lyman;I don't! You've grabbed the wrong quote.:ugh:

"J’ai aucune indication" has been translated as, "I have no displays" which can also be interpreted as, "I've no information".

Just for the record: i do not take credit for the exact words of BEA. I didn´t coment on them either.

Are you in disagreement here with BEA?


Well, BEA is adressing this matter again, and you disagree here again?

I find it not very helpful to discuss the same matters discussed moons ago again while disregarding the BEA Final report when it suits our agenda. That was the reason i made my last three posts. If we are in disagreement with the report, then we should say so in an distinct way .

"The subtile changes to the PFD, as pointed out in the BEA's report, do not appear to have warranted a comment by either pilot. The PF may have conceded this point when he made the comment, "I have no more displays". But I suspect he really was inferring that he couldn't interpret what was being displayed."

How do you get from "I have no displays", or, "I have no information" that he does not understand what he sees?

Really?

Hi TD

"The latest in stall recovery: The current fighters (F-22, F-35) "enter and leave" the deep stall region routinely using engine thrust vectoring."

The A330 in 447 was using thrust to keep themselves (or augment) Stalled.
Unfortunately thrust was symmetrical, and limited as to vector, except for value. Utilizing thrust to recover was available. Unfortunately, again, it was not utilized. Pulling back the levers and pushing forward the stick......but that is not the issue. Once STALLED, the argument is wallowing in irrelevancy.....

Maybe gums could put together a syllabus for recovery from Unusual entry, Stall. Or...

From the outset, for me, this accident happened in twenty seconds, and again, for me, BEA is holding back some cards. From the outset, partisans have been comparing 447 to the other UAS. To me, that is preposterous. Each accident has a unique signature, and basing a conclusion on the similarities to improve safety is arse about. What makes us go forward with new knowledge is to assess what is different.

From the Perpignan Final report:

Maybe DozyWannabe did some mixup with the laws (normal, alternate, abnormal, direct...)?

The trim went to 11° NU in normal law, stopped operating at 15h 45m 15 s when direct law started and remained inop when at 15h 45m 40s abnormal law was latched until the end of the flight (as designed).

No, i don´t. I couldn´t find any suitable explanation in the available documents. But but i´m interested as well, maybe somebody can explain?


The BEA analysis is quite spot on.

The following part still gets my special attention (bolding by me)

For BEA the case was lost there not for this special AF447 crew, but for any average crew. And any average crew would not maintain full NU SS as the crew of AF447 did.
There is reason behind that statement, also it is not specified by BEA what this reason is. Reading through the posts of 9 threads shows, that most of the dedicated and expierienced posters (pilots, engineers...) have simple solutions for recovery, some reference their expierience in the sim as proof for simple managable recovery techniques, engineers come up with their math-model of flying.

Who are we going to trust on this matter, BEA or the other opinions?

Just for clarification, AF447 never should have encountered this situation firsthand, as correct recognition of the failures and the subsequent aplication of the procedures would have prevented the exit of the flightenvelope. Even in the first phase of the exit of the flight envelope recognition of the impending stall and the aplication of the correct procedure would have saved the day.

Why does BEA state, that after descending through FL 315 "Only an extremely purposeful crew with a good comprehension of the situation could have carried out a manoeuvre that would have made it possible to perhaps recover control of the aeroplane."

Is there a conflict? The crews that performed the recovery in the simulator did have "a good comprehension of the situation" and of the "manoeuvre that would have made it possible to perhaps recover control of the aeroplane." The engineers that calculated the manoeuvre did make BEA's caveat.

EDIT: In this type of accident the main problem is that the crews do not understand the situation. Maybe there is merit in developing a system that reliably detects a stall and announces that condition unequivocally to the crew. Would an AoA indicator be sufficient?

A conflict? Yes, in a special way i think it is. We might walk into the same trap as the regulators and the operates did and imho still do, in underestimating the situation and overestimating the abilities of the average pilots as well as the hardware. It´s the average pilot on the controls and not the "extremely purposeful crew" (wording of BEA).

Concerning the AOA indication BEA made a point:

That presupposes that the crew believes that readout and is able to interpret it correctly.

Well you had better explain how the PF got into the situation where he said, "I have no displays/information" if all along he understood what he saw.:rolleyes:

- interesting. You may recall that I 'guessed' that 20k would be the last possible recovery height way back. 315 is about a minute earlier. I assume that BEA put it higher, and perhaps that they expected that a "non-extremely purposeful crew" might re-stall in their anxiety to pull out, or similar? If 315 is correct, there was very little chance for this crew. Just a few seconds after the Captain has returned to the cockpit.

I don't think BEA is expressing an opinion about 'the last possible recovery height'.

So what do you think? The question posed was

I think BEA is saying that, if this was a movie you had been watching, at this point you would give up all hope of a happy ending.

EDIT: What was lacking was 'a good understanding of the situation'. With that they should have known what to do about it, and would not need a 'purpose' to do it. The quote is from the part of the BEA report that is "mainly based on the results of the work of the Human Factors group". IMO it speaks more of the HF than of airframe technicalities.

Hi mm43...

You say..."Quote:
Lyman ...
How do you get from "I have no displays", or, "I have no information" that he does not understand what he sees? Really?

Well you had better explain how the PF got into the situation where he said, "I have no displays/information" if all along he understood what he saw.
*


Thanks for the reply... French is not my forte. Un peu possible...

From the English translation I understand that the PF has said he has no flight data visible on his screen. I have believed that from the first reading. The FDR has not recorded his RHS fully.

You say he is telling us that he does not understand what he sees. Either way, something is very wrong, n'est-ce pas? Do you say he is too dumb to understand the data he sees? That is not possible? If it's comprehension, I would say he is qualified, but that the data makes insufficient sense?

There is no visual record of what either pilot saw, contrary to the claims of one poster. So we have his record to inform us!

When Captain says "What are you doing?" you will need to explain to me what he might mean? In my business experience with French people in California (food business) I have developed a sense of the vernacular, for what it might be worth.

"Er, What are you doing?" is borderline insulting... French men are sensitive to their work, and much care is taken to not offend or challenge one whose work is in progress. So for me, Captain is very stressed, and is most upset with Bonin.

Now this exchange has taken place after the flight path is abnormal, it is upset, so Captain has basis for his piqué.

Franzl.

Thank you for your post. I am beginning to believe PNF has said that the speeds he lost might have been his limit speeds! "bugs". With three ADR kaput, the Stall bug goes away, for example.

And thank you for posting the BEA report about the Stall. I had not read that part of the report. Needless to say, I think it is an excellent description of what happened. For me, even though the pilots were responsible for venturing into that dangerous domain, it explains how they may have missed the Entry to Stall, and how the aircraft and the Airline, and the manufacturer are responsible for the Stall, and some of the difficulty of understanding this situation. It remains to determine how and to what extent the THS affected the entry and capture of STALL. I do not think it is that important, I still believe the crash was a foregone conclusion within fifteen seconds after loss of autopilot.

I have done that type of Stall, and it is exciting...I never thought we were in any danger, and I learned a lot about energy, and rapid descent. I have done these and held nose up, it is exhilarating the excursions in altitude. I do not wish to demean these pilots, the circumstances were as buckwheat to bullets.

Clandestino, (#836) "If the safe conduct of the flight is impacted".
I repeat; this phrase requires interpretation, which you make in hindsight. We do not know what the crew understood and decided.
The CVR / report suggest that the crew observed the loss of airspeed information but did not understand the implications, and possibly did not consider any association with UAS. Previous events reported difficulty in associating the situation with UAS.
Assuming that the PF’s subsequent control activity was based on a conscious decision (local rationality), then this may have just been poor handling skills in maintaining level flight, or an ill-judged attempt to achieve a specific goal, - either an inappropriate UAS pitch value or stall recovery as in the ‘alternative view’ (#816).

At best we only have a small snapshot of what occurred in the flightdeck, and can only speculate on the crew’s mental activity. Such speculation could be made to fit many views of the big picture. My alternative considers one of these, particularly in association with previous events, and enquires if there is anything which the safety of our industry might benefit from.

A single view of the situation may not have this advantage and thus is perhaps disadvantaged in future thought and action.

RetiredF4, (#828), thanks. The ‘alternative view’ aligns with the report when the stall is established; the point of difference / interest is the crew’s mental model and choice of action which resulted in the stall.
With either view, the effects of surprise on situation awareness, and background knowledge, flight and CRM skills (including time management) all appear to be significant contributors to this accident.

Safetypee;

Your post #816: The stall warning resulted from the pull on the sidestick, added to light turbulence. It was real. Stall warning does not occur in normal law, only in alternate or direct law.
Your post #858: You seem to be making a distinction between "loss of airspeed information" and UAS. Do you mean they did not associate the UAS procedure with the UAS situation?

Clandestino

Here: "The rapid reduction in speed was accompanied by an increase in the angle of attack. The lift ceiling, at the Mach at which the aeroplane was flying at that time, was broken a few seconds after breaking through the propulsion ceiling. Due to its momentum,the aeroplane continued to climb: the aeroplane’s kinetic energy was converted into potential energy until the point was reached when the aeroplane unavoidably started to descend.

Here is BEA definition of the depart. Do you see any reference to STALL? The aircraft has climbed after the lift ceiling was passed, it was converting energy to altitude without benefit of aerodynamic lift, IOW, Ballistic. There was no drastic increases in drag, in fact drag was decreasing, due to the lessening of velocity.

Neither was there Stall Buffet sufficient to announce STALL onset. And the Nose remained UP.

These two markers are required by the certifying authority to allow the 330 a waiver for additional STALL warning. Stall is demonstrably available in ALTERNATE LAW, the 330 is no different than any other aircraft in this regard, and yet the requirement was waived? STALL WARN is dependent on Mach plus AoA so the certificate requires the 330 to warn always before BUFFET. Mach is not available in transient UAS, so the 330 is violating its certificate in this entry.

Other aircraft would shake in this regime, yet the Bus gets a pass...


HazelNuts39

Howdy.. You say: You seem to be making a distinction between "loss of airspeed information" and UAS. Do you mean they did not associate the UAS procedure with the UAS situation?

This is not even a nit pick... There is a profound difference between "loss of..."
And "Unreliable...."

Something I will repeat unto the door of no return, "We have lost the speeds."
That means, in it's most probable iteration, that the display of airspeed is.....GONE.

In the part of the CVR that does not exist in our reality, but is present in the reality of BEA and AIRBUS, there will be discussion between all three pilots of the loss of the visual data from the instrumentS.

Nope, wrong... They used pitch (up) to keep themselves stalled.
Misplaced emphasis - using pitch (down) was available, followed by thrust to regain lost kinetic energy is the correct sequence.
That is indeed the issue!
How so?
It happened (time-wise) until the point of no possible recovery as a result of non-recognition of what was happening although the clues (UAS) were there and even commented on "We got - got crazy speeds".
If you Google TWA 800, you will see theorists still claim the same thing relative to the NTSB investigation and report, 20 some years later, besides claiming everything from "electro-magnetic interference" to the missile shoot down theory to justify their theories.
Ah, but you miss an subtle but important point. In the 727-200 accident, the crew had all the information as to what was happening in front of them and elected to follow it, erroneous as it all was, never identifying they were in a stall until it was too late. So Airbus intent was to remove erroneous information so as to preclude making this mistake. However, that depended on shutting off the FDs as a first step and flying the aircraft (P & P) until the situation could be understood. Sadly for AF447, the first step was missed.
True, but this conflicts with your statement on comparing AF447 with other similar incidents. However, it is important for the investigative folks to not be theorists, but realists focused on significant data and information to assimilate conclusions on cause/probable cause. With theorists in charge, we may never have seen a final report in our lifetime...

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