The English version seems, on first reading, to be fairly good English.

Having learned my lesson of extrapolating from a David Learmont post from the Paris Air Show, I'll not revisit the cockpit door.

I will note however that the location of the captain's seat and the co-pilot's seat look to be about 30-35 meters apart on the ocean floor. The fourth seat was found about 10 meters from the captain's seat.

With respect to the belts, the English version says this:

A question is whether there is a missing phrase: i.e., "On the left side seat the lap belts were attached [to the occupant],.." or is the more accurate interpretation that the belts were no longer with the seat?

If the latter, that throws into question the assumption that the first two bodies recovered by the Ile de Sein were those of the PF and PNF in their seats.

Also,
The recording starts at 0009.
____________

Of course I want the aircraft to respond to control inputs but I wouldn't want it to change the trim. That is a very basic thing when flying in turbulence. In this case, it followed what was clearly an erroneous input by the PNF and trimmed them up into a stall, a no-no taught to every student pilot.

stall warning, displays, AoA sensors, BEA comments
 

Thank you, Wozzo, very interesting press release. Seems that some BEA investigators are concerned about some of the same things that several here are, as well. And it's not all strictly pilot error or strictly aircraft system design.

Thank you A33Z for the link to the English version of the report.

- The lack of discussion on the CVR concerning the stall warning puzzles me.

- An AoA indicator is "nice" to have, but we must examine the flight conditions it is intended to support. 'bird, Retired, Smilin' and Gums can testify that the AoA "bracket" in the HUD or the "indexer" lights were extremely valuable for approaches ( especially on the weaving deck of a large boat, heh heh). We didn't need to calculate airspeed to a knot, and we routinely landed at various weights depending upon our external loads. 'nuff said about that.

For a commercial airliner, we don't have the same requirement. Nevertheless, the AoA is very important for stall warning and recovery. The plane produces lift according to AoA and dynamic pressure!!! You can stall at many knots faster than the manual numbers for one gee.

So placing a new indicator in the displays is not a biggie for this ol' dinosaur. seems the 'bus has enough confusing displays as it is.

Use of AoA other than a display is another matter.

- Ask the above pilots if the AoA sensors ( vanes or cones) worked below 60 knots. Even if the AF447 suckers were bouncing around a bit due to an extreme AoA, I'll bet they showed a high AoA, and were not flipping back and forth from plus 30 deg to minus 30 degrees.

For the FBW system to ignore AoA below 60 knots does not seem right. Most military planes use the weight-on-wheels switch to display or even use AoA.

Further, how was the stall warning being sounded if the system had disregarded both speed and AoA?

No doubt training and manufacturer claims will come to the fore here. After all, we're "protected", right.

"We're going down, sir"

"O.K., command the plane to go up"

" I am doing that, sir, but she keeps on descending"

I would suspect she knows nothing of Rugby Union supporters from Toulouse!:}

Hi Ed,

Is that because you can't see any instance when it would be useful or because it goes against the methods you were taught flying aircraft with more "conventional" controls?

IMO (for what that's worth) there's nothing wrong with the autotrim setup as long as the way it works is taught properly. If you look at the traces the trim moves minimally under automatic control. What caused it to deviate so strongly was a series of inputs that trended towards nose-up, the majority of which were around half the stick's rearward travel limit, that were sustained for the best part of 45 seconds. What caused it to continue the movement to the stops was a full nose-up deflection that lasted between a further 30-40 seconds - that's more than 1 minute and 20 seconds of nose-up input at a deflection that ranges from halfway to the stops - at cruise level!

The trim doesn't move in any noticeable way as long as the inputs are relevant to the flight regime. The PNF notices that the PF's lateral inputs seem to be extreme, and admonishes his counterpart. He then further upbraids the PF for commanding a climb when it is unnecessary. This is why the BEA recommend training for manual aircraft handling at altitude, because in this case the sidestick inputs are repeatedly way beyond what is reasonable at that altitude and airspeed.

Well, the press release appears to be in response to the articles that appeared to have sources with in AF who are clearly not happy about the stall warning situation. Whether that relates to a well-researched hypothesis, or whether it is an attempt to muddy the waters in anticipation of the division of responsibility in the coming criminal and civil litigation it is impossible to say.

And it is indeed in the recommendations that have been agreed thus far.

Confusing how? I'd say they're pretty well laid out for mid-80s technology!

Well here's your traces (corrected values and raw) :

http://i1088.photobucket.com/albums/...ed/fdr-aoa.png

Looks pretty spiky to me after 02:11:45...

With all due respect, they never said anything even close to that...

Dozy, The spiky traces are merely an indication of how confused the computers were.
I can promise you that those AOA vanes were essentially pegged to the high AOA position after the stall, moving down slightly perhaps only when the crew tried some nose down stick.
If the traces show the vanes moving that much and that regularly, it has to be bogus.
Probably a good argument for routing the signal to an AOA indicator first, and then to the computers/ADRs as a derived signal. The computers/ADRs, it appears, cannot be trusted with the data in extreme conditions.

Hi,

A nice exercice is to experiment some reverse engineering ...
Just forget all you know about the FDR and the plane datas as released by BEA (this is the most difficult part of the execise)
Just study the CVR and from there .. try to imagine what make the plane ......

You are correct, Dozy, the crew never said that. I was being sarcastic about the system design that "protects" hapless pilots from getting into trouble. Do we have "pinball wizards" or real pilots flying these things?

An "aggressive" design would have used whatever the hell was causing the stall warning to sound to move the nose of the jet down!!! It would have some limits regarding mach, but the main operational function at the time would be to break an impending stall. "We can worry about mach later", says HAL.

The AoA traces show a fairly smooth increase, then we have what looks like a lotta noise. Could be electrical noise, could be effects from being on the bottom of the ocean for two years, but I cannot fathom the vanes/cones moving that much due to basic engineering practices of mechanical dampening and the inertia of the probes themselves. In any case, the "system" can use many techniques to "smooth" the data that is provided the main FCS confuser. Talk with me about data reduction on a test system that had crappy electrical wiring, and took us weeks to figure out the problem.

I am still not convinced that the crew had clear warnings and indications of the situation. Given that the line pilot has not been presented the combination of events and such, I can understand a bit of confusion. But in the end, I see the claims about enhanced safety and "protections" and then I see a situation where all the engineering/laws/protections didn't help at all.

Somebody has suggested the curbs were Excel made. We know from BEA that "void" AOA values are not "transmitted". So, in the BB memories, they are absent or replaced by a non numeric value. With Excel graphes, if you don't tick the option "ignore absent values", they are considered as zero. Perhaps it is simply that?

Hi gums,
It is due to the effect of projecting this graph at this resolution.
What one would see, at a better resolution, is a pike [max-zero] each time the value of one probe is invalid (NCD: no computed data). It looks so "noisy" because the value of each probe is not sampled at the same time.

e.g. if the sampling rate of the recorder is 1 per second:
0.33 s - alpha 1
0.66 s - alpha 2
0.99 s - alpha 3
1.33 s - alpha 1
1.66 s - alpha 2
1.99 s - alpha 3
etc.

With a lot of NCDs, it will become unreadable pretty fast.

data reduction
 

Thank you TK and Shad. Makes my day.

We must be careful looking at the recorded data unless we have put the test vehicle and recorders thru similar environments and exerted a lotta effort to ensure we have "good data" at the end. This incident did not lend itself to a disciplined engineering testing approach. It may well have been a "one of a kind" test point.

From my experience as a data reduction engineer, after I hung up my gee suit, the most noisy data from the sensors was pneumatic pressures. So I can see some spikes in the air data and such. Really great sensors and some clever filtering by the data reduction gnomes can help. But we still have to look at the raw data and make a value judgement.

Takata.
If I understand you correctly, and read the trace correctly, when the system considers the value of the AOA to be invalid, it applies a zero value to the signal which is momentarily overridden by the periodic read of the probe, thus creating the spikes.
When the data is considered valid, the signal remains at its last value until the next read, thus only small steps, and no spikes.

Hi Machinbird,
There is three curves (one per probe) represented at the same time, each with a small time offset. Hence, if three values are NCD, it will paint most of the background due to the three spikes. When there is only a single value, in other graphs, it doesn't produce the same effect as the spikes will be spaced.

Do you mean the case when the bogus mechanism delayed the recovery, to the point of the crash? As a frequent passenger, I would like to see the problem fixed asap, wouldn't you?

@Machinbird
- first is mach
- second is speed
- third is attitude
- fourth and fifth are alpha
NCD values are either 0 or Max. The offset is clearly visible in speed graph, and the alpha graph is unreadable when NCD.

http://takata1940.free.fr/curves.jpg

Takata,
Between the spikey areas of the AOA trace, there are brief interludes where there is a single smooth trace (apparently by all 3 probes). No spikes, and the AOA appears to briefly decrease slightly.

I'm interested in the usability of the AOA data in the system, and with weight off wheels it should be available full time. The 'system' appears to be applying a biasing signal to the data, bringing the signal to zero when the data is considered invalid, but leaving it at last value read when apparently valid. This has potential implications for future (and present) AOA installations on Airbus aircraft.

Essentially airspeed has been given authority to outvote AOA (which we already knew from the stall warning fiasco) but this is not a good situation for present and future AOA installations in Airbus aircraft. This I consider to be a fundamental engineering error, but one that can fixed, probably by better software.
I use the word error, because AOA and airspeed are both fundamental aircraft performance data, but independent of each other and derived independently. To then mix them together and prioritize them is simply bad logic.

I don't understand what you meant by leaving it at last value read?
System doesn't use those "values" as depicted here, this is only a recorded sample of several sources used. Sensors are always sensing something, at any time, when they are not physically failed. Their own output rate is many times higher than that.
If, at one point, an output needs to be considered invalid below a certain level, there is obviously a potential logic about not using it. Now, there is certainly also some room to improve this logic as far as SW is concerned.

Of course not. All air data sensors are influenced by a combination of airspeed and angle-of-attack, in addition to environemental factors which are not exactly the same at sea level or 41,000 ft.
During this stall sequence, what in fact outvoted the alpha probe was the very high alpha achieved ! Alphas outvoted themselves by making other probes displaying wrong values.
Certainly that this was never considered remotedly possible. But keep in mind that limits still apply for everything flying.
Say, maybe this aircraft is able to fly at Mach 1.2 without falling appart. Would you ask for its probes to be certified for not stopping an overspeed warning at such a speed, in the very remote case that someone would ever try it?

Well, a quick look at the English version and it is really awful to read.

A couple of queries - the BEA constantly refer to 'co-pilot's stick' without saying which one. Why is it not 'Captain's Stick' etc? Without trawling through the traces it is difficult to decipher.

According to the CVR extract the spoilers were extended at one point and not 'noted' as being retracted. It is difficult to decipher the FDR trace on this. They appear to be extended for well over a minute which adds to the 'overspeed' mental scenario. Can anyone elaborate?

To anyone puzzled by the nose-up 'pull' at 4000', I ask what exactly would you suggest they did instead at 4000' with around 10,000 fpm down? I think we are down to pretty basic human instinct here.

Hi BOAC,
It still make me sick while reading it today.
I did not noticed that. If it's part of the CVR/FDR table, "co-pilot" would apply for RHS (PF); PNF imputs are correctly labelled "Captain". If part of the narrative, where? (usually they add the seat?)
It makes
0212:04 - 12:07 - PF said "I have the impression that we have some crazy speed, no? what do you think?", and he deploys spoilers. PNF correct him "No! above all don't deploy (them)"; they were retracted immediately (~5 seconds from graph). Captain added nothing.

I am not connected to the Aviation industry.

My question is this, in the English translation in the Interim report, under 3, Conclusions, new findings, I read this:

".the copilots had not received any training, at high altitude, in the “Unreliable IAS” procedure and manual aircraft handling."

Is this perfectly normal and would this apply to other airlines as well?

Glad to notice from the English translation of BEA they concur with my explanation of the French, in that the correct translation of the CDB at 2:12:15 is:

There I don't know
There it is going down

As two distinct sentences, obviously pointing at two different instruments.

The benefit of the english BEA translation is that they will have had the benefit of the intonation. I hope they read PPRuNe as the discussions here give such a good insight in how limiting a written document can be in terms of interpretation of what really happened.

The new observations (page 77?) are absolutely damning for the crew in not calling a potential stall based on the audible warning, let alone identifying the stall and taking appropriate action.

Without wanting to judge anyone I do personally also find the lack of leadership startling. The PF clearly states he is at a loss as to what is happening but neither the PNF or the CDB take a decisive (early) lead. It's like everyone else wants somebody else to take charge.

My airline will "claim", and has recorded, that I have done "High Alt" training, inc Manual Flying / Stall Recoveries. Indeed, in the last year or so, probably as a result of this accident.

In practice this was a well advertised, briefed, exercise. In S&L flight we slowed to the stall (Alt Law), and performed a few recoveries concentrating on the "finesse" of the recovery / height loss, and reocvering at the "incipient (warning) stage".

I happened also to do a Jet Provost Flt Test last year, up to an including FL350 handling, Mach Buffet, turns / stalls.

I'll leave the reader to guess which was the more valuable lesson / refresher in High Level / Mach handling :{

Thanks - I think I can see now which stick it is, but why is there no 'Dual Input' warning at "2 h 12 min 59" onwards?

I also note (must have been asleep!) that the report says there " The pitch attitude varies from 11° to 13°." Do they really mean that? If the minimum attitude was 11 degrees that is extremely high for level cruise to start the manoeuvre.

Here is the whole (English) extract for those 7 seconds.

 The copilot sidestick is positioned:
- nose-up to ¼ of the stop position
- left to ¾ of the stop position then
right to the half-travel position
twice.
 The pitch attitude varies from 11° to 13°.
 The THS is stable at around -3°.
 The roll angle varies between 8° right and 5° left.
 The vertical speed increases to 6,700 ft/min.

RE The spoilers, I am having difficulty looking at the 'LH/RH' 1-6 lines which mean nothing to me, but there is no mention in the CVR extract of speedbrake retraction, only they are 'deployed' at "2 h 12 min 04 - 2 h 12 min 07" - is that Spoiler LH/RH3 as shown in red? Is the other (LH5) triggered by aileron input?

Selected vertical speed?
 

Can anyone explain this?


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

The vertical speed trace, left of the blue line (A/P drop off).
Vert. Speed seems to be compensated by the Selected Vert. Speed at regular intervals to keep it at altitude.
@ ~02:10:10 the zoom climb starts (no more compensation of the automation).
@ ~ 02:10:20 there's a sudden peak up, down and up again.

- Who's generating this compensation in NORMAL
- Is that normal system behaviour or was the A/C unstable before the event?
- What could introduce the peaks at ~02:10:20?


Thanks in advance for answering the questions.

Hi vanHorck,
Congrats vanHorck! your French is better than mine and I noticed that as well (in fact the first thing I looked at!)
All the ambiguous sentences are translated the exact same way a non French native (but anglophone) would have interpreted them. Note also that ambiguousness is more than one meaning, not that any other interpretation is forcibly the bad one. The fact is that we don't know more than the original text but I still doubt seriously of several "interpretations" from the English report... Zut! They were speaking French, not English!

Hence, there is no evidence either that BEA members really cared about this work, after having already released the French text without meaningful punctuation or context helpers (moreover, they are covered by their note: French texte is reference)... they might have subcontracted this translation work.

For example: do you really think that a BEA member would not catch a few things:
- Sal-Amilcar in Heading Verde ... for Cape Verde (Cap Vert)

Or translate :
- the wings to flat horizon the standby horizon (what does it mean, seriously!?)
- no it won’t (not)... not not!
- No above all don’t extend (the) ... extend "the" what?
- er no we’re in computed ... but not in manual mode!

Would you usually call the rudder controls a rudder bar?, spoilers/speedbrakes, airbrakes?
Remember what I expected from this translation: not a single clue added but certainly more errors.
:rolleyes:

DozyWannabee, do you see an anti-correlation? He asks for nose up and gets a very significant nose down. When that happens, what does he think? Does his entire mental process derail, especially if he does not recognize he is stalled?

xcitation, might a 10 degree nose down attitude give them a rather distinct impression they are in a dive, even after asking for full nose up? He asked for nose up. Nothing happened. He asked for more nose up. Nothing happened. He kept this up to hauling back on the stick all it would go. THEN the plane goes nose DOWN 10 degrees over a few seconds?

I suppose if he'd ever been properly trained about stalls in A330s he might have recognized "the real thing" and not a warning. Perhaps if he'd had a real AoA report to look at he might have recognized "the real deal" and not a mere warning.

The plane quit doing what he asked for. It went nose down, and stay there depressingly long, when he had full up on the elevator.

(And it was Takata, bless his heart, who pointed me to this in one of his messages in the last few days here on these pages. I looked at the plots, wondered about the plot being inverted, wondered about translation, wondered about a lot of things until I decided the plane was doing its own thing while the pilot wanted nose up. And I asked, what happens to a pilots mind when that happens if he's not really stall trained in the plane he is flying? Small planes don't stall that way, do they?)

That is EXACTLY why I have not filtered out some of the more irritating posters here. They have experience I do not have. And the annoyance is more at their going way out on a limb, sawing away at it, and then jumping up and down to break the limb off. That sawing and jumping part gets on my nerves.

The out of the box thinking is sometimes helpful if it's dropped once it's seen as nonsense.

There is? later. It is not systematic: this warning is triggered if imputs are not in the same way, if one pilot don't use priority (disabling other imputs)
Still asleep?:)
Increase up to 11° (started from 0°) during the sequence 0210:07 -10:18, pitch was low at the begining (likely due to thrust reduction)

Those are the next 7 seconds after my quote above for 0210:18 -10:25.
Manoeuver started at 0210:07, not 11 seconds later.

Look at straight orange curves: "Spoiler LH6", see both "V" at exact same time: released, retracted. It took less than 10 seconds.

Hi A33Zab,
Yes. the green curve represents the "selected" altitude recorded by flight Guidance. Each time the FD disengage and re-engage, it will take the current FL as the new value for "selected".... and FD disengages a lot during the first minute!
There is no impact on flight controls without AP. There is also another graph with Mach "selected", same thing.
PJ2 already explained that a few dozen pages ago!
:)

Shadoko, if I had to guess I'd suggest there was an analog to digital converter in the picture that saturated and went past saturation. Some specific types will peg and stay there. Others will wrap their N bit counter and start over at zero. It looks like the plane had the latter sort.

Hi JD_EE,
Thanks sweety!
But you should also remember that I had likely found an explanation for the first drop of the nose... not in pilot's flight control imputs!

You'll have to look closely at the thrust settings to see it. This drop happened exactly when they reduced thrust from CLB down to IDLE (hence, the following large pitch down moment) and it certainly also caused the right wing to depart at the same time... consequentrly, it caused twice the amount of confusion as the PF tried desperately to keep his wings level and his nose up at the same time.

Captain watched it, arriving at the same time. During most of the following minute, aircraft pitch was maintained up and down between -10 and +10.... but they re-applied full thrust again... really too bad. If they had stopped their pitch imputs and let the thrust to IDLE, simply controling the turn, she might have recovered naturally at this point.

Hi Takata,

We read from the same page! :ok:

The Brothers of the Christian Church in Thonon Les Bains boarding school at least taught me reasonable French, that's the only good thing to say about my education there......:ugh:

I think reading the French original in combination with the BEA translation at least gives us some indication of what actually went on in combination with the BEA interpretation.

In all I am not a conspiracy theorist and I am impressed with their Diligence so far

I don't and can't know what he thought, because he's dead. But to my mind only two things can make apparently undamaged controls fail to respond in the correct manner, and those things are:

• an overspeed into the transonic region
• a fully-developed aerodynamic stall

It would appear that the PF - initially, at least - believed it was the former, when in fact it was the latter.

Hi takata,
With reference to this question and your reply, how do you explain (on page 112 of the french report, also on page 113) the cycling of 'Mach selecté' between 02:00:00 and 02:09:55? Is this Mach_1, Mach_2 or Mach_3?

Sure, they can. with some (Cessna 150 for example), If you hold back elevator, with a bit of energy, it'll lift the nose to stall, drop the nose and repeat... On the other hand (or with another bird - 172 for eg.), if one gradually enters the stall and retains up elevator you can get the bird to mush all the way down without ever un-stalling the wings. ...The attitude during the "mush" will depend on the bird of course... The tricky bit is keeping the wings level to avoid a spin. ...and on the little birds, use of rudder is the only way to accomplish that. Any aileron input, once stalled, is more likely to induce a spin. (I've also played with that quite a bit with little RC airplanes - I have a little bi-plane that will quite happily adopt a 5-10 degree nose down, 60-70 degree FPA when held in the stall)

When I learned to fly, novice pilots were introduced to these variations of stall during initial training. I guess it might have taken quite a bit of training to get a professional pilot to unlearn stall characteristics, somehow. :confused:

I realise it may seem that way - but AB FBW in ALT LAW feels like nothing else you've ever stalled.

I can only imagine RudderRudderRat... but can it's stall really feel like an overspeed?

a33zab, I don't have the answer, but is it possible, without significant turbulence, to get these g accelerations after N1 was just decreased?

2 h 10 00 > 2 h 10 08, N1 decreases from 100 percent to 84 (or 83) percent (in response to a commanded decrease in Mach)

2 h 10 07 > 2 h 10 18, vertical acceleration varies between 0.9 g and 1.6 g.

2 h 10 23 > N1 begins to increase [from 83 percent].