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AF447 wreckage found

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AF447 wreckage found

Old 15th Aug 2011, 09:39
  #2901 (permalink)  
 
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Dozy Dozy ...

"Above all, don't make lateral inputs so large"
So Dozy, now you even go to the extend to literally modify the CVR translation to make your point ...

Page 92 EN or 96 FR
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Old 15th Aug 2011, 10:38
  #2902 (permalink)  
 
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Must try harder - the actual phrases from the English version were:

"Go back down "

"According to the three youíre going up so go back down"

"Youíre at... Go back down"

"Above all try to touch the lateral controls as little as possible eh"

I don't see any substantive difference between the phrases I pulled from memory versus the ones I just wasted 5 minutes re-downloading just to prove a point.
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Old 15th Aug 2011, 12:46
  #2903 (permalink)  
 
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I think the 727 stall and the same stick back behaviour from the crew finally puts the technology argument to bed. Thanks jcjeant
I am very sorry but I do not quite agree, IMHO.
In the case of that B727, the pilots were erroneously misinterpreting a "consistently" high-speed information given on all speed indicators. They were "tunnel visioned" for the same interpretation of a "high speed situation". And they were all dealing with that false high speed situation. This is consistent with a "there's the high speed mach buffet" statement of the co-pilot.
Later on, the captain "understood" they were on a stall and asked for flaps 2ļ,but failed to properly use ATT indicators.
In the case of the AF447, they had no clue of what speed they were flying. That's when you turn on to the "feed-back" of your flight controls. When there is nothing more one can rely on, one would tend to feel the aircraft. I do concede however that there are a lot of common errors in both cases. The first ones being not to follow ATT indicators and SOPs.
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Old 15th Aug 2011, 13:10
  #2904 (permalink)  
 
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Originally Posted by aguadalte View Post
That's when you turn on to the "feed-back" of your flight controls. When there is nothing more one can rely on, one would tend to feel the aircraft.
But when the control column feel at overspeed (vibration, unresponsive controls) is so similar to that of stall (stick shaker, unresponsive controls), one could argue that the benefit of active artificial feel is limited.

@Intruder, below - I was referring to the NWA 727 incident linked a page or two ago, where the pilots indeed mistook the stick shaker for Mach buffet.

Last edited by DozyWannabe; 15th Aug 2011 at 14:31.
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Old 15th Aug 2011, 14:29
  #2905 (permalink)  
 
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You would have to get significantly over the VMO/MMO to get the vibration similar to a stick shaker. Also, control feel, even artificial, is WAY different at high (over-) speed than at low (stall) speed. Artificial feel is generally designed to be "heavier" at high speed to help prevent overcontrol.
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Old 15th Aug 2011, 15:39
  #2906 (permalink)  
 
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alph2z
PULKOVO 612 Tupolev Tu-154 (85185) seems to have had an AOA indicator and it didn't help them, very unfortunately. Also available, is an official simulator video on Youtube.
That's a different accident. Pulkovo 612 did not have any failed instruments. The official report states that the pilots deliberately tried to climb over a thunderstorm, lost a lot of airspeed in the process, encountered heavy turbulence and hail at FL380 and lost control at FL390. The indicator is there to allow pilots to avoid dangerous AOA well in advance (unlike stall warning/stick shaker). Obviously, it will not help if the pilot insists on flying at a dangerously slow speed, at the aircraft's maximum ceiling, in hail and in turbulence - all at once!!
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Old 15th Aug 2011, 23:56
  #2907 (permalink)  
 
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Originally Posted by DW
I did say "theoretically"
And what does it change to the fact that your following statement is plain wrong ?
Double inputs *are* allowed by the system, but they are summed, meaning that in an emergency situation, the pilots can theoretically command twice normal pitch-and-roll rate in an emergency situation if they co-ordinate
properly
Please quote your FCOM reference ... ?


Originally Posted by DW
"You're going up, you should be going down"
"Above all, don't make lateral inputs so large"
Can you make your mind at least ?

Initially you state it is :
"all in the CVR traces - down there in black and white (along with red, blue and green in this case)"
but when caught out it is suddenly only :
"pulled from memory" ?

But the point is, whatever your CVR quotes are, they show one thing :
2 PNF had no idea what PF was doing with its sidestick, at best they were guessing.

And it is dishonnest from you to substitute :
"Above all try to touch the lateral controls as little as possible eh"
by :
"Above all, don't make lateral inputs so large"

Very different meaning !


Originally Posted by DW on Habsheim
What he did was permanently disable the autothrottles
No he did not.
Or quote the report reference Ö ?

in effect *partially* disabling the alpha-floor protection
There is no such thing as :
"partially disabling the alpha-floor protection".
As you donít understand the system, read A4 post above if youíre ready to learn, maybe you will accept if itís not from me Ö ?
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Old 16th Aug 2011, 07:25
  #2908 (permalink)  
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If this a/c had a yoke instead of a sidestick, then what was happening would have been clearer to the other pilots.

I dont think the Captain and PNF realised that PF was holding so much 'nose up' input.
 
Old 16th Aug 2011, 08:42
  #2909 (permalink)  
 
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If this a/c had a yoke we would have seen an accident report not dissimilar to the one posted by jcjeant.

http://www.airdisaster.com/reports/ntsb/AAR75-13.pdf

The biggest problem here is analogue pilots flying digital a/c. And by that I do not mean remove the pilot from the cockpit but after more than 40 years of digital a/c that have more than proven their safety capabilities it is about time pilots stopped harping on about "old" a/c and moved into the 21st century.

The a/c are sound, the technology is sound, room for improvement yes. The A320 for example is actually one of the safest commercial airliners flying despite all the doom and gloom and the first lightning strike will send it spinning to the ground out of control crap that is often brought into the same sentence.
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Old 16th Aug 2011, 09:13
  #2910 (permalink)  
 
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from Safety Concerns

The biggest problem here is analogue pilots flying digital a/c. And by that I do not mean remove the pilot from the cockpit but after more than 40 years of digital a/c that have more than proven their safety capabilities it is about time pilots stopped harping on about "old" a/c and moved into the 21st century.

The a/c are sound, the technology is sound, room for improvement yes. The A320 for example is actually one of the safest commercial airliners flying despite all the doom and gloom and the first lightning strike will send it spinning to the ground out of control crap that is often brought into the same sentence.

A lot of pilots criticising Airbus are quite used to digital flying. They operate EFIS and FBW aircraft as well, simply from other manufacturers. So your first point is polemics.
Second, such an aircraft is actually the safest, the T7, therefore the whole discussion about the Airbus layout has a point, as there is just as modern an aircraft flying that is, at least at the moment, even safer. So your second point is none.

Here are a few comment and questions from a recent meeting:


Some traps in the Airbus philosophy:
The dead stick on the PNF side (or on both with AP on).
If a PF starts losing it, be it a simple PIO or as here with stress-motivated and effectless swinging around the stick, the PNF, in order to realize, must look over and observe the PF.
This is a waste of concentration, he should be monitoring the instruments. With a moving stick (or yoke), he could continue to monitor instruments and simultaneously would be realizing the PFs error, through his second, tactile input channel. Additionally if he wanted to intervene, he could exerce force on the stick and by that raise attention of the PF, again through the second channel. The first one is quite often absorbed by the situation and trying to talk to a stressed PF is futile, the audio channel is the first to leave us under stress.
Why no feedback?

The fixed Autothrust Lever
The Airbus lever is set in a detent, this applies as well when the AT disconnects. When this happens, the AB pilot needs to realize the ECAM warning. With a moving lever, the disconnected, stuck and no more moving AT sort of warns the pilot additionally through the tactile channel. Furthermore the lever will be in the exact position of the thrust. Not so in an Airbus. The lever is still in the detent and the thrust where it was last. The Airbus philosophy tells us, that when the AT is disconnected, the lever acts like a conventional one, position equal thrust, but in the bad case of an automatic disconnect, this is not true. The pilot has to un-detent the lever to get the correct position vs. thrust ratio. This is an unnecessary additional step in a high stress situation.
Why fixed levers, what is their advantage (pls donít come up with the weight issue)

THS
As I understand, the THS was following the PFs inputs right up to full aft, even though the stall warning was active. On Boeings the stabilizer is inhibited to move further aft when stall speed is reached.
Why can an Airbus THS?

Stick shaker
Where is it on Airbus? One of the most direct warnings, going directly through the hands right into the spine and brain seems to be missing. A whole channel missing.
Why?
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Old 16th Aug 2011, 09:31
  #2911 (permalink)  
 
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All in all an avoidable accident.

Had they flown "pitch attitude and thrust" as in normal flight , as in "unreliable airspeed" it wouldn't have come so far.

Boeing vs Airbus , FBW , sidesticks , THS , normal/alternate/direct law don't matter , it is Attitude and Thrust that counts.
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Old 16th Aug 2011, 09:33
  #2912 (permalink)  
 
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Gretchen what are implying that a/c with stick shakers never stall?

Your last post confirmed everything I said about analogue pilots and digital a/c

A lot of pilots criticising Airbus are still in analogue mode and wishing for a return to stick shakers and throttle movement. The safety case to go backwards isn't there.

Despite your analogue post please correct me if I am wrong. The Lufthansa Frankfurt incident of reverse stick input saw a PNF take control without witnessing any stick feedback or looking over to see what PF was doing. He was digitally minded and in tune with the aircraft.

It is time you tuned in as well. And if you are referring to the Japanese T7, pathetic response.

The sad fact in most of these accidents but not all is that the pilots are not in tune with the a/c. There may well be a case for a different training approach but there is NOT a safety case to change the technology.
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Old 16th Aug 2011, 09:49
  #2913 (permalink)  
 
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Eventually, after two years of drawing the same line in the sand, there would appear to be a shortage of sand.
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Old 16th Aug 2011, 09:50
  #2914 (permalink)  
 
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Actually, Safety, I have to agree with your post.

I simply would like to remind you, with your steadfast and slightly arrogant statements, of this:

The nuclear lobby was reasoning with the same steadfast arguments, even after Tschernobyl.

Then came Fukushima.

The safety case to go backwards isn't there.
Think it over.

(I'm out)
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Old 16th Aug 2011, 09:57
  #2915 (permalink)  
 
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So, unintended consequence......My Bad.

Merely meant that the discussion is well framed, and the canvas is empty.
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Old 16th Aug 2011, 10:32
  #2916 (permalink)  
 
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Safety Concerns

The sad fact in most of these accidents but not all is that the pilots are not in tune with the a/c. There may well be a case for a different training approach but there is NOT a safety case to change the technology.
A strong statement, but does it take care of the human nature?
Do we believe that people, in this case pilots, can be trained sufficiently to follow all technological evolutions without limits (under the present training budget)? Isnīt it necessary to develop the evolution of technology in accordance with the capabilities of the operator and under recognition of the available training?

To be in tune with the aircraft is not only a training issue, its also a design issue.

If design would disregard the human factor (and it does in case of the missing tactile feedback, in case of the intermittent stall warning, which by the way was already a known issue years ago, in case of documentation like in LH at Hamburg) then only a small number of top notch pilots would be eligable to be trained and hired for the job (causing higher costs for training and salary).

.........but there is NOT a safety case to change the technology
It finally depends on the side, from where you are looking at that matter. The manufacturer and his engineers will see no need until the regulatory authority comes into play. And a lot of changes take place anyway later on or even before the final report shows up, but for sure not related to any kind of accident, that would nag on reputation and finally on sale numbers.

The human race has gone lots of different streets, and lots of errors and the recognition and avoidance of those in the future brought us to the point we are standing now. Itīs not at all bad to accept error also in technical matters, because also designers and engineers are humans and not gods.

Sorry to say that here, but sometimes some technical people here seem to be unfailable.

No need to change anything, it worked as designed...............

There are lot of sound recomendations of the pilot community in this forum how some changes would improve the handling of advanced designed aircraft
(AOA indicator, tactile feedback, different law degradation, other trim logic to name a few), why not start working on the implementation of it?

The training side probably changed UAS training and approach to stall training already, lots of pilots sure as hell are busy in improving their knowledge database concerning UAS, flightlaws, stalls, trim..., but the engineering side is occupied by defending .........what???

It might be time to side with the people in the pointy end and make those beautiful air machines safer, close some holes in the swiss cheese in a unified effort.

Together we are strong, arguing against each other will not help much but disqualify it as saving his own a**.
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Old 16th Aug 2011, 10:50
  #2917 (permalink)  
 
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The sad fact in most of these accidents but not all is that the pilots are not in tune with the a/c. There may well be a case for a different training approach but there is NOT a safety case to change the technology.
My dear Safety, I could not disagree more. The question is exactly the opposite. It is the technology that has to serve humans, therefore, it is the technology that has to be in tune with human factors. If you were a pilot, you would understand my point of view. The aircraft doesn't have to behave like an enigmatic robot. It has to transmit "feelings" to the pilot, and they have to "work together" for the same objective, to fly safe. I understand that this XXI Century "new" concepts need a new mindset to be flown. But the interface between man-machine, in step of being reduced, should have been emphasized.
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Old 16th Aug 2011, 10:57
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some good points F4Retired but...

human nature has been taken care of to a certain degree but not completely. We must move away from this "I must have ultimate control" flawed logic.
In the early days of military FBW there were a number of relevant events.

One in particular comes to mind. One FBW fighter had an onboard system which prevented spins and stalls. One particular fighter pilot felt this system limited his dog fighting abilities and so disabled it. "I must have ultimate control". He promptly crashed overcooking it.

Yet that itself doesn't really indicate anything. Had he been shot down with the system enabled that was wrong too. So we need other indicators of a working safe system.

The A320 is one of the safest commercial airliners out there. So it has proven both its safety and design features. This is a fundamentally safe aircraft minus stick feedback and throttle feedback. Tells us a lot.

I do not advocate engineers have it 100% right and one of my earlier posts called for more forward thinking pilots in order to improve on what we have. Fundamentally safe technology.

I could agree more with your points if we were talking about unsafe technology. We are however in the safest period of commercial flying ever. The overwhelming majority of a/c are new technology. This is no coincidence.

Analogue Boeings have stalled and crashed, Boeing pilots have been confused by blocked pitot and static ports and crashed. None of your AOA indications, stick shakers, yoke feedback helped in any way at all. Its pure nonsense, sorry but it is.

Where I totally agree with you is on the together bit. But that requires many of you letting go of the past.

Last edited by Safety Concerns; 16th Aug 2011 at 11:26.
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Old 16th Aug 2011, 12:12
  #2919 (permalink)  
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The Airbus philosophy tells us, that when the AT is disconnected, the lever acts like a conventional one, position equal thrust, but in the bad case of an automatic disconnect, this is not true. The pilot has to un-detent the lever to get the correct position vs. thrust ratio. This is an unnecessary additional step in a high stress situation.
This is not quite correct. If the A/THR disconnects involuntarily (or fails) the ECAM will present:

ENG - ENGINE THRUST LOCKED
THR LEVERS.............................MOVE

Additionally the FMA will be flashing THR LCKD. This will be repeated every 5 seconds, with a single chime, until the levers are moved to match actual thrust setting - simply match the "doughnuts" (small circles above N1 gauge arc) to the indicated N1. So if the A/THR falls over - DON'T PANIC!!! the thrust setting has not changed. Assess what's going on and then move the levers - you now have control of the thrust.

Not having motorised levers has never presented me with any problems. I don't deny that the tactile feedback is lost but you just learn/retrain to utilise the visual feedback from the N1 gauges we're humans and adapting is what we are quite good at. The sidestick issue is different and, as a trainer on the bus, I acknowledge that the lack of feedback from the PF to the PNF is less than ideal.

In the case of AF 447 perhaps a requirement for the unreliable speed procedure should be the selection of the FLIGHT CONTROLS page on the systems display (lower centre screen). It would certainly enable the PNF and any other observer to see what inputs the PF was making - especially in a dark cockpit.

Good discussion guys,

A4
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Old 16th Aug 2011, 12:16
  #2920 (permalink)  
 
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Safety Concerns

some good points F4Retired but...

human nature has been taken care of to a certain degree but not completely. We must move away from this "I must have ultimate control" flawed logic.
In the early days of military FBW there were a number of relevant events.

One in particular comes to mind. One FBW fighter had an onboard system which prevented spins and stalls. One particular fighter pilot felt this system limited his dog fighting abilities and so disabled it. "I must have ultimate control". He promptly crashed overcooking it.

Yet that itself doesn't really indicate anything. Had he been shot down with the system enabled that was wrong too.
If the pilot has the ultimate responsibility for the souls on board, he has to do be able to use all available means the system can provide. I would that not call ultimate control, just give the pilots all methods and systems available to do the decision making and to transfer his conclusion into action. And put the pilot in the loop by all means and all human channels and senses.

So we need other indicators of a working safe system.
Those would be?

The A320 is one of the safest commercial airliners out there. So it has proven both its safety and design features. This is a fundamentally safe aircraft minus stick feedback and throttle feedback. Tells us a lot.
Would it get more unsafe in your opinion with feedback? Why not add feedback and an AOA gauge for aditional safety?

I do not advocate engineers have it 100% right and one of my earlier posts called for more forward thinking pilots in order to improve on what we have. Fundamentally safe technology.

I could agree more with your points if we were talking about unsafe technology. We are however in the safest period of commercial flying ever. The overwhelming majority of a/c are new technology. This is no coincidence.
That is again a thinking in statistics and probabilities, i wont accept. Any near accident is too much, any accident is a waste. Why not improve things some more despite the relative high safety? Money? Pride? Neglecence?
By the way, its not A vs. B, its make things safer when you know how.

Analogue Boeings have stalled and crashed, Boeing pilots have been confused by blocked pitot and static ports and crashed. None of your AOA indications, stick shakers, yoke feedback helped in any way at all. Its pure nonsense, sorry but it is.
What do you want to proove with this statement?
Cars continue to crash despite antiskid and other gimmicks, but nobody would come to the idea to remove those systems or to build a new car without them. Aircraft with or without FBW and with or without all obove mentioned systems and helpers will crash, human race will not be able to produce and operate a failsafe system of any kind. Its just a matter of time and circumstances until anything fails. But it is necessary to improve systems and training out of expierience, develop it further and make it safer.

To deprive the ultimate responsible instance in the cockpit (the pilot, if you forgot) a very important information by disabling the feedback channel (tactile feedback to the hand, which executes the inputs) and saturating other channels with the information (like eyes or ears) does not make things safer.

Where I totally agree with you is on the together bit. But that requires many of you letting go of the past.
If you forgot, we come from the past, everything we have and every development does not found on the future, but on past systems and past expierience. If you disregard the past, you let go of vital expierience and learn it the hard way again. To work it out together, the engineering side has to accept the expierience of the expierienced pilots and the success of previous designs. This expierience is the living one, not the one by death toll. They used tactile feedback and survived with it. No one complained about it being present and no one told the industrie, that we dont need it any more, develop some aircraft without it.

The expierienced pilots from the past having flown with tactile feedback may be the least affected by the absence of this channel, they can work around with their expierience in flying (and handflying) in the past. The young kids like that one in the right seat have no fall back pposition available when the sh++t hits the fan, when they are saturated by alarms, whistles, bells, different coloured displays in the absence of otherwise present navigation and aviation helpers. Then a simple UAS event with a AP+AThr dropout, a slight (pitot induced) altitude deviation coupled with some roll tendency leads to a breakdown of situational awareness.

That is not a training issue alone, it is a problem to tune in the pilot into the system and to keep him in the loop from normal operation to the biggest f****up possible.
And this is also an engineering task, wether you like it or not.

franzl

Last edited by RetiredF4; 16th Aug 2011 at 12:27.
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