Very simply.

The nose down inputs were transient. They were not of sufficient size/duration to cause the THS to move.

One of many 'pitys'. It's an complex and interesting human factors issue. My feeling is that if the aircraft doesn't have valid input then it is preferable not to output (so it turned off the stall warning when the AoA went out of range). Otherwise you risk GIGO. At the end of the day, if the aircraft cannot rely on its own sensors, the aircraft has to hand over to the pilots and expect them to act correctly.

It certainly needs a rethink, though I suspect this functionality was specified by a multi disciplinary team which included test-pilots. Not saying that it cannot be improved on of course. And there is no evidence to suggest it is the a primary cause of the accident.

BOAC,

That's what I thought. So I hope you don't disagree with my crude explanation, and how it relates to Airbus FBW is a bit clearer.

Hi BOAC,

"Between 1 h 59 min 32 and 2 h 01 min 46 , the Captain attended the briefing between the two co-pilots,....
At around 2 h 11 min 40 , the Captain re-entered the cockpit. During the following seconds, all of the recorded speeds became invalid and the stall warning stopped."
9 mins in the bunk would be enough time for me to doze off. If I then entered the flight deck and witnessed what was going on - I'd hope it was just a nightmare and that I'd wake up to reality in a minute or two. Once I had diagnosed the stall (without the expected warnings), and ordered the nose down, idle thrust etc - to be greeted with a new stall warning might just confuse me somewhat - since I wouldn't have the benefit of this hindsight.

@ JCJ:
 

AMM describes the Pitch Nz law as:

1/ Nz Law

This FCPC law is the normal pitch law engaged during the flight phase.
The pilot commands a load factor via a pitch action on the side stick.
The Nz law executes this command, depending on aircraft feedbacks, so that:
- the short term orders are executed by the elevator servo controls.[/COLOR]
- the long term orders are executed by the THS actuator (autotrim function)
The gains depend on Vc, on the flap and slat position and on the CG position.
.....
Under the Nz law the aircraft response is quasi independent of the aircaft speed, weight and CG position.

And then it continues with a description of all kinds of protections, sub laws and system reaction in other flight phases.

The only functions which may be of any influence since they are also active in ALT law:

Abnormal attitude law,outruled by BEA but was it?




If certain values are exceeded abnormal attitude law is triggered.

1. Pitch (50 degrees up, 30 degrees down)
2. Bank (125 degrees)
3. AOA (>30 degrees, < -10 degrees)
4. Speed (>440 kt, < 60 kt)
5. Mach (0.96, 0.1).

These (bold) values where - intermittently - present from @ 2:11:40 when Capt enters cockpit and on, that would justify the absence of autotrim when PF made ND inputs.

and

MLA (Maneuver Load Allevation) - but this would create a nose up pitch moment which should be counteracted by AND reaction.

This FCPC function is activated when the order of the pilot, via the side stick, exceeds a pre-determined load factor in clean configuration. A symmetrical deflection order is sent to the spoliers 4 thru 6 and the inboard and outboard ailerons.
The pitching moments due to MLA deflections are automatically compensated by the pitch control laws.
Taking into account the priority of the MLA function over the speedbarke function, if the MLA is activated when the speedbrakes are extended, spoilers 1 to 3 are retracted to zero and spoliers 4 to 6 are commanded according to MLA orders.
This function reduces the design loads during high-g maneuvers demanded by the pilot.

A33Zab, presume those conditions for abnormal law are all 'or's'. However, if the a/c already knew that speed was less than necessary for valid AoA would the logic still take the value and change law ?

Took your earlier post on 'locked THS' ie a THS fault not applicable here, to be trying to answer the question asked of how much authority the elevators had v the THS which at >8 degrees and in wrong speed regime was 'not enough'. Mind you, I wasn't clear the instructions following that would be very helpful in such a case.

I have lost track of when auto-trim kicked out but as the more knowledgable have said, unless there is evidence that nose down was wanted it is all largely irrelevant (but mightn't have been had the events followed a different path).

From an outsider's point of view, it does seem a great pity that the system 'knew' or was in a position to know that the a/c had been in cruise at altitude, that it was now descending at an emergency rate, that there was, or had been a UAS event, that the control law had degraded, that the apparent airspeed was insufficient to even motivate the aoa vanes, that THS trim was maxed out.......and still present the information to the crew in a way that allowed them to be misled.

If the Capt. wasn't briefed about the initial climb, he may have started thinking in the wrong direction and never come to realisation.

Given the innumerable paths to failure, I wonder if they will decide this will never happen again now we have changed the pitots.

A33Zab,

Great contributions :ok:

If ALT 2 had latched, which appears to be the case, would that prevent a further change to Abnormal Attitude Law?

Chris: Back in the late `90s when I used to conduct a lot of sim training on the A330 one thing became very apparent whilst doing "Recovery from Unusual Attitude" training. (NB. sim lack of fidelity may be an issue here)

With a very high nose-up attitude and the THS driven in the nose-up direction - when it came to the recovery the elevators often lacked the authority to pitch the nose down without the THS being manually run forward. It became one of the main training points to take away from that scenario. In other words - full NU THS could override full down elevator inputs. This is before we even get into considering what valid/erroneous flightdeck readings were presented to the crew on their PFDs.

Meikleour,
(Where have you been lurking...?) ;)

Very interesting, though I note your sim caveat. Don't know what AoA you're talking about, of course, but could it be something to do with forward-fuselage body-lift? And what was the thrust?

PA 18 151, # 994

Even if only a contributary factor. In a rational world, one would
expect the warning to be on at any value under the limit and stay on
until that value was again exceeded. I don't fly these machines, but
would find the present logic, off, on for a narrow window, then off
again, confusing and critically so in an emergency.

Chris: Difficult to remember the exact details but used to get the trainee to close his eyes then put the aircraft into a dynamic noseup position whilst manually applying a large amount of nose-up THS. Usually with power on and attitudes above 30NU. The training point was to show that the THS may have to be moved manually in the recovery which is of course a control that is not normally touched in the air. I don`t believe that the AF reached those high pitch attitudes but nevertheless achieved the gross out of normal position on the THS which would have had to be addressed to regain sufficient elevator authority.

Hi
That seems a bit complex.
1/ You'll need to switch something to make the plane record the PF side, as it changes. What about "quick" changes? "My aircraft" (time sensitive situation): do you have time for the (newly) PNF to look for some tiny button?
2/ If you have the wiring/plugs to record both seats data, then why not "just" add some memory in the box and record all the data ?

I do agree, however, that regarding available data after an accident, the more the better.

IIRC F/CTL SD page is automatically selected when certain types of failures occur. Was the case on 447, based on the ACARS. I think interim reports from the BEA mention that.

- how about the duty autopilot - already an 'SOP', no extra buttons. I do, of course, agree with 'more memory'

Meiklour. Very interesting, thanks so much. I gather you have trained many A330 pilots.

Questions on your Unusual Attitude training.

1. Did you do these in the sim at low (terminal area) altitudes, high altitudes, both?

2. Given how rarely the trim wheels are needed or used, do you feel that the training you described -- in which you showed pilots where using the trim wheels could be be required -- was one of those training points that sticks out because it (using the trim wheels in flight) is so uncommon a task?

3. With that in mind, if we were to put 200 A330 pilots into the same room, how many would not have recalled that novel training scenario?

My guess is that most would recall it, given the rarity that the trim wheels seem to be used, and the association with unusual attitude training. Is my guess consistent with your experience in training A330 pilots?

Authority
 

Meikleour,

Interesting, the lack of enough pitch authority to get the nose down from an unusually high attitude.
NOTE though, that will only be the case if you just try to PUSH the nose down.

That is the reason why we ex-air force guys like to roll the aircraft past ninety degrees bank, you will then be able to get (pull) the nose down with positive g, much more comfortable, pax won't be flying out of their seats, etc.
Have always been appalled by the civvie aversion against this technique.

The AF447 would not have needed such an overbank though, 15 degrees nose up is not yet extremely high, and it SEEMS from flight data that enough authority was available to get the nose down, no matter how vehemently some people try to deny that.

Of course I agree with your training point that the trim should not be forgotten, in extreme situations like unusual attitudes and stalls.

@PA 18 151:

Clearly NO!
As is advertised: This law ensures that the flight control law will never hinder aicraft recovery, after the recovery (within the abnormal att. values) autotrim becomes available again.

A first unknown factor is time, how long should an exceedance of one of the trigger values be present to engage this law or revert to ALT 2 again.
Didn't find it yet.

@MR O:

They are 'OR'.

Yes, but only if not NCD, @ 2:11:40 stall warning sounded, so there must at least 1 valid speed.

The 2nd unknown factor:
AOAsw is generated by highest AOA value while FCPC uses median (3 ADR) or Average(2 ADR) values. 1 ADR was already outvoted.
If average then didn't exceed the 'abnormal' value it would not enter abnormal law.

Could 2 AOA vanes generate such different values?
In this stall condition, "roll oscillations that
sometimes reached 40 degrees" and disturbed airflow airflow around fuselage I don't know.

The question was why didn't THS followed SS ND command.
The only 2 reasons this could be justified are the sort term ND orders or entering Abnormal Law.

I agree that enhancements have still to be made, several are already introduced before or currently in design.
- 'BUSS' - however only to be used FL <250. (because UAS above FL250 is considered transient)
- AOA valid at CAS > 30 Kts (i.s.o. 60 Knots)
- Pitot tubes (change of supplier)
- Experiments with combined AOA/Pitot vanes.
- QRH
- Training UAS, use of GS.
- CRM / TEM

If crew demand is an AOA indicator and/or THS whooler it should be provided asap.
Other demands e.g. change of law philosophy, protections, RH PFD indication on FDR will require a lot more R&D.

Abnormal Law and THS
 

Abnormal law:
While the fact that Abnormal Law and the dropping of autotrim, *seems* like a possible explanation for the THS remaining +13NU, there is no mention of an law change beyond:

While we all recognize the BEA note's undeniable brevity, I also believe that everything included and, perhaps just as importantly, NOT included has relevance - therefore my position, until TOLD otherwise, is the aircraft was in Alternate Law and remained so until impact.

THS trim:
I don't have all the control rate information in front of me, but the premise of the autotrim THS function is to ensure pilot elevator authority over the full range of travel. My understanding is this: If I demand NU, the elevator starts moving, keeps moving and eventually will approach and then achieve the demand, at some point a little later the THS starts to off-load elevator travel. The assumption being that if I continue to demand NU, then I probably want the aircraft to trim that way.

So let's say I now throw in some ND stick. The elevator will move ND and, just as NU will eventually achieve the demand. If left ND, the THS will again start to unload the elevator by moving ND, but clearly there is a time hysteresis involved. So a quick ND input will NOT cause the THS to move. A sustained input will. Otherwise we'd have the THS chasing the elevator all day.

Hence, to those questioning why the THS remained at +13NU, there simply was never a long enough ND input to cause the necessary demand to move it. Any initial demand was handled directly via the elevator.

Thanks.

1. AOA (>30 degrees, < -10 degrees)
2. Speed (>440 kt, < 60 kt)

If the stall warner sounded then speed must have been >60kt or would have inhibited warner, and AoA threshold much less than 30 degrees at that time (I hope). So can understand why it wouldn't law change there.

When speed did get below 60kt at some time (which it must have done to inhibit warner) why did that alone not force change to abnormal attitude law of and by itself given the 'or'? Judging by the time the stall warner was silent I would have thought that it was for a long enough period to exceed any time threshold.

Would a change to abnormal attitude law trigger an acars msg ?

Sorry I seem to be able to only ask questions:O

EMIT: SLF here. Have always been appalled by the civvie aversion against this technique. The success of that method would have been academic to me as I would have died of fright before landing anyway.:bored:

If the THS does NOT "chase the Elevators all day", the pilot ends up flying a very different a/c dependent totally on the THS' position. Auto trim seems such a fine add, but it can certainly wreak havoc. How is the pilot made aware of this critical control position? Without knowledge of control surface deflection, what does he know, and when does he know it?

Not only that, but accustomed as he is to consistent Pitch authority (completely supplied by the FCS) what is his response when the elevators get abandoned by the "Big Dog" and have to fend for themselves? A benign and docile handling Beast turns into a marginally controllable leviathan at best (cruise?) to an out of control house of cards in completely new and different attitudes. Absent some bizarre and totally unknown controls configuration that required back stick whilst Stalled, my money is on the crew believing wholeheartedly they were NoseDown, oversped, and unrecoverable, all the way down. No FD, no horizon, and gobs of airstream noise. At 10k feet, did PNF notice they were NU instead, and instinctively push ND? (Perhaps having seen the Ocean, or even an horizon?)

This thread has a most definite Phugoid of its own. The rhetoric is fascinating and arcane on the way up, and then the fundamentals rear back, and the entire thread changes heading.

The pilots' reputation will have to live or die on the use/nonuse/misuse of the Trim Wheel, perhaps. In their defense, it is blatantly obvious that not even the 'experts' here are comfortable with the Bus and its iterations in these upset conditions.

In pocketing the argument in narrow ways, the solution is impossible. This was a TEAM effort, without doubt. I for one will admit that.

Malfunction, Training, or Act of God, nothing new under the Sun.

For Garage Years. You assume ALT LAW 1 in the entirety of upset? A question, then. After she Stalled, wouldn't the a/c be in Direct, or Mechanical? And if an automatic degrade, what informs the flying pilot?

Honest question.

Lonewolf 50: As far as I recall it was done at medium levels to give a large enough manoeuvering margin to position the Unusual Attitude.
Certainly, with the nose high situation the rate of washoff of the speed can be so great the the extra authority of the THS is needed. It simply runs too slowly with the full forward elevator demand.
I have no knowledge of whether other airlines conducted such an exercise so can only speculate however the main training point about the possible need to use the THS manually was usually quite a shock to the students.
(caution: sim. fidelity alert here!)

EMIT: valid point - however we did not necessarily always do this exercise with wings level - often it was done with large bank angles associated with high nose-up attitudes.

I believe that the A320 `test flight` which crashed on approach to Perpignon also had a large THS nose-up situation which was made worse by the thrust-pitch couple with the selection of TOGA. Would the application of manually run forward THS have helped here? Maybe?

@ Mr O
 

If speed itself < 30Kts it set itself to NCD.
Why? the only reason mentioned in the docs. is due to -accuracy-.
---
The 2nd STALLSTALL started @ 2:10:51 AOA 6° (AOAsw 5.2° later 10.8°)
and sounded untill several seconds after capt entered the cockpit,
at the same time all recorded speeds became invalid (NCD) AOA then exceeded 40°.
Once again AOA for AOAsw is the max of 2(3) values, AOA (and speed) for FCPC the average(median).
---
No, this law will not trigger any message, the only clue will be the absence of autotrim and indications (if present).

@PA 18 151

I think one would be reasonable to accept that if I’ve got an ALT2 jet in my hands (A/P & A/T not available in ALT2), that I should, in fact, be flying “attitude” as a control parameter when I hear the “Stall, Stall”. So I know the aircraft attitude because I "may have" put it there.

With an analog AOA indicator, I can instantly correlate where I am in the aircraft operating envelope with respect to AOA…and observe the AOA trend. "Stall, Stall" is just a preliminary warning that I'm headed that way or possibly risk inducing an accelerated stall. It's not a matter of "believing" one or the other.

More importantly

As is continually being addressed here, the forward SS input may have to be held for some period of time. If all I can reference is a repetitive “Stall, Stall” audio, I have no idea to what extent my recovery inputs are either effectual or not.

“Stall, Stall” doesn’t tell me whether I’m at 35-degrees AOA “locked” or SEVEN degrees AOA trending lower. Neither does a stick shaker. If I can see a trend indicating I’m making the right input, I get positive feedback to hold that input. This might be particularly useful with a Stall Warning which suddenly reactivates.

The analog/digital AOA indicator available on the PFD of some 737 NG’s sits just to the upper right of the attitude display. It would take an unnatural effort not to see and correlate both Attitude & AOA with the stick shaker going. (Someone posted a picture of it eons ago. It is not an additional instrument but an OPC addition to an existing display. And it is certainly not overwhelming in day to day normal flying.)

Someone (LW 50 I think) previously asked if AOA displays were available in airliners and were they useful. Are they useful?

Same answer as before…depends on the driver. :)

Are you sure about that ?
The BEA Note tells us that it took the 30s continuous NU Input to get the THS from 3 to 13°.

Where did you find evidence that it followed suite to every Elevator input ?

+1

I, for one, do not believe that is how the THS works. Otherwise every small SS input would result in a re-trimed aircraft (even though it would be a small change).

henra

howdy. The BEA report "a" left, nose up input. Not continuous. Doesn't the 30s mimic a rate similar to Manual? IOW, .65 degree/second? That gives a total of 20 degrees NU, but with some pauses on the way up, why not a total of Ten total excursion in 30 sec.? How would the THS "know" when to calibrate its rate? Maneuvering and cruise are separate in what way? (To the THS)? Is it not "On" or "Off"? If in Auto, (it was), then it is the FCS that did the inputs, and if not in response to PF, then what was the "Goal"?

If, at a/p drop, the THS was at a trimmed 3 degrees (It's "starting" point), then ten degrees is the total excursion from cruise trim, and we know that the a/c did NOT immediately start to climb, per BEA. This lack of Pitch response is trying to say something, post PF input ("I have the controls").

If unresponsive to PF's initial inputs, would he not increase the input? If ten seconds later, the THS would now have trimmed seven degrees NU? What took the a/c so "long" to start "climbing"? Imagine that, a 150 ton a/c at 350 being "unresponsive". Any vertical acceleration that resulted in 7k fpm climb would be a belly cruncher, and he would have countered the zoom with ND, without question. What made the A340 reluctant to drop her nose in Caraibes? Two conscious and trained pilots would not allow such a climb, and if they could not control it, why?

It is in this climb that some mechanical and/or FCS transient seems to appear. One must grant to each "system" a basic trust in its abilities? To include the Pilots, eh?

The two unsolved puzzles for me are:-
1) Why the climb in the first place
2) Assuming the Captain was able to diagnose a stall, why nothing apart from power really changed all the way down. It is pretty obvious that no further significant recovery action was taken from 10,000' down or the impact would have been quite different - not that I think there would have been enough height.

BOAC,

1. Why is for Philosophers, eh? How? Did not the PF initiate it?

2. Could they have believed they were Nose Down, Oversped, and Unrecoverable by anything other than NU inputs? Could the PNF's sudden input @ 10,000 feet ASL have been a ND? Did he peep an horizon off to his left? Not that ND would have accomplished anything but another STALLSTALL, right? They already tried that. :eek::eek:

Extreme or (wrong) sensed airspeed....????

bear, you take us back to trying to unravel

What nose attitude did the flying crew see?
What nose attitude did the captain see when he re-entered the cockpit?

The primary flying instrument to reference when you are flying in instrument conditions is the attitude indicator.

There were three possible displays for the captian to view.
There is no reported evidence of failed attitude indication.
We do not see BEA report something amiss with attitude indications from the voice info released.
Considerable attention is given to attitude information from the FDR in their description of what happened, just as THS position is given considerable attention.

IF nose down input induced stall warning (the second series) due to an alpha function reawakening (and alpha/airspeed restoration, system confidence, etc) it seems odd to me for a crew to interpret that the alpha driving that warning is a high speed buffet sort of warning. From what I glean in various downloaded pdfs on A330 systems, high speed buffet, or approach to it, doesn't evoke a stall warning alert. If you get too close to VMO, or try to get past it, the system tries to correct you. It doesn't want to get beaten up by high speed buffet any more than the pilots do. (Or so the programming can be characterized).

Does that initial pitch have an innocuous origin?

"The AP will disengage if the high-speed protection is active."

Some have asked if the AP initial disengage led pilots to believe that they were in HS protection ... which if AS wasn't reliable, they'd have no way to cross check.

It seems to be the consensus that Alt 1 Law was in operation, and HS prot looks to be available in Alt 1, but not Alt 2. If the capability degraded to Alt 2, robot isn't making inputs for HS protection.
(From Flgt Trn Manual ... alt 2 ... in the case of failure of 3 ADRs, no high speed protection. )

You can expect up to a 1.75 g input (nose up) from the robot if HS protection is called for. After many posts, and four different threads, and going over this again and again, nobody has solid evidence that this feature is where nose up came from. The Abnormal Law possiblity remains open, but the reported evidence of a nose up command from SS keeps cropping up.

Even with ND inputs followed by a stall warning, there remains the matter of attitude flying.

If your nose is up and your are falling, aren't you usually
either
stalled,
in a deliberate powered descent (no applicable here, their mission was "maintain altitude and course" at this point in the flight)
or
undepowered for your desired flight profile?

The power levers were last reduced to ~55%, so the third consideration must be rejected ... which takes you back to nose high and falling, you are stalling.

What did they see on their attitude display?

One possible explanation would be a prior ADR disagree, invalidating the speeds. If the speeds are considered invalid this could be an explanation why the System did not switch to abnormal law based on speed threshold.
This ADR disagree could result from asymmetric flow conditions to the different Pitots and thus large discrepancies when flow into one pitot was stalled while still attached in the other one(s).

:ok:LW 50

Thanks for the response. I vaguely remember some buzz early on re: no Horizon, or attitude prompt, and a long discussion re: to the option of an AH, (offered by Bus, to be placed upper left on Captain's side of Panel. Such option not selected on this 330 by AirFrance.

It is a seductive argument, this "What did he see"? It isn't particularly relevant, except to make a foundation for some future finding, to wit:

1. He saw nothing. Unlikely, because he did make manual input (BEA)

2. He saw something. Likely, see above.

3. He saw too much. This falls just short of being demonstrable, by discussion.

4. He saw just what he needed and made the most bone-headed call of his short 37 years on the Planet.

I wish the in fighting would stop, but I think it is merely reflective of how BEA and the other players are playing the Public.

The fact that I can still ask these simple questions, and not be accused further of "Bunkum", must mean that we have not progressed much further than where the discussion was after the ACARS leak.

Nowhere on the Planet can I avail myself of data such as is here. Helo pilot, (:ok:), 330 instructor, :D, Aero E, :cool:, etc. ad vol. BEA has made possible a political and economic discussion also, by being coy.

This is my idea of Heaven, but for the grim results of what will most likely eventuate as a mundane "told you so," by myriad posters.

henra. You mention "Asymmetric airflow to the Pitots". This is not new, and likely precisely what occurred. What do you suppose is the obsession with ICE, here? As in, turbulence caused a/p loss? Consistent with W/S and T/CAS alerts (for arguable reasons). Given P/F made instant input at a/p loss, and the a/c did not climb straightaway, turbulence seems to have some back-up evidence, whereas ICE?

Or they could see their (true) attitude and interpreted the situation in such a way as to render nose up the best option. How about they had lost all faith in their plane and were of the opinion that it was not responding appropriately to their inputs, eg a major structural/system fault. When they tried nose down, the infernal stall warner was a shock and the last input was reversed to allow more thinking.

@AZR:
 

Correct, F/CTL page was called @ ~2:10:16 due to F/CTL RUD TRV LIM FAULT.
SD returns to normal Cruise page (if no other pages in queue) after confirmation by crew and clearing ECAM message.

Other faults present at this time don't call any SD page.

@ 2:11:40 'Capt enters cockpit', the Cruise page would be in view at the time. F/CTL page only if crew didn't cleared the messages. (not acc. protocol)

The other warnings which called F/CTL page are F/CTL PRIM 1 FAULT and F/CTL SEC 1 FAULT @ ~2:14:00 much later in the sequence.

Hi BOAC,
1. Not only the climb but the persistence of NU imputs by the PF.
2. Everything recorded (leaks) by the CVR is pointing at the conclusion that it seems that nobody ever acknowledged the stall situation, Captain included. This time, I could give some credit to the leaked informations as they are comming from BEA officials during interviews.
Today, another press article: Le Figaro - France : AF 447*: le pilote n'a pas compris la chute

Either that or they didn't trust the AI.
Maybe it contradicted their 'picture' of the situation and they considered it unreliable as well ? When bombarded with Warnings and Failure messages it may become difficult to sort out what exactly is still properly working and what not.

As a response to the question by a member here in the thread of what the pilots felt acceleration wise it has to be noted that they would have felt a normal vertical g and accelerating (slightly increasing) feeling of an order of magnitude of a take off acceleration (~ 0,2g) (Due to Pitch attitude).
Without any visual reference this could heavily contradict the preconceived notion of what you would feel in a stall.
(When training stalls in Light Aircraft at the beginning of the career you will have a ND attitude after the stall leading to a more decellerating/falling sensation rather than accelerating and normal vertical g). This together with no outside reference and dubious instrument readings might give you a misleading picture of what is going on.
Don't underestimate the power of the human 'Seat of the Pants' feeling on our perception.

@henra:
 

+1

NAV ADR DISAGREE needs 10s monitoring to trigger.

ACARS msg was received @02:12:51; CMC has 60s maximum to correlate
to any failure message ~02:11:51 - 10s monitoring = ~02:11:41.


"At around 2 h 11 min 40

We can't exclude that.
But it would only make sense if there was a prior significant and persistent attempt to try the classic stall recovery.
In a 200t Airliner you don't give up a serious recovery attempt after 5s. It will for sure take a siginifcant amount of time to get such a thing flying properly again after really enetring a stall.
At least i fail to see any significant indication of that in the information bits we have at hand.

So now that the discussion is back to the THS position, I'd like to repeat my question from post 514.

It seems that the crew made little or no ND inputs (apart from briefly shortly after the captain's return). So the THS position was not have been a factor. Whether there is enough elevator authority to recover is only a factor if they actually attempted it, no?

(I'm not making a statement on whether or not there was enough authority.)

henra, thank you. (Note: :cool: I don't underestimate seat of the pants, I've had the leans (vertigo) more than once while flying. Hate it. It's got to be fought through, and the usual starting point is by getting the attitude indicator back into the scan and keeping it there.)

By classic stall recovery, are you referring to lowering pitch (slightly, or a lot) to reduce AoA, or the TOGA and set X attitude (5 or 10, based on high or low alt environment) recovery technique? Seems the latter was attempted. (TOGA selected at any rate ...)

BOAC:

I think the problem here (system design wise) is what to do when the sensors are outside their reliable range.

Presumably the AoA sensors have some envelope in which they work. The system designers would not have turned them off for no reason. The most likely reason is that (for some reason) the AoA is not realiable at that airspeed. Or perhaps there is another failure mode they are worried about (don't throw stall warnings at the pilot if it could be because of a bad AoA sensor).

In this case, continuing the warning was the right thing to do (ie would have led to the least confusion). In other cases it might be wrong.

IMHO a better solution would be to put "?STALL?" on the display somewhere (ie tell the pilot "might be stalled but not sure"). It is hard to do when the normal stall warning is the verbal stall-stall though.

Good Point !
I referred to the lowering of the pitch.
Indeed setting TOGA could be indication of a stall recovery attempt.
However, if that fails (TOGA) the next logical iteration I assume would be ND maybe in conjunction with thrust reduction before trying rather weird techniques like full NU.