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AF 447 Thread No. 11

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AF 447 Thread No. 11

Old 17th Jun 2013, 20:26
  #101 (permalink)  
 
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Originally Posted by Natstrackalpha View Post

If the A/H was operational, then, why did they not look at it? -
Looking at the corrections applied to the roll excursions I think it is safe to assume they were looking at the A/H that is called PFD.
There is also not the slightest indication it didn't work correctly. Please don't let us go back to that tinfoil hat discussion.

It just seems what they saw didn't ring a bell?
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Old 17th Jun 2013, 20:27
  #102 (permalink)  
 
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HN39,

You may be correct.

The fact that pitch was in the process of being reduced until the moment the FDs made what may have been a decidedly untimely appearance is just one of many observations made in the report.

I think, if nothing else, the fact that until any two ADRs are back within 19 knots (< 20 knots) in a situation like this, the FDs are removed but remain physically selected and then can reappear, may just be one of a number of lessons learned concerning A330 systems functionality that may or may not be specifically relevant to the incident.
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Old 17th Jun 2013, 21:02
  #103 (permalink)  
 
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NTA

Ok, lets try this from a different angle. What would/could have caused the attitude display failure?

Last edited by busTRE; 17th Jun 2013 at 21:17.
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Old 17th Jun 2013, 22:24
  #104 (permalink)  
 
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mom pls +++
thanks.

Ice freezes the static and pitot (covers the static and pitot)
Affecting CADC
Affecting the 3 IRS
Affecting (SADC?)
the FACs thus affected (any back up to the FACS similarly affected)

Therefore in my astoundingly limited knowledge the PFD, displays no input from any of the aforementioned. Assuming the acceleromoters in the 3 IRSs
without the input from the CADCs and also the FACs do not function on their own. . . .to produce ATT info - thus rolled and banked - whether we are looking at normal Pitch alternate roll, and/or the whole nine yards - it was not happening because of the Ice/CADC/ and FACs.

Considering the freeze up happened in more or less S+L flight, then that is where (the ATT) remained.

Another theory, for your joy and entertainment is that Stall condition (which came later . . ?) and the protection trying to pitch down is thus offset by a certain somebody holding back press on the stick.

Hmm, considering that 2 stick inputs would sum algebraically would not the same summation occur if airplane wants to pitch down and something is stopping it from doing so? If this latter missive is the case, it would not explain limited or no indication in roll, whereas the CADC and FAC failure might - considering FACs had no input. However, just to shoot that idea down in lfmaes, and stick input woulr override/

Did the THS freeze over? At full forward trim? That would encourage one to pull the stick back coupled with the auto tendency to push the nose down (due to the stalled condition)

but your question was, what, in my mind, caused the ATT to freeze, excuse the pun.

Thanks a bunch bus TRE!

Last edited by Natstrackalpha; 17th Jun 2013 at 23:40.
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Old 18th Jun 2013, 07:11
  #105 (permalink)  
 
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I see where you're going wrong.

The attitude data is provided by IRs. An IR has no air data input for its core functions and its attitude data is unaffected by loss/corruption of air data from pitot or static sources. The ADR would be affected but the IR would not.

Does that help?
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Old 18th Jun 2013, 07:39
  #106 (permalink)  
 
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@OK465
I think, if nothing else, the fact that until any two ADRs are back within 19 knots (< 20 knots) in a situation like this, the FDs are removed but remain physically selected and then can reappear, may just be one of a number of lessons learned concerning A330 systems functionality that may or may not be specifically relevant to the incident.
But that's not really the problem; it along with other matters this crew immersed themselves in was provided for in the FCOM and QRH procedures.

The failure of a crew to follow SOP's, to the extent that what happened here, was never envisaged by the designers, test pilots, or TRE's who helped to compile the appropriate documentation.

It really falls into the, "You can lead a horse to water, but ..." equation.
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Old 18th Jun 2013, 07:46
  #107 (permalink)  
 
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OK465

FD 1 and 2 ....................... OFF
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Old 18th Jun 2013, 08:07
  #108 (permalink)  
 
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Ok, fine.


Thank you for your time and input - so do you want me to delete my original post now, as people may be queueing up to see it?

Last edited by Natstrackalpha; 18th Jun 2013 at 08:11.
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Old 18th Jun 2013, 08:51
  #109 (permalink)  
 
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Thank you for your time and input - so do you want me to delete my original post now, as people may be queueing up to see it?
That's a great idea!
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Old 18th Jun 2013, 08:51
  #110 (permalink)  
 
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Just a thought, as I exited the front bog recently at cruise altitude.

My feet and ankles are used to a floor at 2.5-3.0 degrees nose up for the short walk, or the loiter in front galley to liaise with CC.

Even when I'm inspecting the plumbing I'm aware of the step climb the F/O has negotiated in my absence

Can anyone explain why Monsieur Le Capitain did not notice an unusual deck angle during his sprint to the flight deck? Any of us who've walked in the aircraft during initial climb, especially on empty positioning sectors as pax, have been aware of the deck angle and the extra effort to walk uphill.

This must have been a tactile clue to the standing crewmember on his return to the "control center" and yet it failed to trigger a suitable response from him? As a non 'bus driver I felt like getting the thread away from all the exotic Laws various which others have said tend to make diagnosis more difficult.

No AoA probes, no vacuum/wind powered AHs, no reference to expensive ADIRU sourced blue-side up, brown-side down displays, just the plumb bob on a string which we all are when airborne. Yes the craft was probably speeding up, slowing down and bucking around, but the general trend could have been obvious to a standing & walking crewmember, uncontaminated by the confusion forwards of the cockpit door

After that Eurocents worth, back to the darkened room.
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Old 18th Jun 2013, 13:44
  #111 (permalink)  
 
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Originally Posted by HN39
That's really anybody's guess, and I've given mine earlier. He had been*keeping the nose up at around 15 degrees, and applied full back stick when the nose dropped below that target.
According to your graph, he was already applying full back stick a short time before the nose dropped below that target.
IMO the correlation with the FD reappearance is obvious.

Originally Posted by Clandestino
Panic
No panic here but the attempt to blindly obey the reappearing FD.
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Old 18th Jun 2013, 14:27
  #112 (permalink)  
 
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No panic here but the attempt to blindly obey the reappearing FD.
Have a look at pages 60-62 and 95-96 of the English report.

Flight director is out between 2:10:08 and 2:10:18, yet the right stick is in nose up position, pitch increases from 3 to 9.

FD returns at 2:10:17 for two seconds and commands between 3/4 and full nose down, yet pitch is maintained around 10

Then it goes out again for a couple of seconds, pitch hovers around 12.

Between 2:10:26 and 2:10:36 it's back, demanding 6000 FPM climb and nose up, yet nose is slightly lowered, Roc goes from 6000 to 4000.

Again it passes out, still pitch is decreasing towards 6.

It is back again at 2:10:47, demanding 1400 fpm climb. Stall warning goes off, nose is abruptly pitched up. Flight director is now firmly below aeroplane symbol, yet the pitch goes up and up and up.

Finally, FD moves to nose up command as stall breaks the climb and aeroplane commences her final descent.

Under no circumstances I would find this to be even distantly similar to "blindly following the FD".
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Old 18th Jun 2013, 14:31
  #113 (permalink)  
 
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A few seconds earlier, when full left SS didn't arrest the roll to the right, PF announced: "Je n'ai plus le controle de l'avion la"

No panic?
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Old 18th Jun 2013, 14:45
  #114 (permalink)  
 
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Deck angle and Captain's movements?

BARKINGMAD,

I assume that the captain made his way forward up the aisle, flustered and sleepy, while the aircraft was rounding the top of its flight profile - and thus he didn't have to climb upwards. On entering the cockpit, I assume that he sat down right away - and thus did not have to hold on as the attitude steepened into the stall.

If he'd woken earlier or later, or crouched between the flying crew, then maybe he'd have experienced some inertial cue from his body, and would have recognized what was going on. Perhaps also if he'd had to grab to hold on in the terminal-velocity nose-high descent rather than just sit in his seat?
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Old 18th Jun 2013, 15:00
  #115 (permalink)  
 
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Cool

Hi,

I assume that the captain made his way forward up the aisle, flustered and sleepy,
First is to check where is the rest accommodation for the captain (or the other pilots) in the A330
It's not in the rear toilets .. but just near the pilots office
And that why I don't understand why the captain don't go immediately in the office .. cause all the alarms sounding in the office..
I have always suspected that the captain was not in the rest accommodation

Last edited by jcjeant; 18th Jun 2013 at 15:03.
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Old 18th Jun 2013, 15:07
  #116 (permalink)  
 
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Hi Barkingmad & awblain,

It is impossible for the human brain to distinguish between linear inertial acceleration (or deceleration) from a pitch change. We need a natural horizon or an ADI/PFD to distinguish between the two.

See http://www.blackholes.org.uk/pp/soma... illusions.ppt
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Old 18th Jun 2013, 16:03
  #117 (permalink)  
 
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Rudder...rat,

Sure, I agree that you can't keep an internal reference to an absolute position, or distinguish whether you're on a vehicle that is slowing down or going downhill. The pitch-up illusion on acceleration on take off in an airliner is by 10-15 degrees or so.

However, when you stand up out of a seat, you can still tell whether the floor is apparently sloping or not. You can tell whether you have to grab the seatback in front and pull to climb into the aisle, or push against it to slow yourself.

During the pitch up (which woke/roused the Captain?), had he been on his feet, he would surely have felt himself to be heavy, and known there was upward acceleration, as in an elevator. When the aircraft was reaching its maximum height he might have been felt a bit light. As he put one foot in front of the other on (the short?) way to and into the cockpit, would he not have noticed whether he had to haul himself up a slope, or was rushed forward downhill? While not being able to perceive absolute motion, he surely would have been able to get a sense of an unusual attitude, unless the acceleration and attitude were unfortunately aligned to make things feel normal when he was on his feet. Or maybe his heart was pounding, and the aircraft was shaking, and he couldn't get any such subtle cues?
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Old 18th Jun 2013, 16:05
  #118 (permalink)  
 
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FD 1 and 2 ....................... OFF
toffeez,

yes sir, I've done this many times.

My comment was in reference to the fact that they didn't.

Before reading the report, I was unaware of the exact ADR tolerances (both speed, 19 knots, and time, 10 seconds) that were in play when this FD error is made, nor was I made aware in 330 ground school of the fact that the FD buttons remain latched even though the FDs are removed in certain airspeed discrepancy situations.

One of the recurring complaints about the so-called 'children of the magenta line' is that their training is being 'dumbed down'.

I personally hate the phrase, 'You don't need to know that'.

The failure of a crew to follow SOP's, to the extent that what happened here, was never envisaged by the designers, test pilots, or TRE's who helped to compile the appropriate documentation.
mm43,

I understand the importance of SOPs, cockpit discipline and following the recommended procedures, but I also believe in knowing everything I can glean about each aircraft I've ever flown so that maybe I have a better chance of dealing with something which 'hadn't been envisaged'.....

not being told,

'You don't need to know that.'

Last edited by OK465; 18th Jun 2013 at 17:46. Reason: brevity
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Old 18th Jun 2013, 16:42
  #119 (permalink)  
 
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Hi awblain,
or distinguish whether you're on a vehicle that is slowing down or going downhill.
Exactly.
unless the acceleration and attitude were unfortunately aligned to make things feel normal when he was on his feet
Since they didn't change the power initially (thrust lock), then I suggest the deceleration was masked by the increased pitch attitude.

Any short term vertical acceleration could be confused with turbulence.

Last edited by rudderrudderrat; 18th Jun 2013 at 16:43.
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Old 18th Jun 2013, 18:42
  #120 (permalink)  
 
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It is back again at 2:10:47, demanding 1400 fpm climb. Stall warning goes off, nose is abruptly pitched up. Flight director is now firmly below aeroplane symbol, yet the pitch goes up and up and up.
(bolding mine)

Clandestino,

Using the plots from page 60, 61, & 62......

the pitch attitude is 6 degrees at 2:10:48 and transitions to 11-12 degrees (with 2 very short duration plateaus evident, one at 11 degrees, one at 12) at 2:10:57

this is a pitch increase of 6 degrees in 9 seconds....2/3 of a degree per second. I don't consider this as "nose is abruptly pitched up". It is, however, entirely consistent with use of the FD as airspeed bleeds off.

Using the PFD representations from page 96 (Fig. 69), at 2:10:48 and 2:11:05, they show the pitch steering command within 1 to 2 degrees of pitch attitude, presumably for the entire 7 seconds and maybe longer (next PFD representation is at 2:11:39).

I'm unable to see this as "Flight director is now firmly below aeroplane symbol"

From this point as the airspeed decays more rapidly, yes, the nose goes up, up, up...as does, if you notice, the FD pitch steering command (PFD picture at 2:11:39).

Whole sequence is entirely consistent with attempted use of the FD initiated at 2:10:47....(or it probably wouldn't be included as a possibility in the report).

edit: BTW the PFD picture with the FD well below pitch attitude is from 2:10:27, well before that very critical moment at 2:10:47 when pitching direction is reversed.

Last edited by OK465; 18th Jun 2013 at 18:46.
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