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AF 447 Search to resume (part2)

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AF 447 Search to resume (part2)

Old 20th May 2011, 04:03
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That's true but it feels better with it.
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Old 20th May 2011, 04:06
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Cool

Hi,

At cruise, you don't even need altitude for a while, "pitch, power and attitude" is the minimum required... with pilot experience and adequate training.
So .. we know the lack of speed indication (pitot tubes) was not the cause of AF447 loss
What can be the other causes ?
Seem's it's not a big range of choices ....
1-Structural destruction (due to weather circumstances) ?
2-A malfunction of aircraft systems ? (Exept pitots tubes of course)
3-Bad behavior of the pilots ?
Note:
I eliminate the point 1 of the list due of the state of the wreck and BEA preliminary reports
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Old 20th May 2011, 04:18
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Hi jcjeant,
Originally Posted by jcjeant
So .. we know the lack of speed indication was not the cause of AF447 loss
What can be the other causes ?
Seem's it's not a big range of choices ....
Structural destruction (due to weather circumstances) ?
A malfunction of aircraft systems ?
Bad behavior of the pilots ?
Well... don't ask me to guess about the cause(s) now, because all my previous speculations (about engines and ice) seems to be "rumored" false. Nonetheless, I never believed to a single cause, a single upset... and neither to a single "culprit". So, I'm waiting for more official releases of informations before starting a new "speculation" about it.
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Old 20th May 2011, 04:37
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As SLF, I’d like to know that if/when the computer throws up its metaphorical hands, the pilot in command has the training/experience/skills to take control of the aircraft and fly it in what has often been referred to in this forum as “stick-and-rudder” mode.
I am also a SLF (whatever that stands for - assume it means "non-pilot type"). From what I understand the lowest level of Airbus control (excluding the "stuff-has-hit-the-fan-all-the-chips-are-down mechanical pitch trim and rudder) is direct law - the control surface deflection is directly proportional to the stick (or rudder pedal) position. In this regard it is exactly like a normal aircraft, and the computers merely translate the stick's position into control surface deflection without adding their own inputs or limits. In this case, and if my understanding is correct, the pilot should be able to handle the aircraft - after all, he or she has probably spent much time in his or her early flying lifetime flying airplanes that behave in exactly this way. Ultimately the Airbus aircraft are aerodynamically conventional, so they should be stable and well within a pilot's ability to fly, even without computer compensation.

I hope I did not mangle the facts too badly there, and if I did I apologize and I would welcome any corrections - but as far as I am aware, the answer to your question is "yes, they do".
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Old 20th May 2011, 04:55
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Basically, AF447 had only its Gee force prot left and everything else was direct.
Who has control of the THS in Alternate law?
Who has control of the THS in Direct law?
If the THS is in the wrong place with regards to trim, which law would you rather be in?

Last edited by Machinbird; 20th May 2011 at 05:58.
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Old 20th May 2011, 05:23
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@gums With all of the above in mind, I have tried to show that flying about with a cosmic computer-assisted flight control system is not fool proof. With virtually no limits compared to the Airbus, we quickly found a way to beat the computers and wind up in a deep stall. It was a combo of aero and aft center of gravity. We couldn't get out unless we could turn off the computer control of our elevator. Only the elevator. This is prolly not a great idea for the Airbus, but who knows?
hy gums, did we have today to establish the fourth senior-faktor ?

in troubble:
beat the computer, aviate, navigate, communicate......
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Old 20th May 2011, 06:07
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Originally Posted by Machinbird
Who has control of the THS in Alternate law?
Who has control of the THS in Direct law?
If the THS is in the wrong place with regards to trim, which law would you rather be in?
a) Normal/Alternate Law: PRIMs.
b) Direct Law: Manual wheel.
c) If THS at a wrong place: Normal/Alternate/Direct.
In any flight Law, manual trim is available (manual overide PRIMs settings without causing faults in Normal/Alternate). Manual trim imputs are prioritized over electrical imputs and PRIMs are reconfigured at manual settings position.
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Old 20th May 2011, 06:37
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A330 - Normal, Alt1, Alt2 and Direct Law

As there is a bit of discussion regarding what happens in which law, a good explanation and summary table is provided in a document by Andy Tracy. The link provided once more is:-

http://countjustonce.com/a330/a330-flight-laws.html
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Old 20th May 2011, 06:51
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the pilot should be able to handle the aircraft - after all, he or she has probably spent much time in his or her early flying lifetime flying airplanes that behave in exactly this way. Ultimately the Airbus aircraft are aerodynamically conventional, so they should be stable and well within a pilot's ability to fly, even without computer compensation
I wish I had your confidence

See the threads on 200hr pilots... re
spent much time in his or her early flying lifetime
- there is no "early flying lifetime".

There is little comparison between a SEP or even MEP bumbling around at 3000' (where the 200hr training was done), and a swept wing jet close to Mach and Stall limits ~35K'. We have airlines and posters on this forum saying it is "poor aimanship" to manually fly in e.g. London TMA, we have airlines forbidding crews using Manual Thrust in normal Line Ops.

I've flown Airbus FBW types for ~10 years. Not sure I've ever done the "Direct Law" handling sim practice at ~35K', let alone in turbulence, dark, and maybe with further failures.

I also fly military jet trainers (as instructor) and dong a recent Test/Check flight, the profile called for some FL350 handling inc 180 turns etc. It was an eye opener for me, and took me back ~20 years to RAF days, to recall the basics of handling a jet at high altitude. Something of course we were taught properly (in the Student guide), but a modern airliner pilot really has very little recent practice or training at this...
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Old 20th May 2011, 06:54
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Smile

Nick L
I am also a SLF (whatever that stands for -
SLF... Self Loading Freight
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Old 20th May 2011, 07:29
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Takata,
Thank you for the thorough answer with regard to THS trim.

To take it a bit further.
What happens when you take your hand off the trim wheel after putting it where you actually want it and you are still in alternate law? Doesn't it run back to where the computer wants to put it? Could this be inconvenient if the aircraft was actually in a stall and you were trying to recover?
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Old 20th May 2011, 08:08
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Originally Posted by Machinbird
Doesn't it run back to where the computer wants to put it?
Not really, manual-trim mode is activated:
"microswitches, actuated by the override mechanism, ensure that the computers remain synchronized with the manually-selected postion.
"
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Old 20th May 2011, 08:16
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plasmech,

The BEA is continuing to do a read-out of the two recorders. There have been no disclosures of the content of the CVR, yet. The BEA has said that based on the initial read of the FDR, that no major hardware or software problems were found, but that as the data is further analyzed, anomalies or problems requiring corrective action or steps may be identified.

The two bodies recovered in their seats have been flown to Paris, and the examining laboratory has announced that the bodies can be identified using DNA.

The Ile de Sein is headed back to the site of the plane; it had been in Dakar for a crew change. Quite likely it off-loaded in Dakar those parts of the plane, e.g., engine, cockpit seats, that had been retrieved, and these are probably being flown back to France. It is not clear what parts of the plane will be retrieved, possibly cowlings if these were not retrieved in the initial recovery of parts. I believe two judges in Paris will now determine whether any more bodies will be retrieved.
Thanks so much. Could you kindly fill me in on why one of the um...rumors being discussed now pertains to the *possibility* of "non pilot" / "inappropriate" personnel in the cockpit during the crisis?
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Old 20th May 2011, 09:07
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CONF iture:

Quote:
Originally Posted by HN39
The curious thing is that the threshold did not change to 10° when the speeds became invalid.

I think the answer is in the FCOM 3.02.34 (also mentioned in the Air Caraibes Note) :
Quote:
Rely on the stall warning that could be triggered in alternate or direct law. It is not affected by unreliable speeds, because it is based on AoA.
As you say, the stall warnings ACA got were not false, they were only inappropriate in the way that the crew did very well to ignore them by maintaining a pitch and a thrust setting and not destabilizing that precarious situation.

I must say this ACA note is terrific. Congratulation to Mister HOUANG. Not much to see with the usual bla bla of a BEA report ...
I'd be very interested to hear Airbus pilots' thoughts on what might have happened if the Air Caraibe pilots (for there were 2 almost identical incidents...) had *not* made the quick decision to ignore the stall warnings, when flying through high-level turbulence, with iced pitots, and in alternate law.....

Also, their actions tend to test the general rule proposed above by DeSitter,

All this discussion of what the Airbus FMCs do is interesting, but irrelevant - when humans are confronted by a computer that is either not working, or working in a regime they are not intimately familiar with, they freeze - they go into brain lock.
Which obviously those Air Caraibe guys didn't.....

Last edited by Jetdriver; 20th May 2011 at 09:21.
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Old 20th May 2011, 09:11
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Originally Posted by takata
all Airbus aircraft are, at first, fully certified (in their final commercial configuration) without FBW (in pure direct law)
As a point of personal interest, does that include flight test demonstration of stalling characteristics?
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Old 20th May 2011, 09:15
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Just for Comparison

I believe the 747-400 was the last new plane without FBW.

Can anybody visualize how it would have reacted with iced pitots in the approximate same coinditons as AF447?
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Old 20th May 2011, 09:23
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Originally Posted by CONF iture
I think the answer is in the FCOM 3.02.34
I think you may have missed the point of my remark, which is that the following BEA explanation does not match the Air Caraibes occurrence:
If none of the three Mach values is valid, a Mach value close to zero is used. For example, it is of the order of 10° at Mach 0.3
Doesn't ADR DISAGREE imply that the stall warning computer has no 'valid' airspeed?


Last edited by Jetdriver; 21st May 2011 at 05:20.
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Old 20th May 2011, 09:51
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Originally Posted by HazelNuts39
As a point of personal interest, does that include flight test demonstration of stalling characteristics?
I don't have any detail about those test flight programs. Certification sheets don't tell much: http://www.easa.europa.eu/certificat...9-06052011.pdf
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Old 20th May 2011, 10:10
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Hi,
Originally Posted by Graybeard
Can anybody visualize how it would have reacted with iced pitots in the approximate same coinditons as AF447?
For my part, I'm still waiting to know how AF447 reacted to its pitot icing and what actually the real conditions were. If you are comparing this end result with known cases, on the same fleet, it doesn't match either any of them so far.
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Old 20th May 2011, 10:16
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At cruise, you don't even need altitude for a while; basically, all you need is "pitch, power and attitude"... beside pilot's experience and training.
Power for me is in a nut shell what got them , i believe to the core that the thrust levers where at idle put there by the crew.

They flew a magnificent piece of engineering for what every reason(all though this might be one of them - let's not go there, shall we ? Nice lasses but not appropriate for the thread .. JT - in to as it has been put before "a beast", without a doubt to me they would have tried to reduce to turbulence penetration speed or lower, enter blocked pitots, and or steaming, indicated airspeed does not reduce, but in-fact appears to increase, thrust reduced further, attitude being held as best possible in the turbulence they where experiencing, still no indications of reduction in airspeed, multiple warnings going off, over-speed clacker going off, severe turbulence, do they even notice the stall warning????
when humans are confronted by a computer that is either not working, or working in a regime they are not intimately familiar with, they freeze - they go into brain lock.
Or in this case "task saturation".

Quote:
when humans are confronted by a computer that is either not working, or working in a regime they are not intimately familiar with, they freeze - they go into brain lock.

I believe you are referring to untrained non-professionals, no?
Nonsense, train professionals can and do freeze when confronted with the unexpected, insert multiple unexpected and its again " task saturation" and in this case theres no freezing the sim to have a wee discussion on how to sort it out, as i have no doubt when this is all over and the cause has been found that in some way or another most of us will have to do.

There where just to many things going on at one time.

Remember Aeroperu 603 and Birgenair Flight 301, both cases where the crews where overwhelmed by the information given to them by the aircraft, both cases where the aircraft was flyable and recoverable, especially in the case of 301 where both high speed clacker and stall warning where going off and the fo knew what was wrong the captain kept the thrust levers at idle, why should 447 be any different.
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