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AF447 Thread No. 3

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AF447 Thread No. 3

Old 27th May 2011, 14:06
  #41 (permalink)  
 
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Can somebody correlate the ACARS messages with the recently released CVR/FDR information? It would be interesting to see some of the mysteriousness cleared up as to what triggered the ACARS messages and their meaning in light of this new information.

Thanks
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Old 27th May 2011, 14:06
  #42 (permalink)  
 
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hi takata

Originally Posted by takata View Post
An explanation was that the right wing stalled, due to lack of speed, and then the PF tried to counter it by rolling to the left, but it is useless or will make the things worse.

Until you are using the manual wheel which is overriding it.

Recorded (and displayed) speed dropped (LHS and stand-by) due to ice, down to 60 kt (false) during one minute and come back to 215 (real), then 185 (real). They heard those stall warnings... no overspeed.
We don't know that the roll to the right happened because of the stall or just before it. The report mentions the roll, the pitch up and then the stall warning in that order. Perhaps the PF merely thought the a/c was rolling and and pitching down, having forgotten that the engine thrust was set at a lower level when AT disconnected.
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Old 27th May 2011, 14:08
  #43 (permalink)  
 
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how they ended up in a CB IN THE FIRST PLACE,would most likely be ,the blame of the weather radar.To me 10 000 fpm descent, might have been aided with the CB downdraft.
There is no evidence to even slightly suggest that they were in a CB. In fact, based on the statements in the report (the call to the cabin, the 12 left turn, the decel to M0.8) they knew very well what was going on with the weather and were steering around the worst bit. IMO they were obviously not in a CB, but in cloud in bad icing conditions.
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Old 27th May 2011, 14:09
  #44 (permalink)  
 
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Vertical stab isn't the THS, but thank you for the load factor.
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Old 27th May 2011, 14:10
  #45 (permalink)  
 
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I cannot access the BEA report - will wait until later and try again.

Meanwhile I have a question for anyone with actual technical knowledge of the A330:

If stablizer trim is full nose up (why is not important at this point) and TOGA is applied - does the elevator have the ability to overcome the consequences if full nose down input is made and held (without changing stabilizer trim)?
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Old 27th May 2011, 14:12
  #46 (permalink)  
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Well, I'm no clearer now that I was! There are too many inexplicable events to make sense of this, including pilot input and THS angle. It is unfortunate we do not have the RHS IAS readings, and I'm not clear from that report which seat PF was in, nor which IAS readings he was reacting to. A 'zoom' from FL 350 to 375 with 7000fpm is pretty dramatic. It also appears that they were close to being unstalled at the 375 point.

The only observation I can make is that I have seen a full and maintained nose-up demand from a pilot in a different aircraft before, in reaction to a large (and unexpected) rate of descent while stalled.

Way to go yet.
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Old 27th May 2011, 14:15
  #47 (permalink)  
 
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Stall training

takata wrote :

That may be the confusion if one is only trained to low alt, low speed, Normal Law stall recovery, even if both Pilots aknowledged they were in Alternate Law. Something that need a serious investigation here.
Agreed.

PENKO wrote :

And it is not a momentary confusion either, it is a persistent pitch up command. There were two other pilots there who did not react to this inconsistent action by the PF which makes it all the more puzzling. I maintain that we are missing half the information.
Agreed, too.

One hypothesis is along the lines of "stall training" such as airline pilots usually get during recurrent simulator training. Since the aircraft is reputedly "protected" against stall, training for upset recovery, stall identification and recovery has been, at best, extremely poor. The only manoeuver which is considered is "approach to stall, minimum altitude loss". And as takata pointed out, in Normal Law, perhaps modified through landing configuration (such as was attempted in Perpignan).

In this specific sequence of "approach to stall, minimum altitude loss", the reaction is to power out of pre-stall condition using TOGA thrust, maintaining some kind of "average" pitch attitude. This is of course completely self-defeating in a high-altitude post-stalled condition. But this condition must be identified first...

Both major manufacturers produced together a video document about upset recovery a few years back. But that was likely the only "training" the accident flight pilots ever got about it. And of course, I am with those who will claim that a pilot should know how to get out of a stall (like someone mentioned from a beginner's PPL experience, very valid point).

Unfortunately, what we have here is the glaring example of why pilots should remain pilots for real, and not become system operators, or cockpit managers, or what have you. The design of any aircraft, especially one as revolutionary in its time as that which appeared in the late eighties, will have an influence on what the role, function, skillset, attitude of those on the flight deck will become. I maintain that these changes were intentional, but of course not from individual engineers or programmers, this is ludicrous. It is a political decision.

One does not live through the career of an airline pilot in isolation, working their skill at home with personal dedication. Any airline pilot is essentially the product of a whole system, regulator, airline and manufacturer included. The only personal thing that can be added to this is personal light aircraft training (as can or cannot be afforded depending on work and wages conditions...), homework with the FCOM and other documents, personal discipline regarding sleep, food, physical activity, and personal ethics.

But even if I was ready to pay for it in person (I cannot), I doubt I could get even a 12hrs simulator training syllabus to get me vaguely up to par about all the upset and stall conditions I would have perhaps to face one day in a large heavy jet airliner. But in all likelyhood, I will never face these conditions. How expensive would that statistically useless training make me ?

Finally, as the pilot's responsibility with the life or death of his charges justifies inquiring in detail into all his actions even post-mortem (and this occasionally includes very personal details), similarly, the authority claimed by the aircraft (design policy-makers, technical designers, head of project and so on) over life and death "protection" justifies that it be subjected to a similarly detailed scrutiny. There is enough evidence already to justify such scrutiny.
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Old 27th May 2011, 14:15
  #48 (permalink)  
 
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Question.

Most of the new BEA info regarding instrument read-outs explicitly relates to the left-hand seat displays (with the right hand-seat displays not available in the FDR). But which seat was the PF - at the time of the initial upset - sitting in?

There was speculation in one of these various threads that he would almost certainly have been in the right-hand seat. That he handed over control in the final moments (presumably to the Commander, who had returned to the cockpit) seems to support that.

Could the initial PF have been seeing different values on his displays than on those recorded in the FDR?

[Obviously, everyone could hear the stall alarms wherever sitting / standing.]
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Old 27th May 2011, 14:26
  #49 (permalink)  
 
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How about moving stick, throttles and trim wheel?

Can the captain in the jump seat, even SEE that PF was giving pitch up input, not pitch down? After all, they are impulses, not stick positions?
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Old 27th May 2011, 14:27
  #50 (permalink)  
 
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spagiola comments:

Quote:
And it is not a momentary confusion either, it is a persistent pitch up command. There were two other pilots there who did not react to this inconsistent action by the PF which makes it all the more puzzling
My emphasis added
.

We do not know that the others didn't react, as the report does not tell us either way.
Agree that the report is very light on some details but that does bring up a question in my (obviously not heavy pilot) mind:

Given the lack of feedback/coupling between the 2 sets of controls what other immediate clues are available to the PNF on the action the PF is taking?

Note: This is a sincere question not an attempt to stir the A/B pot.
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Old 27th May 2011, 14:28
  #51 (permalink)  
 
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Hi glenbrook,
Originally Posted by glenbrook
We don't know that the roll to the right happened because of the stall or just before it. The report mentions the roll, the pitch up and then the stall warning in that order. Perhaps the PF merely thought the a/c was rolling and and pitching down, having forgotten that the engine thrust was set at a lower level when AT disconnected.
First, I fully agree that we don't know (nothing is said about it) and I may be totally wrong about that!
I just tried to answer the sharp turn to the right as seen on the BEA map:
- Red dots as legended:
(1) 0135:15 (last contact with ATC)
(2) 0159:32 (meteo briefing with Captain, light/moderate turbulences expected
....................Captain leaves flight deck)
(3) 0208:07 (12 deg offset manoeuver start, light turbulences, Mach 0.80)
(4) 0210:05 (icing: autopilot off, autothrust off, ALT law, stall alarm -twice-, right wing bank;
.............PF: pitch up, left roll ordered, speed decr. 275-> 60 kt)
(5) 0210:51 (stall alarm again. PF: TOGA, max pitch up and left during 30 sec., THS +10, ...
(6) 0211:40 (Captain is back in the cockpit...

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Old 27th May 2011, 14:28
  #52 (permalink)  
 
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AoA vs Pitch

Question from ignorant SLF, the BEA report quotes different values for AoA and pitch at the same point in time.
Are these not the same datum?
Or is pitch calculated from the [email protected] ring gyro and AoA via an aerodyamic sensor?
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Old 27th May 2011, 14:31
  #53 (permalink)  
 
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What we won't know is where the PF's eyes were. (Interesting question on if PF and PNF were seeing the same things on their instruments) Where his eyes were would inform what his hands were doing while he tried to regain control of the aircraft.
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Old 27th May 2011, 14:31
  #54 (permalink)  
 
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In a CB or not?

There is no evidence to even slightly suggest that they were in a CB. In fact, based on the statements in the report (the call to the cabin, the 12 left turn, the decel to M0.8) they knew very well what was going on with the weather and were steering around the worst bit. IMO they were obviously not in a CB, but in cloud in bad icing conditions
But there was convective WX around and we don't know what the tilt setting was - they could have been dangerously overscanning the storms, leading to a false impression that the flight path choosen (10 left) was clear:

http://http://www.weathergraphics.com/tim/af447/
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Old 27th May 2011, 14:41
  #55 (permalink)  
 
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Manual pitch trim

jcjeant posted :
In alternate law .. the trim is in "auto-trim" ?
takata answered :
Until you are using the manual wheel which is overriding it.
takata, have you ever flown an Airbus ? Have you ever trained for type rating on either 320, 330, 340 or 380 ? I will tell you a ghastly secret : using manual pitch trim is one of the very first things one has to unlearn in order to be accepted as a candidate for type rating. After which, during all operational flight hours, and during every simulator training and check, it is verboten to touch that wheel.

CPT : A330/340 experience -> 1700hrs (plus all hours on A320 not mentioned)
F/O 1 : A320/330/340 experience -> 6500hrs
F/O 2 : A320/330/340 experience -> 2900hrs

It would seem obvious that touching that verboten wheel would have perhaps been useful. But the pilots here had never touched it, even in benign conditions, for a total of more than 10000 hours...
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Old 27th May 2011, 14:44
  #56 (permalink)  
 
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Sad and deadly combination of factors

Having read the BEA document, to the SLF I am, and with all due respect to people who lost their lives, this sad accident seems to result from :

1. loss of airspeed indication resulting from ice-clogged pitots

2. inappropriate reaction of crew that did not immediately apply the recommended unreliable airspeed procedure which prescribes 5 pitch and CLB thrust setting (see HyperVeloce post in part #1 of this thread) until the situation has been sorted out

Yet another combination of technical failure and human error. Apart from R&D work about how to prevent UAS condition, this seems to call for a better training of pilots in unusual situations.

Professional opinions welcome of course.

Last edited by JPI33600; 27th May 2011 at 14:51. Reason: correction of typo
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Old 27th May 2011, 14:45
  #57 (permalink)  
 
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Originally Posted by Interested_Layman
Question from ignorant SLF, the BEA report quotes different values for AoA and pitch at the same point in time.
Are these not the same datum?
Pitch is the aircraft attitude vs. the horizon, while Angle-of-attack is wing airfoil vs. airflow direction (an air vector is needed but may be calculated by Inertial Reference). When you have a pitch of 0 deg and an AoA of 90+ deg, you are in "ligne de vol", but you are falling down vertically. BEA says that [edited: pitch was 16.2 deg at impact and AoA was not valid].

Last edited by takata; 27th May 2011 at 14:56.
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Old 27th May 2011, 14:50
  #58 (permalink)  
 
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Originally Posted by Svarin
I will tell you a ghastly secret : using manual pitch trim is one of the very first things one has to unlearn in order to be accepted as a candidate for type rating. After which, during all operational flight hours, and during every simulator training and check, it is verboten to touch that wheel.
You are only a troll, Svarin. If Airbus didn't want someone to ever use the trim wheel, the very simple way was not to put one in the cockpit at the first place. They would even have made the electrical imputs to have a precedence over the pilot mechanical control which was, of course, made the other way.
Get a life.
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Old 27th May 2011, 14:50
  #59 (permalink)  
 
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takata, the pitch angle was 16.2 degrees on impact, there was no valid AOA data at that point.
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Old 27th May 2011, 14:54
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takata, the pitch angle was 16.2 degrees on impact, there was no valid AOA data at that point.
Right, I stand corrected. wrongly remembered "incidence" instead of "assiette".
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