CVR
 

Roland-Garros or not, ChristiaanJ, do you know any French people saying so little in 4 minutes ... ?

bearfoil,

Lex parsimoniae.

The picture is incomplete, but the gist is clear. The a/c did not behave badly, nor unexpectedly. Certainly not according to the report.

1. The PF for some reason nosed up and stalled.

2. In the stall, the corrective response was TOGA + nose up.

The answers as to why 1 and 2 happened are currently simply guesses. The clues will be in the CVR and the traces. I suspect that the answers will be much more "human" than technical - for example if the UAS was interpreted as a windsheer speed loss, then the low altitude response is TOGA + pitch up. That drill is always done at low level in the sim, and it is a regular. You know you are doing it, because it is as bumpy as hell and your speed just vanishes...

If you think that the IAS is erroneous, but you are convinced that you are flying quickly, then the lack of response to TOGA + NU will just be confusing. It's easy for us to say "well you weren't flying quickly, laddy", but if some other clue biased or confirmed his decision, then there was no escape.

The CVR will, as ever, be interesting.

I have said it before, but I'll say it again. More high altitude training is needed, including dealing with serious faults in nasty conditions. It simply isn't done at the moment.

HundredPercentPlease

With you.....100%. I framed it differently, but I did include that the a/c behaved as it was programmed to do. One can squeak a greaser in the Navy and get no more than "satisfactory".

One should not expect applause for doing what one is expected to do. The problem is almost certainly where you indicate it to be.

Are their mitigations? youdambetcha........

Responsibility is the issue, not Blame. Should the pilots develop their own paid for syllabus (pun intended)? To include coverage of events that happen once in a blue Moon? Some one has to. We have here Pilots who could write a training manual, and improve the performance of aviation. Simply reading their critique of the 'system' shows that. Tradition would have it that this Manual would not be 'selected'. The final moments of 447 were a Trade, Experience for Programming, and the result was a breached contract. As with all contracts, this one will be also 'unwound', the salient soft spots hardened with some resin, and push, please.

This time, I am hoping that the flying public, and aviators, will be better served by the ones traditionally expected to 'Fix It'.

DJ77; Since I cannot find an answer in the material available to the question you and others have asked, "What Garage Years has been asking for a while now is the value of the critical AoA (AoAc) which is used by the confusers to trigger the stall alarm in ALT law when airspeed (including Mach number) is unreliable.", I am wondering if the actual stall AoA is a function of the individual aircraft with the actual numbers supplied with the fin. We know that in Normal Law, the stall warning is inhibited at < 23deg AoA. In any case, here is something. Note that it is not the stall warning which is unavailable below 60kts but the airspeed, which is considered to be invalid data.

AOA computationThe A/C is wired in the AOA unique selection, so the ADR computes the AOA with the reading of one resolver. The second resolver is used as a back-up.

The ADR determines the corrected angle of attack value which depends on the system number and the SLAT/FLAP position.

For a CAS less than 60 kts: AOAc = 0 and status matrix is coded NCD [no computed data].

For a CAS more than or equal to 60 kts, the corrected angle of attack is calculated as follows:
AOAc = (AoA ind / K) + where:

AOA ind = Indicated Angle of Attack; K, I = Correction coefficients which are a function of system number, slat and flap configuration and magnitude AOA indication.

Hi PJ2, thanks for all you have added here. I have a simple, perhaps an even simplistic question(s), hoping you have the time to reply.

Re: your last post, what are your thoughts relative to LAW and the STALLSTALL @ a/p drop, and after PF's first control input? Had the a/c entered ALAW 1 or 2 at that point? If so, wouldn't the Alert have been somewhat close, (following) the a/p loss alerts? Would the AoA have been responsible for the Warning? If so, could the AoA have been influenced by either UP or DOWN Flow? Could the AoA have been (transient) in either very Low or very High values?

Is there any chance that the a/c could have been in Normal Law long enough for the Alert to have been triggered by greater than AoA 23 degrees? Or, if a DOWN Flow, a negative AoA?

If in ALAW 1 or 2, Would the AoA have been indicating legit? If so, how could it then silence (Cricket, STALL) and allow for a somewhat large increase in PITCH? Also a climb to 380? At the zenith of the climb, when PITCH 16, and AoA 6, instead of decreasing, could the AoA have actually been increasing to +6? I know many would appreciate your thoughts...

Caution, warning
 

From this old curmudgeon, I would wait a bit more until we can look at second-by-second replays of all the data.

Surely, several of us here have misgivings about control law reversion and cockpit displays and faulty sensors. No big deal.

I would not try to recreate the actions of the crew, especially after we have now seen many of the criteria for displaying caution and warning indications to the crew.

just some thots from an old fart......

Hi,

The solution ??
HeadUpFlight.net

Hi Bear;

At its zenith ...At that point the v/s became rapidly -10k ft/min and the AoA continued to increase except for a short period when ND inputs were made and the SW sounded again.

Hyperveloce,
Symantics. It is reporting events, it is a report. The fact you say it was released under pressure from Airbus before an airshows says that this is intended to be a damage limitation exercise, which is pretty damning and would confirm my worst fears about the politics. It is then clearly apparent that the intention is to get the pilots to take the blame, as evidenced by the lack of clarity and spin in the report.

jcjeant,

Thanks for the HeadUp Flight link. I read the article relative to who is in command, the pilot or the computers. It is a worthwhile read, like anything, some will agree, some will not, but it is food for thought.

The article can be found here:
Pilot or Computer in Command

mm43

Thanks much. So one can assume that acceleration down from the top was pretty much non-aero? For a visual, would it be correct do you think to say that the tail was falling faster than the nose? (At first, AoA from 16 to 35 degrees, til impact?)

Also, that the increasing AoA during climb may have had little to do with controls, more to do with loss of velocity?

Sciolistes

Actually I have rarely read an aircraft accident report more loaded with innuendo.

A great deal is made of

however despite...

...it is perhaps more significant that

I believe it is likely they had insufficient pitch authority to recover from this. The only question is whether there where any other things they may have tried. However the lack of detail between 2 h 12 min 02 and 2 h 14 min 28 means we do not know.

Knowing it all
 

JD-EE

Just to clarify: Regarding a pilot being "Released" for flight, no where would I indicate anyone "knows it all" or is a seasoned pro. But instead is merely qualified. Period. Hopefully as you said one will continue to learn and grow.
But you can't also make the case based on merely numbers of hours.

With the extremely limited bits of information on conversations between the pilots no one really knows what went on and what happened amid all of the confusion.

Yes. Limitation, or prevention of damages, by media speculations, including the internet.

Feeling the speed
 

Regarding feeling the speed, every pilot knows that if you're eyes are closed and you jiggle the stick, you cannot tell anything regarding speed, attitude, or up or down. It is called VERTIGO.
Trust your instruments, and if they don't work then you got trouble.

Bearfoil;
The following graphic (an adaption of one originally posted by Tailspin Turtle) should help with the conception. Note that all the speeds are in terms of GS and that the THS angle of incidence is 13° less than the nominal AoA experienced by the wing.

http://oi56.tinypic.com/52lv5t.jpg

The 13° NU position of the THS will most likely have helped in stabilizing the descent - see post #1393 by PickyPerkins and post #1395 by grity.

Stallstall
 

The complete STALL WARNING Tables:
Typed it over and copied as image, so no warranty on typo errors!!

http://i474.photobucket.com/albums/r...STALLSTALL.jpg

bear;

I'm a data guy and gums is right - a detailed analysis isn't wise nor is it possible. I think dissecting the BEA Note word-by-word and looking for subtle meaning between the lines is a mug's game. We'll have a lot more in less than a month and they know that. They'd choose their words carefully of course but eventually it will all be there to examine.

Re your questions:

Re: your last post, what are your thoughts relative to LAW and the STALLSTALL @ a/p drop, and after PF's first control input?
The a/p dropped out due to NCD [No Computed Data - airspeeds]. As a result of the NCD, the flight laws reverted to Alt2 as designed. No control is lost, no squirrelly behaviours lurking, just an airplane with the same flight controls as before. No big deal. Really. Ailerons respond the same way, pitch is gee-driven with "limited feedback and gains." If one is accustomed to the airplane, hand-flying it at FL350 is a non-issue providing one is gentle and makes tiny corrections. The airplane WILL respond aggressively (as it is designed to) if large, swift inputs are commanded. Take it from there.

Had the a/c entered ALAW 1 or 2 at that point? If so, wouldn't the Alert have been somewhat close, (following) the a/p loss alerts?
The Monitoring process of the paired, "Command/Monitor" design of all flight computers provide input to many other computers including the FWC which distributes the messages to the CMC (ACARS) in the manner described in the first BEA Interim Report.

The timings of events are details and may not even be specifically recorded at the moment they occurred, though their occurrence is recorded. As with the ACARS messages when we saw them for the first time in July 2009 or so I don't think we can take very much from the order of failures.

Things were unfolding rapidly and it takes time for other things to catch up.

In part, that's why its important to wait for things to settle down, and, other than maintaining controlled flight by maintaining pitch and power before the failure, see how the loss of airspeed unfolds.

Very little by way of aircraft behaviour or external environmental factors when flying a transport aircraft requires immediate, instant response from the crew. The pilots here could name the few that do require swift, accurate action, and the UAS is not one of them at cruise altitude. A TCAS avoidance event should never be noticed in the back, for example.

Would the AoA have been responsible for the Warning?
The stall warning is AoA-driven as is now known, but as per A33Zab's excellent and very helpful post above, the AoA at which the stall warning triggers is the summation of Tables A & B and where applicable, C. (I don't know what the 2 and 3 digit numbers mean in the Slat-Flap Table in the table below Table A.) Other than what the tables indicate, the airspeed (CAS & Mach) do not have any link to the stall warning system.

If so, could the AoA have been influenced by either UP or DOWN Flow? Could the AoA have been (transient) in either very Low or very High values?
Very momentarily, perhaps, but the variations would be tiny - half a degree, etc. I've accessed the "Alpha Lab." parameters page in the ACMS menu many times and watched the AoA as well as the VRTG and LATG while in turbulence. The AoA varies around a pretty constant reading of 2.3deg NU or so, (>3 would be unusual, in my experience), depending upon weight. There is no evidence of a significant, sustained up/down draft in what has been provided by the BEA. While the aircraft was in unstalled flight, I doubt very much whether low or high values would obtain at all by up/down draft - weather. One minute before the first event, no one was especially excited or concerned about the plan to divert around weather. Not impossible, but unlikely/improbable.

Is there any chance that the a/c could have been in Normal Law long enough for the Alert to have been triggered by greater than AoA 23 degrees? Or, if a DOWN Flow, a negative AoA?
No on both questions. The pitch up did not begin until after the reversion.

If in ALAW 1 or 2, Would the AoA have been indicating legit?
We have to grant that the AoA data from all three sensors was working normally in the three hours before the event. Finding/seeing an abnormality in the data would not be difficult, even given the small changes; such would likely have been mentioned in the BEA Note. On the reversion to Alternate Laws, the flight control laws have nothing to do with the AoA-Stall warning system.

If so, how could it then silence (Cricket, STALL) and allow for a somewhat large increase in PITCH? Also a climb to 380?
Please reference the very fine work done by mm43 - an excellent presentation I think, then in the mind's eye, rotate the airplane about its center, imagine high-speed airflow from left-to-right and imagine what that flow does at the surface of the wing, and how the angles he has drawn change. Not to simplify but to emphasize, airflow around the "interruption" of an aircraft wing into airflow, is a "living" process, always changing, always in motion, always balancing the forces in response to where it is pointed and where it is actually tracking. (That is the value in the FPV on the PFD...used it many times to do steep turns in the sim! - they may have tried it to verify what would have been a "beyond-belief" rate of descent).


Specifically, Pitch and AoA are not linked so a conclusion that the pitch was "higher" does not necessarily link to a higher AoA which had originally triggered the stall warning.

Pull a bit too quickly on the stick even for a second or two and the AoA can go from 2.5deg to 6 very quickly while the pitch remains essentially level as the huge mass (airplane) catches up in another second or two.

High altitude flight is very different than work down lower. As Davies points out and as those who do this work know, the damping effects upon the aircrat of thinner, (at 350, less than a quarter of the density at SL), air are far less effective. He specifically, clearly, cautions that one must be gentle with the aircraft. That hasn't changed in fourty years whether cable-and-pulley or fbw with protections.

At the zenith of the climb, when PITCH 16, and AoA 6, instead of decreasing, could the AoA have actually been increasing to +6?
That's a question which must be answered by the data. We cannot go by how the text is written in the BEA Note - the data's the thing. We know the AoA rapidly ended up at 16deg just after the zenith and increased from there.

There is nothing "new" in any of this. It is standard stuff learned in courses on high altitude flight, weather, aircraft systems and so on as part of the craft. As always there will be nods and disagreements but the general principles hold.

PJ2

A bonanza, and I am most grateful; I am sure others are also. I note especially the need for gentle handling at altitude!

Milsabords,
If an accident investigation is manipulating the release of information in order to manage the debate on a particular accident, then by definition there is is an intention to subvert the message. This is quite clearly apparent in this BEA report and the subsequent news coverage. Therefore, in effect the effect of the report is to create speculation, in this case speculation over the implied sub-standard performance of the pilots.

If there were no interim or update reports of this nature, then there would not be any, meaningful speculation in the media as the public would be aware the final and most complete assessment practically possible will be released in due course.

It is extremely concerning that people justify the release of that BEA update, clearly worded to divert attention away from a sub-standard aircraft configuration ahead of a major sales event! I just don't understand how this can be acceptable.

PJ2, re # 1805, 1819, DJ77, #1793, et al.
As I understand, there is a step change in the value of stall warning at the transition between normal and alternate laws (upper vs lower tables in # 1818) and it is also possible to infringe the lower, alternate boundary, in turbulence or gentle maneuvering at high altitude.
Both values of stall warning are a function of Mach as aerodynamic stall AOA decreases with increasing mach No, and alternate law has no stall protection; thus at higher speeds the warning is at a lower AOA. The details are explained in What is a stall.
Also at higher Mach No, trim (THS) is biased to counteract the Mach induced nose up pitch moment (Mach trim in conventional aircraft); I assume that this moves the THS slightly nose down.

At the moment of changing law (airspeed mismatch / failure), the control response is identical except for the stall warning. In addition, the aircraft aerodynamics and the control surfaces, THS/elevators, are matched - the aircraft is 'in trim'.

“Hypothesis”. If we consider a slow blockage of the temperature sensor (cf Vh-EBA ~ 30secs), at some time before the pitot blockage, and that this resulted in an increase in computed Mach (cf VH-EBA); then the Mach Trim function could be incorrectly biased nose down. In auto flight, this would probably be countered by an up elevator demand (all small amounts), but the aircraft would be technically mistrimmed as the wing aerodynamics and the control surfaces, would not be matched, i.e. the wing was not creating a nose up moment – no real Mach increase, but the trim was set to a real nose down position due to a false Mach increase.

When changing to Alt Law, - the point of pitot blockage and autopilot disconnect, the aircraft would be mis-trimmed for level flight. If the trim aspects (THS, control stick – elevator) were not zeroed out electronically (and I can’t see how this might done at this time), then the resultant effect might offset the 1g level flight demand such that nose up control input was always required, i.e. the zero control position did not result in 1 g flight – in this instance level flight. An obvious question is what exactly does the FDR record as ‘control demand’?

Following on, the PF would require a nose up movement just to fly level, but at some point, this should command auto trim (THS) – nose up, but what the null trim datum would be, either the stick centre (no demand), or offset THS datum due to previous false Mach, is unknown.
Again, the values might be small, but sufficient such that the PF would have to control a mistrimmed aircraft, perhaps with increased sensitivity and tendency to over control which could trigger the earlier stall warning.
Add to this any control activity with regaining altitude; cf VH-EBA, -300ft (more nose up demand and thus THS nose up), and any latent perception of increasing Mach (false value), again nose up attitude demand to reduce speed.

This is a very complex technical scenario dependant on where the trim datum (null control) might be positioned when changing to alternate law with erroneous Mach. The elements which trigger the mismatch are highly likely to be present; the details in the control law are unknown.
However, the hypothesis might provide a reason for the propensity for nose up control and trim movement (FDR), the early stall warning, and in the extreme (and perhaps most important), the mis trimmed interaction with normal control in alternate law might provide a reason why the trim ran fully nose up and ‘apparently’ did not move in the opposite direction, as the THS never achieved its (false) null position.

AoA sensor experiment
 

I had a Giannini Controls Corp, vane type AOA sensor in my hands today and took it for a ride in my car. Wind was still, so no wind correction needed. Movement of the vane was slightly damped, but I noticed the vane come alive at 15 mph on the speedometer.

I also accelerated the unit perpendicular to its axis at around >1 g and did observe the vane moving, but smoothly and without slamming. When turned so its axis is horizontal (normal aircraft mounting position), the vane stayed where it was left and did not fall "down" under gravity.

This vane is typical of those used on Airline aircraft in the 1970's and 1980's (and the A-4 Skyhawk). Physical characteristics of this vane are assumed to be comparable to the A320 AOA vanes.
There appears to be no valid vane function reason for invalidating AOA indications at 60 knots.

The military AOA systems I flew were fully functional on the ground and in the air and at any speed. When we flew a bit of a tail slide maneuver in the A-4, the indications were useful in preventing post stall gyrations.
I avoided tail slides in the F-4 since it had some flat spin modes that were unrecoverable, but at very high AOA, it always told you what you had to do with the controls to recover normal flight, even if you were well below level flight stall speed.

Sciolistes

Very interesting reading of the tea leaves floating at the top.

For extra credit could you interpret for us why no additional information has been released.

Do you suppose they are now sitting on a bombshell that changes their direction? Or are they, like this forum, struggling to understand who commanded what and why in the flight of the aircraft ?

In normal conditions, to achieve +7000ft/min from FL350 on a single NU input, you effectively need a lot of speed initially, or a quite aggressive input, or ...
Be aware that the BEA did not mention that the trim moved during the initial climb from 350 to 375.
Please, would you have again a link for VH-EBA.

CONF iture...this should do it:

Investigation: AO-2009-065 - Unreliable airspeed indication - 710 km south of Guam, 28 October 2009, VH-EBA, Airbus A330 202

lomapaseo,
I don't suppose anything other than why?
They are struggling to understand it less than us, I know this because it is clear that they released a report that contains less information than they are obviously aware of?

Just re-read the BEA report looking to see if the word 'stall' was reported at any time as having been used. If the pilots had recognised a stall, surely even a very summary report would state that at x time the pilot recognised the stall. Anyway,

First off, would the normal response to: :
At 2 h 06 min 04, the PF called the cabin crew, telling them that "in two minutes we should enter an area where it’ll move about a bit more than at the moment, you should watch out" and he added "I’ll call you back as soon as we’re out of it".
be to secure the cabin ?

Second:
At 2 h 12 min 02, the PF said "I don’t have any more indications", and the PNF said "we have no valid indications". At that moment, the thrust levers were in the IDLE detent and theengines’ N1’s were at 55%. Around fifteen seconds later, the PF made pitch-down inputs. In the following moments, the angle of attack decreased, the speeds became valid again and the stall warning sounded again.
At 2 h 13 min 32, the PF said "we’re going to arrive at level one hundred". About fifteen seconds later, simultaneous inputs by both pilots on the sidesticks were recorded and the PF said "go ahead you have the controls".

Is this all the information released ? That statement leaves a period of one and a half minutes empty of data, that is a big fraction of the whole incident time. And these simultaeneous inputs, no information on what they were, eg NU ?

I thought I saw other information but can't find it so apologies if I am behind the curve.

Hi,

I assume your question has to relate with the many victims found on the surface and thus apparently were not sitting in their seats or did not have their seatbelts closed ?

I believe the report was released to show that the plane did everything the pilots told it to do so that AirBus could use that at an air show. The plane did what it was told to do and what published documents declare it was programmed to do. I don't believe it was done to give any additional useful data.

Do you see anything to make you think otherwise?

Jcj, indeed so, especially as the message was I'll let you know when it is ok again. Doesn't seem like the dynamics were sufficiently severe to prevent taking a seat, as the forces would have produced some recognition and action from the FD, other than what seems like incomprehension. So why weren't they sitting down - were they also unaware through the nature of the forces that something was so wrong ? If the instruction from the FD was such that it was a command to secure, then all this musing by me is irrelevant.

Despite all the thoughts about control laws, aoa indicators, what should have been done and so on, I hope the first step is to understand why these capable pilots were not presented with the crucial defining information to let them understand the situation in a timely way. Hence my unproductive search to see if 'stall' was said at any stage.

Edit: JD-EE, well it does make you wonder I agree.

Stalled tilplane
 

Thanks for that picture, mm43. I tried in a previous post by numbers, but your picture is excellent and shows, that the tail was stalled as well , and that trimming the THS ND would have increased the AOA of the THS and thus probably would have had no effect in getting the nose down. Hell, at 60° AOA that THS is nothing more than a big door producing no lift but only drag.

Might be, that the NU input by the PF causing a reduction of THS AOA produced some response (also not the desired one, probably smoothing the ride down), the ND input causing negative response symptoms due to complete stalling of the THS.

I´m familiear what happens when a wing profile stalls (relative airflow from the underside of the profile), however in the case of the THS the relative wind hits the top of the profile, as the THS has the camber on the downside (producing downforce).

Could somebody explain the behavior of an airfoil like in that case? At what AOA would it loose it´s effecftiveness and could even a kind of "reversal" take place?

safetypee,

Mach number calculation depends only on impact pressure and static pressure. Possible TAT probe anomaly (due to icing) is no factor.

RetiredF-4

Wie gehts? What do you make of the initial STALLSTALL?

At Mach.82, it takes very little NU to produce the (cricketStall)?

IF PF input of NU caused the alert, could it in some way be related to an unloading of the a/c such that the ensuing climb was negative "g"? Actual Stall?

That would make the climb negative g, and ballistic in character. If g = < 1 wouldn't the PF maintain pull? Likewise, would not the a/c follow his input with THS (Leading Edge) DOWN?

If negative, the pilot would feel a profound "falling" sensation, as would the airframe? Hence his pull throughout in concert with THS TRIM? He had no visual reference, and his instruments would not be helping, "No valid indications". He would not feel deceleration (It would also be felt as -g), and at "over the top" the negative would increase rapidly as the a/c started to "fall" having run out of energy? This could explain his reversal to ND at the top, the additional neg. g he may have taken for the Nose falling through at "Stall".

Was the game over at a/p loss and first "STALL". This is a heavy a/c with beaucoups energy to sustain a short climb of 3k feet?

For this, the a/c would not have fallen off the Nose, so was the THS stalled, and Center of Gravity aft enough to prevent the Nose from falling through?

When I trained, we practised "maintaining Stall". Instead of releasing the HS and Pushing, we held it back, sufficient to continue the Stall, the effect was a MUSH, a way to lose gobs of altitude in short order.

There was a trainer available that was rumored to have "Inadvertent IMC" recovery solved by initiating this >MUSH< descent through the TStorm, and break out beneath to recover. It was said this a/c could actually "land" in this configuration, and slowly enough to prevent serious injury.

Every pilot knows it is possible to "fall" UP.

Stallstall
 

@Mb:

Maybe, not sure! this lower CAS speed limit is introduced for maintenance. Sometimes we need to jack (WoW) the A/C for a longer period of time and don't like to introduce spurious Stall Warnings because its highest priority (#1) will prevent other aural attention getters to be noticed.

Why would one jack the A/C in a 60 Knots violent storm? We surely don't!!But for certain tests we have to simulate a - as close as possible flight situation- and therefore can select all kinds of WoW situations. (Nose, LH or and RH main gear) in CMC and that's allowed with all kinds of wind speeds.

Pulling CB of FWC's -to silence the STALLSTALL- for maintenance isn't an option because will also prevent other alerts and warnings to be shown.

I think 60 Kts was initial a compromise, as said before they have changed that with the BUSS mod.

Hi, and eventually sorry by advance if this have allready been said.

It seems to me somewhat indredible the aircraft computers did not give any warning: as they were registred by the "black boxes", the vertical speed AND AoA were "known" by the computers. Even if there was some abnormalities about air speed , those datas had to trigger some warning: they, alone, were the sign the aircraft was stalled and falling.

About the NU inputs: somebody has told they can be the result of PF thinking of windshear. It would be very interesting to know about the two or three last simulator trainings of the PF (and other two crew). If one or more of those trainings were about windshear, maybe he (they) had (have) a tendancy to reproduce this case. It is a phenomenon well known, in medical domain for example: if you read some litterature about a rare pathology with relatively common symptoms, you have a tendancy to think about this one if your patient has those symptoms, even if it is not the most probable, statistically speaking.

I think it is not acceptable to post this kind of rubbish about what you call a sub-standard aircraft configuration based on the limited amount of data we have at the moment.
There was a really good discussion going on about the technical aspects.
Can we please refrain from spoiling this with this kind of drivel ?!
Thanks !

Historical Info
 

What is heartbreaking all the way around is the mode of failure. One moment all is fine, and the next the speed is unknown/unavailable/kaput. There was no opportunity to take note of the situation immediately prior to failure. Had the PF had his eye on speed at the time of pitot icing, he would have known the stall warning was spurius. Is that true?

Would it help to have a display of a minute or two of historical data, something like an FDR trace on a display with a few parameters such as speed, altitude, AoA available for a situation like AF447? It would have been immediately obvious that the speed was fine 5 seconds ago. Maybe there is a way to display this information in a more helpful way. Or, would that just contribute to the confusion?

Altimeter display?
 

From an ignorant newby.
I have found no mention of altimeter display either here or in the BEA report. You mentioned the aircraft falling vertically. Is it assumed that the pilots knew this? If they did they would also have seen the initial climb, wouldn't they.
Please be gentle, I almost did not dare to post.

I would expect that NU input would not unstall the THS as the AoA at the leading edge remains unchanged. And that is where the separation occurs at a stall.What happens downstream won't change that.

NU input will only reduce drag and effective area, so reduces drag in the direction of movement, thereby reducing Pitch Down forces. At an AoA of 61 ° drag acts also as lift (Factor 0,87) .
ND Elevator on the other hand would increase drag and effective area, thereby increasing Pitch Down force.
Albeit probably not by much.
But I would not expect any inversion effects in this case.

Why AOA is disabled <60 kts?
 

A33Zab
That would be an unfortunate tail wagging the dog approach to a minor engineering problem.

With a computerized aircraft you no doubt have maintenance modes you can enter (that are locked out during flight operations). Besides, how do you test the stall warning system on the ground then?

The 60 knot limit below which AOA is disabled more than likely results from another corner of the envelope. Something such as flow impingement from thrust reversers at low speed (on the ground of course).