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AF 447 Search to resume (part2)

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AF 447 Search to resume (part2)

Old 7th May 2011, 04:28
  #841 (permalink)  
 
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Rob21, I understand (from the old thread) that this is not at all uncommon for bodies floating in water. The flexure and water action effectively strips corpses.
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Old 7th May 2011, 05:08
  #842 (permalink)  
 
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oldengmkr, that report is rather interesting to this non-pilot for a couple reasons.

I had something modest to do with developing GPS. So I am well aware of the likelihood that planes will end up perfectly aligned vertically if they are on the same track. This raises an interesting question for such cases. Should there be a generic track offset of maybe 400 meters per thousand feet with some mean flight level being on the nominal track so those above deviate port and those below starboard? It should be possible to maintain that separation very closely.

And I also received with interest your primary reason for posting this. I believe some remarks have opined something of this sort is likely to be what happened to AF447. Take the 340s upset and add to it loss of airspeed indication; and, I (still) consider it very unkind for the AP to metaphorically speaking throw up its hands and say, "Pilot has control." That's an inaccurate and impolite way to phrase it; but, it surely gets attention around here when I phrase it that way.
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Old 7th May 2011, 07:24
  #843 (permalink)  
 
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Takata - thanks for the notation on the debris map!

What is the large (largest?) item/section far to the right of the engines (circled in blue)?

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Old 7th May 2011, 08:38
  #844 (permalink)  
 
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oldengmkr;

Thanks for the link to the AAIB Airprox report. I note that the analysis focus is TCAS and RVSM issues, whereas I am mostly interested in the autoflight aspects as they relate to AF447. Would you know where to find Appendix B?
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Old 7th May 2011, 10:29
  #845 (permalink)  
 
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mm43,

To the contrary, biological activity continues in the deepest parts of the ocean, and includes critters engaged in active "recycling".
Yes, it´s clear now. I reached this conclusion by myself after reading about "marine snow".
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Old 7th May 2011, 11:54
  #846 (permalink)  
 
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Originally Posted by ventus45
1. there is a black/green-ish square
(A) what is it's significance ?
(B) where they expecting the recorders to be within that area perhaps ?
(C) where the the recorders actually found within that area ?
(D) if not, do you know where they were located ?
From what I heard in the BEA videos, this is the penciled square zone where they were looking in priority for the CVR/FDR and they called it "the heavy debris field / North East zone"; There is also, inside it, a black circle with a black cross drawn on it: I guess it is where they discovered the FDR's chassis.

Originally Posted by ventus45
2. the engines are marked one and two.
(A) do you know if that means port and starboard respectively for sure ?
(B) could they be just convenient number designators ?
(C) could they be reversed, ie, starboard and port respectively ?
3. the two wing & MLG groups are marked, but not annotated.
(A) do we know which group is port and which is starboard ?
For sure, no but they are labeled by hand on this map: "Engine #1" and "Engine #2", so I guess also it means what you think.

I can't read most of the details written about the wings and I'm not even sure the western one is finally a wing as it looks like one from its shape on those video frames but when I cross-checked with other documents, I believe now that I may have been wrong. The first big piece of wreckage west of those engines seems also to be captioned "wing".

The legend at the top of the eastern wing looked like a couple of capital letters followed by "MLG" but it may be simply "WING". "Wing" is also handwritten below it (most captions are a mix of French and English). I can clearly read "fuselage section [unreadable]" from various captions.

Originally Posted by ventus45
4. do you know where the APU is ?
5. do you know where the flight deck is ?
6. do you know where the avionics bay is ?
7. do you know where the HS is ?
No, no, no, no!
There is definitively not enough pixels on those frames to go further into the details and, well... it is also killing my eyes.

Originally Posted by Machaca
What is the large (largest?) item/section far to the right of the engines (circled in blue)?
You are right about the engines circled in blue and I have no idea what is this lonely large piece of wreckage east of them (which is not pictured on the other map). I'll guess this is a fuselage part which had some buoyancy remaining and that drifted back to this place as all the wreckage, excepted it, seems to be obviously spreading from East to West in the deep.
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Old 7th May 2011, 12:29
  #847 (permalink)  
 
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autoflight etc.

JD-EE

It is, at the very least, "unkind" of the AP to "dump" control of the aircraft back in the hands of the pilot under such highly adverse circumstances - perhaps beyond the skill of any human to deal with. I find the work being done by the folks at Bielefeld University (AG RVS - Welcome to Networks and Distributed Systems) on the human/machine interface encouraging in this regard. Hopefully they, or others engaged in such work, will soon find a better mode of the AP relinquishing control when circumstances are beyond its capabilities. They have some additional comments on the AAIB report here: AG RVS - Computer-Related Incidents with Commercial Aircraft. The AAIB recommended that overtaking aircraft indeed adopt a lateral separation approach but its implementation is complicated by rules in differing flight juristictions. Bielefeld also has an ongoing analysis effort related to "Computer-Related Incidents with Commercial Aircraft" found here: AG RVS - Computer-Related Incidents with Commercial Aircraft.

HN39

Unfortunately, I have not been able to find Appendix B of the AAIB report but I will search further later today. I had hoped the Bielefeld link I mentioned above would lead to the Appendix B but it did not. The AAIB, IMHO, "punted" on the autoflight aspects of the incident stating "The fact that this law was not triggered until 10 seconds after the autopilot disconnected was a random event driven by the severity of the turbulence. Had the turbulence been more severe at the first encounter and coincident with the overspeed warning, reversion to AoA law could have been triggered as soon as the overspeed condition disconnected the autopilot. Nevertheless, it should be noted that had the autopilot remained engaged, the AoA law would not have been invoked because it is inactive except in manual control." Note the italics and bold are mine for emphasis of that sentence. Perhaps AF 447 also experienced such a "random event".
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Old 7th May 2011, 13:16
  #848 (permalink)  
 
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MLG = main landing gear.
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Old 7th May 2011, 13:37
  #849 (permalink)  
 
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Originally Posted by Aileron Drag
MLG = main landing gear.
That is what I thought at first [?? MLG] at the top and below in small letters "wing". But, more likely, it is simply written at the top also "WING" in capital letters as the first sign is a large "W" instead of two unreadable letters.
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Old 7th May 2011, 14:01
  #850 (permalink)  
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takata

Bonjour. Thank you for your debris map, it was most welcome.


Let me run past an elementary proposition, to see if, as a simple set, it establishes some foundation.

Three miles port side of the airway, at cruise, the pitots Ice, and airdata is lost. Due Unreliable Airspeed, the ADIRUS 'quit', auto flight/autothrottle are lost, Normal Law is degraded to Alternate, and the pilots need to quickly manage the a/c to retain control.

The exact mechanism of LOC is not known, but the a/c contacts the water below, Belly down, Tail low, mostly intact, and is destroyed. From the debris field, it appears that due to its very compact spread, there was little current to cause dispersion, but the direction of the current is suggested as East to West, and that if the debris field is searched further to the west, at some point debris would reach its ultimate distance from the heavier pieces.

No conclusion relative to the flightpath can be discerned from the orientation of the debris ?

No conclusion can be ascertained from the debris as to which direction the nose of the aircraft was pointed at impact ?

The impact point can be estimated to some degree with data known about the rate and distance of the sinking engines, by unwinding its path down ?

The Captain's rest ended at 0200, and he was likely in the cockpit, perhaps even taking his Left Seat at the time of the Master Caution (Cavalry Charge), leaving only the F/O seated and restrained ?

The attitude excursions allowable by the a/p affect the ride of the a/c; did the a/p disconnect due its inability to manage the a/c ( Turbulence ), or due an already Unreliable A/S ?

Merci beaucoup, mon ami. Vous ete l'Homme.
 
Old 7th May 2011, 14:08
  #851 (permalink)  
 
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Rob21,

From the article in the New York Times where the author met with the coroner in Brazil who did the autopsies.

The far wall lighted up, and we began viewing images from the autopsies. “We took pictures of everything,” Sarmento said, scrolling through pictures of watches, necklaces, earrings and rings, still clinging to blue-green wrists and necks. “We were able to make all of the identifications.” As the images flashed by, he added: “All the autopsies were observed by the French and by Interpol. Not one country, not one family, complained about the identifications.”
...
He leaned forward in his seat and wrapped his arms around his knees. “They were like this,” he said, holding the crash position and looking into my eyes. Then he sat up quickly and held his hand flat above the table. “When they hit,” he said, slamming it down, “fractures. I believe the pilot tried to land in the water. This is consistent with the fractures. But when the bodies arrived, the lungs were already in a state of decomposition. We didn’t have conditions to see if anyone drowned.”
....
“So it’s possible that some of them were still alive?” I asked.

Sarmento nodded. “Most died on impact,” he said. “Some could have survived.”
....
A few days later, in Paris, I stopped by the office of Alain Bouillard, the lead crash investigator for the B.E.A. After studying thousands of pieces of wreckage, Bouillard came to the same conclusion as Sarmento about the plane’s landing. Many of the items recovered, like meal carts, were found with their contents compressed from the bottom, and pieces of the plane’s underbelly were flattened as if struck from below. “There is a high probability that the aircraft landed in one piece,” Bouillard told me. “We are reasonably certain.”

“The medical examiner also said it’s possible that there could have been survivors,” I said. “Do you think so?”

Bouillard was silent. “I don’t know,” he said. “It’s impossible to say.”
http://www.nytimes.com/2011/05/08/ma...ted=1&_r=1&hpw

I don't think that a body losing clothes would retain a necklace.
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Old 7th May 2011, 15:30
  #852 (permalink)  
 
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Hi Bearfoil,

Originally Posted by Bearfoil
Let me run past an elementary proposition, to see if, as a simple set, it establishes some foundation.

Three miles port side of the airway, at cruise, the pitots Ice, and airdata is lost. Due Unreliable Airspeed, the ADIRUS 'quit', auto flight/autothrottle are lost, Normal Law is degraded to Alternate, and the pilots need to quickly manage the a/c to retain control.
At least two automatically monitored reliable ADMs were needed to keep all flight enveloppe protections active, which was not the case anymore at this point (02:10). Then, most automatisms turned off, but were supposed in "safe mode" (A/P, A/THR, PFD, RTL,...), kicking ALT2 law, until the crew took some action by selecting which AS data was still to be considered reliable (by rejecting other). Note that this state (ALT2), once kicked on, can not be reversed until after landing. Then, the action required was for this crew to monitor all their informations about curent air speed after having selected a safe and defined pitch & thrust profile. This aircraft control should not have been compromised by this event alone, meaning, an adequate crew reaction (or without reaction at all. In some other cases, they just did nothing until A/S anomalies ended by themselves).

Originally Posted by Bearfoil
The exact mechanism of LOC is not known, but the a/c contacts the water below, Belly down, Tail low, mostly intact, and is destroyed.
I'll add, four or more minutes later, as the exact time for impact is still to be confirmed.

Originally Posted by Bearfoil
From the debris field, it appears that due to its very compact spread, there was little current to cause dispersion, but the direction of the current is suggested as East to West, and that if the debris field is searched further to the west, at some point debris would reach its ultimate distance from the heavier pieces.

No conclusion relative to the flightpath can be discerned from the orientation of the debris ?

No conclusion can be ascertained from the debris as to which direction the nose of the aircraft was pointed at impact ?

The impact point can be estimated to some degree with data known about the rate and distance of the sinking engines, by unwinding its path down ?
Well... the impact point was certainly very close to the vertical of those engines. Considering that below surface currents are negligibles for such a mass, they would sank straight down from where those impact forces will send them; mm43 observation is relevant: 35 m separation instead of the original 17 m or so under the wings.

I'm feeling that most of the wreckage at the bottom is somewhat related with the heading at impact (WSW), but it may be due to an illusion without having on hand the specific model showing all the mechanics involved.

Originally Posted by Bearfoil
The Captain's rest ended at 0200, and he was likely in the cockpit, perhaps even taking his Left Seat at the time of the Master Caution (Cavalry Charge), leaving only the F/O seated and restrained ?
Not so sure about that.
The contrary is more likely: taking one third watch for each pilot at cruise level (From departure FL200 to descent), The capitain being on the deck at both end, he will have watched the first cruise leg which might have ended around 0200.

Originally Posted by Bearfoil
The attitude excursions allowable by the a/p affect the ride of the a/c; did the a/p disconnect due its inability to manage the a/c ( Turbulence ), or due an already Unreliable A/S ?
Icy conditions (see my many posts about that) doesn't imply any level of associated serious turbulences. But ice issues are acertained by pitots fault, consequently A/P and A/THR certainly kicked off due to an unreliable airspeed event, freezing also the Rudder Travel Limiter at its cruise settings for Mach 0.82 cruise level flight.

Last edited by takata; 7th May 2011 at 15:45.
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Old 7th May 2011, 16:09
  #853 (permalink)  
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takata;
This aircraft control should not have been compromised by this event alone, meaning, an adequate crew reaction (or without reaction at all. In some other cases, they just did nothing until A/S anomalies ended by themselves).
Exactly. The aircraft was stable before the loss and any change in that state would require input, (crew, aircraft weather); if none, stable flight would remain, requiring only minor adjustments until the event passed, as shown by the previous events. The aircraft wasn't "out of control", and there was no need for the pilots to "control" the aircraft...as with any abnormality, there was the need to respond as per training, in this case, to ensure that everything remained the same, within the bounds of possibly-turbulent flight. A loss of airspeed data does not cause a loss of control.

For a number of reasons, I concur with your comments regarding the crew break. It makes sense to infer that the RP was in the left seat, as P2.

oldengmkr;

I was wondering when or if this AAIB report would surface again and had been considering the events and responses described for some time. The link to the Report was first posted by delta092b on the second thread (of four, this being the fourth "major" thread) on June 5th, 2009, post #239, four days after the accident.

The report as quoted above, states: "Ten seconds after the autopilot disengaged, the corrected or phase-advanced angle of attack (a computed parameter which is not recorded but can be calculated by Airbus Industrie from the DFDR data) reached the 'alpha prot' value. This angle of attack excursion beyond alpha protcaused a change in the pitch flight control law from normal law (NZ law) to angle of attack protection law (AoA law). "

To keep any response to a reasonable length, the CAoC or "Corrected Angle of Attack", (I hadn't seen the term "phase - advanced" in my research), is calculated by the ADIRS; it may or may not be recorded. AoA is certainly recorded; I have accessed it and monitored it in turbulence using the ACMS-Parameter Alpha Call-up mode, available in the MCDUs.

Among other uses, it is used by the SFCC [Slat-Flap Control Computer] as part of an anti-retraction mode which is based upon CAoA, (nominally, 7.5deg) and <148kts CAS) if I recall.

The outcome for the A340 is dramatic: 6000fpm up, a loss of 65kts or so and a climb of over 4000ft.

We must bear two things in mind, (notwithstanding the crew's surprise and concern in re the A330 800ft or so above them!) - a) For this to obtain for AF 447, the aircraft would have to be in Nz Law before the other events occurred, and b) as per the Report, full forward stick would return the aircraft to Nz Law (from Angle of Attack Law).

What I don't see explained in the report is why the AoA Law was triggered. Was it Mach-related or low-speed related? Was it turbulence-related, and if so, what was the AoA and what were the exact circumstances (re Mach number) that exacerbated the event and possibly opened the door for subsequent factors to trigger the AoA Law? I don't think this was just a case of "Mach buffet".

We do have the evidence which shows a very high vertical impact force. A number of theories are "in play" so to speak as to the loss of control, including some which contemplate a controlled descent followed by loss of control lower down. Possibly - nothing we know verifies this or a LOC near cruise vice lower down - We can only infer but not conclude.

One item I have considered is the UAS QRH checklist, which can, I think, be misinterpreted. Examining flight crew training manuals explains the correct way to handle the memory drills and subsequent read-do checklist but I think this notion should be examined if only to dismiss it.

gums;

Just waiting and reading. There is really nothing to say at this point.

There will be time enough for robust debates after the data is read and some general hints at what happened are provided. The discussions will be interesting when a 3rd Interim Report is released in due course, (which I would expect to include the maps, an outline of the way of LOC, some flight data examination and comparisons with the ACARS series).

HN39;

I was unable to locate "Appendix B". If the report has something to contribute to an understanding of the AFS especially the reconfiguration of flight laws from Nz to AlphaProt Law, I'm sure what there is in this report will be available and its relevance hopefully established. There are some primary differences in that event: For an AlphaProt Law response, the aircraft must be in Nz Law as the response (HIGH AoA and PITCH ATT) wouldn't be available in either Pitch Alternate law.

As we are aware, the AD that was released on December 22, 2010 states, "However, in some cases, the autopilot orders may be inappropriate, such as possible abrupt pitch command.

In order to prevent such event which may, under specific circumstances, constitute an unsafe condition, this AD requires an amendment of the Flight Manual to ensure that flight crews apply the appropriate operational procedure.
" The AD does not mention those "specific circumstances", nor do we know to what event(s) the characterization of "abrupt" refers, if any.

Perhaps the dots are still too far apart to see viable connections but this event and the one to which I refer above concerning the UAS QRH Drill, are possible areas to focus upon along with weather.

Last edited by Jetdriver; 8th May 2011 at 00:47.
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Old 7th May 2011, 16:34
  #854 (permalink)  
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In preparation for the next report, I am trying to tie up some loose ends for my own edification.

"I'm feeling that most of the wreckage at the bottom is somewhat related with the heading at impact (WSW), but it may be due to an illusion without having on hand the specific model showing all the mechanics involved."

This is a puzzlement. There is a point in the 'sea' where 447 hit, may we call it the IP (Impact point)??. I will make it the center of a circle, (or the apex of a cone), and derive some information from this cone's base, a circle drawn (on the bottom) around the vertical spine of the cone.

I'll make it concentric circles, at certain radii from the base center, described by the location of various debris, Engines, LG, other, etc. Now the direction of the stream of debris is certainly a result of the direction of the sub surface flow, mated to the velocity downward of the various masses as they sink. It cannot have any relationship with the direction of the a/c's nose, or any other part of the airframe as the impact happened.

All motion was arrested of the aircraft at impact, and the system became an independent ballistic aggregation, subject to density of mass, surface area, and other considerations having nothing whatever to do with "En Ligne de Vol". So my opinion is that the Direction (Heading, under protest), of the a/c at impact is absolutely random, and could have been exactly opposite of WSW, or any other bearing. The various pieces in the debris field were at the mercy of the sea, and it's whims. How could any direction present in the Field of Debris be anything but simply an increasing radius from the "center" of the circle described above ?? Not only is it not known now, it will never be known, the "direction at impact" of this a/c.

Are their possibilities of "Last recorded bearing" on the DFDR ?? And a time stamp at impact ??

To me, this accident almost certainly had a pedestrian cause, but circumstances were lain in front of the flight that could not be avoided. The absolute procuring cause may not be known, ever, but I think enough is already known to suggest some improvements in the industry.

I will sit on my hands until some new developments pop up.

Thanks, Olivier. From you and others I have learned much...

bear

edit. From comment on this thread, my understanding is that Captain launched, and established cruise, then took his rest. Three hours later puts his schedule at "Re-enter, and assume command". (0200). I am not persuaded that UAS is a given, that Discrepant a/s data from the pitots caused the disagree. A sudden, and unrecoverable LOC would point to the doubt that UAS occurred. As described by PJ2, UAS is not a guarantee of LOC, controlled flight continued ?? The boxes will out, but the simplest, though unlikely explanation may be that discrepant air velocities at the pitots were station related (position on the airframe), and not caused by ICE. This makes the a/p drop the problem, not the result. The positioning of the control surfaces can be done by either Automatics or Manually, and both have limits, neither one is infallible, ask gums.

Last edited by bearfoil; 7th May 2011 at 17:07.
 
Old 7th May 2011, 17:11
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PJ2;

Thanks for your reply. (Remainder deleted after further consideration).

Last edited by HazelNuts39; 7th May 2011 at 18:58.
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Old 7th May 2011, 17:11
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Conf_iture,
Thanks for reminding me tactfully about the Dassuault Mercure having a cockpit AoA gauge: it rings a bell sorry, no pun intended. (Did it also have a high Vmo?) Am now waiting to be corrected re the Russians, and maybe the Anglo-French "pointy one".

takata,
Without invoking further eye strain, are you confident of the annotations for engines #1 & #2? I'm wondering how easy they are for the recovery team to distinguish in the debris field. For example, I'd be surprised if the accessory gearboxes are handed, and the pylons and cowlings are presumably elsewhere.
You will remember the argument some of us had, when the debris field was first pictured, about debris-orientation versus heading/track at sea-level impact? [wink] (Don't get yourself into hot water like I did.) You suggest:
"I'm feeling most of the wreckage at the bottom is somewhat related with the heading at impact (WSW), but it may be due to an illusion without having on hand the specific model showing all the mechanics involved."
That was my feeling at the time, but if labelled correctly the engines seem to have switched sides.

PJ2,
Am wondering if the engagement of Alpha-Prot Law could be reconciled with the Alternate Law message.
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Old 7th May 2011, 17:48
  #857 (permalink)  
 
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Originally Posted by Chris Scott View Post
Thanks for reminding me tactfully about the Dassuault Mercure having a cockpit AoA gauge: it rings a bell, sorry, no pun intended. (Did it also have a high Vmo?) Am now waiting to be corrected re the Russians, and maybe the Anglo-French "pointy one".
Chris, I should be in Paris next week, so maybe I can ask about the Mercure.
The Anglo-French "pointy one" (aka as Concorde), did have an AoA indicator (bottom left...), but I'm not sure to what extent it was included in the scan, or when.
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Old 7th May 2011, 19:04
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pj2 / HN

I'm slightly mystified by the bulletin's discussion of High Angle of Attack Protection. Shouldn't they discuss the zoom-climb in the context of High Speed Protection:
My reading is partially as yours.

Crudely:
High Speed Protection:

Prevents exceeding VMO or MMO by introducing a pitch up load factor demand.
The pilot can NOT override the pitch up command.
This "protection" is entered at the same point as the AP disconnects. 0.86M is the limit, 1st excursion <<In the two second period after the initial speed excursion above Mach 0.86 the Mach number decayed to 0.855>> to 0.87M disconnected the AP. The small / brief excursion probably did not generate much of a pitch up, but <<and then increased again to 0.882. It remained above 0.86 for two seconds before decreasing and remaining below 0.86 for the remainder of the turbulence encounter>> the next probably did more (longer / greater exceedence) and the combined 2 excusions now left the aircraft in a climbing attitude.

Meanwhile <<Five seconds after the autopilot disengaged, the thrust levers were closed>> and <<Ten seconds after the autopilot disengaged, the corrected or phase-advanced angle of attack (a computed parameter which is not recorded but can be calculated by Airbus Industrie from the DFDR data) reached the 'alpha prot' value>> i.e. we had a climbing attitude, zero thrust, and reducing (due windshear) M No hence IAS etc., all at Cruise Alt. Hardly surprising it got to Alpha Prot - it would have to eventually.

For 18 seconds after the autopilot disengaged the aircraft remained within 200 feet altitude of FL360 but once AoA law was invoked at 14:21:50 hrs, the aircraft's attitude began to pitch nose-up.
The pitch-up trend continued for 17 seconds reaching a peak of 15° nose-up shortly before the first nose-down sidestick command was applied
I don't wish to judge, but 'AP Disconnect' is a Red Warning, and whatever else is going on, my training is someone (preferably HP) has to say "I have control" and fly the ac (Rule 1 of any emergency...)

NB the duration of this climb is 35s... that is a long time to leave an aircraft with nobody flying - especially in severe turbulence. 18s is still a long time, and the A340 hardly deviated in altitude more than the A330 (AP in throughout).

I only add this in answer to the points above - I have not followed the AF330 theories as to exactly how this incident might relate to that accident.
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Old 7th May 2011, 19:07
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Chris
Thanks for reminding me tactfully about the Dassuault Mercure having a cockpit AoA gauge: it rings a bell sorry, no pun intended. (Did it also have a high Vmo?)
Vmo = 499 kts (925 km/h) according to several Mercure 100 datasheets. A "civilian fighter plane", as pilots used to say...
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Old 7th May 2011, 19:21
  #860 (permalink)  
 
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bearfoil, the New York Times article states, and I am doing a bit of paraphrasing, that the BEA is adamant that AF 447 was never south of the LKP.
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