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AF447 wreckage found

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AF447 wreckage found

Old 6th Aug 2011, 14:57
  #2661 (permalink)  
 
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Quoting RWA:

...if they'd wound the trimwheel forward to reduce the huge (13-degree) 'up' angle the systems appear to have imposed, the autotrim would presumably just have wound it back to 'Square Thirteen' again
The systems only imposed the 13 degree up angle because the pilot asked for it by backwards pressure on the SS that increased the pitch angle to the point where the aircraft stalled - the system was doing exactly what the pilot requested. Even then, if he'd moved the SS forwards again to try to reduce the pitch angle (and consequently the AOA), as you'd expect any pilot to do when in a stall, the system would've moved the THS accordingly.
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Old 6th Aug 2011, 15:00
  #2662 (permalink)  
 
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Cool

I don't think so, Neptunus. Don't forget, 'autotrim' was still operating; and I don't think Airbus pilots have the option of turning it off? So if they'd wound the trimwheel forward to reduce the huge (13-degree) 'up' angle the systems appear to have imposed, the autotrim would presumably just have wound it back to 'Square Thirteen' again?
I don't think so
If pilot had moved the trim .. he take authority over the auto trim and the trim will stay where the pilot put it ... and the trim will not return in primitive position
AFAIK

Remember the Westland Lysander ??
This old plane had already "auto flaps" !
They deployed or retracted regarding of the aircraft speed ...
They had a big effect on the flight attitude of the plane (don't forget to trim !!)
If the pilot dont know that .. it was the crash as result .. at landing or take off
If you don't know the plane you fly .. the result can be a catastrophe .. Lysander or A330 .. same results

Last edited by jcjeant; 6th Aug 2011 at 16:29.
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Old 6th Aug 2011, 15:03
  #2663 (permalink)  
 
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Quote from grimmrad:

Regarding the question about a license... does that mean you can be pilot in a major carrier WITHOUT the license??
No - all of the pilots had licences - the list of qualifications each pilot held is in the BEA report. The captain was asking whether the licence he held "qualified [him] to act as relief" (quote from from the BEA report).
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Old 6th Aug 2011, 16:18
  #2664 (permalink)  
 
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Cool

No - all of the pilots had licences - the list of qualifications each pilot held is in the BEA report. The captain was asking whether the licence he held "qualified [him] to act as relief" (quote from from the BEA report).
Indeed .. and it's a odd question of the captain when replaced in the context
(this copilot made also with same captain the flight Paris - Rio ... and captain don't know the qualifications of his crew ... show at least the no professionalism of the guy ... or bad Air France rules )
Go figure the logic .....
By the way .. it's not a part of the CVR transcript ... it's reported by BEA
Waiting for the full CVR transcript ....
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Old 6th Aug 2011, 16:28
  #2665 (permalink)  
 
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Still unanswered

OK, I've gone and read details in the Tech Log thread, but there still seem to be some questions the BEA hasn't answered, or hasn't tried to answer. (Or if so, I've missed them.)

Why the initial climb?

As for the pilots not recognizing they were in a stall, I think that is because they knew some instruments were not working --- but did not know which were working --- so they were totally confused about what was true and what wasn't. I know someone said earlier pilots were supposed to know which instruments were fed by what, but that's not the same as knowing in a real life situation which instruments can actually be relied upon. I wonder how many pilots would really know. I don't think any amount of training would solve this problem. Obviously technical solutions are limited. Put an indicator next to the instrument indicating its value is valid or not, then how do you know if that indicator is working correctly!
But I certainly don't see this as pilot error.

From the transcript, the conversation suggests they clearly didn't know the seriousness of their situation.

Why WAS the THS stuck up? Down inputs were recorded or mentioned. The BEA emphasizes the plane was fully functional and responsive, so why was the THS stuck up and remained stuck up?
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Old 6th Aug 2011, 16:32
  #2666 (permalink)  
 
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It wasn't stuck up.
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Old 6th Aug 2011, 16:40
  #2667 (permalink)  
 
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jcjeant said:
If pilot had moved the trim .. he take authority over the auto trim and the trim will stay where the pilot put it]
Well said master!

Will edit once more... Reminder: "Speed = Life"... On doubt... Always Speed! Why?
Coz the wings fly... (And speed is AoA, no engines involved).

Last edited by TioPablo; 6th Aug 2011 at 16:56.
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Old 6th Aug 2011, 16:51
  #2668 (permalink)  
 
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Cool

Why WAS the THS stuck up? Down inputs were recorded or mentioned. The BEA emphasizes the plane was fully functional and responsive, so why was the THS stuck up and remained stuck up?
Check Technical Log forum
It's explained (many time by takata and some others) with drawings of the system logic and also graphs extracted from BEA report N*3
Make your searches .. be informed.
BTW the THS is not stuck (blocked)
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Old 6th Aug 2011, 17:16
  #2669 (permalink)  
 
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THS

OK, I stand corrected that the THS wasn't "stuck up". I recall a number of posts trying to figure out why it was up, and whether it was stuck, broken, etc. But it seems to have been up (for whatever reason) and stayed up. Has the BEA explained why?
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Old 6th Aug 2011, 17:17
  #2670 (permalink)  
 
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RWA-

be interesting to know whether Airbus, Air France, or the BEA had warned pilots that this sort of 'impasse' could occur; and indeed had occurred, as far back as Perpignan in 2008? I very much doubt it........
Amongst all the hot air generated on this topic, I think your analysis may pretty well hit the nail on the head. Unfortunately, a lot of people may not be seeing things in quite the same light. Quite a few posts ago, I made the comment that a very small pull on the stick at high altitude, if you were heavy and close to max altitude, (should'nt be there in the first place, especially if turbulence is present, as the FCTM clearly states), could put you in stick shaker very quickly, together with a zoom up into "coffin corner" territory, (don' t hear much talk about that phrase these days, do we!)

Combine that startle factor (for the unprepared/untrained) with a full up THS and you can see why a certain element of confusion may have arisen. I think we will eventually find there is more to this than simple pilot error. Not bashing Airbus, (they build great aircraft, and I speak from experience of operating the type as well as Boeing), but nevertheless Toulouse will have some explaining to do here.

Regrettably, over the years, Airbus have usually blamed the pilots in most accidents ("they did not understand the systems"), but then they quietly go ahead and change some bit of software/hardware.

Last edited by Phantom Driver; 6th Aug 2011 at 17:36.
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Old 6th Aug 2011, 17:54
  #2671 (permalink)  
 
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But it seems to have been up (for whatever reason) and stayed up. Has the BEA explained why?
The reason is simple. The pilot's nose-down inputs only reduced the elevator deflection a little - the elevator still stayed "up".

He didn't keep the stick forward far enough or long enough to move the elevator back to neutral, and then into the "down" position. The THS would only have started moving "down" again once the elevators were pushed beyond neutral.

The THS behaved exactly as designed.
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Old 6th Aug 2011, 18:51
  #2672 (permalink)  
 
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Originally Posted by Phantom Driver View Post
Regrettably, over the years, Airbus have usually blamed the pilots in most accidents ("they did not understand the systems"), but then they quietly go ahead and change some bit of software/hardware.
Not wishing to sound facetious, but would you care to provide examples of where this has been the case any later than, say, 1994 (when the death of senior test pilot Nick Warner on a demonstration flight caused them to re-examine their priorites)?

Originally Posted by Kalium Chloride View Post
He didn't keep the stick forward far enough or long enough to move the elevator back to neutral, and then into the "down" position.
Neither, importantly, did he exercise the option to re-trim the aircraft manually using the trim wheels, which would have taken significantly less time - presumably because he was not taught how.
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Old 6th Aug 2011, 19:20
  #2673 (permalink)  
 
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Cool

Hi,

Not wishing to sound facetious, but would you care to provide examples of where this has been the case any later than, say, 1994 (when the death of senior test pilot Nick Warner on a demonstration flight caused them to re-examine their priorites)?
One from head is Mount St Odile (some changes after .. despite pilots made some mistake about descent rate settings if remember well) about interface
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Old 6th Aug 2011, 19:25
  #2674 (permalink)  
 
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The systems only imposed the 13 degree up angle because the pilot asked for it by backwards pressure on the SS that increased the pitch angle to the point where the aircraft stalled - the system was doing exactly what the pilot requested.
That might be how the system is designed to work but is it how a human "naturally" expects a system to work? Hasn't it been proven over the years that in an emergency we revert to how we expect things to work regardless of how they actually work or how we're trained to use them?

If I turn the thermostat up on my heating system I wouldn't expect the temperature to get hottor and hotter indefinitely.

If I turn the steering wheel of my car I wouldn't expect the turn to get tighter and tighter until the steering rack is on full lock.

Even the accelerator pedal on my car mostly behaves like a speed control rather than an accelerator. Once I have reached the desired speed I don't lift off the pedal to maintain that speed. I have to keep it pressed.

What other familiar systems have a "runaway" behavior like the auto trim?
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Old 6th Aug 2011, 19:33
  #2675 (permalink)  
 
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puzzling...

One thing that is puzzling me is the speed of PF's hand on his movements aft and forward on the sidestick.
From 02:10:13 to 02:10:16 (only three seconds) he moved his sidestick 9 times. That's three times a second...
And with significant amplitude also.

What was he chasing?
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Old 6th Aug 2011, 19:36
  #2676 (permalink)  
 
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Originally Posted by Denise Moore
Why the initial climb?
The answer can be speculated from the BEA report.
When AP disconnected the a/c was pointed down slightly (Pitch=0 deg) and it was descending. Also altimeter might have jumped down a few hundred feet because of impared pitots and air temperature sensors due to a possible ice build up from the strom they were in.
Pilots are trained to maintain altitude in cruise so he correctly pulls the stick back to keep at FL350. It appears he was in a down draft because it took a large stick deflection to maintain altitude for a few seconds. At high altitude and speed his strong stick input has dangerous effects and a stall warning is triggered. He then notices airspeed is broken. We can speculate that he was distracted, took his attention away from altitude and tried to process what was happening. More errors occur further distracting him. Finally the a/c has risen to FL375 before he figures out he has climbed, he had exited the downdraft and had held the nose up attitude.

Climbing the aircraft without adding power results in a drop in speed. Same as a pendulum swing up. Now a/c was in a dangerous high altitude and low speed condition with impared flight controls (ALT LAW).
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Old 6th Aug 2011, 19:43
  #2677 (permalink)  
 
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What other familiar systems have a "runaway" behavior like the auto trim?
It didn't runaway. The pilot made such high nose-up demands via the SS for such a long time that to satisfy his demands the system gradually trimmed to full nose-up. If he'd relaxed the back pressure for long enough (ie. taken "standard" stall recovery actions) the trim would've moved back towards the nose down position. It just trimmed to try to satisfy what the pilot what was asking of it - a high nose up attitude.

If I turn the thermostat up on my heating system I wouldn't expect the temperature to get hottor and hotter indefinitely
No, but if you set the thermostat to a temperature that was higher than the heating system could achieve the temperature would rise to that limit. Similarly, the pilot was requesting a nose-up attitude that the aircraft, with it's low speed, couldn't achieve and the trim ended up moving to the nose-up limit.
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Old 6th Aug 2011, 20:03
  #2678 (permalink)  
 
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Originally Posted by Rob21
puzzling...
One thing that is puzzling me is the speed of PF's hand on his movements aft and forward on the sidestick.
From 02:10:13 to 02:10:16 (only three seconds) he moved his sidestick 9 times. That's three times a second...
And with significant amplitude also.

What was he chasing?
Agreed. Look at the accelerations too.
Looks to me like he was over sticking then having to correct for each input.
Instead i imagine he should have used smooth gentle deflections.
Ever seen a nervous person drive a car like this? Constantly twitching the wheel having to correct over steer in each direction. A smooth small input is all that is required. I have also seen people use accelerator and brake in the same way, constantly pressing one peddle then the other. Instead of just calmly pressing accelerator to desired speed. You are pulled back and forwards in your seat. Can't say i've seen that behaviour much in pilots.
Totally speculative - is this consistent with anxious/un-trained behaviour from the onset.
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Old 6th Aug 2011, 20:04
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In alternate law we are still in load factor demand correct?
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Old 6th Aug 2011, 20:20
  #2680 (permalink)  
 
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Can't say i've seen that behaviour much in pilots.
Could be a passenger was flying it while waiting for the toilet? Or could be an instrumentation or recording error
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