TD. PITCH AND POWER was used, and it kept them stalled. Reducing thrust would not have helped? You are strict on sequence, did you not get my point?

Reducing thrust and pushing the stick forward would not have recovered the flight path, according to BEA, unless you maintain that this crew was exceptionally clever, and not average Line. So yes, the issue was they were lost at STALL, the rest is truly irrelevant to the accident, but not to us....

Why do you bring up TWA800, it is insulting. I am no conspiracist. You think listening to the entire CVR would add nothing to the PUBLIC perception of the pilots' actions? Now that is truly remote.

In saying that prior events should be isolated from the one we see, I am speaking of crew action, it is always the problem, since humans can and do misunderstand, make huge blunders (727-200). What did the crew do that was unique? Mechanically, the idea is that repetition is far more insightful, machines do not take abstract thought, and are of course different in that it requires a differ and unique analysis for recommendations.

Sad for this flight that the FDs were not turned off? It is outrageous, in my opinion. I am of the opinion that the crew were unaware they dealt with UAS for precious seconds, and made decisions based on their belief that NORMAL LAW obtained, and this is what started the crucial disconnect between the PF SS and actual PITCH.

The sidestick conveys no information, either by position or feel, and losing track of one's inputs over time can be profoundly confusing. Without an instrument to track PITCH, ( And there is NO instrument for AoA data) , the a/c was utterly doomed. Now people say that PITCH data was available, but there is no positive proof, and it is not disallowed to consider that the pilots were put in the weeds by a partial, or missing, panel full of reliable data.

May I see an artifact or image that shows an horizon? I'll wait.

Yes theory. I take your point re: practical realities. Are you saying the BEA report is a compromise? It is, but I would not mind hearing it from you, you are esteemed from my vantage point, and not without good reason! :ok:

What are you getting at?
I cited the discussed matter word for word out of the BEA Final report, or do you have a different one? It does not cover the creation of a script for a movie, but this report is the work of experts with a lot more data at hand than we ever will, created over a two year period for the sake of safety. .

What evidence do you have, that it is the result of the human factor group, which is covered in the report under point 1.16.8?

The above cited statements from BEA is found under
2. Analysis
2.1 Accident Scenario
2.1.3 From the triggering of the STALL 2 warning until the end of the flight

Bolding by me
If it would have been a simple stall recovery maneouvre, why did BEA use those cryptic words?

My bolding

Incomplete excerpt, bolding by me, please read the report for full version

Lyman;
Ballistic, in my vocabulary, is zero 'g'. Figure 66 of the final report shows the variation of normal acceleration prior to, and through the stall. Prior to the the stall warning, the PF push on the SS in response to the PNF's urging resulted in less than 1g. Then the PF started to pull, increasing the LF to 1.13 g until the airplane stalled. The stall resulted in (was associated with) a large increase in drag, which caused the subsequent steep descent without an increase in airspeed.

RetiredF4;

You're taking my post out of context. I was responding to BOAC's question: What do you think? The issue was whether BEA intended to say that FL315 was the last point where recovery was possible.

My apology if i misunderstood your post, was it meant humorous? Your explanation makes no other sense to me.

I disagree - A few here have mentioned FL200 as the last call and it would be also my guess, maybe 5000 feet lower ... ?
It means the captain had 90 seconds to correctly evaluate the situation before taking or directing the corrective actions.

But first things first, the BEA had to evaluate what was the influence of the autotrim in the process.
Take the same airplane, one with no autotrim under stall warning, one which trims almost to the stop.

Before developing HF the BEA had to first extensively analyze the technical aspects ... Instead of that they kept silent on what Airbus is not interested to see discussed.

RetiredF4;

What do you think? Is the BEA saying that no recovery was possible after passing through FL315?

HN39 (#859), I had considered that the first stall warning could have been an artifact of the ADC changeover, but ‘real’ as you describe does not alter the thrust of my view (#816).
The important inference was that (at least) the PF decided that this alert represented a real stall and commenced the erroneous action, even though we know (in hindsight) that a warning would not be given in normal law. I surmise that the PF did not consider this, nor re-evaluate the situation even when the PNF called the Alt Law condition. The PF may never have appreciated the change in control law as his attention was fixed on the erroneous ‘stall recovery’ pull up manoeuvre.

Do you mean they did not associate the UAS procedure with the UAS situation?
Yes, this supposition is supported by the crew reports from previous incidents. The loss of an airspeed display in itself is not ‘unreliable’ – it’s not there, reliability as such cannot be judged (unreliable might mean it’s not there very often).
This may be playing with semantics, but it is an exploration of how the PF might have interpreted the situation, or how this procedure might have been taught which then influenced the assessment.
IIRC the distant history of the UAS drill probably came from accidents involving flight without airspeed, was this taught. Or perhaps the UAS training was done against the backdrop of ice crystal icing, a completely different context. Therefore there may not have been an immediate association between loss of an airspeed display and a drill relating to ‘ice crystals’ and aircraft handling.

I am going to need a rewind here again, I'm afraid:

a) References appearing to the Airbus 'stall recovery pull-up' manouevre. Is this right?

b) References to the fact that the stall warning 'cannot' sound in Normal Law. Is this right?

c) References to situations where alpha floor protection in some species of Alt Law might be absent. Is this right?

Putting these together, this means, does it not, that it is considered 'correct' to pull up as hard as you like at the 'stall' in Alt Law where you might have no stall protection? I am just not understanding why the logic of all the years of aviation is suddenly overturned. I do hope I have got this wrong.

BOAC, it seems to me, from the information I have available, that the audio warning of a stall* begins before the wing actually stalls, in terms of the AoA value that triggers the crickets. Since the crew can't see their AoA, they must rely on such a trigger to become aware of an impending stall if they don't realize that they are approaching one.

(* = or warning of impending stall)

I reached back to find some info on PPRuNe discussion on alpha floor, and am interested in how confusing references to it seem to remain.

Safetypee;
IMHO you are reversing cause and effect.

Loss of airspeed display means that you have to manage flight without it. In cruise that means maintaining current attitude and power setting, not pulling to climb.

BOAC,
A. My reference to this considered that there was an ‘invented’ stall recovery procedure in normal law involving a pull up because the protections were there (#816).
B. AFAIK, correct.
C. AFAIK, correct.
Thus combining A (on the premise of B) with C, and due to poor situation assessment, surprise, inappropriate training, application of automation, etc, the PF pulled up believing that the aircraft had stalled at the time of speed failure, the resulting climb did actually stall the aircraft. Then by supposition, the ‘normal law’ mindset maintained the control input resulting in complete confusion, particularly when back stick stopped the stall warning and forward stick started it (AoA cut-out logic).

HN39 “IMHO you are reversing cause and effect.” :ok: Hence my consideration of the ADC, or even turbulence / poor handling with the lower stall threshold?
“Loss of speed …”, I agree, but if the mindset was that of ‘a higher priority’ stall warning, then what?

I don´t see any reason to do an opposing assumption to a clearly written text from BEA, or am i hitting the language barrier here as a non native english reader?

As I (a non-pilot) understand it, there has been a commonly (A+B) accepted drill for "approach to stall recovery" which involves application of power and sometimes a pull-up to minimise altitude loss? Now both A & B are saying that this approach can lead to confusion and possible accidents if the aircraft actually gets into a state where the only possible recovery action is to push the nose down, reduce AoA and only then pull up. They are jointly recommending that this drill becomes standard even for approach to stall conditions.

No doubt if I have that wrong in any particular the flak will fly ;)

"Cannot" is perhaps the wrong word - "will not" would be more accurate since the system in normal law is supposed to prevent any transgressions above alpha max. Consequently there is no audio stall warning associated with normal law.

Alpha floor depends on a functioning autothrottle - it is, so far as I know, not available in any of the alternate law manifestations.

The audio warning is actually an "approach to stall" warning and is typically triggered a couple of degrees AoA below the actual stall. There is a subtle twist in that the trigger is modified by a 'rate of change of alpha' signal which is intended to give warning of a rapid approach to stall AoA. So far as I can judge, the stall warning would be triggered just above the AoA at which buffet becomes perceptible, but below that at which buffet is deemed to be intolerable.

CONFiture...

"Quote:
Originally Posted by Lyman
I still believe the crash was a foregone conclusion within fifteen seconds after loss of autopilot.


Hi... I am more or less in agreement with BEA, in fact, I am unwinding their conclusions to include the errant climb, vis a vis the skill/perception quotient.

At one point I was willing to say that the flight path was recoverable perhaps immediately, from the beginning of the descent from apogee. I have seen it done, never in an airliner, which means I am choppless in the discussion.

HazelNuts39.... For purposes of discussion, words like "apogee" and momentum, suggest ballistic influences. Totally Ballistic? It depends, everything is subject to gravity in our environment, BEA suggest the wing has passed its ceiling, just after Power passed its, and. Omentum caused the a/c to continue climbing. Where is the "drastic increase in Drag" Clandestino points up? Certainly not drag from lift exchanges, or do I read BEA incorrectly? The pilot keeps the NOSE UP after limits pass, and starts descending, at virtually identical AoA, so where is the conversion of loss of lift to lowering of the airframe's nose? I suggest that "0" gravity is not possible in any portion of the trajectory, only exceedance and shortfall, so less than "1" suggests ballistic is at work. "Descent" is the result of gravity, always, yes? In any case, My take on the regime around apogee is that the a/c was already Stalled, if your definition is the wings have stopped lifting?

And my conclusion from that is that the pilots were unaware that a Stall had taken place?
One cannot escape the impression forced upon us by the relevant and released data, this crew were not up to UAS recovery in these conditions. That means the discussion should practically revolve around crew, CRM, and flight data issues.

The mechanical/electrical/avionical (?) is there as well, and since there is incomplete data involved for any conclusions, BEA have removed these areas from discussion, IMO. More's the pity, also IMO.

In theory it shouldn't - the Stall Warning is not inhibited in Normal Law, but the idea is that the protections should kick in before it becomes necessary. However, I've heard anecdotal evidence that it has sounded briefly when external factors such as adverse weather have pushed the aircraft outside the intended envelope.

Alpha floor is a function of autothrust, as opposed to Alpha protection which is part of the flight control logic. In Alternate Law the hard protections are lost except for load factor manoeuvering, with a "soft" low-speed stability function taking the place of alpha protection. However with speeds out, that stability function can no longer work, hence the secondary mode.

According to Clandestino, Alternate Law handling is trained to assume a worst-case scenario (i.e. all protections lost).

You're correct. However the caveat applies that the old approach to stall procedure indicated a maximum NU pitch angle of 5 degrees - what the PF pulled in this case was 3 times that. The other issue was that as far as I can tell the first Stall Warning on the CVR was *in response* to the back-stick command due to "G".

BOAC,

Re (a): From Annex 11 to BEA FR:
Re (b): In normal law, stall warning is not inhibited, but the threshold for its occurrence is set at 23 degrees, whereas the High AoA protection does not allow AoA greater than alphamax (approx. 14.5 degrees at low Mach, 5.2 degrees at M.8) (all in clean configuration).
Re (c): The alpha-floor protection is inoperative in Alternate law (FCOM 1.27.30)

Don't think so. Two things could confuse with that though.

One is the AB GPWS escape procedure - namely pull the stick back to the stops and alpha-prot plus alpha-floor will automatically give you climb performance (without risk of stall) that you would need a sky god to get on a conventional a/c. Nowt to do with stall recovery or 447 though.

Second is the practice noted by BEA and others before of emphasising minimum altitude loss in (approach-to) stall recovery, and perhaps teaching stall as a speed problem not an AOA problem. That is an industry problem though, not an AB problem.

Arguable. Stall warning can trigger in normal law, but I believe the immediate effect will be a law degradation. In normal law the system thinks it is keeping within the envelope, plus a margin, so this is a "should not happen". If it does happen, the system is going to drop envelope protections because it is clear the envelope simply isn't where it was thought to be...

I suspect that it is true to say the by the time you hear the stall warning you are not in normal law...

EDIT: disregard the bit above, it's memory playing tricks (i.e. it's b***ocks). I sit corrected.

Alpha floor is an autothrust function, not sure it is really a "protection". It will add thrust as AOA rises, to give you more performance, but in the absence of alpha protection (which will put the nose down to keep AOA in bounds) it cannot protect you from stall. TOGA alone does not prevent you stalling, as 447 shows.

Alpha floor is, as far as I know, not active in any law outside Normal [maybe on some AB type - but I don't think so].

If you were right, I think we'd already have a dozen or more AB on the ocean floor as a result.

Something, however, made this crew think it was correct to pull (and Colgan and Ethiopian and many others further back)...

My confession is that I believe PF was not utilizing a version of "pull back hard it will not Stall..." I think he was honestly trying to regain a cruise Pitch or thereabouts. I do not think he was instantly on board with UAS, and all that it demanded. Whether he sussed it ever is arguable. The data is insufficient to make a perfect conclusion.

So I agree with Infrequentflyer. This accident is not well understood, but it does not suggest that anything like it will occur at all, ever.

bubbers, by " not well understood " I mean by me.

You have a reference for for this immidiate law degradation effect?

reference BEA FR Appendix 11