
 
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Originally Posted by CONF_iture
We are instructed to use alpha max and to totally rely on the capacity of the system to deliver alpha max when needed. That'show the protected aircraft is able to outperform the non protected one. That you disable alpha floor has nothing to do with the capacity to deliver alpha max
Really in 2014! With very limiting gusts values? And are you instructed for deepstall (AF447 style) after alphamax?
Which are your alphaprot,alphafloor,alphamax and steady level speeds and Vs1g at MTOW and MLW?
Thank you CONF_iture . You are from the few Posters here testing with your life these undescribed figures...
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Old 28th Feb 2014, 12:43
  #566 (permalink)  
 
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Better is the enemy of the good.

We see here all the perversion from protecting pilots against themselves.
Magic stall protection pushed these pilots who where able to avoid stall by their traditional learning to put themselves and the SLF in the mouth of the wulf, and replace a nice airshow afternoon in a catastrophic way.
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Old 28th Feb 2014, 17:03
  #567 (permalink)  
 
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Thank you, Rouli. Well stated.

I flew two jets with AoA limiters, and I never failed to notice what was happening, nor did I depend on the limiters to "save" me because I flew into a dire situation.

It's called airmanship, piloting skills, knowing your own limits and that of the jet. The FBW systems can only do so much to protect you from yourself. It is not supposed to be a system to protect you from the results of your poor judgement.

Going back to the peanut gallery, now.
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Old 28th Feb 2014, 21:38
  #568 (permalink)  
 
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It's called airmanship, piloting skills, knowing your own limits and that of the jet. The FBW systems can only do so much to protect you from yourself. It is not supposed to be a system to protect you from the results of your poor judgement.
Gums, amen to that.
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Old 1st Mar 2014, 01:09
  #569 (permalink)  
 
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Originally Posted by roulishollandais
You are from the few Posters here testing with your life these undescribed figures...
To be honest, never had to experience the protection system. Up to now, all I got was one SPEED low energy audio warning for not following the FD under auto thrust - My fault - For me, to go to the limit, has been a simulator experience only.
You're correct to mention how in the every day operation we know nothing about the speeds associated to the different protection alpha values. They are accurately displayed on the PFD, of course as long as the probes work correctly and the system don't silently discard the only reliable data to ultimately lie to the crew ...

Originally Posted by HN39
That seems to me to be a misrepresentation of training objectives. You are instructed, in situations of immediate danger, to rely on the the stall protection to prevent stalling.
No - We're instructed to not think to go and get the maximum performance by applying full back stick.
And that is precisely what the FCS accomplished at Habsheim.
Absolutely not - The FCS had simply no intention to deliver anything more than 15 deg when the max performance had been established at 17.5 which is alpha max for CONF 3 and not alpha stall.
The FCS did not prevent the stall in Habsheim. That is pure Airbus propaganda to not have to detail why the FCS limited directly or indirectly the AoA between 14 and 15 deg.
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Old 1st Mar 2014, 01:15
  #570 (permalink)  
 
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Originally Posted by roulishollandais View Post
Magic stall protection pushed these pilots who where able to avoid stall by their traditional learning to put themselves and the SLF in the mouth of the wulf...
The airmanship stuff is true, and I wholeheartedly agree with that, but the above statement is not.

Asseline's own words indicate that Airbus's test pilots only performed the Alpha Max manoeuvre with *other pilots* on board over the Toulouse region (and probably the French Alps as well), which would have necessitated a much higher altitude than 100ft RA. Thanks to alonso1986's detective work, we've seen a video of their chief test pilot demonstrating the technique, again at a much higher altitude. Some displays were flown by Airbus test pilots at or near 100ft RA (though no lower), but I'd be prepared to wager that none of those flights were carrying pax.

Neither Airbus nor AF mandated that the Habsheim flight demonstrate Alpha Max at 100ft RA, and given his confidence on the CVR prior to the accident I wouldn't be surprised if it was Asseline himself who likely suggested doing so. If this was the case, regardless of where he got that level of confidence from, the responsibility for the decision to perform that manouevre that low and with pax on board must ultimately rest with him. The poor level of preparation can largely be laid at AF's door, however - as we've discussed - Asseline could have used his airmanship and judgement to improve safety margins at several points during the flight, which he did not.

For all his words about prior Airbus FBW demonstrations, as far as I know the fact remains that he was the only pilot who ever attempted that technique at an altitude that low with no prior recce and with pax on board. That he still can't accept that this was shaving the safety margins far too close continues to astonish me.

@CONF iture - We've been over this several times. 17.5deg AoA is the absolute value for Alpha Max. The FCOM not only does not give specific quantitative values on the graph, it states in black and white that with full back stick, Alpha Max "may be achieved". Not "will be", much less "will immediately be" - and we've had input from engineers involved with the programme as well as line pilots who, like Asseline, were A320 "early adopters" giving very useful input as to why that is.

I know you harbour an argument that Asseline could, given direct elevator control, have finessed the aircraft over the trees, but given the slipshod approach to the flypast as a whole I have to argue that this is highly unlikely (particularly with no AoA gauge fitted to the aircraft).

The FCS did prevent stall, *because the aircraft did not stall*.

Last edited by DozyWannabe; 1st Mar 2014 at 01:48.
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Old 1st Mar 2014, 03:31
  #571 (permalink)  
 
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Originally Posted by DozyWannabe
as far as I know the fact remains that he was the only pilot who ever attempted that technique at an altitude that low with no prior recce and with pax on board.
Still happy it was not!! Flying the first A320 delivered to AF certified two days before and n°9 of the manufacturor nobody should have performed such a flight!And after the crash noboddy should have imagined such a flight!
Originally Posted by DozyWannabe
That he still can't accept that this was shaving the safety margins far too close continues to astonish me.
Pedagogy does not worry about words said or written in books , magazines or said during talks , courses, and lectures, but how these words are understood by the learning people. Greatest part of Instructors' work needs to know and preview how a particular person is interpreting instruction words, gestures, process and will reproduce or modify them. Airbus has been master in creating trouble in pilots' mind, sometimes near of schyzophreny. Using such words like "Concierges", "can't stall", "test pilots", "fools", "as designed", etc. or letting think -or worse imagine- AoAs, speeds, algorithms, aerodynamic knowledge, and desorganisation of working experience to create a new paradigm is the worst pedagogy I have ever seen in my whole life.

Last edited by Jetdriver; 1st Mar 2014 at 05:38.
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Old 1st Mar 2014, 04:50
  #572 (permalink)  
 
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@roulish:

It is part of the job of a technically competent operator to differentiate sales and promotional bumpf (and the press interpretation of it) from the reality.

BZ's "concierge" reference was purely a promotional aside and not part of formal training. I'd argue that he might have had a point, as this non-pilot who hadn't been privy to flight controls since he last got out of a Chipmunk in 1993 managed to land an A320 simulator successfully (if not particularly elegantly) on the second attempt.

The FCOMs clearly delineate the limitations of the systems and always have. In this case, no amount of quibbling over systems specifics can alter the fact that the aircraft crashed because it collided with terrain that it should have been clear of if the approach had been handled correctly.
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Old 2nd Mar 2014, 03:38
  #573 (permalink)  
 
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Originally Posted by Dozy
17.5deg AoA is the absolute value for Alpha Max. The FCOM not only does not give specific quantitative values on the graph
But the BEA did ... 17.5 deg for CONF 3
The graph is generic only - values vary with configuration

it states in black and white that with full back stick, Alpha Max "may be achieved".
As you like that much that "may" ... show me that black and white FCOM reference ... ?

The FCS did prevent stall, *because the aircraft did not stall*.
Impressive logic really ...
Actually the FCS made sure the crash was going to happen.
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Old 2nd Mar 2014, 16:32
  #574 (permalink)  
 
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Originally Posted by CONF iture View Post
But the BEA did ... 17.5 deg for CONF 3
The graph is generic only - values vary with configuration
And for other reasons too I expect.


As you like that much that "may" ... show me that black and white FCOM reference ... ?
See post #23 in this thread:
http://www.pprune.org/tech-log/52803...ml#post8200752

Actually the FCS made sure the crash was going to happen.
That's your opinion only, and one that doesn't seem to be widely held.
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Old 2nd Mar 2014, 18:12
  #575 (permalink)  
 
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To Conf #573

I doubt that the "tours de piste" were flown at 50 ft height! Same for the Airbus shows. It is what makes a large difference.
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Old 2nd Mar 2014, 18:41
  #576 (permalink)  
 
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Originally Posted by Dozy
And for other reasons too I expect.
Which are ... ?

See post #23 in this thread:
http://www.pprune.org/8200752-post26.html
The Airline has some latitude to customize the Airbus FCTM - If Cathay wants to word it that way, that is their responsibility.
Still expecting your black and white FCOM reference ...

That's your opinion only, and one that doesn't seem to be widely held.
That an opinion is widely held is not a criteria of veracity - What matter are the facts, and the fact is that the FCS refused to follow the pilot orders despite the possibility for the aircraft to accept an AoA increase of 2.5 additional degrees.

Originally Posted by Bidule
I doubt that the "tours de piste" were flown at 50 ft height! Same for the Airbus shows. It is what makes a large difference.
Strictly speaking about the alpha protection behavior, what is that large difference ?
Are you going to reveal something Airbus did not want to mention ... ?
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Old 2nd Mar 2014, 19:17
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@CONF iture:
Why would Cathay rewrite what is essentially a universal technical fact across the Airbus FBW types?

The EFCS *absolutely* complied with the command, it's just that you have chosen to interpret things such that you believe that full back stick will immediately command and deliver an AoA of 17.5 degrees, which is not supported by any documentation that has come to light.

The point Bidule seems to be making is that Asseline cut safety margins much more significantly than Airbus's own test pilots, which is a fair criticism.

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Old 2nd Mar 2014, 19:35
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As one who formerly earned his living by being able to milk the last bit of performance from swept wing jet aircraft, I would like to offer the following opinion regarding the Habsheim accident.

Other than poor pre-planning, the direct cause of the accident was mismanagement of the aircraft's engines. Asseline needed to have been waking up those engines much earlier to avoid the acceleration lag. One should be gradually walking the throttles forward from idle as the ground gets nearer until arriving at a stabilized power at the desired minimum altitude.

It is quite possible that if given direct control of the elevator, Asseline could have developed sufficient g a bit earlier to clear the trees, but in so doing, the aircraft would likely be entering a stall over the tops of the trees (but with the engines coming fully up to power). If he was good and he was lucky, he might have been able to fly out of that without losing altitude. If he was unlucky or not so good of a stick, then the accident would have been moved a bit further from the airfield. Elevator response is thus a secondary issue to the mismanagement of the engines.

The idea is to avoid having to use your superior airmanship to extricate oneself from the consequences of your inferior planning.
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Old 2nd Mar 2014, 19:43
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Originally Posted by Machinbird View Post
The idea is to avoid having to use your superior airmanship to extricate oneself from the consequences of your inferior planning.
Exactly (agree with the whole post - with the caveat that he'd have had to have been *extremely* lucky).

Last edited by DozyWannabe; 2nd Mar 2014 at 20:07.
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Old 3rd Mar 2014, 02:34
  #580 (permalink)  
 
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Originally Posted by Dozy
Why would Cathay rewrite what is essentially a universal technical fact across the Airbus FBW types?
What wrote Cathay is not in my Airline FCTM and I doubt my Airline would take the liberty to remove such information if it was part of the Airbus FCTM ...

The EFCS *absolutely* complied with the command
No it did not - If it had it would have commanded the elevators to permit some pitch up for an AoA increase.

it's just that you have chosen to interpret things such that you believe that full back stick will immediately command and deliver an AoA of 17.5 degrees, which is not supported by any documentation that has come to light.
Where is the documentation to state that the AoA will be restricted to 15 deg when alpha max is at 17.5 ?
Is it part of the same FCOM you still have to quote ... ?

Originally Posted by Machinbird
Other than poor pre-planning, the direct cause of the accident was mismanagement of the aircraft's engines. Asseline needed to have been waking up those engines much earlier to avoid the acceleration lag. One should be gradually walking the throttles forward from idle as the ground gets nearer until arriving at a stabilized power at the desired minimum altitude.
Asseline has always said that's what he did.
The BEA has not produced the extensive data to prove that he did not.

If he was good and he was lucky, he might have been able to fly out of that without losing altitude. If he was unlucky or not so good of a stick, then the accident would have been moved a bit further from the airfield.
But if the high AoA protection feature had simply worked as advertised, he could have been bad but still lucky.
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