Go Back  PPRuNe Forums > Flight Deck Forums > Tech Log
Reload this Page >

AF 447 Thread No. 5

Tech Log The very best in practical technical discussion on the web

AF 447 Thread No. 5

Old 4th Aug 2011, 09:08
  #1501 (permalink)  
 
Join Date: May 2006
Location: Yearning for sun and sea
Age: 79
Posts: 249
I am not connected to the Aviation industry.

My question is this, in the English translation in the Interim report, under 3, Conclusions, new findings, I read this:

".the copilots had not received any training, at high altitude, in the “Unreliable IAS” procedure and manual aircraft handling."

Is this perfectly normal and would this apply to other airlines as well?
GANNET FAN is offline  
Old 4th Aug 2011, 09:12
  #1502 (permalink)  
 
Join Date: Jan 2008
Location: Cotswolds
Age: 64
Posts: 1,263
Glad to notice from the English translation of BEA they concur with my explanation of the French, in that the correct translation of the CDB at 2:12:15 is:

There I don't know
There it is going down

As two distinct sentences, obviously pointing at two different instruments.

The benefit of the english BEA translation is that they will have had the benefit of the intonation. I hope they read PPRuNe as the discussions here give such a good insight in how limiting a written document can be in terms of interpretation of what really happened.

The new observations (page 77?) are absolutely damning for the crew in not calling a potential stall based on the audible warning, let alone identifying the stall and taking appropriate action.

Without wanting to judge anyone I do personally also find the lack of leadership startling. The PF clearly states he is at a loss as to what is happening but neither the PNF or the CDB take a decisive (early) lead. It's like everyone else wants somebody else to take charge.
vanHorck is offline  
Old 4th Aug 2011, 09:36
  #1503 (permalink)  
 
Join Date: Jan 2001
Location: UK
Posts: 2,044
".the copilots had not received any training, at high altitude, in the “Unreliable IAS” procedure and manual aircraft handling."

Is this perfectly normal and would this apply to other airlines as well?
My airline will "claim", and has recorded, that I have done "High Alt" training, inc Manual Flying / Stall Recoveries. Indeed, in the last year or so, probably as a result of this accident.

In practice this was a well advertised, briefed, exercise. In S&L flight we slowed to the stall (Alt Law), and performed a few recoveries concentrating on the "finesse" of the recovery / height loss, and reocvering at the "incipient (warning) stage".

I happened also to do a Jet Provost Flt Test last year, up to an including FL350 handling, Mach Buffet, turns / stalls.

I'll leave the reader to guess which was the more valuable lesson / refresher in High Level / Mach handling
NigelOnDraft is offline  
Old 4th Aug 2011, 09:47
  #1504 (permalink)  
Per Ardua ad Astraeus
 
Join Date: Mar 2000
Location: UK
Posts: 18,582
Thanks - I think I can see now which stick it is, but why is there no 'Dual Input' warning at "2 h 12 min 59" onwards?

I also note (must have been asleep!) that the report says there " The pitch attitude varies from 11° to 13°." Do they really mean that? If the minimum attitude was 11 degrees that is extremely high for level cruise to start the manoeuvre.

Here is the whole (English) extract for those 7 seconds.

 The copilot sidestick is positioned:
- nose-up to ¼ of the stop position
- left to ¾ of the stop position then
right to the half-travel position
twice.
 The pitch attitude varies from 11° to 13°.
 The THS is stable at around -3°.
 The roll angle varies between 8° right and 5° left.
 The vertical speed increases to 6,700 ft/min.

RE The spoilers, I am having difficulty looking at the 'LH/RH' 1-6 lines which mean nothing to me, but there is no mention in the CVR extract of speedbrake retraction, only they are 'deployed' at "2 h 12 min 04 - 2 h 12 min 07" - is that Spoiler LH/RH3 as shown in red? Is the other (LH5) triggered by aileron input?
BOAC is offline  
Old 4th Aug 2011, 10:10
  #1505 (permalink)  
 
Join Date: Jun 2009
Location: somewhere
Posts: 451
Selected vertical speed?

Can anyone explain this?




The vertical speed trace, left of the blue line (A/P drop off).
Vert. Speed seems to be compensated by the Selected Vert. Speed at regular intervals to keep it at altitude.
@ ~02:10:10 the zoom climb starts (no more compensation of the automation).
@ ~ 02:10:20 there's a sudden peak up, down and up again.

- Who's generating this compensation in NORMAL
- Is that normal system behaviour or was the A/C unstable before the event?
- What could introduce the peaks at ~02:10:20?


Thanks in advance for answering the questions.
A33Zab is offline  
Old 4th Aug 2011, 10:21
  #1506 (permalink)  
 
Join Date: Jun 2009
Location: Paris
Posts: 691
Hi vanHorck,
Originally Posted by vanHorck
Glad to notice from the English translation of BEA they concur with my explanation of the French, in that the correct translation of the CDB at 2:12:15 is:
There I don't know
There it is going down
As two distinct sentences, obviously pointing at two different instruments.
Congrats vanHorck! your French is better than mine and I noticed that as well (in fact the first thing I looked at!)
All the ambiguous sentences are translated the exact same way a non French native (but anglophone) would have interpreted them. Note also that ambiguousness is more than one meaning, not that any other interpretation is forcibly the bad one. The fact is that we don't know more than the original text but I still doubt seriously of several "interpretations" from the English report... Zut! They were speaking French, not English!

Hence, there is no evidence either that BEA members really cared about this work, after having already released the French text without meaningful punctuation or context helpers (moreover, they are covered by their note: French texte is reference)... they might have subcontracted this translation work.

For example: do you really think that a BEA member would not catch a few things:
- Sal-Amilcar in Heading Verde ... for Cape Verde (Cap Vert)

Or translate :
- the wings to flat horizon the standby horizon (what does it mean, seriously!?)
- no it won’t (not)... not not!
- No above all don’t extend (the) ... extend "the" what?
- er no we’re in computed ... but not in manual mode!

Would you usually call the rudder controls a rudder bar?, spoilers/speedbrakes, airbrakes?
Remember what I expected from this translation: not a single clue added but certainly more errors.
takata is offline  
Old 4th Aug 2011, 10:31
  #1507 (permalink)  
 
Join Date: Jun 2009
Location: I am where I am and that's all where I am.
Posts: 660
DozyWannabee, do you see an anti-correlation? He asks for nose up and gets a very significant nose down. When that happens, what does he think? Does his entire mental process derail, especially if he does not recognize he is stalled?
JD-EE is offline  
Old 4th Aug 2011, 10:46
  #1508 (permalink)  
 
Join Date: Jun 2009
Location: I am where I am and that's all where I am.
Posts: 660
xcitation, might a 10 degree nose down attitude give them a rather distinct impression they are in a dive, even after asking for full nose up? He asked for nose up. Nothing happened. He asked for more nose up. Nothing happened. He kept this up to hauling back on the stick all it would go. THEN the plane goes nose DOWN 10 degrees over a few seconds?

I suppose if he'd ever been properly trained about stalls in A330s he might have recognized "the real thing" and not a warning. Perhaps if he'd had a real AoA report to look at he might have recognized "the real deal" and not a mere warning.

The plane quit doing what he asked for. It went nose down, and stay there depressingly long, when he had full up on the elevator.

(And it was Takata, bless his heart, who pointed me to this in one of his messages in the last few days here on these pages. I looked at the plots, wondered about the plot being inverted, wondered about translation, wondered about a lot of things until I decided the plane was doing its own thing while the pilot wanted nose up. And I asked, what happens to a pilots mind when that happens if he's not really stall trained in the plane he is flying? Small planes don't stall that way, do they?)
JD-EE is offline  
Old 4th Aug 2011, 10:58
  #1509 (permalink)  
 
Join Date: Jun 2009
Location: I am where I am and that's all where I am.
Posts: 660
Originally Posted by DozyWannabe
Franzl, I've never put a single person from a single forum of which I am a member on ignore list in my life! I'm quite capable of mentally filtering out waffle if I need to, and I've always operated under the assumption that even people who get on my nerves probably have something to teach me, so it would be ignorant of me to ignore them.
That is EXACTLY why I have not filtered out some of the more irritating posters here. They have experience I do not have. And the annoyance is more at their going way out on a limb, sawing away at it, and then jumping up and down to break the limb off. That sawing and jumping part gets on my nerves.

The out of the box thinking is sometimes helpful if it's dropped once it's seen as nonsense.
JD-EE is offline  
Old 4th Aug 2011, 11:01
  #1510 (permalink)  
 
Join Date: Jun 2009
Location: Paris
Posts: 691
Originally Posted by BOAC
I think I can see now which stick it is, but why is there no 'Dual Input' warning at "2 h 12 min 59" onwards?
There is? later. It is not systematic: this warning is triggered if imputs are not in the same way, if one pilot don't use priority (disabling other imputs)
Originally Posted by BOAC
I also note (must have been asleep!) that the report says there " The pitch attitude varies from 11° to 13°." Do they really mean that? If the minimum attitude was 11 degrees that is extremely high for level cruise to start the manoeuvre.
Still asleep?
Increase up to 11° (started from 0°) during the sequence 0210:07 -10:18, pitch was low at the begining (likely due to thrust reduction)

Originally Posted by BOAC
Here is the whole (English) extract for those 7 seconds.
Those are the next 7 seconds after my quote above for 0210:18 -10:25.
Manoeuver started at 0210:07, not 11 seconds later.

Originally Posted by BOAC
RE The spoilers, I am having difficulty looking at the 'LH/RH' 1-6 lines which mean nothing to me, but there is no mention in the CVR extract of speedbrake retraction, only they are 'deployed' at "2 h 12 min 04 - 2 h 12 min 07" - is that Spoiler LH/RH3 as shown in red? Is the other (LH5) triggered by aileron input?
Look at straight orange curves: "Spoiler LH6", see both "V" at exact same time: released, retracted. It took less than 10 seconds.
takata is offline  
Old 4th Aug 2011, 11:08
  #1511 (permalink)  
 
Join Date: Jun 2009
Location: Paris
Posts: 691
Hi A33Zab,
Originally Posted by A33Zab
Can anyone explain this?
Yes. the green curve represents the "selected" altitude recorded by flight Guidance. Each time the FD disengage and re-engage, it will take the current FL as the new value for "selected".... and FD disengages a lot during the first minute!
There is no impact on flight controls without AP. There is also another graph with Mach "selected", same thing.
PJ2 already explained that a few dozen pages ago!
takata is offline  
Old 4th Aug 2011, 11:11
  #1512 (permalink)  
 
Join Date: Jun 2009
Location: I am where I am and that's all where I am.
Posts: 660
Shadoko, if I had to guess I'd suggest there was an analog to digital converter in the picture that saturated and went past saturation. Some specific types will peg and stay there. Others will wrap their N bit counter and start over at zero. It looks like the plane had the latter sort.
JD-EE is offline  
Old 4th Aug 2011, 11:31
  #1513 (permalink)  
 
Join Date: Jun 2009
Location: Paris
Posts: 691
Hi JD_EE,
Originally Posted by JD_EE
The plane quit doing what he asked for. It went nose down, and stay there depressingly long, when he had full up on the elevator.

(And it was Takata, bless his heart, who pointed me to this in one of his messages in the last few days here on these pages.
Thanks sweety!
But you should also remember that I had likely found an explanation for the first drop of the nose... not in pilot's flight control imputs!

You'll have to look closely at the thrust settings to see it. This drop happened exactly when they reduced thrust from CLB down to IDLE (hence, the following large pitch down moment) and it certainly also caused the right wing to depart at the same time... consequentrly, it caused twice the amount of confusion as the PF tried desperately to keep his wings level and his nose up at the same time.

Captain watched it, arriving at the same time. During most of the following minute, aircraft pitch was maintained up and down between -10 and +10.... but they re-applied full thrust again... really too bad. If they had stopped their pitch imputs and let the thrust to IDLE, simply controling the turn, she might have recovered naturally at this point.

Last edited by takata; 4th Aug 2011 at 11:43.
takata is offline  
Old 4th Aug 2011, 11:37
  #1514 (permalink)  
 
Join Date: Jan 2008
Location: Cotswolds
Age: 64
Posts: 1,263
Hi Takata,

We read from the same page!

The Brothers of the Christian Church in Thonon Les Bains boarding school at least taught me reasonable French, that's the only good thing to say about my education there......

I think reading the French original in combination with the BEA translation at least gives us some indication of what actually went on in combination with the BEA interpretation.

In all I am not a conspiracy theorist and I am impressed with their Diligence so far
vanHorck is offline  
Old 4th Aug 2011, 13:05
  #1515 (permalink)  
 
Join Date: Jul 2002
Location: UK
Posts: 3,182
Originally Posted by JD-EE View Post
DozyWannabee, do you see an anti-correlation? He asks for nose up and gets a very significant nose down. When that happens, what does he think? Does his entire mental process derail, especially if he does not recognize he is stalled?
I don't and can't know what he thought, because he's dead. But to my mind only two things can make apparently undamaged controls fail to respond in the correct manner, and those things are:
  • an overspeed into the transonic region
  • a fully-developed aerodynamic stall

It would appear that the PF - initially, at least - believed it was the former, when in fact it was the latter.
DozyWannabe is offline  
Old 4th Aug 2011, 13:06
  #1516 (permalink)  
 
Join Date: Jul 2009
Location: France - mostly
Age: 80
Posts: 1,689
Originally Posted by takata #1503
Hi A33Zab,
Quote:
Originally Posted by A33Zab
Can anyone explain this?

Yes. the green curve represents the "selected" altitude recorded by flight Guidance. Each time the FD disengage and re-engage, it will take the current FL as the new value for "selected".... and FD disengages a lot during the first minute!
Hi takata,
With reference to this question and your reply, how do you explain (on page 112 of the french report, also on page 113) the cycling of 'Mach selecté' between 02:00:00 and 02:09:55? Is this Mach_1, Mach_2 or Mach_3?
HazelNuts39 is offline  
Old 4th Aug 2011, 13:08
  #1517 (permalink)  
 
Join Date: Feb 2001
Location: right here inside my head
Age: 61
Posts: 178
Originally Posted by JD-EE
Small planes don't stall that way, do they?
Sure, they can. with some (Cessna 150 for example), If you hold back elevator, with a bit of energy, it'll lift the nose to stall, drop the nose and repeat... On the other hand (or with another bird - 172 for eg.), if one gradually enters the stall and retains up elevator you can get the bird to mush all the way down without ever un-stalling the wings. ...The attitude during the "mush" will depend on the bird of course... The tricky bit is keeping the wings level to avoid a spin. ...and on the little birds, use of rudder is the only way to accomplish that. Any aileron input, once stalled, is more likely to induce a spin. (I've also played with that quite a bit with little RC airplanes - I have a little bi-plane that will quite happily adopt a 5-10 degree nose down, 60-70 degree FPA when held in the stall)

When I learned to fly, novice pilots were introduced to these variations of stall during initial training. I guess it might have taken quite a bit of training to get a professional pilot to unlearn stall characteristics, somehow.
3holelover is offline  
Old 4th Aug 2011, 13:27
  #1518 (permalink)  
 
Join Date: Oct 2009
Location: UK
Posts: 1,271
I guess it might have taken quite a bit of training to get a professional pilot to unlearn stall characteristics, somehow.
I realise it may seem that way - but AB FBW in ALT LAW feels like nothing else you've ever stalled.
rudderrudderrat is offline  
Old 4th Aug 2011, 13:36
  #1519 (permalink)  
 
Join Date: Feb 2001
Location: right here inside my head
Age: 61
Posts: 178
I can only imagine RudderRudderRat... but can it's stall really feel like an overspeed?
3holelover is offline  
Old 4th Aug 2011, 13:37
  #1520 (permalink)  
 
Join Date: Mar 2001
Location: us
Posts: 694
a33zab, I don't have the answer, but is it possible, without significant turbulence, to get these g accelerations after N1 was just decreased?

2 h 10 00 > 2 h 10 08, N1 decreases from 100 percent to 84 (or 83) percent (in response to a commanded decrease in Mach)

2 h 10 07 > 2 h 10 18, vertical acceleration varies between 0.9 g and 1.6 g.

2 h 10 23 > N1 begins to increase [from 83 percent].
SaturnV is offline  

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information

Copyright © 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.