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AF 447 Thread No. 7

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AF 447 Thread No. 7

Old 14th Nov 2011, 20:41
  #241 (permalink)  
 
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LW. With respect, the discussion of instrumentaion comes up in the CVR, clearly, and neither one claims AFU. PNF, "lost speeds, ALTERNATE LAW".

"Je ne comprends rien". "I understand nothing". That is not, "my dash is AFU".

Then, "We've lost all indications." WE, not ME. It has NOT been discussed, to my knowledge. Neither pilot made the distinction to which you allude. It is for this reason I am concluding neither pilot requested hand off to the other. Later, this changes. I too am not sure what PF saw, and no one can be. The communication was restricted to adversarial critique, and lacked team work, I'll say that. But change controls?

CRM issues are critical here, but I am reluctant to grant them causative weight. I believe the a/c was UPSET, responding erratically (via instrumentation), and there is no reason to believe the PNF had a better shot. EXCEPT in retrospect.

There was a cadence in that cockpit that resists the panacea offered by those here who think they have the picture; they do not. I am at a loss to define one single cue/comment that was absolutely bankable re: recovery post A/P loss.

Last edited by Lyman; 14th Nov 2011 at 20:56.
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Old 14th Nov 2011, 20:47
  #242 (permalink)  
 
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Dozywannabe
(You know this - I don't need to say it. Or are you simply picking holes in what I'm saying because I've annoyed you for not sticking to talking about software?)
My jumping into an ongoing discussion with you or with other posters is to comment on incorrect and misleading statements in an area i feel familiar and competent with.
As you recognize yourself that may happen with you more often when you are making statements outside your primary area of knowledge and expierience.

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Old 14th Nov 2011, 21:17
  #243 (permalink)  
 
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Originally Posted by Lonewolf_50
In a few of above cases, more than one life was saved.

Had some Real Close Calls in between.
On the line or when training? During training then of course the situation is different (and as an aside I'd never consider independent sidesticks to be a good idea in a PPL trainer), however on the line with SLF behind you, isn't it better to be absolutely sure (even if to be sure takes only a fraction of a second)? I can't help but think that if it were me and I'd just taken control, misread the situation and caused a crash I'd be absolutely gutted.
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Old 14th Nov 2011, 21:23
  #244 (permalink)  
 
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I can't help but think that if it were me and I'd just taken control, misread the situation and caused a crash I'd be absolutely gutted.
So would you feel better, if you are being crashed because taking too long to come to a decision?

Pilots sit in the front end to make those decisions and act upon them. They are paid to be prepared and act.

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Old 14th Nov 2011, 21:41
  #245 (permalink)  
 
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Dozy--
The best and simplest solution I can think of is therefore to latch the current stall warning state when the data becomes invalid, and unlatch it when it becomes valid again.
OK, don't call it an "algorithm bug," call it a "specification," who really cares(?), BUT, otherwise, it appears that everyone who has weighed-in on this shortcoming appears to agree! How 'bout THAT??? In speculation mode, it is possible that the designers/programmers never foresaw this scenario. Ya can't think of everything, after all (until it happens).

There's no doubt in my "mind,", albeit no proof, that the on-and-off behavior of the SW did not help the pilot's understanding of the sitch.

Now.
@Organfreak - it's got nothing to do with being right, it's to do with the fact that left to their own devices we'd have "yokes r teh awesoem, sidesticks drool" from the same four or five posters over and over again with no dissenting opinion. I respect pilots greatly, but it doesn't mean that they're always right, nor does it mean that one should genuflect before them by rote.
I'd be the last one to genuflect, although I have tremendous respect for ATPLs in general. OK, say you're right: it's the same old culprits (I wouldn't know). Consider this: again, I have no flying experience and no axe to grind, but I came blowing in here out of the blue, and immediately and independently saw the sense of the yokes argument. Again, no proof, but what those in favor have said makes eminent sense to me, and does not appear to be the mindless, drooling AB criticism that you pretend it to be. That's not nice. Some of the reasoning has been quite sophisticated and well thought-out. Seems that you can't acknowledge that.

OK, OK, public disclosure: I do live in Boeing Country, but I have plenty of problems with them, too, especially after they basically let MD take them over in a management coup. Mostly, all Boeing has done for ME is to keep me awake at night with their incessant engine testing. But I digress. [where's the dang belly-laugh icon???]
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Old 14th Nov 2011, 22:11
  #246 (permalink)  
 
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AirTren
No that isn't my thought at all. Perception works differently for different people and some actually process audio signals quicker than visual signals. We don't know that this was the case in this situation but it is an important factor that has to be born in mind. Furthermore you don't transform an audio signal into a visual signal unless that is what you want to do. This is a fallacy - sound is sound and is interpreted as such.
The big factor missing from the discussion is interpretation. If we take a direct signal and interpret it or misinterpret it, it takes time to correct and re-evaluate. In certain circumstances an audio signal is more reliable but as we know that also is subject to interpretation. The point is that using your instruments for example, instead of a yoke provides you with an organised initial frame of reference with graduated levels. Glancing at a yoke and trying to decide where it is when you are suffering say spatial disorientation can be remarkably misleading. What you see and what you think you see can be two different things - the banana experiment is very relevant here. A calm person will see something different to a panicking person.
Looking at your instruments will provide you with a much better indicator and what is more it will aid your interpretation because the initial frame of reference is already set - you don't have to judge to the same extent and importantly to create a frame of reference in which to judge. Evidence from the CVR indicates that the PNF was quite able to judge the situation as was the Captain (initially) but neither took the physical action necessary to override the PF.
This is also another reason why the yoke is a red herring - given the ineffective intervention by both non-flying members of the crew it is highly unlikely that their behaviour would have been any different had the aircraft been equipped with yokes. Short of direct physical intervention it seems that nothing was going to divert the PF from his actions but we must also factor in that incomprehension of the whole flight crew. I hold no brief for the side stick or the yoke but in this situation the type of input device is irrelevant.

Last edited by Old Carthusian; 15th Nov 2011 at 00:00.
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Old 14th Nov 2011, 22:18
  #247 (permalink)  
 
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"The type of input device is irrelevant..."

Erm, ok. What about its location?

What Instrument was the Captain seeing when he advised the PF to "Climb, Climb..." The PF responded, "But I have been climbing for some while...."

Thoughts? Any?
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Old 14th Nov 2011, 23:30
  #248 (permalink)  
 
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Subtle changes in terms of words, but major changes in terms of meaning. The exchange was actually:

02:13:39 - PNF : Climb climb climb climb
02:13:40 - PF : But Iíve been at maxi nose-up for a while
02:13:40 - CDB : No no no donít climb
02:13:40 - PNF : So go down
It was the PNF that was saying "climb", immediately followed by a bunch of DUAL INPUT warnings. I think the Captain suddenly realised what had happened at this point.
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Old 15th Nov 2011, 00:02
  #249 (permalink)  
 
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Thanks, Dozy. So it was the two with you know, screens who could not decide what to do? PNF says CLIMB, (What was he looking at?), and the PF had already been "Climbing"?

Do you see a problem with what they both may have been seeing on the instrumentation? What was telling them to input Nose UP? Rather than a solution, Captain insists, "NO, No Climb." NOT, "DO THIS..." Instead, a command to do nothing.

They were all three privy to the only ticket home, the instruments.

How long had the a/c been so confused? YES, the a/c. The pilots and Captain are screaming that, they had NOTHING to go on of any value, OBVIOUSLY.

Three pilots in the weeds, but you say the a/c was "Doing as it was programmed...." How do you reconcile this?

A/C? "Nothing wrong, just three confused pilots". You kidding me?
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Old 15th Nov 2011, 00:12
  #250 (permalink)  
 
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Cool

Hi,

DW
When we were discussing things earlier, we were talking about the AF447 accident sequence as we know it to have occurred, and I was of the opinion that the PNF had a better handle on the aircraft's situation and as such, should have felt empowered to take control.
DW
Subtle changes in terms of words, but major changes in terms of meaning. The exchange was actually:

Quote:
02:13:39 - PNF : Climb climb climb climb
02:13:40 - PF : But Iíve been at maxi nose-up for a while
02:13:40 - CDB : No no no donít climb
02:13:40 - PNF : So go down
It was the PNF that was saying "climb", immediately followed by a bunch of DUAL INPUT warnings. I think the Captain suddenly realised what had happened at this point.
After that ..do you stay scotched on your first opinion (I was of the opinion that the PNF had a better handle on the aircraft's situation and as such, should have felt empowered to take control.) ?
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Old 15th Nov 2011, 00:30
  #251 (permalink)  
 
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Lyman, if you're going to continue to make such wild extrapolations, I honestly don't see the point.

We know the ADI on the LHS was OK from the DFDR, and the ISIS seems to have been OK too, otherwise the Captain would not have pointed it out. When the Captain comes in, the PF's stick is all the way back and remains so for another 30 seconds, during which time the PF is actually talking to the PNF and the Captain (and at one point tries to extend the speedbrakes). This is a mushing stall and the ADI is varying considerably in pitch and bank as the aircraft tries to get it's nose down (which the PF is almost constantly counteracting). It would appear that they focus on the lateral problems to the exclusion of all else, and the question of pitch doesn't even seem to come into it until they are passing through 10,000ft.

Despite no indications (and a pretty strong counterindication from the stall warning), the PF seems convinced they are in an overspeed situation initially, and following that incorrect intuition consistently applies a recovery technique which is the precise opposite of what he should be doing, unwittingly putting them further and further outside of the flight envelope. By the time the Captain arrives, nothing seems to make sense, but the PF continues to pull.

I'm pretty sure it's not a case of the PF's instruments telling lies, I think that both EFIS and the ISIS were telling the truth, but the truth made no sense to them because nobody asked the right questions. Arguments over yokes aside, the question of "what are you doing?" was never asked, and by the time the PF volunteered the information it was too late.

@jcjeant - Earlier in the sequence, the PNF seems to have a better handle on things (and it's a reasonable assumption that his anxiety for the Captain to return is related to that - he's not happy with the performance of the guy the Captain implicitly put in charge). By the time the exchange where the PF says he's been pulling up for some time happens, confusion seems to have overtaken all three crewmembers.

Last edited by DozyWannabe; 15th Nov 2011 at 00:55.
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Old 15th Nov 2011, 00:32
  #252 (permalink)  
 
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Lyman
I think the key here is the people not the instruments. None of them show any real understanding of the situation they're in. As I mentioned perception is a vital factor and it looks like none of them could be described as being in a state where they could perceive correctly. Others have written of the natural impulse to pull back on the stick and this seems to be the PF's reaction. Initially as I have pointed out the PNF was telling the PF to go down without effect. By the time the Captain arrived the PNF had also succumbed to panic and was not coherent.
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Old 15th Nov 2011, 01:15
  #253 (permalink)  
 
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Cool

Hi,

I think the key here is the people not the instruments
At the end .. the human factor investigation team will certainly conclude (IMO) as a case of hypervigilance and tunnel vision (results of stress , fear and panic)
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Old 15th Nov 2011, 03:01
  #254 (permalink)  
 
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@Dozy
Your summon up in #251 is imo totally correct. Hopefully BEA will come to the same conclusion in their final report.
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Old 15th Nov 2011, 03:26
  #255 (permalink)  
 
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Not if the AoA gets the value zero for <60 kCAS.
Not too sure to get that HN39 ... at zero of AoA aircraft is not stalled.

airtren, would you be kind enough to let me know how you proceed to be able to present the data in a different order.
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Old 15th Nov 2011, 03:56
  #256 (permalink)  
 
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Originally Posted by Clandestino
By grabbing the controls with little or no warning you risk startling your colleague, which is in fact incredibly dangerous and you could end up "fighting" each other.
"I HAVE CONTROL" - no more - no less - no anbiguity
Forget your 'incredibly dangerous'

One of the advantages to the sidestick system is that by holding the priority button you can "lock out" the other stick if you need to.
Only partially true - If a fight there is, both fighters could endlessly retake control.

@CONF - Or you could have had a split elevator condition (as in EgyptAir990) and a nasty crash.
If there was a 'split elevator + nasty crash' every time a change of control is done on short final we should know it by now ...
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Old 15th Nov 2011, 05:28
  #257 (permalink)  
 
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Excuse me for interrupting this excellent dog fight.
It occurs to me, that 3 months from the news conference that introduced the 3rd BEA report on AF447 has more than elapsed. At that briefing Jean-Paul Troadec introduced their new recommendations with the following (translated) comment:
First of all, a word or two about what it means to issue a recommendation. A recommendation is not a pious wish from the BEA. A recommendation is something that we make, of course, when we think that it is useful for safety but also that has a reasonable chance of being implemented. Because when we make a recommendation to an authority in general, it must answer us within three months and provide us with the follow up that it intends to give to this recommendation. So, this is something that commits us that also now commits the authority since the implementation of the new European regulation on accident investigations.

The underlined portion has my interest. What is the upshot of the recommendations? Has anyone seen anything?

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Old 15th Nov 2011, 06:24
  #258 (permalink)  
 
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Originally Posted by Old Carthusian
AirTren
No that isn't my thought at all. Perception works differently for different people and some actually process audio signals quicker than visual signals.
We've established earlier that the sounds of a couple or several words needed to describe the new position of a cockpit control takes several seconds.

Therefore, the perception of those sounds, those words, cannot take less time than it took to produce them, and that is several seconds.

I don't think a person that needs more than the above several seconds to perceive a new position of a cockpit control will be considered as not having vision problems and allowed to fly commercial passenger airplanes..

Furthermore you don't transform an audio signal into a visual signal unless that is what you want to do. This is a fallacy - sound is sound and is interpreted as such.
The transform is done involuntarily, and unconsciously. You may not be aware it happens.

The change of the position of a cockpit control is a spacial element, which can be perceived directly without translation, only visually, or tactile. An articulated sound perception - a series of words - is not a spacial perception. Therefore a translation/transform takes place.

Last edited by airtren; 15th Nov 2011 at 07:03.
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Old 15th Nov 2011, 06:38
  #259 (permalink)  
 
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Originally Posted by CONFiture
... at zero of AoA aircraft is not stalled.
Exactly! Some time ago someone (A33Zab, IIRC) explained that the stall warning stops because the ADR outputs AoA=0 when airspeed is <60 kCAS.
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Old 15th Nov 2011, 06:55
  #260 (permalink)  
 
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AirTren
This is not what I say at all - what the statement says is that some people PROCESS audio signals quicker than they process visual signals. You could say that their hearing functions at a higher rate then their vision if you wanted to simplify. The processing and interpretation of the signal are the significant factors not the receipt or transmission of the signal. Some people will even respond to an audio signal whilst they may overlook a visual cue. In fact visual cues are often missed - a simple example, think of the times you've missed someone waving at you but responded when they spoke to you.
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