bad weather, et al
 

To Old Car. and others.......

There is no doubt that some weather started the sequence that resulted in many lives being lost. The stoopid air data sensors went into la la land. That started the sequence of events and human responses.

Anybody disagree?

So we have air data becoming unreliable, we have a system that keeps reverting to less and less "limits", we have a myriad of cautions and warnings for the crew to accept and act upon, and it is NIGHT!

I will gladly take any non-pilot system engineer or software engineer or..... and place them into the situation that the AF447 folks faced. What would they do?

Well, what's your point, Gums?

The point is to get from point "A" to "B", or drop bombs on the enema, or take recce pictures, or take some SLF's to see the Grand Canyon, or .....

BOTTOMLINE:

If we insist upon human crews in our commercial aircraft, then we have to design and implement systems that help them, but still demand some degree of basic airmanship and training.

I cannot judge the actions of the AF447 crew we see from the sparse reports from BEA, given the data we have now.

I can surely judge the sensors' failure and the control logic that causes warnings and cautions and does not take inton account a basic principle of aero - angle of attack.

I would hope we give the humans just a fighting chance to keep the plane flying when unexpected things happen, and we could point fingers at each other later.

I know that many here have flown thousands of hours and have delivered millions of SLF's. Makes me feel comfortable, to a point.

But how far are we gonna go with automation and systems that will "protect" you regardless of your basic airmanship and training?

respectfully.......... and maybe we need another forum/thread for these thots.

jcjeant : I have many sources of information, of which that was one (admittedly not a good one, but it stuck in my head). For example I don't have anything concrete on the Boeing 777 systems other than a rough outline, but rest assured, I'm not just a TV junkie getting my kicks from talking to pilots on here.

CogSim : The Colgan pilots pulled their aircraft straight into the ground - I'm not saying that's what happened here, but it does happen.

I pity the pilot in charge of this unfortunate task. :\

Gums
I think you fail to understand the nature of the FBW system used on Airbus aircraft. I must admit I don't fully understand it but from what those who know have said it is more about placing limits on what you can do with a very stable aircraft. The comments on the various threads by those who fly the beast do not talk about an unstable monster kept in the air by computers but a stable platform which is easy to fly without the protections. As the aircraft encounters different situations the protections or limits drop away but the aircraft doesn't become suddenly unstable.
It may be that there is a problem with the training regime for these aircraft and that not enough attention is paid to flying without these protections but I am not qualified to comment about this and I haven't seen any comments from Air France pilots on this board about their training and whether there were deficiencies so I just don't know. It may also be that the flight crew were deficient in their knowledge but I would not like to make that judgment yet - I believe that it is far too premature to even form that conclusion. Certainly, the pilots actions need considerable more scrutiny but to go as you seem to for a theory that myriad system faults incapacitated the pilots is too reckless at the moment.

Far too much noise and assumption here to comment on it all, but

gums #436: - please join the thread on the 'Safety' forum?

All this comment on 'deviation'/lack of is based on NO KNOWLEDGE whatsoever! Cells do move around, flight paths differ, mostly we only seek around 20 miles clearance in normal ops. We do not know what they saw on the radar nor what they discussed between themselves apart from going a 'bit left'.

I still remain surprised that the 2001 near accident to the 340 which entered an un-commanded zoom climb to a very low speed remains dismissed by many? No-one has yet explained (simply please) why the system there decided it needed to pull up so violently. That sure as hell would have confused me in the dark of the Atlantic in the ITCZ - and I would have mentioned it to the other pilot........

Edited for my mis-read of Vls.

Are you sure? From the AAIB report:
In cruise, VLS is a speed that provides a certain margin (0,3 g?) to buffet onset. The zoom climb occurred because the FCS entered into alpha-prot law and then maintains AoA=alphaprot until the pilot moves the sidestick. Alphaprot is less than alphamax and maintaining it stick-free prevents the airplane from stalling.

As we all now know from earlier posts, no such thing as "stall speed" its all about AoA. The A340 clearly went into a 'ballistic trajectory" too slow to maintain level flight at that altitude even with full thrust, around 20 seconds of "less than 1g" as it went over the top with a sharp drop in pitch angle? Its not too clear to me whether it was the pilot or protections that successfully managed the flightpath to recover speed. No mention of stall warnings, and as previously commented AoA not shown, nor how how deep the nose down pitch during recovery. See also Sully's landing on the Hudson - pilot or protections managing pitch/AoA?

No - you are right, HN, my mistake and I have edited my post - not stall speed, but pretty slow whatever you call it.
- please explain the logic here - the a/c was now here near 'stalling' when it all started and was then placed near it by the software??? So why? This defeats me. Suppose for a moment that this happened to 447. Desirable - no. Helpful - no. On a dark night in the ITCZ, confusing - yes. We know that the alpha-prot 'inhibit' would probably have been disabled by the IAS readings.

Hi DozyWannabe,
True, but that is not in any QRH / FCOM procedure. Additionally, in all laws (except Direct Law) the elevators will attempt to maintain the last requested pitch attitude (1g value) even when stick free. So there would still be no "feel" in pitch that the aircraft was slowing down. Deprived of reliable airspeed indications and pitch feel, I believe the crew would have had a more difficult task to avoid a stall than if they had been in a conventional aircraft.

Hi wallybird7
Never did I say that one can recover an out of control plane with trim alone.
And I do agree that the (auto) trim seems weird, based on the may 27th note : why did it go (almost) full NU, but didn't go less NU (or ND) when the crew pushed the sidestick ? Many answers come to mind, I choose to wait for more data on that.
That said, and it's all about semantics :
- the alpha prot/alpha floor protection in normal law does restrict the crew's control
- the bank angle protection (67° max) in normal law does restrict the crew's control
- the overspeed protection (inducing a NU command) does restrict the crew's control
- OTOH, the Auto Trim doesn't restrict the crew's control (until proven there was a mechanical and/or logical/software failure). It is designed AFAIK to follow the crew's commands (and to maintain 1g without crew's command).
And as DW stated : if the pilot doesn't like what autotrim is doing all he or she has to do is keep their hand on that trim wheel.
That's the difference I make between restricted and not restricted. And it certainly doesn't mean that I try to say the plane is "perfect" and the blame must "go to the crew". That's not what I think ;)

Turbulence caused a momentary excursion of "phase advanced" AoA beyond alpha-prot, and that put the FCS into alphaprot law (High AoA protection). That protection is lost in Alternate Law 2. I believe I have read on this thread that this particular logic has been changed as a result of the A340 AirProx incident.

Why are we not steering our cars with a knurl?
 

The way we flew airplanes before FBW had been refined over decades and was satisfying almost everyone. Why change? Why did Airbus needed to invent a new way of flying airplanes? Until now, I fail to be convinced the reason was for the pilot’s better.

It is my opinion that, after going FBW was decided, the governing specification was to extract the highest possible performance and reliability benefits off the new technology, a respectable challenge for designers, I must say. You can easily trace the major changes that took place and see where the focus was.

In the team that overview specs, the engineer/pilot balance favored the former. Of course, the engineers made a very good job. They reached their goals. Then, they managed to make the design acceptable by certification authorities and by line pilots, a not-so-easy task.

The Airbus FBW provides an elaborate high AoA protection in normal law. Is it just because it was not required by regulations that unless you trip the auto-trim it does not even provide classical low speed longitudinal stability in ALT law?

Hi,

BOAC
And I still remain surprised that the AF445 event remain dismissed by many
Even the BEA was forced to remain dismissed
Incident: Air France A332 over Atlantic on Nov 30th 2009, Mayday call due to severe turbulence

- yes, but that does not explain the logic, merely the mechanism. Why is it so designed that it operated in cruise? Why did the a/c need "High AoA protection" whilst in a high altitude cruise, and such that it would pitch the a/c up into a ...........High AoA environment? I understand the 'change' was an inhibit related to a certain Mach - not particularly useful, I feel, in an a/c without ADC data?

JC - on the face of it, 445 looks quite different. The primary need for investigation is in the handling by AF of the report and data, I think.

*Part* of the reason was, otherwise, why would they have bothered including pilots in the requirements capture phase? Also, what you're saying is just not accurate. The fact is that the "refinements" you're talking about were inexorably leading up to the point where FBW would be introduced in airliners, it was just a question of when and how. The aircraft on the drawing board in the mid-60s (B747, DC-10, L-1011) simply weren't capable of being controlled by the mechanical linkages that had been used in the past, and so the decision was made to go all-hydraulic. This led to it's own set of problems, but that's a subject for another time. FBW technology had been around since the '60s and there were a lot of advantages to it's use. It had also undergone many refinements since its introduction, making it a logical choice for fighter jets in the '70s and - as had always been the case before, what was good for the military found its way into civil aviation a few years later.

I still believe Airbus missed a trick by not instituting a pilot outreach programme at the same time it was courting airlines with the economy and safety aspects. All they had to do was say to pilots "Look, our aircraft fly like spacecraft - want to know how Neil Armstrong felt in the Eagle?", and I suspect it may have been looked on a lot more favourably. Much is made by Airbus detractors of the involvement of Bernard Ziegler in the early days of the Airbus FBW programme, which is fair enough - he's a controversial individual who said some less-than-clever things. However not so much is made of the presence of Gordon Corps at the same time - I don't think he could be described as anything other than a "pilot's pilot", and he was *very* comfortable with the design. There's a thread kicking round here somewhere from someone who was suspicious of the A320's ability to get out of extreme situations and Captain Corps took him up on the challenge - in every case the A320 in Normal Law fared better than the conventional aircraft, albeit in the simulator.

When I first read HTBJ, I was struck by D.P. Davies mentioning that some in the piloting fraternity kicked up an almighty stink about the presence of the "stick pusher" in CAA-certified aircraft - the arguments used then were much the same as those made against the Airbus FBW system today - claims of "encroachment on a pilot's authority" etc. The "stick pusher", as many will know, was a simple hydraulic ram system designed to force an aircraft which did not have good stall characteristics (particularly rear-engined T-tail designs, but a "stick nudger" was fitted to all G-registered B707s as well) into a nose-down attitude, and yet pilots of the time still claimed that it was a technological step too far. In other words, the bunfight that always occurs when the subject of automation comes up is nothing new.

The truth is that while Airbus marketed their FBW designs as a quantum leap forward, in fact it was very much an evolutionary rather than revolutionary step in terms of aeronautics - the only thing radical about it was that it was the first time it had been applied to an airliner. Boeing knew this too, and that's why the B777, when it arrived, was basically a FBW airliner with a computer-controlled force-feedback system, kind of like how a nicotine inhaler is compared to a cigarette - the old feelings are all there, but it's artificial - under the hood it's a very similar computer-driven system to that of the FBW Airbii.

Whether it has "classical low speed longitudinal stability in ALT law" has yet to be confirmed - I'd need someone who's more familiar with the systems to answer that question.

DozyWannabe's #451 describes very well my own thinking on the matter. I've had no professinal involvement with FBW but witnessed that evolution from the sidelines. I saw the evolution from fully mechanical controls, through mechanical with hydraulic boost, to hydraulic with mechanical backup plus AFCAS (Auto Flight Control and Augmentation System, IIRC) plus FMS. If I had to reply to this kind of question from a fellow-layman across the street, I would say that Direct Law gives you an airplane pretty much as a conventional airplane, but gets rid of the weight, maintenance burden and vulnerability of cables and pulleys. Alternate Law uses the opportunity that FBW offers to make the airplane easier to fly by ironing out the 'imperfections' that conventional airplanes have: it provides stability in roll and pitch, adds turn coördination and dutch roll damping. Normal Law then adds the envelope protection, and with it the age-old debate about "encroachment on a pilot's authority", expertly discussed in DW's post.
I believe that envelope protection enhances safety, even if it turns out to have features that can be improved in the light of service experience.

The question of when auto-trim should be on or off is not limited to FBW in my view, and I must admit that I don't understand the drama that some make of it. As I view it, when it operates, autotrim obeys the pitch-orders from sidestick or AP by following the elevator. If the order is nose-up, THS trims nose-up. If the order is nose-down, THS trims nose-down. At FL350 there was plenty of time for that to take effect. Maybe I got that all wrong.

HN39:
 

Actually, I used the AOA Stall warning trigger values.

Mach threshold ... AOAsw (I did edit this in the chronlogy diagram)
0.82 .................... 3.8
0.75 .................... 5.2
0.53 .................... 7.6
0.35 .................... 9.9
<=0.28............... 10.8

Quote:

---

In alternate or direct law, the angle-of-attack protections are no longer available
but a stall warning is triggered when the greatest of the valid angle-of-attack values exceeds a certain threshold.
In clean configuration, this threshold depends,in particular, on the Mach
value in such a way that it decreases when the Mach increases.
It is the highest of the valid Mach values that is used to determine the threshold.
If none of the three Mach values is valid, a Mach value close to zero is

used.
For example, it is of the order of 10° at Mach 0.3 and of 4° at Mach 0.8.

---

Just for information...

Under many conditions, there are times in both Alternate and Normal laws when the auto-trim will briefly operate opposite the pilot SS input when the SS input causes the aircraft to experience "G" noticeably above or below 1 "G" as displayed in amber on the lower display.

The same thing occurs in terms of elevator surfaces movement (SD F/CTL page) if the manual trim wheel is rolled briskly in one direction or the other with hands off the SS, i.e. the elevator will briefly deflect opposite during the manual trim wheel input.

OK, what you describe strikes me as a design "feature" that is aimed at mitigating over control, or enhancing a stability function.

But I may misunderstand you.

Is the "opposite" input driven after the initial response following SS input, or it is made if the SS input exceeds a certain rate? :confused:

LW 50:

My impression is that it's rate driven. It is most noticeable with more aggressive SS inputs creating "G" excursions, and does not occur while making the slower smooth SS inputs associated with normal flying technique.

Only my impression though, I don't know what all the computers are "discussing" at this point. I do know it has no impact on aircraft control and doesn't bother me.

L337:
 

This is correct,
thrust(N1) will be locked untill PF move T/L out of climb detent.
The cyan "Predicted N1(TLA position)" indicator is visible at the outer edge of the N1 scale.
To make the T/L setting in agreement with N1, PF needs to move T/L, as indicated by TLA position indicator, towards the N1 pointer (locked).
This must be done in 1 continuous movement otherwise N1 will travel towards this TLA pos 'bug' once TLA is out of Climb detent.

Forget the transient and trend indications these are only available in A/ Thrust.



http://i474.photobucket.com/albums/r...99/N1Indic.jpg

Although I don't disagree with much of what you wrote these items warrant some comments.

- Uncommanded climb:
Unsure what you consider uncommanded. BEA note stating that PF commanded NU on the stick prior to this climb points to the fact that it was at least not completely uncommanded although we don't know if it was deliberate (potentially not).
- Evidence of 60-70kts updraft:
I'm not aware of any indication/confirmation that the plane encountered significant updraft.
- Aispeed falling to 60kts:
Almost surely only the measured speed in the pitot due to stall of the airflow into the pitot. AoA during descent + descent rate points towards a horizontal airspeed >120kts until very shortly prior to impact where it decreased to 107kts.
- Flight Control ineffective below 120kts: Im not aware we have any positive confirmation for this although it is reasonable to assume that their effectiveness will be reduced below that speed.

ZOOM CLIMB What really happened
 

Hi Henra

All Valid questions.

“Uncommanded 7000 fpm rate of climb”. Why I think that it was uncommanded.

When a plane is at max cruising altitude (35,000) which the crew noted because the temps were higher than forecast, and therefore unable to maintain a higher altitude, why would they intentionally try to do it? Why would they climb to a higher altitude when they knew they could not maintain it?

In weather a normal climb should not exceed 1000 fpm. Beyond that you are out of normal control. Without access to the performance charts I can’t believe it would be possible to execute a climb at a higher rate than that.

There was never any indication that the pilot requested a climb nor received clearance for one.

At the same time, all hell broke loose and everything turned off.

What would cause all of these events?

Would entering a severe thunderstorm have anything to do with it?

The meteorological analysis showed evidence of strong up and down drafts of up to 60-70 knots. Which translates into 6000-7000 fpm rates of climb approximately.

Is it possible that the plane encountered a severe updraft that carried or pushed it up to a rate of 7000 fpm? Is it possible that the updraft or severe turbulence pushed the nose down at the same time the plane was gaining altitude? And if so, is it not possible that the trim reacted in the opposite direction?

And with the pitots icing up is it possible that the sensors were providing false info to the computers? Some indicate overspeed, some indicated > 60 kts. Which is which?

Was it the pilot commanding nose up or the trim system itself? Which?

And at the top of the zoom what was the state of the plane? To me in a stall that they never recovered from.

Check the charts to determine minimum control speed. I know if you’re anywhere near 120 kts you better be on the ground. Not at 35,000 feet.

Do we really “know” any of this? Of course not. Nobody does or ever will.

Stall speed
 

Hi Sensor

As we all now know from earlier posts, no such thing as "stall speed" its all about AoA.

In all my years in aviation there were no AoA indicators flying mostly all the A/C made in the US. It was/is all about Stall Speed.

Take-off speed, V1, Vr, V2, climb speed, and approach speed -- all based on STALL SPEED.
Fighters, Transports, DC-4, L-188, B-737,27,57,67. A-310, L-1011, DC-10 etc

WB, yes we agree no normal pilot would pull the side stick up at that altitude for loss of airspeed indication but according to the BEA report they did. No pilots I know would do it so why did they? The BEA report said they pulled full back, I would like to hear the CVR for why they thought that was necessary. Some day we will hear it. Probably well after the Paris air show.

jcjeant, I have been on a plane when the pilot ordered the cabin crew to their seats and said there will be some heavy turbulence. So a simple "watch out" is not even severe turbulence as I've ridden through going from the ONT to ORL or MSP. I'd not read too much into that warning to the cabin crew.

Now, there is a theory that they saw the storm ahead, thought they had a clear path, and discovered it was blocked at the far end by the grand-daddy storm. This supposes misuse of the radar due to, you guessed it, lack of training.

Lonewolf 50, "If the aircraft "knows it is stalled" but the pilots don't, what are your suggestions?"

If the aircraft is well enough instrumented to detect a stall (an AoS sensor we know it has) then why in the seven circles of Hell is that data not on the pilots displays?

jcjeant, regarding short data recorders it'd be nice if the plane was also wired with a 256 gigabyte auxiliary solid state disk on the FDR and CVR that recorded simultaneously with the survivable disk. That should be moderately recoverable in some crashes and would also have upset (and normal) data virtually for the full life of the plane.

Hi,

You forget to open the "sarcastic mode" ... this can help some who don't clever follow this thread :)
I suppose it's lesson learned for AF and they are presently installing the system you advocate ... :sad:
How do they not have thought of earlier ? ... it is a mystery that adds to all those already mentioned in this thread :8

So the A-310 didn't use this same AoA stall definition philosophy?

Technically a stall is about airfoils and peak lift AoA, and in a complex wing shape as the A330 this will not be a sudden transition.

There is a definition of "stall speed" which is the "speed below which the airplane cannot create enough lift to sustain its weight in steady 1g flight", and it is clear to me that the A340 in the airprox event went below this. The AF447 must have been close when almost levelling off @37,500 hence I have previously questioned the timing of stall warnings.

The DFDR data released in the BEA Update point in the direction of an initial climb that was commanded but unintentional and unnoticed. The performance charts you refer to show the rate of climb obtainable at constant Mach and CLB power setting. The 7000 fpm was not sustainable, it was obtained at the expense of airspeed.

The Meteo France analysis in Appendix 1 of BEA's Interim report no.1 states (values in knots added by me):
Tim Vasquez' analysis mentions that "updraft velocities of 20 to 40 kt occur occasionally" in oceanic equatorial cumulonimbus clouds.

There is no evidence at all that these updraft velocities existed in the CBs that AF447 was trying to avoid, nor that they were actually encountered.

The 1 g stall speed is obtained at 1 g at the stall AoA. It serves as a reference for operational minimum speeds such as take-off speeds, V1, Vr, V2, climb speed, and approach speed.

The stall itself occurs at the stall AoA, not at a particular speed, but at particular combinations of airspeed and "gee".

Hi HN39, re # 452

I too started my career with mechanical controls and I have really nothing against FBW or automation: I enjoyed it during my last 10 years on the 777. Perhaps it is not necessary to call Darwin :).

I think you missed my point about what I called “a new way of flying aircrafts”. It’s a way you don’t learn at flight school (at least not yet). I meant the throttle system, the sidestick controller with the mechanical link replaced by a priority pushbutton, the auto-trim and perhaps other minor systems. I understand these choices and see that they were, justified from an engineering POV. Airbus knew they were removing some feedbacks the pilots were used to. They admittedly tried to mitigate the drawbacks but pilots had to adapt. These changes were not introduced to please the pilots. Pilots don’t buy airliners anyway, airlines do.

About the auto-trim, when AoA protection is active, further nose up trim cannot be applied. You must move the sidestick backward to fly at a greater AoA. With neutral stick, speed will return to alpha prot speed. This provides stability. In ALT law, when AoA protection is not available, auto-trim is always active. Chris Scott explained that the THS would move to full nose up when unable to satisfy positive g demand in a stall. Is he wrong?
I am sure you know flight dynamics enough to understand why preventing the THS to trim up as soon as stall warning is triggered could achieve.

The function of the High AoA protection is to keep the airplane out of the stall. So it is entirely logical that this function is activated at an AoA that is sufficiently close to alpha-max so as not to hinder normal operations, yet far enough below it to ensure correct operation in all reasonably expected operating conditions. These considerations govern the selection of alpha-prot.

What might be considered illogical are certain aspects of its implementation. The AoA vanes obviously cannot distinguish between the 'mean AoA' and the short-period fluctuation caused by turbulence. These fluctuations can be mitigated by suitably filtering the AoA signal, but that would make it less sensitive and hence increase the necessary margin between alpha-prot and alpha-max. Obviously you wouldn't want to filter out the 'real' increase of AoA that occurs when the airplane flies into the powerful updraft that some posters on this thread theorize about. The designers have made the opposite choice by applying "phase advance", which amplifies the sensitivity to turbulence. I guess you need to ask the designers to elaborate the pros and cons of their choice.

The other illogical element in my view is that alpha-prot law is not cancelled when AoA decreases below alpha-prot. Again I suspect that that choice has been made after intensive investigation of all the "what if"-s, but you have to ask the designers.

Every design involves compromises between conflicting requirements ...

- I am aware of all that, but it does NOT explain why the a/c was pitched by the system towards alpha max from level cruising flight - that is the explanation I am seeking. I can see absolutely no logic in this function.

Can anyone?

Maybe you haven't fully digested my sentence: Otherwise, what would you propose for the protection to do once it has been activated?

- do I take it that you are saying that the 2001 incident was caused by alpha reaching alpha-prot during an over-speed event, then? - I would suggest that a far better solution would have been to have it NOT activate in the first place?

BOAC;

I resign.

If I may be pedantic for a moment, the absence of evidence is not evidence of absence.

The range of potential updraft and downdraft magnitudes you present, (28 kt to 60kt, depending) bounds the issue wally is pointing to well enough.

There is no reason to believe there wasn't some vertical movement in the vicinity. The questions are:
a. Did they hit a patch of it at some point during the event?
b. What was the magnitude?

Vertical air column velocity, were it encountered, would vary from about 2800 fpm to 6000 fpm based on the numbers you offer in your response to wally. That cannot account for the 7000 fpm climb by itself. It seems pretty obvious that the "big climb" was an energy tradeoff, if not in whole than at least to a substantial degree. There may still have been some vertical airmass aiding and abetting this excursion.

Take the smaller magnitude, for example. Assume for a moment that the plane encounters a 2800 fpm up draft as the pilot has begun to operate in alternate law. To get the 7000 fpm vertical rate, the pilot contributes about 4200 fpm to that via trading energy for altitude ... that's a hell of a change from level flight.

If the magnitude of air column movement is at the higher end, 6000 fpm, then the pilot (or the pilot and the plane, if that's how one sees this event) contribute about 1000 fpm to that dramatic initial climb toward 37,000 plus.

That climb input fits wally's 1000 fpm standard, doesn't it? Sure, but one still needs to consider the pitch attitude. As I was trained, when penetrating turbulent air in instrumnt conditions, you set a pitch attitude (wings level) and do your very best to maintain that pitch attitude as you get bounced around, until you get to the other side of the turbulent patch of air. The FDR data points to attitude increasing, not remaining at a particular value.

Given that data, it is unreasonable to assert (wally) that an updraft is the sole, or even primary, cause of that initial rapid climb.

That doesn't mean that vertical air movement necessarily had no input. It's an unknown, but there may be some indirect evidence that BEA can analyze to get a better grasp on that.

A gust load of that magnitude from outside would, I think, leave a trace in the g sensed by the flight control system. Whether or not this is a parameter captured by FDR is another matter. I don't understand the FDR well enough to say. I also don't grasp how the flight control system filters such external loads in the various laws.

OK's point on rate and dampening suggests to me that the system does filter of such external inputs, perhaps as part of the stability features.

If we are still discussing the A340 airprox the only explanation I have is that with A/P off due to overspeed, so flight control in Normal mode, engines put to idle by pilot action to stop the engine cycling. Turbulence caused a predicted AoA measurement above alpha prot and the High alpha protection triggered to keep the AoA down to alpha prot. Also possible the initial pitch up triggered "alpha floor" and the subsequent pitch up was in response to the sudden throttle increase?

Further references - first is by mm43?
A340 - A330 Control: Flight & Laws
Aerospace/Aviation: Airbus, thrust levers, thrust system

Only direct relevance to AF447 is that if the pitch up can be caused by an AoA spike we have possibility of a QF72 style (pitch down) uncommanded pitch up if there was a period on Normal before Alt2? I do not believe QF72 event ever explained - two faults one the generation of spurious spiky AoA data, the second the incorrect use of the bad data - they were waiting for further info from AF447 before finalizing report - hardware not identical, but maybe control philosophy?

There is evidence of absence. You can do the energy calculation yourself or look at http://www.pprune.org/tech-log/45465...ml#post6523817