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AF447 final crew conversation - Thread No. 1

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AF447 final crew conversation - Thread No. 1

Old 19th Oct 2011, 16:35
  #241 (permalink)  
 
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That said, even with the trim the way it was, the extreme attitude was being held with the elevators - letting go should have brought the nose down to some degree
Dozy, I don't think that is correct. Letting go would cause the aircraft to hold an attitude as long as it was above stall speed. Below stall speed it will bobble its nose up and down. It needs nose down input on the controls for a significant period of time or actually running the trim down manually to have a hope to recover.
The elevators have some influence, but the THS and the pitch up moment from the engines' thrust hold the trump cards.

The PF didn't actively hold the nose on the level flight pitch attitude when he took control and all bad things flowed from that.

When the nose tried to fall through at the stall, the PF actively fought it and that is the reason for most of his nose up input after the stall. Do you agree?
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Old 19th Oct 2011, 16:51
  #242 (permalink)  
 
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Originally Posted by Gretchenfrage View Post
Agreed, because they could oversteer the protection ......
Nothing of the sort - Capt. Burkill himself says that all he did was raise the flaps while his F/O tried to keep the aircraft as on track as he could - no "oversteering", no disabling of the protections.

The Air Transat Azores incident proved that you can deadstick an A330 quite handily too.

@Machinbird, agreed - to be clear the nose coming down "to some degree" means exactly what you're describing - not enough to change the situation in itself, but the FCU would not be trying to hold the elevators in place if the PF let go.
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Old 19th Oct 2011, 16:55
  #243 (permalink)  
 
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Maintain altitude, full (or 'enough') power, indicated at approach to STALL.
Use back stick to maintain level.

TOGA, PITCH 15 degrees NOSE UP, indicated at Wind Shear.

Full back stick, full power, CFIT recovery.


All published, all trained, all wrong. Everything is in the "Stick". And the stick is 'invisible'. Without full disclosure, this gets stuck on myth, and bias. Or on a guess at the Pilot's thinking. Excellent way to improve safety, eh?
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Old 19th Oct 2011, 17:18
  #244 (permalink)  
 
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Let's have a look at the DFDR traces:

Dozy,
the FCU would not be trying to hold the elevators in place if the PF let go.
The PF released (sort of) back-pressure on the sidestick between 02:12:15 and 02:12:30, without any change in the elevator (full nose-up). When he then moved the SS forward, the elevator moved away from the up stop, pitch attude decreased, and lift (normal acceleration) increased. Similar but slightly lesser responses between 02:13:45 and 02:14:00.

Machinbird,
The traces show similar responses in pitch when thrust is reduced between 02:11:45 and 02:12:15.
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Old 19th Oct 2011, 17:23
  #245 (permalink)  
 
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Lyman,

I am constantly amazed at what I perceive to be total fabrication and mis-statement. Their is absolutely no indication that the PF acted in any logical or correct manner. He was totally incorrect in his actions and the PM knew it but for some reason did not take control of the plane.
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Old 19th Oct 2011, 17:33
  #246 (permalink)  
 
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As an ancient engineer, and one not fully familiar with all the Airbus FCS subtleties, I hesitate to bring this up once again....

But, wasn't there a suggestion, early in one of the earliest threads, that AB pilots are 'not encouraged' to use manual trim (except after full reversion to "mechanical")?

Not to mention the absence of a "bicycle bell" while autotrim was winding the THS to full nose-up, contributing to a lack of "configuration awareness"?

Is "trim" still being taught, or is it now left to George entirely?
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Old 19th Oct 2011, 18:05
  #247 (permalink)  
 
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Maybe I'm missing something here, but I fail to understand how none of the pilots recognised (or mentioned anyway), that the plane was stalling. As far as I know the vertical speed/altimeters and attitude indicators were functioning correctly. Once the plane was in a rapid descent despite the fact the nose was pitched up, I'm sure most trainee pilots or even aviation enthusiasts could tell you the aircraft had stalled.
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Old 19th Oct 2011, 18:19
  #248 (permalink)  
 
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Basic training used to emphasise the importance of not only recovering from a stall but also to recognise it. As MU99 says, slow speed, high nose att, RoD all give it away. I feel that these guys were disorientated, they had forgotten their basic flying training and were engulfed by the wrong mental model. As a general principle, if an aeroplane does not respond as you expect, reduce the AoA and try again. That's good for anything that you put in the air, fast or slow.
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Old 19th Oct 2011, 18:22
  #249 (permalink)  
 
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Emergency Action

Maybe I'm missing something here, but I fail to understand how none of the pilots recognised (or mentioned anyway), that the plane was stalling. As far as I know the vertical speed/altimeters and attitude indicators were functioning correctly. Once the plane was in a rapid descent despite the fact the nose was pitched up, I'm sure most trainee pilots or even aviation enthusiasts could tell you the aircraft had stalled.
A close reading of the thousands of posts shows that, apparently, there would have been little or no sensation of falling. Having said that, had I been on board, I would have "stormed the cockpit." (Yeah, right, buddy!)

It's clear to me, after having read everyone's input here, that there is a fundamental difference between 'A and B,' and that difference amounts to: to fly B, you need to be a thoroughly-trained pro. To fly A, you don't need to be unless the poop hits the fan. And so, they all died. So far, without complete information, there will be plenty of blame to go all around.
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Old 19th Oct 2011, 18:33
  #250 (permalink)  
 
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Originally Posted by HazelNuts39 View Post
Dozy,
The PF released (sort of) back-pressure on the sidestick between 02:12:15 and 02:12:30, without any change in the elevator (full nose-up).
He blips the controls forward from full back-stick to half-forward for a second, if that - there's a corresponding blip in elevator movement (which will take a second or two to respond in any case), before he returns to ordering half-nose-up pitch, which pushes the elevator back to max nose-up position

When he then moved the SS forward, the elevator moved away from the up stop, pitch attude decreased, and lift (normal acceleration) increased. Similar but slightly lesser responses between 02:13:45 and 02:14:00.
Yes, and if you follow the overall trend during those periods, the stick spends more time around neutral than it does during the 2:12:15 to 2:12:30 period (of which approximately 1s is spent with the stick forward of neutral, the other 14s is spent with it back). I don't need to tell you that hydraulically-assisted controls need a few seconds to respond to demand now, do I?

@CJ - As I recall, it was only 1 poster, Svarin IIRC, who stated that his airline were very strict about their Airbus crews not touching the manual trim wheel. This is worrying to me because even if autotrim is there more than 99% of the time, you still need to know how to recover the aircraft if it isn't - so it should be trained for regardless. The trim "whooler" was deleted from the A320 onwards, probably because it would be an annoyance with autotrim active during turbulence - it would be sounding almost constantly. Maybe a compromise with the whooler sounding if the trim goes beyond a certain limit could be looked into?

Originally Posted by Tourist View Post
Erm...
I think you'll find 100% are down to human error if you look deep enough.
I was referring to aviation accident investigation terminology, in which "structural failure" and "adverse meteorological conditions" are considered distinct and separate.

Last edited by DozyWannabe; 19th Oct 2011 at 18:54.
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Old 19th Oct 2011, 18:52
  #251 (permalink)  
 
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Originally Posted by DozyWannabe
Nothing of the sort - Capt. Burkill himself says that all he did was raise the flaps while his F/O tried to keep the aircraft as on track as he could - no "oversteering", no disabling of the protections.
Knowing what we now know after the Hudson NTSB report, there is a good chance a 330 would have hit the road, fence, loc antenna for refusing to the pilot the possibility to reach Alpha Max.


Originally Posted by ChristiaanJ
But, wasn't there a suggestion, early in one of the earliest threads, that AB pilots are 'not encouraged' to use manual trim (except after full reversion to "mechanical")?
  • It is not trained or 'encouraged' to use manual trim in Normal or Alternate Law.
  • Manual trim is used in Direct Law, and trained for.
  • Manual trim and thrust are the only way to 'control' pitch in Mechanical Backup, and 'trained' for.
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Old 19th Oct 2011, 18:57
  #252 (permalink)  
 
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Originally Posted by CONF iture View Post
Knowing what we now know after the Hudson NTSB report, there is a good chance a 330 would have hit the road, fence, loc antenna for refusing to the pilot the possibility to reach Alpha Max.
That's your opinion, but BA038 was never anywhere near alpha max after the FMS was taken offline and manual control established - in fact it should not have been anywhere near Alpha Max even under FMS control (although the FMS did order a relatively alarming pitch-up initially) because of the FMS's own limitations.

I'm still not convinced by your arguments on the Hudson incident either - but I'm not going to argue the point.
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Old 19th Oct 2011, 19:07
  #253 (permalink)  
 
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Self Loading Freight in Arizona.

You have some ironclad conclusions. You are without doubt basing these on what you read here. What the Pilot did, and did not do, was undoubtedly based on what he made of his situation. It turned out badly.

For you to extrapolate beyond that makes you one who parrots what is readily available here, in great quantity.

Oddly, someone as yourself might easily take the opposite tack. I don't presume to know how what happened, happened. I think you do. Is there an explanation for what the PF did? Without doubt. I am baffled. As you are not, I defer to your report of the accident.

What you see as fabrication I present as "what ifs". If you do not suss the difference, no harm, no foul.

Don't choose fish.

What some here do not get, is that this a/c is a known quantity, and has a diary that shows what she did and did not do. The pilots are human, and have to pay for their individuality in knee jerk condemnation because the BUS has a pedigree, a huge fan base, and has her own recorders to cement her reputation. The interpreters of said recorders are her friends.
The pilots are "unquantifiable", to some extent, and that looms large when one's jury is engineers who reject a challenge to their sense of the World as it "is". What bonus, advantage, or future consideration is worth the open mind? None, as they see it.

Human factors are not the same, and instantly put dead men on the defensive.

Last edited by Lyman; 19th Oct 2011 at 19:19.
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Old 19th Oct 2011, 19:24
  #254 (permalink)  
 
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Originally Posted by DozyW
I don't need to tell you that hydraulically-assisted controls need a few seconds to respond to demand now, do I?
I would not expect the delay to be as much as 'a few seconds'. In fact it isn't - if you look at pitch response to SS at 02:10:05. The point is that I suspect that after having held the SS fully back for a considerable time, you probably have to push it forward of neutral to affect the elevator. In consideration of the control law in pitch, just releasing the stick does not demand a reduction in pitch or load factor.
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Old 19th Oct 2011, 19:29
  #255 (permalink)  
 
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Lyman

Help me out here, guys. Is it me, or are Lyman's posts increasingly odd?

It doesn't matter a damn what the aeroplane is. How crude or sophisticated. You do NOT pull the stick hard back when the autopilot disconnects at altitude. You fly attitude, attitude, and attitude. Then, you fly attitude.
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Old 19th Oct 2011, 19:29
  #256 (permalink)  
 
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@HN39 - It's going to take some time to respond from a 100% pitch-up to 50% pitch-down, as was the case during that trace.
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Old 19th Oct 2011, 19:44
  #257 (permalink)  
 
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@Dozy,
I was talking about the elevator moving from 30 deg ANU to 20 deg ANU.

Last edited by HazelNuts39; 19th Oct 2011 at 19:51. Reason: typo
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Old 19th Oct 2011, 19:50
  #258 (permalink)  
 
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Aileron Drag
Help me out here, guys. Is it me, or are Lyman's posts increasingly odd?
AD, no, you are quite on target. His approach is often skewed from physical reality.
But sometimes he has his points. Just pick and choose what you want to actually consider and ignore the rest.
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Old 19th Oct 2011, 20:04
  #259 (permalink)  
 
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@HN39 - I must confess I'm a little confused. At approx 2:10:07, the pitch attitude trace registers nose-up in response to the initial pitch-up command from the sidestick. The aircraft is at normal cruising speed at this point, so the elevator deflection only needs to move very slightly to effect a significant result.

I thought we were taking about the later traces at 02:12:15 to 02:12:30, when the aircraft is stalled and the PF makes a 1-2s "blip" forward on the sidestick, whch triggers a very small deviation in the elevator trace, followed by the 2:12:31 to 2:12:45 traces where the stick spends most of it's time either neutral or forward, with the corresponding elevator movement, and the 02:13:45 to 02:14:00, where the PNF's inputs achieve the same thing.
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Old 19th Oct 2011, 20:41
  #260 (permalink)  
 
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Lyman . . .

One should look for proof that PF was causing the climb to 38. Not the aircraft.
Are the FDR recorded nose-up inputs by the P/F's stick in doubt?

...FDR at 2h 10min 51 "the P/F continued to make nose-up inputs." What difference would it make if he was commanding the climb or trimming into it ....when he should have been commanding nose-down and if trimming at all, then nose-down.

Tell us: With A/P switched off, could the A330-200 climb and trim itself into a 3000' climb without manual inputs?
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