AF 447 Thread No. 6
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Sunbird
In this case probably not. In Alt 2 law, the aircraft is trying to hold a pitch attitude. The attitude was not an appropriate one for recovery.
One wonders what would have happened if the aircraft would have rolled over. She could have possibly built up speed in that manner, but with the THS set so high, it is possible that g may have shot past the ability of full down elevator to limit. Then again, depending on how the nose did or did not fall, it just might have created an inverted stall..
HN39, any ideas on this?
Could the aircraft have recovered from the stall by itself. Most jets if not in a spin will recover from a stall hands off,given enough altitude.
Is it possible for the A330 to recover from this particular stalled state?.I do not know.
Is it possible for the A330 to recover from this particular stalled state?.I do not know.
One wonders what would have happened if the aircraft would have rolled over. She could have possibly built up speed in that manner, but with the THS set so high, it is possible that g may have shot past the ability of full down elevator to limit. Then again, depending on how the nose did or did not fall, it just might have created an inverted stall..
HN39, any ideas on this?
bear, JE-EE admits she is not a pilot. If I gave her some latitude for colorful language, so be it. At the core of her musing was the issue of how important the weather was as a factor in that flying problem at hand. Given the evidence from the CVR that we do have, versus that which we don't, I am not so sure her pizza idea isn't too far from a practical remedy. (But the pizza is a metaphor for better application of standard CRM, IMO).
Replace term "fear" with "concern" and it's a more likely state of mind in the event under consideration. I don't think he ever got to fear, he was involved in hand flying and then a bit of 'what's it doing now' for most of the way down, if CVR excerpts are an accurate description of what transpired. As to "deathly afraid" it depends on what impact his training in re Tstorms and big buildups had on him, and how many "sea stories" he heard, or accidents he reviewed, in which a significant vertical development figured. (Won't digress on how sea stories inform how people sometimes react to malfunctions, not enough space.)
In my reading, "poor fellow" comes from the fact that he is no longer among the quick. 
If you saw it as an indictment, OK.
Regardless of the style in presentation, I believe the matters of task management and compartmentalization, and task priority ordering are very relevant sub topics to this general topic, given the information available to date.
Machinbierd:
If I recall this right, it is keeping a chosen pitch due to all 3 ADIRU's being cut out, right? 
Originally Posted by JD-ee
... I mused a little about the state of mind of the pf. He's above a heck of a storm that was big enough to reach out and "touch" the airplane and cause airspeed indications to fail. After he overreacted and zoom climbed 1500' he found himself in stall warning conditions. He overdid the increase thrust part and under-did the ND part. I got to wondering if he was deathly afraid of descending into the storm even if it was required for stall recovery. He'd not have to descend all that much to gain back most of his lost airspeed if he reacted sensibly and rapidly. Could the fear of the storm been bouncing around in his head biasing his thinking away from the intuitively insane* ND action?
I can't help thinking, "I really really don't want to go down into that storm," was bouncing around in that poor fellow's head. So, ironically, he descended all the way down through that storm he might have been trying with all his might and soul to avoid.
If you saw it as an indictment, OK. Regardless of the style in presentation, I believe the matters of task management and compartmentalization, and task priority ordering are very relevant sub topics to this general topic, given the information available to date.
Machinbierd:
In this case probably not. In Alt 2 law, the aircraft is trying to hold a pitch attitude. The attitude was not an appropriate one for recovery.
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Hi,
Just read ( I learn every day
)
Aircraft certification in Europe (CS25), which says in paragraph 1309 :
What about Airbus A330 ?
Just read ( I learn every day
)Aircraft certification in Europe (CS25), which says in paragraph 1309 :
CS 25.207 Stall warning
(c) Once initiated, stall warning must continue until the angle of attack is reduced to approximately that at which stall warning began.
(c) Once initiated, stall warning must continue until the angle of attack is reduced to approximately that at which stall warning began.
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Is there anything in the behaviour of the crew to suggest they were concerned about traversing a 'heck of a storm', and were 'deadly afraid' of descending into it?
HN39, beyond the hyperbolic language used by a PPRuNe poster, is it your position that the crew of AF447 were either oblivious to, or unconcerned about, the weather they were experiencing and expecting along their flight planned route?
From what I have read in 3 BEA interim reports (translated) there is ample evidence that they were concerned about it.
If you feel that the language used in JE-EE's musing, or speculation, is over the top I understand.
The point behind the musing, however expressed, should not be overlooked in analysis of this event.
As I noted a few posts back, the guess may be wrong. We cant' read minds, and we can't read minds two years ago. That doesn't mean we ought to ignore how various factors play into cockpit decision making.
From what I have read in 3 BEA interim reports (translated) there is ample evidence that they were concerned about it.
If you feel that the language used in JE-EE's musing, or speculation, is over the top I understand.
The point behind the musing, however expressed, should not be overlooked in analysis of this event.
As I noted a few posts back, the guess may be wrong. We cant' read minds, and we can't read minds two years ago. That doesn't mean we ought to ignore how various factors play into cockpit decision making.
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Just read ( I learn every day )
Aircraft certification in Europe (CS25), which says in paragraph 1309 :
Quote:
CS 25.207 Stall warning
(c) Once initiated, stall warning must continue until the angle of attack is reduced to approximately that at which stall warning began.
What about Airbus A330 ?
Aircraft certification in Europe (CS25), which says in paragraph 1309 :
Quote:
CS 25.207 Stall warning
(c) Once initiated, stall warning must continue until the angle of attack is reduced to approximately that at which stall warning began.
What about Airbus A330 ?
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In 447's case, re: the STALL followed by PF's NU, a very good question. One assumes the WARNING will off if the AoA reduces, so PF's input of NU "REDUCED" AoA?
I was not being facetious about the lack of a shaker/pusher?
By what fortunate waiver come they by this? Because,,,,,,,,etc.
Would it be expensive to refit shaker pusher on this family of a/c?
That would be, Yes.
I was not being facetious about the lack of a shaker/pusher?
By what fortunate waiver come they by this? Because,,,,,,,,etc.
Would it be expensive to refit shaker pusher on this family of a/c?
That would be, Yes.
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Originally Posted by Lonewolf 50
HN39, beyond the hyperbolic language used by a PPRuNe poster, is it your position that the crew of AF447 were either oblivious to, or unconcerned about, the weather they were experiencing and expecting along their flight planned route?
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@Machinebird:
In this case probably not. In Alt 2 law, the aircraft is trying to hold a pitch attitude.
ALTERNATE is Nz LAW, like NORMAL LAW.
Stick relaxed it will retain 1g, SS deflection is a Δ gee command.
If SS (pitch) remained relaxed after the A/P drop-off event it would not
have been in this upset situation.
For SS (pitch) relaxed:
If you follow the Nz (Normal Acceleration) traces for every Nz above 1g
the elevator would have been deflected ND.
For Nz below 1g the elevator would have been NU to achive the 1g.
So it depends at which time the SS (pitch) was relaxed and you have to
keep in mind that after that the Nz trace would have been very different.
IMHO if altitude did permit this A/C (SS relaxed) would have
been stabilized finaly to normal flight.
A larger and sustained SS ND command (initiating THS to drive to normal value)
would have helped a lot!
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Hi,
HazelNuts39
Maybe..
Seem's the BEA forget it also ... maybe it's the reason why they put up a special task force for study the "Stall alarm" problem ...
HazelNuts39
Quote:
Originally Posted by JCJeant
Just read ( I learn every day)
And forget the next day?
Originally Posted by JCJeant
Just read ( I learn every day)
And forget the next day?
Seem's the BEA forget it also ... maybe it's the reason why they put up a special task force for study the "Stall alarm" problem ...
Last edited by jcjeant; 22nd Aug 2011 at 21:53.
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In ALTLAW2, the THS is inhibited below 0.75, and above 1.25g. So it would not move in between these values? How does that affect the g demand input and availibility of the Tail Plane? If the a/c was in between these g values the whole while, wouldn't that mean that the THS is functionally unavailable for ND? Because it sure did not move, and the elevators did.
Now I know the argument is the elevators were not 1) sustained and/or, 2) not commanded beyond "Neutral", so was the THS available at all, in spite of, because of elevator deflection anyway?
Now I know the argument is the elevators were not 1) sustained and/or, 2) not commanded beyond "Neutral", so was the THS available at all, in spite of, because of elevator deflection anyway?
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Originally Posted by 3hl
What about Airbus A330 ? Sounds like an excellent question... HN39? Has this already been answered?
Last edited by HazelNuts39; 22nd Aug 2011 at 22:25.
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Maintained Stall
From Zorrin
OK let's not get carried away with nomenclature so the question can be avoided.
Can you name another civil airliner where the pilot can effortlessly hold the aircraft in a stable stall from 35,000 ft to the surface?
Had the THS not been fully nose up, what would the behavior of the A330 have been even with continual full NU elevator? Would that behavior have made it more obvious that the aircraft was stalling?
The 'deep stall' theory came up because it seemed much more plausible that a professional crew couldn't get out of a stall rather than wouldn't even try to. Especially the media picked it up readily, because it sounds appropriately dangerous.
Now many use it as a synonym for "really bad stall", which unnecessarily confuses people. See Ian's question, "were they told of the possibility of deep stall?"
Uhm, no, it wasn't in the "locked-in" kind and yes, it's got wings so obviously it can stall...
It's a garden-variety stall, do we need a special name for it?
Now many use it as a synonym for "really bad stall", which unnecessarily confuses people. See Ian's question, "were they told of the possibility of deep stall?"
Uhm, no, it wasn't in the "locked-in" kind and yes, it's got wings so obviously it can stall...
It's a garden-variety stall, do we need a special name for it?
Can you name another civil airliner where the pilot can effortlessly hold the aircraft in a stable stall from 35,000 ft to the surface?
Had the THS not been fully nose up, what would the behavior of the A330 have been even with continual full NU elevator? Would that behavior have made it more obvious that the aircraft was stalling?
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Can you name another civil airliner where the pilot can effortlessly hold the aircraft in a stable stall from 35,000 ft to the surface?
Excellent question!
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Originally Posted by Ian W
Can you name another civil airliner where the pilot can effortlessly hold the aircraft in a stable stall from 35,000 ft to the surface?
Last edited by HazelNuts39; 22nd Aug 2011 at 22:43.
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Ian, yes, all that makes sense...
When I first used term deep stall a few hundred posts ago, I did qualify it (knowing well the original meaning & the eybrows it would raise)
Controls Induced Deep Stall as suggested then, or similar
Only if manually trimmed heavily NU, would any other aircraft be likely to behave likewise I think... without that, (and with sensible s-s control feedback, not this arbitrary spring feel), aircraft should be difficult to hold into any sort of stall let alone a deep one...
.. that is how aircraft used to work, remember
When I first used term deep stall a few hundred posts ago, I did qualify it (knowing well the original meaning & the eybrows it would raise)
Controls Induced Deep Stall as suggested then, or similar
Only if manually trimmed heavily NU, would any other aircraft be likely to behave likewise I think... without that, (and with sensible s-s control feedback, not this arbitrary spring feel), aircraft should be difficult to hold into any sort of stall let alone a deep one...
.. that is how aircraft used to work, remember
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And that is why I posit the a/c 447 would break even with FULLNU elevators and 0 degrees of THS. I do not think 447 will remain NOSEUP and mush without these other factors, aft cg. (incl fuel, MAX THS NU etc.). The idea is not only NOT TO STALL, but to drop NOSE if she DOES. None of this, "We aren't affected, we have NORMAL LAW PROTECTIONS."
No aircraft should be 'exempt' from PHYSICS. Shouldn't that be on a bumper sticker somewhere? And the idea is not to have protections only when the weather is fair, but at least fundamental ones when things go PEAR. Can there be a more egregious Hypocrisy? Not to mention LETHAL?
Exclusive of POWER, as well. Including TOGA. "But the PILOTS......."
NO MORE SCAPEGOATS
No aircraft should be 'exempt' from PHYSICS. Shouldn't that be on a bumper sticker somewhere? And the idea is not to have protections only when the weather is fair, but at least fundamental ones when things go PEAR. Can there be a more egregious Hypocrisy? Not to mention LETHAL?
Exclusive of POWER, as well. Including TOGA. "But the PILOTS......."
NO MORE SCAPEGOATS