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AF 447 Thread No. 7

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AF 447 Thread No. 7

Old 17th Mar 2012, 17:44
  #861 (permalink)  
 
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We can't say

Hi,

Organfreak

I am of the impression that many/most pilots here would have sussed this stall



and flown out of it


Too many variables to take into account (uncertainties)

For them (and for us)

Last edited by RR_NDB; 17th Mar 2012 at 17:46. Reason: Link add
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Old 17th Mar 2012, 17:49
  #862 (permalink)  
 
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Cool

Hi,

Lyman
Once in the climb, and probably very quickly, the odds go sour for recovery
Organfreak
Code:
Please cite an authorative source or support your contention with known facts
In this video ... at time 46 minutes 18 seconds
Pouvait t-on sauver l'avion ? ask the interviewer? ... on ne sais pas répond le chef instructeur pilote d'Airbus ....
Interviewer question:
It was possible to recover the plane?
We don't know answer the chief instructor pilot of Airbus !
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Old 17th Mar 2012, 17:53
  #863 (permalink)  
 
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We will be able to understand what occured?

Hi,

Bear,

Perfectly K.I.S.S.

Even BEA may not have all required info

Last edited by RR_NDB; 17th Mar 2012 at 17:57. Reason: "'s
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Old 17th Mar 2012, 18:09
  #864 (permalink)  
 
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Finite State Machines could present "surprises"

Hi,

Bear:

but no one could ever say why she behaved that way


Even the designers cannot explain all anomalies occurred since the introduction of these advanced planes.

Important information is simply lost. And FDR is not designed for that.
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Old 17th Mar 2012, 18:37
  #865 (permalink)  
 
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Originally Posted by RR_NDB
And FDR is not designed for that.
Is it proven that the Quick Access Recorder data cannot be resurrected from its time in the depths? I don't remember the answer anymore.

Personal opinion only, since the AP and A/THR dropped at the beginning of the AF447 event, it is extremely unlikely that any control inputs came via that route. Any surprise control inputs would then have to be through the basic ALT2 control structure which appears to have been debugged quite well.
(Although the aircraft must have 10000 times more experience in Normal law than in ALT2 law.)
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Old 17th Mar 2012, 18:40
  #866 (permalink)  
 
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The aircraft's behavior in pitch was consistent with stick input.

In really does take the cake to accuse BEA of manipulating data while doing so repeatedly oneself. While the aircraft entered alternate law, it seems some here entered alternate reality.
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Old 17th Mar 2012, 18:43
  #867 (permalink)  
 
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HN39 Post #807
If I may ask as a non-pilot: If you're struggling with roll control and your scan has narrowed to the ADI, is it plausible that you miss pitch altogether? Is it possible that he was aware of increasing pitch attitude, but didn't care because 15° was his target all along? Perhaps he only reluctantly and half-heartedly gave in to the PNF's urging "You're climbing, go down" until at 02:10:49 he changed his mind and went for 15°

HN39 Post #815
The second stall warning came at 02:10:51, 2 seconds after he began pulling up again.
It would appear from NeoFit's chart that FD data became available just in time to be suspect as a cause for the second pull up leading to the stall.
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Old 17th Mar 2012, 19:01
  #868 (permalink)  
 
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Originally Posted by Hamburt Spinkleman
In really does take the cake to accuse BEA of manipulating data while doing so repeatedly oneself. While the aircraft entered alternate law, it seems some here entered alternate reality.
I hold similar views to Mr. Spinkleman's and have discussed this with a prime offender via PM. I would be great if that person adopted the suggestions discussed.

It is now a free speech world, however, and we are all free to step on our lolly as many times as one can stand. Credibility? What's that?
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Old 17th Mar 2012, 19:02
  #869 (permalink)  
 
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Angel scans and safety

Hi Maching Bird,

Originally Posted by Machinbird
We had to hawk the pitch attitude very carefully and note any trends on the altimeter, then apply a correction to pitch to hold altitude. There was too much lag in the VSI to use it for altitude maintenance. All I used the VSI for was to verify I had set pitch and power about right for a descent rate or climb rate.
It is interesting to learn that there has been a change in scan patterns as a result of new technology.
Thank you for your scan instruction. What I have written in my post is the most academic manner to do which is learned for IR in France, on slower and less powered aircrafts that yours !

In all cases scan has to be rapid, effective, used, and AF447's CVR shows a very different scenario !

What do you think about learning effective stall with aerobatics to all airline pilots (and not airline too) ?

Computer systems cannot help us to land when we have fire on board, no more electricity, no more system. A pilot must be able to try to do that, and bring the aircraft and the passenger on the ground.

That is only pleasure !
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Old 17th Mar 2012, 19:04
  #870 (permalink)  
 
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Prime factors are what was in the loop after Law change

Hi,

Machinbird:

...it is extremely unlikely that any control inputs came via that route.


I agree!

We have to concentrate (first) on "elements" working in the "great loop". This includes PF (receiving "inputs" we don't have) and A/C "mechanisms" (all that had to work).

Other factors, IMO are to be neglected. Including:
basic ALT2 control structure

Last edited by RR_NDB; 18th Mar 2012 at 00:25. Reason: Text impvmt including Title
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Old 17th Mar 2012, 19:15
  #871 (permalink)  
 
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Scientific (and serious) approach requires patience and "Stability"

Hi,

Hamburt Spinkleman:

We can assume this, i agree.

While the aircraft entered alternate law, it seems some here entered alternate reality.
With some months (years) delay.

This happens in high profile cases.

As MB said:
It is now a free speech world
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Old 17th Mar 2012, 19:19
  #872 (permalink)  
 
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Prime factors (to be considered first)

Hi,

Machinbird:

, i agree.
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Old 17th Mar 2012, 19:40
  #873 (permalink)  
 
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Redundancy and reliable inputs

Hi,


no more electricity, no more system.


fire on board
With current design this is "almost" impossible.

Smoke can be much worse:

See Dubai flight 6

PF had no chances even to change comm to other ATC. The "element" suddenly inserted in the loop had no vision ahead. We may say: smoke from a cargo fire "broke the loop".

You need fresh air to be able to see ahead. This can be done with a hood.

PS

The same (similar) effect that could explain AF447 PF actions. No valid and reliable inputs to him? Almost zero confidence in the inputs (them) received? This may explain what we learned so far.

Last edited by RR_NDB; 17th Mar 2012 at 19:52. Reason: Text impvmt
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Old 17th Mar 2012, 19:49
  #874 (permalink)  
 
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Originally posted by Machinbird ...

It would appear from NeoFit's chart that FD data became available just in time to be suspect as a cause for the second pull up leading to the stall.
Perhaps a graphic refresher of what the aircraft was doing around that time may help. Then answer what the FD data may have shown during the period in which the stall was entered and the SW sounded continuously.
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Old 17th Mar 2012, 20:27
  #875 (permalink)  
 
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Organfreak

Lyman claimed:
Quote:
Once in the climb, and probably very quickly, the odds go sour for recovery
Please cite an authorative source or support your contention with known facts. There have been hundreds of comments in these forums stating that the stall may have been recoverable. Is it just that you enjoy being a maverick?
Last edited by Organfreak; 17th Mar 2012 at 17:30. Reason: HTML typo
I don´t know, whether you consider that as an authorative source.

http://www.pprune.org/7066105-post66.html

As for the AF447 accident: I am an instructor on the A320 and we are now doing high altitude stall demonstrations during recurrent training. When given similar circumstances as the AF447 guys, less than half of the pilots can successfully recover even when they know it is coming. It is not because the pilots do not know how to recover from a stall, it is because pilots at all levels have not been trained in the dynamics of high altitude stalls. High altitude stalls are very different animals. Recovery at high altitudes require significant nose low pitch, to be held for a very uncomfortably long time, and you have to accept a VERY high rate of descent (15,000fpm or higher). AFTER that you have to have a very slow pitch up because a secondary is very easy to occur. Historically when training stalls pilots are taught to lower the nose to the horizon and add full power and to minimize altitude loss. You cannot recover from a high altitude stall using that procedure. If you read what happened, and know how to correctly recover from a high altitude stall, it becomes clear that the AF447 guys were caught off guard because the aircraft did not recover in a way they were accustomed to when training lower altitude stalls.

I have a lot more sympathy for the actions of the AF447 guys having trained and demonstrated high altitude stalls in Airbus FBW aircraft.
It is not enough to look at the ability of the aircraft to be flown out of the stall, but to judge the success of recovery atempts in view of the knowledge of the crew (and not only of this AF crew) and the ability of the aircraft.
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Old 17th Mar 2012, 21:20
  #876 (permalink)  
 
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Originally Posted by Machinbird
FD data became available just in time to be suspect as a cause for the second pull up
What are your reasons for suspecting that the FD causes the second pull up, when the vertical Flight Mode is ALT CRZ, selected altitude is FL350, actual altitude is 37500 ft? I must admit that my understanding of FD commands is very limited, and I'm just assuming it 'mirrors' the commands that would have been given by an active autopilot.
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Old 17th Mar 2012, 22:20
  #877 (permalink)  
 
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MACH:

IF (big IF), in fact, the FD 'bit' him at any point, I 'spect it's the return at 2:10:47 when the CAS is 216k and aircraft vertical speed is +1500 FPM which is what the FD vertical command would have defaulted to because the FD buttons were still engaged. With the nose already having come down from 10-12 degrees to 5.6 degrees (1500 FPM) this would be a 'relatively' subtle nose up command initially that, if flown, could rapidly go full scale taking him back to the documented 13 degrees after 2:10:51 as airspeed continues to decay.

V/S 1500 would also have been annunciated on the FMA at this time.

The FD would indeed only default to ALT CRZ* if within FMGEC CRZ ALT altitude capture parameters (i.e. 34,976), and the FD would, at the earlier time of 2:10:17, have been in the process of providing a vertical command consistent with leveling off at FMGEC/FCU CRZ ALT. It was only available in this mode for 4 seconds before it dropped out again. By 2:10:47 they were well above FL 350 (default mode is V/S).
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Old 17th Mar 2012, 22:26
  #878 (permalink)  
 
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Why Persistent NU?

Hi,

After saying "i have the controls" PF became (with the tacit concordance of PM and later the CPT, most of time) the "processor" and the "controller". He was put in the loop substituting in a difficult environment important elements, A/P and A/THR.

PF "output" (SS handling) was evidently based on uncertainties (as per NeoFit graph). His "inputs" are unknown to us and he expressed "high speed" suspicion. His "outputs" were not random, and soon showed a definite "bias to climb" the plane. A bias so strong, to put the plane in a steep climb going above REC MAX.

Probably this is not just explained by "lack of training", surprise, etc. Something very important, together the lack of "reliable" inputs may be was feeding his "processor" during important moments, leading (or misleading him to do that).

His "output" was not random. There was a pattern. This pattern was about the same during most of critical moments before stalling the plane.

After stalling, the reason could be partly explained by what was put in post #66


RetiredF4::

It is not enough to look at the ability of the aircraft to be flown out of the stall, but to judge the success of recovery atempts in view of the knowledge of the crew (and not only of this AF crew) and the ability of the aircraft.


IMO, in this case is very important is to understand why the plane was put in the stall. Looking to all reasons that lead to this: Crew error(s), System anomalies (it's outputs, processing of UAS data), man-machine interface issues, etc. In order to learn from this crash this is absolutely necessary.

PS

The wreckage orientation in seabed proved later to be the coherent with A/C heading when hitting surface. When you have a "pattern" this normally "carries" important information.

Last edited by RR_NDB; 17th Mar 2012 at 22:29. Reason: txt impvmt
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Old 17th Mar 2012, 22:54
  #879 (permalink)  
 
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His "inputs" are unknown to us and he expressed "high speed" suspicion.
Using that simple description, the reality is that his "inputs" rejected the visual evidence in favour of the cockpit vibration and unusual noise actually being what he "expected" in a high speed situation.

No pilot actually commented on the "noise", and perhaps this created a common acceptance of "over speed". The don't use the spoilers pronouncement could fall into this "thinking".
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Old 17th Mar 2012, 22:57
  #880 (permalink)  
 
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Accelerated degradation of the "effective aircraft"?

Hi,

After worsening conditions: WX then ice crystals, obsolete AS sensors failing simultaneously, "law change", non trained (to this situation) PF applying large SS inputs at high FL, etc. one may ask:

The lack of reliable info during so many time together with non reliable SW and other factors (noise, alarms, etc.) are to promote, GRACEFUL DEGRADATION of the "effective aircraft" (System+PF) or are a recipe for ACCELERATED DEGRADATION? Stressing HF, etc. Actually their fate was sealed VERY FAST.

It seems like exactly when they needed most reliable resources,( e.g. good man-machine interface to allow them to do just the very basic: aviate.) their inputs (mainly the input to PF) were sub standard (lacking, intermittent and perhaps, misleading). This probably will be understood by summer.

PS

mm43:


his "inputs" rejected the visual evidence in favour of the cockpit vibration and unusual noise actually being what he "expected" in a high speed situation.

We have to check carefully the timing.

The attitudes of PM and later CPT are coherent with "lack of enough info.". Like being unable to do any better, despite some moments briefly raising some "not so strong questioning". Seeming (with available info. we have) more doubts than what would be required to act with confidence.

Last edited by RR_NDB; 18th Mar 2012 at 00:15. Reason: Post #880 inclusion
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