AF 447 Thread No. 12
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As PJ2 has kindly pointed out, the fact is that there are currently more accidents involving aircraft with traditional controls where the PNF has not picked up on what the PF was doing than there have been with the passive sidesticks.
But if the pilot is incapacitated, in a spiral dive 4g+, with thumb on priority switch...
From final report
At 2 h 11 min 37, the PNF said “controls to the left”, took over priority without any callout and continued to handle the aeroplane. The PF almost immediately took back priority without any callout and continued piloting.
In an aircraft with traditional controls, Robert would say "My airplane", then he would notice the colum moving in his lap. Probably he would say "listen Bonin, trust me I know what is wrong, give me the controls!"
Why the designers could get away without adding haptic feedback is a mystery and dual input is a hilarious stupidity
Last edited by _Phoenix_; 1st Oct 2014 at 02:50. Reason: spelling
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Dual inputs on side sticks
AF447 : un accident d'une extraordinaire complexité - Page 2
AF447 : un accident d'une extraordinaire complexité - Page 2
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Lot of very interesting and highly technical information which even very experienced pilots would not have access to has been put out on this thread. But I think it's time to move on from some of the endless aspects of the argument. Nothing new is being discussed or brought out. It's like the warring factions trying to give one last blow as a sign of having won the context. some of the salient points I noted to end the argument are:
FBW is here to stay whether you like it or not.(No one's designing conventional airliners)
Value of duplicating side stick movement is not likely to be proved till the end of the world (same as yoke VS side stick)
Tactile feedback on the controls will remain personal opinion.
FBW is here to stay whether you like it or not.(No one's designing conventional airliners)
Value of duplicating side stick movement is not likely to be proved till the end of the world (same as yoke VS side stick)
Tactile feedback on the controls will remain personal opinion.
vilas, with respect, I think there are new things on the thread and they are the more enlightened and informed discussions on human factors and that's a good thing for those encountering this from this thread and not from the eleven previous ones. I think awareness is half the battle, including a readiness to encounter frailties which have not always formed a part of "the pilot psyche", if I may use the term.
Vilas
Tactile feedback on the controls will remain personal opinion.
Tactile feedback on the controls will remain personal opinion.
We have two major Aircraft manufacturers with different steering concepts, Boing and Airbus. We tend to see the difference in the SS vs traditional control column layout of the cockpit. Enough has been written by Dozy and others why AB choose that layout and why tactile feedback was considered unimportant.
Boing is sticking to the old layout with tactile feedback. To assume they did it due to personal oppinion of their engineers or their pilots falls short considerably. Imho their view on importance of tactile feedback and the difficulties to implement such a system in a SS concept are the main reasons that B Aircraft are still produced with the column.
The day might come when we will see the SS concept with some kind of tactile feedback, wether it will be a Boing or an Airbus. My bet would be in Boing.
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DozyWannabe
100% agree about flight deck commonality. I realised I forget to mention that aspect after posting. Never the less, it makes any redesign even more expensive because it has to be applied across more aircraft types.
RetiredF4
I agree that Boeing will apply lessons learned from Airbus' experience to arrive at a better system. Once any system has been proved to grant a commercial advantage, all manufacturers jump on the bandwagon. There is no doubt that sidesticks and fly by wire offer a huge reduction in mechanical complexity by avoiding the need for multiple control cable and hydraulic pipe runs to the cockpit. Problems occur when the controls are operated in a way that the designers never envisaged and instruments fail to display information because the readings are outside predicted design parameters.
Commercial aviation is very safe and ultimately any further safety improvements will need to be justified in commercial terms. It all comes down to the value placed on a human life, and it is surprising low, generally between Ł5,000 and Ł50,000 sterling per fatality. The real cost to the individuals and their bereaved families is of course incalculable.
100% agree about flight deck commonality. I realised I forget to mention that aspect after posting. Never the less, it makes any redesign even more expensive because it has to be applied across more aircraft types.
RetiredF4
I agree that Boeing will apply lessons learned from Airbus' experience to arrive at a better system. Once any system has been proved to grant a commercial advantage, all manufacturers jump on the bandwagon. There is no doubt that sidesticks and fly by wire offer a huge reduction in mechanical complexity by avoiding the need for multiple control cable and hydraulic pipe runs to the cockpit. Problems occur when the controls are operated in a way that the designers never envisaged and instruments fail to display information because the readings are outside predicted design parameters.
Commercial aviation is very safe and ultimately any further safety improvements will need to be justified in commercial terms. It all comes down to the value placed on a human life, and it is surprising low, generally between Ł5,000 and Ł50,000 sterling per fatality. The real cost to the individuals and their bereaved families is of course incalculable.
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PJ2
Maybe the design could have less things for the Pilot to think about at the point of degradation to Alt law. When Alt law is entered the pilot has to resolve the issue that caused the law degradation and he also has to change his control input method (as confirmed by Vilas in post 585).
A similar thing could be said about the unconnected side sticks. I understand after 1000s of hours flying in normal law you get used to the controls in the accompanying level of work load but what about at the point of law degradation when the workload can increase considerably? Could the tactile feedback be beneficial at this point? Is there even a slight chance this extra information could have helped Robert understand what was happening?
Cool Guys, re, "I really think the designers of this system could of been a bit kinder to the pilots."
Well, in what way?
Well, in what way?
A similar thing could be said about the unconnected side sticks. I understand after 1000s of hours flying in normal law you get used to the controls in the accompanying level of work load but what about at the point of law degradation when the workload can increase considerably? Could the tactile feedback be beneficial at this point? Is there even a slight chance this extra information could have helped Robert understand what was happening?
Last edited by Cool Guys; 1st Oct 2014 at 12:48. Reason: grammar
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Originally Posted by PJ2
there are numerous clues to the condition of the aircraft still present
2- Airbus suppressing one clue is detrimental to the situation awareness
Two crew members, even 3 in this case, worked on their own with different mental representations of the situation. The Airbus concept or an obstacle to an otherwise natural tool for CRM optimization.
We have more examples of control columns in the full-aft position than we do sidesticks when loss-of-control or a full-stall has occurred.
Airbus concept contributory as it deprived the crew from that wonderful conventional way to gather information which participated to the confusion prevailing on board.
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Hi,
I agree
Airbus concept contributory as it deprived the crew from that wonderful conventional way to gather information which participated to the confusion prevailing on board.
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@CONF, jcj - I know how you feel about the subject, I think we all know how you feel about the subject. But it doesn't make you right, and conversely it doesn't make people who think or feel differently about the subject right either.
At the end of the day we have to take the facts as we have them and make our own calls - personally I don't think there's any point in going round the houses with this particular argument again.
At the end of the day we have to take the facts as we have them and make our own calls - personally I don't think there's any point in going round the houses with this particular argument again.
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What if...
What if the Egypt 767 would have been an A330? Who would have had control? What would the outcome have been??
It is obvious in AF447, having the yoke in his lap for 3 minutes would have given the PNF and the Captain (when he came back to the cockpit) a visual clue as to what was going on. Instead, after not really knowing what Bonin was doing for three minutes, Bonin finally told the rest of the crew he'd had the stick full back for a while and the realization they were stalled hit the Captain like a ton of bricks. What if, when he walked in, he saw the yoke in the laps of both pilots?? Quite a different outcome I'd bet.
I mean come on...you walk into a cockpit of an airliner that should be at 35K+ feet and you see the yolk in the laps of the pilots? You would instantly know something was very wrong. If I am wrong, please let me know when a pilot would have the control stick full back in cruise flight at 35K+ feet...
What amazes me about the BEA report is this very important point wasn't even discussed and sure wasn't made a point of failure in the cockpit CRM. To me, that smells of collusion between the BEA and Airbus. Many pilots on this forum agree it is a problem but BEA glossed right over it. Boeing felt it was important enough to justify the added weight and complexity and I agree with them.
Why would you intentionally leave a hole in the cheese?? Save a little weight, make the cockpits common?? Doesn't sound like a good enough reason to me.
It is obvious in AF447, having the yoke in his lap for 3 minutes would have given the PNF and the Captain (when he came back to the cockpit) a visual clue as to what was going on. Instead, after not really knowing what Bonin was doing for three minutes, Bonin finally told the rest of the crew he'd had the stick full back for a while and the realization they were stalled hit the Captain like a ton of bricks. What if, when he walked in, he saw the yoke in the laps of both pilots?? Quite a different outcome I'd bet.
I mean come on...you walk into a cockpit of an airliner that should be at 35K+ feet and you see the yolk in the laps of the pilots? You would instantly know something was very wrong. If I am wrong, please let me know when a pilot would have the control stick full back in cruise flight at 35K+ feet...
What amazes me about the BEA report is this very important point wasn't even discussed and sure wasn't made a point of failure in the cockpit CRM. To me, that smells of collusion between the BEA and Airbus. Many pilots on this forum agree it is a problem but BEA glossed right over it. Boeing felt it was important enough to justify the added weight and complexity and I agree with them.
Why would you intentionally leave a hole in the cheese?? Save a little weight, make the cockpits common?? Doesn't sound like a good enough reason to me.
I'm not going to get further into the connected yoke vs. side stick debate - I'm obviously biased (for some strange reason I think the Boeing system is better 
). But something else keeps coming back to me.
As an engineer, the idea that you could pull back full, at any flight condition (but especially at cruise), and hold it there for more than a handful of seconds (never mind minutes) without stalling the airplane defies physics (unless you're talking a fast jet or stunt plane, which would pull a loop). So I'm left with two options:
1) Bonin honestly thought he couldn't stall an A330, or
2) Bonin lacked the most fundamental understanding of how airplanes work
Both come back to training.
). But something else keeps coming back to me.As an engineer, the idea that you could pull back full, at any flight condition (but especially at cruise), and hold it there for more than a handful of seconds (never mind minutes) without stalling the airplane defies physics (unless you're talking a fast jet or stunt plane, which would pull a loop). So I'm left with two options:
1) Bonin honestly thought he couldn't stall an A330, or
2) Bonin lacked the most fundamental understanding of how airplanes work
Both come back to training.
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I know how you feel about the subject
Sidestick : work as per design (pilot don't see or feel the position of the opposite one .. as per design)
Pitot tube : work as per design (freezes with ice .. as per design)
ECAM : Work as per design (not indicate a defect on pitot tubes when this happen ... as per design)
Stall alarm : work as per design (stop warning of stall even when the plane is stalled .. as per design)
So .. we can remove sidestik .. Pitot tube ECAM and stall alarm behavior as contributors to this accident .. as all work as per design
What stay to analyse ?
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There it goes again the circle continues. This is what I meant. The subject has been examined thread bear. Boeing is not going to replace the yoke nor Airbus is not going to duplicate the side stick motion. All technical and human engineering aspects have been exhausted. Only thing left is the way pilots individually feel about the issue. That is not going to change. Dry fish stinks to high heavens yet many people consider it a flavour.
Moderator
One could, as an alternative, not read the thread were it to cause one offence ?
The specific control device is only a part of the discussion .. although, as you suggest, the sidestick is in the game to stay regardless of what individual folk think and prefer.
The specific control device is only a part of the discussion .. although, as you suggest, the sidestick is in the game to stay regardless of what individual folk think and prefer.
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@jcjeant,
How about the dog to warn the pilots that they are now in charge, where due reliance on situational awareness, good CRM, and their supposed knowledge of the basic laws of physics could be expected to see them (and the dog) enjoy another meal when safely back on terra firma. 
What stay to analyse ?
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JT
Make no mistake this thread has given me great details about Airbus FBW which even the most experienced pilots do not lay their hands on. I am just against reviving an issue that is already studied in all aspects that too with same objections. If some one has a new aspect by all means it is more than welcome.
Make no mistake this thread has given me great details about Airbus FBW which even the most experienced pilots do not lay their hands on. I am just against reviving an issue that is already studied in all aspects that too with same objections. If some one has a new aspect by all means it is more than welcome.
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No contest.
I, for one, not having any direct AB exposure, have learned heaps from the whole saga as discussed on Tech Log. Don't claim to understand it all but I know a lot more than I did before ..
I, for one, not having any direct AB exposure, have learned heaps from the whole saga as discussed on Tech Log. Don't claim to understand it all but I know a lot more than I did before ..
A variation on what may be a familiar flight safety approach to some here is quoted in Beyond Aviation Human Factors, (by Dan Maurino, Jim Reason, Neil Johnston & Bob Lee, 1995), is what was called the substitution test. As far as I can recall, (not far, these days), the question has not been asked on the thread.
It is a common one when doing various tests within a Just Culture, but I think it is particularly relevant here when we're trying to sort out ways of examining cockpit behaviours, ergonomics and human factors. What it helps do in normal practise of airline work is place issues succinctly before those who must manage a Just Culture on a day-by-day basis and handle events which their airline's safety and data programs present, some of them serious. They are examining the "incidents" before they occur, so to speak and this is one way to sort out which way to focus when fixing a problem that is emerging in the data.
So the context is a bit different here I know, but not that different that the question can't reasonably be asked. And it may also help some put on new glasses to see flight safety work and these programs in a new way even if in this case the accident has occurred.
The point is to consider, think and imagine a bit further than focussing too closely on this or that isolated theory, and such a question helps move one off top-dead-center, so to speak.
If someone else who had the same qualifications on the airplane and similar experience ran into the same circumstances (which weren't that unusual for the area), the question asked is, "In the light of existing knowledge and how events unfolded sequentially, is it probable that this new individual would have behaved any differently?"
It is a common one when doing various tests within a Just Culture, but I think it is particularly relevant here when we're trying to sort out ways of examining cockpit behaviours, ergonomics and human factors. What it helps do in normal practise of airline work is place issues succinctly before those who must manage a Just Culture on a day-by-day basis and handle events which their airline's safety and data programs present, some of them serious. They are examining the "incidents" before they occur, so to speak and this is one way to sort out which way to focus when fixing a problem that is emerging in the data.
So the context is a bit different here I know, but not that different that the question can't reasonably be asked. And it may also help some put on new glasses to see flight safety work and these programs in a new way even if in this case the accident has occurred.
The point is to consider, think and imagine a bit further than focussing too closely on this or that isolated theory, and such a question helps move one off top-dead-center, so to speak.
If someone else who had the same qualifications on the airplane and similar experience ran into the same circumstances (which weren't that unusual for the area), the question asked is, "In the light of existing knowledge and how events unfolded sequentially, is it probable that this new individual would have behaved any differently?"
Last edited by PJ2; 2nd Oct 2014 at 07:34.
In the stall: No one of the three uttered any word which would indicate he realized that they were stalled, despite the many visual clues present. So, it is pure speculation. If you don't know that you are stalled, does it matter what you do whith the sidestick or yoke?
Before the stall: The biggest puzzle, in my opinion, is Robert. He did notice that Bonin was behaving erratically. But he didn't follow up on that thoroughly enough. Why not? Langewiesche has the idea that, when Bonin took away his control immediately after Robert took over, Robert didn't notice this and wondered why his sidestick didn't work. Maybe that is a clue: Did he think his machine was uncontrollable even before it really was? If you want to question unconnected sidesticks, I think that would be the moment.