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AF447 final crew conversation - Thread No. 1

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AF447 final crew conversation - Thread No. 1

Old 30th Oct 2011, 11:55
  #541 (permalink)  
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Originally Posted by svhar
Who knows what a lightning strike can do?
- excuse me, Mr Oozlum - which lightning strike are you referring to for AF447?
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Old 30th Oct 2011, 12:37
  #542 (permalink)  
 
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I remember an Airbus incident some years ago, where some wires were crossed so that a left stick input resulted in a right bank.
svhar, please supply details/reference for this.
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Old 30th Oct 2011, 12:54
  #543 (permalink)  
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Monarch, I think, and a brilliant bit of flying to get it back on the ground.
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Old 30th Oct 2011, 13:02
  #544 (permalink)  
 
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The wires were not crossed. I believe the sidestick transducer was put in the wrong way around reversing the roll inputs, even though it was designed to fit only the correct way. The flight control check may have also have been done without looking at the flight control page (as is the norm now) and only the sidestick position Cross, on the PFD, which gave the correct indications.

This has no bearing on AF447!

Lufthansa I think and the FO's sidestick worked correctly as he took control.
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Old 30th Oct 2011, 13:11
  #545 (permalink)  
 
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Lufthansa in 2001. A faulty repair to an ELAC plug.

http://www.bfu-web.de/cln_030/nn_226...kfurt_A320.pdf
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Old 30th Oct 2011, 14:01
  #546 (permalink)  
 
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The yoke (OK, why not take digital input from a yoke?) has the benefit of being in clear view and both are linked mechanically.

These features might have helped or even saved 447.
Quote from tech log:
The main goal of unusual-attitude training is breaking the deeply ingrained and nearly universal “panic pull” reflex that causes pilots to haul back on the stick or yoke when bank angles exceed their comfort levels.
The PF was pulling back regardless if he had a side stick or a yoke...and that's what caused the stall in the first place. The fact that he kept pulling back puzzles people, but the real problem is that the crew never knew they were in a stall.....if the PF, or for that matter any of the 3 pilots on the flight deck knew they were in a stall, I am sure he would have stopped pulling back...

PM to PF: "Climb, climb, climb." PF responds: "But I've been pulling back on the stick for a while now."
That pretty much sums it up...
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Old 30th Oct 2011, 14:22
  #547 (permalink)  
 
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The Captain wasn't as "old school" as his age might indicate. I think he changed from steward to pilot around 1980.
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Old 30th Oct 2011, 14:28
  #548 (permalink)  
 
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There was the crash that killed Aristotle Onassis' pilot son, where either cables or hydraulics were transposed and right bank and left bank were switched.
Of course, on AF447, the PF said he had the stick back, and the data reflects that.
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Old 30th Oct 2011, 14:51
  #549 (permalink)  
 
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Originally Posted by BarbiesBoyfriend View Post
What are the benefits of a SS for a pilot?
More room to work and less chance of bumping the thing inadvertently for starters.

(I know they have a way of summing them or for one SS to take priority, but how can either of these features benefit the pilot???)
By clearly delineating who is in control. Because the controls are digital and decoupled from the controls (as are modern yoke designs), there's no need for two yokes to provide extra leverage, so that's half the reason for having them linked gone. With a procedure that is based around only one pilot having control at any given time you've got a significant dent in the other half of the reason.

I know the F-16 has a SS, but most F-16 are single seaters and in the two seaters (mostly) one pilot is an IP.
And in the FBW Airbus, only one pilot is supposed to be in control at any one time, so it's much the same.

The yoke (OK, why not take digital input from a yoke?) has the benefit of being in clear view and both are linked mechanically.
Well, I'd be interested to have it confirmed or denied that the 777/787 yoke "connections" are not mechanical, but in fact controlled by the software-based force-feedback system. Bearing in mind that one of the rationales for FBW is weight saving, it would be counter-productive to retain a mechanical link.

These features might have helped or even saved 447.
There have been LOC accidents in yoke-equipped aircraft - so it's just as likely they might not have. Right now we're all basically arguing from our own positions, and I'm trying to stay as neutral as I can, because as with all engineering solutions there are benefits and drawbacks to both.

Re: The Lufthansa cross-wiring of the controls. I've said this before, but imagine how difficult the thing would have been to control if the sticks were linked via force-feedback as opposed to the priority-button design!
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Old 30th Oct 2011, 15:05
  #550 (permalink)  
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'more room to work and less chance of bumping the controls'.

Is that it?

Because, I've never felt short of room (the seat moving helps if I need a wee bit more for some reason) and as for 'bumping' the yoke-must have bumped it a few times in 10,000 hours worth? No major issues so far.

So, what's in it for the pilots?

B**ger all as far as I can see.
 
Old 30th Oct 2011, 15:24
  #551 (permalink)  
 
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That's your opinion and you're as welcome to it as anyone. Someone asked me why I brought up EAL401 a while back, and it was precisely for that reason - the initiating event that caused the deviation from assigned altitude was an inadvertant bump on the column (with a background loss of situational awareness due to the faulty nose gear bulb).

All my position has ever been is that the sidestick approach solves some of the shortcomings of the yoke design, but has shortcomings itself. No system is perfect.
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Old 30th Oct 2011, 15:40
  #552 (permalink)  
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I think I suggested...

...that if the fact that two pilots couldn't see what inputs the third was making WAS a factor in this crash, then it shouldn't require two dirty great control yokes to fix it - just a little tell-tale on the instrument panel with a crosshair on it and showing the current 'virtual stick position', as familiar to anybody who has ever played a computer flight sim game using a keyboard instead of a joystick. If the little glowing dot was at the bottom of the circle, everybody would know that 'the stick is being held all the way back', without needing to re-engineer the entire cockpit to stick a big old yoke into their crotch...
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Old 30th Oct 2011, 16:13
  #553 (permalink)  
 
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I think it's far more worrying that despite verbally handing control to the PNF twice, the PF continued to make inputs. The concept of a single pilot in control at any given time is a fundamental aspect of the Airbus operating procedure and it should be drilled into cadets and pilots as soon as they start their type rating.

Yes, the fact that the PNF could not see or feel that the PF had not relinquished the controls can be considered a shortcoming of the design, but ultimately the PF should have known that "you have control" means immediate hands-off-the-stick unless or until control is explicitly handed back. Even in the old Chippy I used to fly, if I was physically stronger than my instructor I could have overpowered his inputs - and had I done so and lost control as a result, few would argue that the brute-force aspect of the old cable controls was at fault.
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Old 30th Oct 2011, 16:16
  #554 (permalink)  
 
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The SS is very old technology (already a caveman tool)
The way to go for modern management of FBW computer flying (actual technology) is touch (tactil) screen (even it can be wireless .. so portable)
Very safe and more space to "work"
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Old 30th Oct 2011, 16:25
  #555 (permalink)  
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Which conjours a mental image of the pilot sitting in the aft economy lavatory, enjoying a 'constitutional', all while flying the plane on his iPhone...
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Old 30th Oct 2011, 16:58
  #556 (permalink)  
 
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Nah, I suspect that stage will be skipped and they'll go straight to brain-mapped control, which if it keeps advancing at it's current rate will probably be plausible in about 30-50 years.

Although this is off-topic silliness, in all seriousness the idea that the sidesticks offer as little resistance as a common-or-garden home analogue controller is completely incorrect - these are industrial-grade, certified components (I've never flown an Airbus, but we visited a Level D A320 sim with Uni - not that I was on that course mind, but a friend sneaked me along for the day).
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Old 30th Oct 2011, 17:19
  #557 (permalink)  
 
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If LHS PNF/PM wanted to take control he grabs his SS, presses and holds down the takeover button and says the usual, "I have control". The aircraft is under the control of the LHS SS all the time he has that button down.
Done it in the sim, practising baulked landings by RHS in case, as has happened, they freeze on the RHS SS.

I repeat my 535 post as no 330 capt has disputed my 320 view that the RHS SS is visible from the LHS even if the lighting is down. You just have to look across the flight deck. OK when the capt appeared from the bunk he would struggle to see either SS from the jumpseat.
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Old 30th Oct 2011, 17:39
  #558 (permalink)  
 
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Beagle’s view at #527 is a dated and unhelpful view of safety. Even during training and within limits, it might be possible to weed out the less capable pilots, but the process should be based on a deeper understanding of an individual’s capabilities and reasons for poor performance, and not just on a the outcome of a single event.
Humans learn (or should learn) from their variable behaviour; the source of our success is the same as for the ‘failures’. Throwing out the ‘failures’ does little to help others avoid similar situations.

A key issue throughout this event is human performance - situation assessment; similarly the technical aspects of the flight system and human interaction, but another contributing area, the regulatory process is generally overlooked.
With hindsight, why was the aircraft allowed to fly with ‘suspect’ pitots, or if, with reasoned argument, flight was allowed, why into conditions which might result in problems.
These judgements are typical of airworthiness processes, similar to MEL approval, arguing that flight with ‘suspect’ pitots would be safe – the reasonable containment of risk, and based on previous events, knowledge of the environment, technical system behaviour, and human performance. All of these involve assumptions and thus ‘expert judgement’.
However we should not conclude that the regulators ‘failed’, as this too would be the same as blaming the pilots; each group experienced variable performance, which with hindsight was insufficient for the conditions encountered.

Thus the industry might learn from this and manage to turn some of this hindsight into foresight. In this event, a primary assumption was that the human would manage an ice crystal encounter, recognise the ‘system failure’, and fly the aircraft until conditions improved.
We can reflect that a better strategy would have been to avoid the weather situation and only use the human resource in the event of misjudgement of this first step; there would be greater depth in the safety defences. Obviously fixing the pitots would be better, but this alleviation is similar to the balance of risks taken every day and necessary for operation, and which regulators and crews managed very successfully.

In the view above there are also similarities with other recent accidents. In the 737 AMS approach accident and the Madrid MD-80 take-off, the human was relied on as the first line of defence where existing technical solutions were available. The 737 with grandfather rights used a lower (unmonitored) standard of rad alt, and similarly the MD-80 had an unmonitored TOCWS, where other aircraft have improved systems.
Therefore we might review the process of design and certification, and of continued airworthiness (MEL), and enquire if in modern, complex operations, the industry relies too much on the human as the first line of defence.
Also, we might consider that human performance may not be as assumed due to different training standards, fewer opportunities for experience, and different social attitudes to flying modern aircraft – automation dependency, instant gratification (information) Wiki-Google-geeks, and reliance on SOPs.

Has the industry drifted too close to a safe boundary, or have we identified a new boundary involving a complex interaction of the many factors in modern operations?
Alternatively, in our ‘very’ safe industry, the rare and unusual accidents stand out and our natural human bias focusses on the most salient aspects or easier ‘blame’ option; this might be the public perception, but it should not be that of the industry if we are to learn from this event.
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Old 30th Oct 2011, 18:51
  #559 (permalink)  
 
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Originally Posted by kwh
...that if the fact that two pilots couldn't see what inputs the third was making WAS a factor in this crash, then it shouldn't require two dirty great control yokes to fix it - just a little tell-tale on the instrument panel with a crosshair on it and showing the current 'virtual stick position', as familiar to anybody who has ever played a computer flight sim game using a keyboard instead of a joystick. If the little glowing dot was at the bottom of the circle, everybody would know that 'the stick is being held all the way back', without needing to re-engineer the entire cockpit to stick a big old yoke into their crotch...
As long as you don't further overload the PFD ...
Then which sidetick displacement will you display ?
  1. left
  2. right
  3. sum of both
  4. all these answers
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Old 30th Oct 2011, 18:54
  #560 (permalink)  
 
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1066

Tray table OUT or IN ?
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