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.

We all know that for a while, don't we ?
How does it justify to not look one step further ?
Why speculation should be your exclusivity ?

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.

Asseline writes on Page 29 :

Haven't we all been looking at least one "step further" for nearly 30 pages and nearly 600 posts now?

That makes no sense - OG's specifically inviting you to speculate there.

"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.

Apologies for rough Google translation:
Such equivocation stands in marked contrast to Asseline's confident attitude during the briefing on the CVR:


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

he says:

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 :
Which clearly indicates that his intent *was* to disable Alpha Floor, and it seems he missed it in the event.

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 ... ??

It does not have to defy any laws of physics to stabilize at alpha max ... what a strange concept you have here ...

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.

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 ... ?

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...:(

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.:ugh:

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.

Gums, amen to that. :D

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 ...

No - We're instructed to not think to go and get the maximum performance by applying full back stick.
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.

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*.

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!:mad:
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.

@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.

But the BEA did ... 17.5 deg for CONF 3
The graph is generic only - values vary with configuration

As you like that much that "may" ... show me that black and white FCOM reference ... ?

Impressive logic really ...
Actually the FCS made sure the crash was going to happen.

And for other reasons too I expect.


See post #23 in this thread:
http://www.pprune.org/tech-log/52803...ml#post8200752

That's your opinion only, and one that doesn't seem to be widely held.

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.

Which are ... ?

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 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.

Strictly speaking about the alpha protection behavior, what is that large difference ?
Are you going to reveal something Airbus did not want to mention ... ?

@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.

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.:}

Exactly (agree with the whole post - with the caveat that he'd have had to have been *extremely* lucky). :ok:

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 ...

No it did not - If it had it would have commanded the elevators to permit some pitch up for an AoA increase.

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 ... ?

Asseline has always said that's what he did.
The BEA has not produced the extensive data to prove that he did not.

But if the high AoA protection feature had simply worked as advertised, he could have been bad but still lucky.

The audio track of the video of the accident shows that he did not get the throttles up until way too late. He should have been sorting out problems with getting the engines accelerated way before he got down in the weeds.

Thank you, 'bird.


Exactly right, Confit. And 'bird. The spool up was very late, regardless of what the pilot intended. It was too damned late. The big fans take lots longer to spool up in the commercial jets than the fans in the newer lites flown by the military. If the motors take 15 seconds to spool up, what then? Maybe someone here flew the T- 33 and remembers how careful you had to be when doing a go-around.


Point two: 'bird has a point about getting a degree or two of alpha to get a few feet of altitude. He is also correct - temporary AoA increase, then increase in drag, then settle into the trees further downrange.

Until the commercial dudes have a checkout that shows the limits of the FBW systyems or even the "conventional" ones, we will likely see another crash like this one.

That's my story, and I am stickin' to it.

Well, the answer is "far too late" to the first, and presumably the same to the second.

Isn't this just back to the heart of the old conspiracy theory that the aircraft failed to respond to the pilots' commands?

The rise in note on the soundtracks is consistent with a ~5s spool up, with the engines roaring as the trees were upon them. I'm sure the video could be analyzed to produce an almost complete reconstruction of the flight path independent of the data recorder, especially given the background clutter from the forest.

The thing that's striking about the video on just watching it again for the first time in ages is the speed of approach. It's not like the displays where an Airbus is held steady at high power, high angle of attack and low speed in a pass, it just comes whizzing in.

So to get that information, the CVR audio (which includes the sound of the thrust levers being set to TOGA) and the audio track from the video recording can be synchronised using audio processing techniques (primarily spectral analysis).

That is in fact precisely what the BEA did, and they then synchronised the result with the engine data from the DFDR. Again, please forgive the poor Google Translate grammar:

Sorry gums, I've got to dissent a bit there. For one thing, we're talking about a crash that happened almost 24 years ago and there hasn't been one like it since. For another, the manufacturer had zero input on the conduct of this flight - this was an AF aircraft with an AF crew flying an AF special charter operation. If we make the reasonable assumption that the "early adopter" line crews were given a demonstration and handling training akin to what was on the Gordon Corps video, then it is also reasonable to infer that the sales bumph should not have influenced them.

As I alluded to earlier, Airbus's own demonstrations appear to have been performed *either* at higher altitudes with persons other than crew (e.g. pilots in training, press, VIPs) aboard - *or* at lower altitudes with only crew aboard. I can find no evidence that they ever combined low altitude demonstrations with non-essential people on the aircraft as this AF sortie did.

On top of this discrepancy in approach, there is also the sense that the unexpected deviation from the briefed sortie led to rushed decision-making and a level of improvisation that many would consider unacceptable, particularly given the crew's unfamiliarity with the airfield.

Regardless of what CONF iture seems to have interpreted the details around Alpha Max to mean, the undeniable fact is that the EFCS did not point the aircraft at the trees, nor did it command the excessive reduction in thrust which necessitated such a drastic escape.

[EDIT : I'm not demonising or casually disregarding Asseline here, and as I said I do sympathise with the guy. However, the sympathy tails off somewhat after a point because as far as I know he has not publicly acknowledged that there were several points where he could have done things better - maybe because that requires at least entertaining the notion that there was no cover-up and conspiracy. That he apparently continues to refuse to at least entertain the thought is troubling to me. After a while, it just seems to come across as making excuses. ]

Dozy, you make statements but when time comes to back them up you're unable.

Which video/audio track are we looking at exactly ?

Frankly, I'm a little bit tired of playing this game. I think I've provided enough info to satisfy reasonable enquiry, but you're unlikely to ever be satisfied. So how about we turn it around a bit? If *you* can find a single piece of documentation from Airbus which states that full back stick will instantly (or thereabouts) deliver 17.5 degrees AoA in that configuration, then I'll sit up and take notice. I don't believe it was ever, as you put it, "advertised" as such.

The sources of the video and audio as well as the methods used to synchronise them are all documented in the BEA report, but then I suspect you know that already. What more is there to say?

Of course you're tired as you cannot back up your statements - And you don't have to stick around either.
So sit-up and take notice :

BEA Report Page 14
A tout moment, si l'incidence atteint 14,5°, la loi de pilotage est modifiée et le terme en facteur de charge ou le terme en assiette (modifié ou non par l'ordre de dérotation) est remplacé par un terme en incidence (écart entre l'incidence mesurée et la valeur de 14,5°). Cette loi de pilotage assure en particulier une protection automatique empêchant l'avion d'atteindre une incidence supérieure à 17,5°, pour conserver une marge suffisante par rapport au décrochage, même si le pilote maintient sa demande au plein cabré.
Note that it is NOT written :
This flight law provides in particular an automatic protection preventing the aircraft to achieve an AoA greater than 15 degrees, to keep a sufficient margin with the stall, even if the pilot maintains his request to the full nose-up.
And nobody said it had to be "instantly".

FCOM DSC-27-20-10
HIGH ANGLE OF ATTACK PROTECTION
In normal law, when the angle-of-attack becomes greater than α PROT, the system switches the elevator control from normal mode to a protection mode, in which the angle-of-attack is proportional to sidestick deflection. That is, in the α PROT range, from α PROT to α MAX, the sidestick commands α directly. However the angle-of-attack will not exceed α MAX, even if the pilot gently pulls the sidestick all the way back. If the pilot releases the sidestick, the angle-of-attack returns to α PROT and stays there.
Note that it is NOT written :
However the angle-of-attack will not exceed α PROT

No I don't know - Do you have that documented reference ?

I must say as a "lurker" throughout the course of this thread, I have found it compelling reading. The tidbits that have been added by other than the main protagonists have added to the value of the thread overall.

The hidden algorthmns used by AI in their application of αPROT have certainly been "teased" and "tormented" for the benefit of all. :ok:

@CONF iture:

Again, you're taking selective quotes and turning them around. In the case of Habsheim, it would have *had* to be a near-instant response, because the Captain did not apply full back-stick until a few seconds (exact values are earlier in the thread) before impact.

And the supposition that the AoA was restricted to A. PROT is also unsubstantiated. As I recall from earlier in the thread, the AoA was in fact slightly more than 15 degrees - 15.4 if memory serves me correctly. You have the Gordon Corps demonstration video showing that even keeping the thrust on, full back stick will initially get you a little more than 15 degrees AoA. You've had other posters tell you that the transition from that state to full A. MAX takes time to achieve in order to maintain stability and to allow for introduction of bank if necessary.

You put the difference down to CONF FULL vs. CONF 3, but have not substantiated that with hard evidence.

The video would have been the original cassette from the camcorder which filmed the flypast and subsequent crash.

Dozy #596


" We're talking a crash that happened almost 24 years ago and there hasn't been one like it since."


In the 1950s and 1960s many of the accidents were regular " repeaters". They happened again and again, somewhere, not always " Type specific".

The local AAIBs may have been unable to produce reasonable reports before memories had faded and any lessons passed on before the next similar accident occurred.


Habsheim had the advantage of actual video coverage which has been repeated, until the lessons are absorbed.


"DON'T DO THIS..."

That it was a few seconds or ten changes nothing to the fact that the elevators for that period just did the opposite of the pilot request. The FCS had simply no intention to let the pilot increase both the attitude and the alpha whenever 2.5 deg were still avail.

15 deg even at TGEN 334 and that value seems to have been the limitation the FCS was ready to accept.

Right on, alpha max all the way for CONF FULL, no hesitation, even possible alpha max transient overshoots. That's how the alpha protection feature is supposed to work.

Gordon Corps just proved them wrong.

Part of the reports you don't read but comment ...

Is it "documented" or not ?
A few camcorders have filmed the event ...

Yes, clearly that is fact, and amply demonstrated.
Noteworthy is that "that period" is quite short.

OTOH, that is not.
From an aerodynamic point of view, there were probably more than 2.5 deg before stall. From an FCS point of view, for this to be correct, the FCOM should read that alphamax was to be attained immediately and without any damping.
Does the BEA report or the FCOM read this? No. You just quoted both.
The NTSB report on Hudson event, and numerous other discussions here and there have put forward several explanations as to why alphamax(17.5) would, in certain circonstances, not be reached immediately.

Yes, clearly that is fact, and amply demonstrated.

No. That's the way it works when in the conditions of the test flight. Which are different from the conditions of Habseim flight.

No. See above.

I'm sorry to be a bit harsh, CONF. I have no certainty myself as to why precisely the FCS did what it did on the last few seconds before the crash at Habseim. I would like to be sure, but I'm not.
The BEA says it's normal behavior, Airbus says nothing (or more or less rephrase the BEA report), and external experts don't have access to the code or specifications of the A320 FCS.

But there have been a number of attempts from contributors here (and elsewhere) to explain this "why" (sometime using the NTSB contribution, which had access to whatever it needed to explain Hudson).
I judge those explanations convincing.
You seems not, but don't explain yourself on that matter.

As neither of us can proove them right, or wrong, without access to the code and specifications of the A320 FCS, we can either agree to a "stalemate", or you can try and explain why you (seem to) dismiss each hypothesis.

Cheers.

From the NTSB Performance Group Chairman’s report on the Hudson river ditching:

It seems to me that the elevator response to the sidestick input at Habsheim was quite similar, except that the sequence was interrupted by the airplane striking the tree tops.

What is puzzling to me is that the simulator did not reproduce it when capt. Bechet flew it to duplicate the accident sequence. In that simulation the elevator moves immediately nose-up, and the airplane pitches up 5 degrees in 2 seconds. Why is it different?

P.S.
Sorry for posting when I should have thought a bit longer. Both moved the thrust levers forward at 120 kts, 12 deg alpha. The difference is in pulling the sidestick back - Bechet at the same instant and Asseline 3 seconds later. So Bechet was still in pitch control law when he pulled the stick back while Asseline was in alpha-prot. Nevertheless, Bechet would still have hit the trees if he had not been in a simulator.

Awesome explanation - though I should point out that the reproduction was not flown in a simulator, it was flown in a real A320 over the test runway at Toulouse, with (I believe) obstacles set up reproducing the "bosquet" at the start of the reconstruction.

Important knowledge of flight laws figures, understanding with great precision how they work actually, real suffisant briefing including alpha prot mention and preparation.:ugh:

Thank you HazelNuts39

Forgive me, but I can't find the reference to a re-enactment of the crash, Doze. Where?

I also go with 'bird and others that another degree of AoA would only have increased drag unless the power was sufficient to overcome that extra drag.

Sheesh.

I don't think many here have actually flown at the "edge of the envelope". You have to see it to believe it, and learn. We can't do that for most commercial jets, and sure as hell not try it with pax aboard on a poorly planned/practiced demo. Practice was the key, IMHO.

Be that as it may, but I was basing my observation on the graph on page 9 of the 'Additif' of the Final Report bearing the notation "Essai simulateur 20/7/89 Recoupement Habsheim CPT. C. Bechet".

BEA report section 1.16.1.4.3. Approximate (Google) translation below:

@HN39 - Understood, and it wasn't a criticism, I just wanted to make sure that as the thread meanders to its late stages we got as many of our facts in a row as we can. :)

IMHO, since you want to 'get your facts in a row', that doesn't refer to Bechet, who was president of the Commission of Inquiry.