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AF447 wreckage found

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AF447 wreckage found

Old 3rd Sep 2011, 12:46
  #3421 (permalink)  
 
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Cool

Hi,

kwateow,

Here's BEA's summary of their recommendations on flight recorders:

"One recommends that the regulatory authorities require that aircraft undertaking public transport flights with passengers be equipped with an image recorder that makes it possible to observe the whole of the instrument panel. Another recommends defining strict rules relating to the use of such recordings."
Another more "black box" to retrieve .......
Why not electrodes placed on the heads of the pilots to record the activities of their neurons ?
Another more "black box" to retrieve ......
More "black boxes" = more safe flight ?
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Old 3rd Sep 2011, 13:00
  #3422 (permalink)  
 
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More "black boxes" = more safe flight ?
well actually it does. We would be better able to work out why something happened. I remind you that in stall situations on other less modern aircraft the crew did exactly the same and pulled back on the stick.

We will never know why but images may well help to explain why. Once we know why we can develop a safer system.
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Old 3rd Sep 2011, 13:47
  #3423 (permalink)  
 
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Cool

Hi,

Funny you should say that...
Not so funny ..
well actually it does. We would be better able to work out why something happened. I remind you that in stall situations on other less modern aircraft the crew did exactly the same and pulled back on the stick.
as the pilots unions (their primary concern is of course the safety of the flights for their members and the passengers as all we know ... ) will refuse it .. as they already in the past refused video recording in cockpit...
Or maybe a extra increase of wages as incentive will make change their view on those safety problems ?
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Old 3rd Sep 2011, 17:09
  #3424 (permalink)  
 
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Safety Concerns

More "black boxes" = more safe flight ?
We will never know why but images may well help to explain why. Once we know why we can develop a safer system.
I doubt that .... in the end we only think we know why and still will address the same contributors.

We know the leading contributors now ... let's get on with putting the resources there rather than waiting to satisfying our last subjective doubts with video recordings.

Just look at the CVR, do they prove anything? or do they just focus us to consider possibilities?
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Old 3rd Sep 2011, 17:42
  #3425 (permalink)  
 
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well it is a dilemma I accept. However every little bit helps I would say. Video would require strict controls and a short recording period. Most accidents happen pretty quickly.

But I believe they would bring something positive to accident investigation.
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Old 3rd Sep 2011, 17:43
  #3426 (permalink)  
 
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Thales Cleared

Simultaneous reject of ADs. All three. This suggests Ice was not at work, but something else. Entry into upwelling airmass, which decreases the speed readings. What else is affected by a large shift in wind direction? AoA vanes, which would read (again, simultaneously) falsely high, perhaps quite high. What would the AutoFlight do? Decrease thrust, and PITCH DOWN, Another result? WIND SHEAR, and TCAS action.

As the a/c responds, the computers have by now rejected the airspeeds as too quickly divergent from cruise speed, and the a/p drops out.

The a/c has 1000fpm UP/VS, the Nose is DOWN 4 degrees from cruise, and due a tangential entry into the upwelling vertical, a ROLL (Left wing rise, to be more precise).

This is all on the traces, (save for the tangential entry) for the last four seconds of autoflight. I repeat, it is on the traces supplied by BEA.

The false high AA's and low "speed" have caused a spurious STALLWARN in the cockpit, as PF takes over. All but this have been done to death. Anyone? TurbineD?

So would a "resident" LKas (Last Known airspeed), have helped? Subject to inertial updating? A reserve Probe, to enter an abruptly presenting "new" airmass, and sample the "new" attitude dependent a/s? Because if this is what happened, then the Probes are fine, and the Autoflight needs some serious work.
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Old 3rd Sep 2011, 18:46
  #3427 (permalink)  
 
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@safety

Obviously you don't like these questions.

So what the hell with a (still) living PPRuNer ?

Get along with the facts!
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Old 3rd Sep 2011, 19:33
  #3428 (permalink)  
 
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there is nothing mysterious about pilots not being in tune with their aircraft. Scary yes, mysterious no.
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Old 3rd Sep 2011, 21:18
  #3429 (permalink)  
 
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Originally posted by Lyman ...
Simultaneous reject of ADs. All three. This suggests Ice was not at work, but something else. Entry into upwelling airmass, which decreases the speed readings. What else is affected by a large shift in wind direction? AoA vanes, which would read (again, simultaneously) falsely high, perhaps quite high. What would the AutoFlight do? Decrease thrust, and PITCH DOWN, Another result? WIND SHEAR, and TCAS action.
Now that 'take' on what may have happened is not unreasonable.

Away back in the 'AF447' thread I posited that mesoscale system to the east of 447 had a high level clockwise circulation. So it could well be that the pocket of upwelling air that confronted the a/c could have also been a southerly of + 60 KTS. If it had impacted the right wing first, the wing would have lost lift and hence the right roll and nose down.

Perhaps a closer look is needed, though super cooled icing could also have played its instantaneous card - as the conditions seemed to have been ideal for that phenomenon.
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Old 3rd Sep 2011, 22:16
  #3430 (permalink)  
 
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Lyman

Re: Thales Cleared

I don't think so.

What would the AutoFlight do? Decrease thrust, and PITCH DOWN, Another result? WIND SHEAR, and TCAS action.
@ Just prior to 2h 10min 0sec, they are cruising in A/P A/T @ 282 CAS and a Mach of 0.82

@ 2h 9min 58sec, the speed handling is change (probably by the PNF, my words) from managed to selected. The selected Mach is 0.80, the turbulence penetration speed.

@ 2h 10min 0sec, the pitch attitude decreases from 1.8 NU to 0 in 3 seconds and the engine N1 begins to decrease from 100% to 84%, reaching 84% in 8 seconds. This was accomplished by moving the thrust levers while remaining in A/T, my words

@ 2h 10min 03sec, the nacelle anti-ice switches for the engines are changed to ON.

@ 2h 10min 05sec, the A/P2 disconnects. The roll angle changes from 0 to 8.4 in 2 seconds but the sidestick is a neutral. The pitch atitude is 0.

@ 2h 10min 06sec, the flight control law changes from normal to alternate.

@ 2h 10min 07sec through 2h 10min 18sec, the copilot sidestick is positioned:
- nose up between neutral and 3/4 of the stop position
- to the left in half-travel position then to the right in half-travel position and twice, alternatively left to the stop position then right to the half-travel position.
- The pitch attitude increases to 11
- The vertical acceleration varies between 0.9 g and 1.6 g.
-The roll angle fluctuates between 11 right and 6 left.
- The vertical speed increases to 5200 ft/min.

@ 2h 10min 08sec, the FD1 and 2 become unavailable. The A/THR disengages and the THR/LK mode is activated. The N1's are 83%. The CAS changes from 274 kt to 156 kt. The CAS ISIS changes from 275kt to 139 kt then goes back up to 223kt. The Mach changes from 0.80 to 0.26.

Now I am going to skip a little bit to around 2h 10min 17sec. It is here they recognize the THR/LK is active. I think shortly thereafter then they reset the thrust levers back to 100% N1 as depicted on the chart, my words.

So you see, the speed changes were made by the pilots not the A/THR. They also recognized there was the likely presence of ice or they would not of turn on the nacelle anti-ice. This recognition came a little late and was probably due to the use of the weather radar. They had it set on a long range ND and reduced it several times which lead to the request by the PNF, "You can maybe go a little to the left I agree that we're in manual, eh?" The magnetic heading selected decreases to 34 from 35.5. The pitch down may have resulted from the decrease in Mach and the roll back of the N1 from 100% to 84% and was only from 1.8 to neutral.

The roll tendency is interesting, something that I can't explain other than the weather situation at the time.

These are my thought, I think the pitot tubes icing started the event as they entered a weather system perhaps they should have avoided.
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Old 3rd Sep 2011, 23:39
  #3431 (permalink)  
 
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TD

At ~2:10:02, the a/c is VS 1000fpm UP. The PITCH is ND 4 degrees from cruise.

This is exquisitely consistent with entry into a robust Updraft. If this upwelling has a velocity of 60 knots, we take 6000 fpm as the new airmass vector to add to the horizontal of cruise. This produces a distinct reduction in air speeds. All that is required is a reduction of 30 knots in the sensed a/s in less than one second, and the ADs get tossed.

To cause a 200 tonne a/c to climb @ 1000fpm might require an updraft of such a value, quite high. Then we can add to the a/c Attitude the free moment arm of the Horizontal Stabilizer, elevators. The mass will not lift immediately, but it will articulate longitudinally, ie: tail UP, Nose DOWN.

Those two bumps at the tail end of a/p duty are interesting.

Thanks for your reply

mm43... I continue to try to put together the airframe responses prior to and during the PF's capture of the controls. Obviously, it is here that I will look with great care, firstly because BEA have left it unaddressed, and the data is sparse; Secondly, the rest of the released data and all the one sided rhetoric shouts: SORTED! I don't think so, but it is largely irrelevant to me, the fascinating discussions are a follow on to an almost immediate LOSS of control, so this is where the Grail must be......

cheers
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Old 3rd Sep 2011, 23:57
  #3432 (permalink)  
 
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The next time you are at FL350 at M .82 in your airliner try pulling the controls into a full nose up position. Guess what, you end up 3,000 ft higher in a full stall. It will happen every time. No updraft in my opinion. Just bad aviating. I think the FDR supports this.
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Old 4th Sep 2011, 01:03
  #3433 (permalink)  
 
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Lyman

Re: Vertical Speed

A 1000 fpm vertical speed up sounds like a lot, that is, if it lasts a minute or more. It didn't. The A/P handled it very well and within seconds it was back to neutral. It was like a bump experienced in moderate turbulence. However, approximately 12 seconds later, it increased dramatically, about the time the sidestick was in use by the PF, that's when it increased to 5200 fpm.
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Old 4th Sep 2011, 01:31
  #3434 (permalink)  
 
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THRUST RESOLVER ANGLE

Originally Posted by TD
@ 2h 10min 0sec, ... and the engine N1 begins to decrease from 100% to 84%, reaching 84% in 8 seconds. This was accomplished by moving the thrust levers while remaining in A/T, my words
No - The thrust levers were not moved according to the TRA traces P113 EN.

... around 2h 10min 17sec. It is here they recognize the THR/LK is active. I think shortly thereafter then they reset the thrust levers back to 100% N1 as depicted on the chart, my words.
Again, TRA traces don't show that. First time a thrust lever movement is recorded is just after 2h 10min 45sec
But, the thrust levers must have been quickly recycled out of and back into the CLB detent around 2h 10min 22sec in order to leave the THR LK situation (P108 EN), quickly enough that nothing has been recorded on the TRA traces. IMO.
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Old 4th Sep 2011, 01:56
  #3435 (permalink)  
 
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TD Yes, 1000 fpm is perhaps 13 knots. The importance of this value is not the velocity, but the energy involved in moving the airframe. For this, any UPDRAFT acting in a three second frame to move 200 tonnes has large energy values, as above, let's put it at 6000 fpm.

More important is the Moment arm of the Tail, it lifted the aft airframe up until the body caught up, at this point the evidence is that the NOSE was PITCHED DOWN. So the a/c is PITCHED ND, and moving UP at 1000 fpm.

Again, it is the energy, not the velocity. This preceded the Pilot's back stick, and again, he was not patient, the a/c was starting to move, and he was inputting the ss max. The FCS loaded the airframe, which was already moving, and this caused the rapid climb. We know that the NOSE was rising at a/p drop.

Keep in mind that with Tail high, a "rotation" will drop the tail very quickly, to accomodate the desired PITCH UP. This is a very emphatic rotation, similar to TAKE OFF, and at T/O Pitch can easily be 15 degrees UP. This explains the radical PU, for me. Once at this PITCH, and w/o cues, the PF hasn't the clues he needs to pin the PITCH. If the energy latent in the column was still in play, the climb becomes a very problematic maneuver.

Now I cannot divine the cues and clues, and his maneuvering has me at a loss, but if I entertain the preceding holes, I gain some perspective, relative to the initiation and maintenance of the climb, which led to the STALL.

Which is the place I have been since day one, why the UPSET?

regards, Sir
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Old 4th Sep 2011, 14:09
  #3436 (permalink)  
 
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Due to the incessant, speculative, hamster wheel evolution of this thread, it has been decided to move it to the Tech Log forum for posterity and close it. There is already a thread in the Tech Log forum on this accident and any further debate can carry on there.
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