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AF447 wreckage found

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AF447 wreckage found

Old 10th Aug 2011, 08:55
  #2781 (permalink)  
 
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Simple question to those who fly A330:

At 2:10:23 the thrust lock mode was "de-activated".

If the autothrust was already disengaged, how does one then de-activate the thrust lock?

Is there a button to push, or can it only be done by manually moving the thrust levers?
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Old 10th Aug 2011, 09:24
  #2782 (permalink)  
 
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THR/LVR in CLB detent

Originally Posted by RWA
Just from reading, that's the correct procedure, as far as I know - except that, once the autothrust has signed off, I'd expect that the pilots are supposed to use the throttle levers 'normally' - that is, move them forward or back to adjust the power, presumably by reference to the N1 gauges? Again as I understand it, in the absence of the autothrust, just using the 'Climb' detent could have been either too much for the situation or insufficient to maintain level flight?
  1. To move the thrust levers in the CLB detent is part of the drill for UAS.
  2. At FL350 with no A/THR the output is absolutely the same whatever the thrust levers position from CLB to MCT to TOGA.

Originally Posted by JH
Is there a button to push, or can it only be done by manually moving the thrust levers?
It has to be done by manually moving the thrust levers - No PB.
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Old 10th Aug 2011, 13:39
  #2783 (permalink)  
 
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Originally Posted by Gretchenfrage
Quote:
It was all meant to shout: If humans are on the flight-deck, they MUST be able to fly the aircraft. Really fly it. Oh, and be allowed to fly it.
Your words in gods ear!

The reality is that whenever the automatics are no longer capable of handling, due to invalid signals they need, they throw the aircraft back at the human.

- Perfect - It will be him screwing up finally.
Good for statistics and engineers.
Statistics here mean more souls staying here on Earth, well and alive.

There is a serious misconception repeated on this forum (as well as elsewhere) that pilots are reduced to be system monitors and all that nonsense. Simply monitoring would be much more comfortably done from the ground. Those guys/gals in front are there for a reason. They are there to command the thing and to handle all the situations which might arise. Not monitor - command!

I already wrote a bit about that in one earlier post: http://www.pprune.org/rumours-news/4...ml#post6582987

What's worrying is that aforemntioned misconception is taken as truth by some pilots flying those birds...

Originally Posted by Gretchenfrage
Second reality is that even when the automatics switch off autopilot and autothrust, it can still intervene with pilot inputs, through automatic protections, and therefore limit his authority.

Why on earth? ?
It had detected itself incapable of handling the aircraft, but still messes with controls.

Isn't that a paradoxon?
It's not. It only looks like a paradox for those who do not understand how those things work.
AP is completely different system than flight control computers. AP works on completely different abstraction level. AP directs airplane through the air. Flight control computers translate commands given to the plane into flight controls. So there is nothing paradoxical nor even strange that one function might work wile the other could not. For example partial loss of airdata does not prevent G-load-demand driving of control surfaces while it prevents automatic directing of the bird (i.e. AutoPiloting).

Originally Posted by Gretchenfrage
I am not entirely against automation and technology to improve safety. But the implemented systems must work flawlessly.
Otherwise I don't need them.
So before introducing even more protections, please fix the technology that's already on board.
Nope. It just must work better that humans performing the same tasks. And statistics, i.e. number of people still alive, shows that it works. If some pilot feels bad because of that, so be it, but those few hundred souls behind him/her might be still alive just because that damn electronics prevented his/her error altogether or just reduced it's effect to be much less significance.

Computers (and generally artificial devices, i.e. tools) are better (often significantly) than humans in many areas. Smart humans will take advantage of that and let the computers do the stuff they're good at while keeping doing stuff computers are bad at or even completely incapable of.

Originally Posted by Gretchenfrage
Concerning statistics, lots of contributors just love those, I am still missing a serious one about automation induced pilot errors. This would give a clearer picture than the one containing just plain pilot error. Not that it would excuse any such error, eliminating those should be just as noble a cause, but it would point back at the magic automatics that benefit from too big a confidence and a lack of genuine criticism, as it would mean responsibility (meaning doe) from you who I mean.
Such statistics would be meaningless without automation prevented pilot errors. And that last one, while impossible to be known exactly could be pretty easy estimated. And the (estimated) result is that it simply dominates other statistics. Crashes caused by pilot error dominated (i.e. were more than 50%) statistics before FBW era. Now, total number of crashes of contemporary, FBW aircraft is significantly less the number of earlier crashes caused by pilot error. Thus either pilots are so much better now, or those new birds reduce possibilities of errors and reduce effects of many such errors to get them off accident/incident tables. This reduction comprises vast majority of pilot errors which had bring down older planes.
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Old 10th Aug 2011, 14:14
  #2784 (permalink)  
RWA
 
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Quoting Sebaska:-
"FBW aircraft is significantly less the number of earlier crashes caused by pilot error."

Apologies, Seb, can't resist quoting a BBC radio witticism that I heard many years ago. A 'voice' supposedly coming on to the airliner's PA and telling the passengers that they were flying on the world's very first fully-automated passenger flight. That there were no pilots up front, that the only airline personnel on board were the cabin crew.

I recall that the radio sketch ended with the guy saying, "Please do not be alarmed. All the systems involved have been exhaustively tested over many years of development - and we can give you all a positive guarantee that nothing can possibly go wrong.......go wrong.....go wrong.....go wrong........"

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Old 10th Aug 2011, 15:12
  #2785 (permalink)  
 
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rwa Yes, it is the twilight zone, then?

Commercial travel is so safe it is boring. That makes an accident stick out in dramatic invitation for taking sides.

This discussion is two years old, and before that, and by the grace of God, the 777 at Heathrow. Some lazy ice arrived at the inlet tyoo late to kill all on Board.

What is on the surface is interesting, and seems to have been well shepherd into perfect corrals.

Today in this country, one thousand peoplle will die in auto accidents. Because this is a large place, the slaughter will appear dilute, and less important than 228 falling out the sky two years ago.

Tomorrow, only five hundred could die in autos, but these vehicles would be more expense, and the roads extremely more costly.

The tragic and heartbreak is when the possible prevention is from humans.
Operator Error? Likely. but by the time the other causes have come to the reports, people will be looking at different things.

Sometimes Air Travel is not the bargain we think, most other times, it is.

It is not this Stabiliser, nor the young pilot, nor the conveyance. It is our desire to skirt the basics, the Physics, to please ourselves and the Bank. Please to not cut these margins so fine, Paris will be there next week.
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Old 10th Aug 2011, 15:28
  #2786 (permalink)  
 
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ENG THRUST LOCKED

Originally Posted by Jazz Hands
At 2:10:23 the thrust lock mode was "de-activated".
If the autothrust was already disengaged, how does one then de-activate the thrust lock?
Is there a button to push, or can it only be done by manually moving the thrust levers?
a) one need to understand why the "THRUST LOCK" function was activated:
In our case, it means that AUTOTHRUST disconnection was due to a system fault and not to any pilot action (like using the disconnect pb, or setting levers to IDLE).
Consequently, thrust will remain locked at its last setting which is unrelated with THRUST LEVERS actual position: at cruise at FL350, with turbulence, thrust could be anywhere between IDLE thrust and CL thrust = (MIN-MAX range: this is autothrust range of operation when active and engaged - MCT is only used in case of one engine failure). Hence, when A/THR disconnect, actual Thrust doesn't change (increase to CLB if actually set below this level), it is locked.

b) What caused the loss of A/THR was both FMGS (auto flight system) faulting due to their IAS monitoring function (A/THR fault is recorded at 0210:08, three seconds after A/P OFF at 0210:05).

c) Unlocking THRUST action is only manual by moving the levers. If one re-engage them where they already were set (CL detent), like in our case, DFDR record won't show any change of detent setting: they were set off CL detent, moved and engaged back in CL detent. Nonetheless, DFDR will record the manual action of Unlocking the Thrust and the total duration of the "THR LOCK" period before crew reaction (about 15 seconds).



During this period (0210:08-0210:23), thrust was locked at N1% 83.

@ FL350, standard settings for pitch/thrust should have been adjusted to:
Mach .80 ; GW > 190 t ; pitch = 3.5°
Mach .80 (260 kt) ; 200 t > GW < 210 t = 91.9 > N1% < 93.1

@ FL370:
Mach .80 ; 200 t > GW < 210 t = 94.3 > N1% < 95.9
And, of course, there is no N1 value for above levels.

Consequently, she was starting to climb up to FL380, at an high V/S and pitch rate (close to take off), without initialy enough thrust to maintain FL250 in level flight (as she was decelerating just prior this sequence started). It took about 25 seconds to manually increase N1 up to 104% while she had already bleeded a good deal of her speed in between.


Last edited by takata; 10th Aug 2011 at 15:44.
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Old 10th Aug 2011, 15:49
  #2787 (permalink)  
 
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A very subtle language thing, but I think important.

The Thrust is NOT LOCKED. AB says so, but it is not "LOCKED".

It is "retained". If anyone thinks words don't matter, consider, "MOVE THROTTLE". "CYCLE LEVERS". Left in last position, "VALUE".

It is politics and Philosophy, not an accurate description of Throttle avail.

The AB is NOT pilot friendly in many ways, even in subtle ways that start an argument. It has an "ATTITUDE".

"LOCKED", in an emergency, with impaired conditions, means "DON'T TOUCH". If you think ergo and linguistics are not life and death, think again.
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Old 10th Aug 2011, 17:40
  #2788 (permalink)  
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Quoting CON fiture:-

'at FL350 with no A/THR the output is absolutely the same whatever the thrust levers position from CLB to MCT to TOGA.'

Sincerely hope that I've misunderstood, CON fiture?

You appear to be saying that, due to a total lack of logic in the Airbus auto-throttle controls, the unfortunate AF447 pilots spent most of their last three minutes on this Earth pissing about with throttle settings like CLB, MCT, TOGA, and whatever - but that ALL of those settings simply resulted in no change at ALL in the actual power generated by the engines - which remained at TO/GA?

As a law graduate, on the face of it, I'd say that if that's even halfway true, it provides adequate evidence for the designers of any such systems (AND their parent companies) to face manslaughter charges, at the very least?

Almost can't believe that any designers could generate systems which were THAT stupid?
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Old 10th Aug 2011, 17:52
  #2789 (permalink)  
 
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but that ALL of those settings simply resulted in no change at ALL in the actual power generated by the engines - which remained at TO/GA?

Not true, RWA.

Page 113 of the interim report shows the engine power commanded by the crew (N1 Command), and the resulting engine thrust generated (N1 Actual).

The thrust is clearly not staying at TO/GA, but following the power level set by the pilots.

From CONfiture's post, I think he was specifically referring to the maximum power available during high-altitude cruise.
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Old 10th Aug 2011, 18:55
  #2790 (permalink)  
 
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TOGA / CLB

Originally Posted by RWA
You appear to be saying that ...
Negative.
I just say that at FL350 TOGA thrust will not deliver anything more than CLB thrust would, and this is normal.
Nothing 'stupid' here, just altitude density.
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Old 10th Aug 2011, 19:29
  #2791 (permalink)  
 
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@Lyman:

As long as the AB crew will know what to do with:

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

all others are allowed to never understand it.

The B. EICAS message:

'THRUST ASYM COMP'

will be known by B. crew but says as less as an A. message.
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Old 11th Aug 2011, 01:39
  #2792 (permalink)  
 
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Quoting CON fiture:-

'at FL350 with no A/THR the output is absolutely the same whatever the thrust levers position from CLB to MCT to TOGA.'

Sincerely hope that I've misunderstood, CON fiture?

You appear to be saying that, due to a total lack of logic in the Airbus auto-throttle controls, the unfortunate AF447 pilots spent most of their last three minutes on this Earth pissing about with throttle settings like CLB, MCT, TOGA, and whatever - but that ALL of those settings simply resulted in no change at ALL in the actual power generated by the engines - which remained at TO/GA?

As a law graduate, on the face of it, I'd say that if that's even halfway true, it provides adequate evidence for the designers of any such systems (AND their parent companies) to face manslaughter charges, at the very least?

Almost can't believe that any designers could generate systems which were THAT stupid?
That being said you combine that with a junior pilot that insists on pulling the SS up for over a minute while the stall warning is going off without realizing he is stalling and his 2nd pilot not correcting him for over 3 minutes gives no chance of survival. Stupid was not just the engineering, it was the pilots too.

No experienced pilot would pull up continuously with a stall warning blaring for almost a minute. I don't care how many other alarms were going off, that one is the big one, ignore the others.
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Old 11th Aug 2011, 03:58
  #2793 (permalink)  
 
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Cool

Hi,

FBW aircraft is significantly less the number of earlier crashes caused by pilot error
I dunno to what FBW aircraft statistics you take reference ... but for the Airbus FBW serie .. all important accidents were the cause of pilots errors (and some human errors associated) ..... never the aircraft (system or engines or structural) was plain implied in the cause of accidents.
And it's seem's that the AF447 (and the Libyan A330) accident will be added to this list
In fact .. so far .. after read all BEA or NTSB or other reports about Airbus accidents .. the aircraft was always working fine (minus the Sully one and the Qantas A380...) .. the pilots .. no.
Globally today the statistics shown that 75-80 % accidents are caused by pilot errors .....
That's normal that the balance change (more accidents cause pilot errors ) .. as the technology (engines and systems and structures) are more reliable today

Last edited by jcjeant; 11th Aug 2011 at 04:15.
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Old 11th Aug 2011, 13:34
  #2794 (permalink)  
 
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Isn't the aircraft at fault, at least in part, if it's certificated pilots repeatedly fail to understand what is happening with it in an emergency?
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Old 11th Aug 2011, 13:35
  #2795 (permalink)  
 
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Slightly off-topic, but this popped up today:

EASA to order checks on A320 angle-of-attack sensors
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Old 11th Aug 2011, 14:15
  #2796 (permalink)  
 
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thats great info Takata.

I dont have access to an Airbus Simulator, but ive run this accident at home twice now with the worst thunderstorm i can find, a pretty much fully loaded aircraft and all the other parameters , and those power settings and pitch attitudecsettings are about right. I an early BBC documentary I think they mentioned power in the high 80's (at least85%) and 3-5deg pitch up. I even dialled up an aft COG to see what effect it would have on stability...nps..

Just maintaining reasonably steady altitude to within a few hundred feet would have been a good proxy, with nil or minimal thrust alteration if they wanted a decent turbulence penetration speed. The climb at low power was the toxic confection. I even wonder if a gentle descent would have given them safer tolerances to a possible stall..done in a planned way, but of course they seem to have chosen to fly right through the densest and widest part of the storm, which would have left yhem with more weather than neccessary to have tolerate(read..survive)
My own simof it didnt seem that difficult and no hint of overspeed or stall...just bumpy and needed patience and gentle hands.

I think the poor guy just lost his scan discipline very quickly, got distracted and probably spatially disoriented, couldnt prioritise,and ignored the (expletive) stall warning and the very good advice he was getting ...
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Old 11th Aug 2011, 14:19
  #2797 (permalink)  
 
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I think the BEA report makes it entirely clear that there was nothing "wrong" with the airplane. This statement is in the broadest sense, yes the airplane had significant fault warnings however the plane responded correctly to all system inputs and the AP " kicked out" leaving the plane in a reasonably stable configuration.

At the time of the AP disconnect the airframe did not need to be "recovered" just flown. The upset was entirely pilot induced and not influenced by any erroneous instrument displays. The PF was simply overwhelmed and either forgot his training or never had appropriate training to begin with.

In spite of knowing that the PF was responding to the crisis inappropriately and immediately taking command he allowed the PF to continue a course of action that led to a potentially unrecoverable situation. To me the apparent company culture as it relates to CRM is the root cause of this accident. The least qualified pilot happened to be the designated PF and was somehow to allowed to continue flying the airplane in circumstances clearly beyong his ability to handle.

The PM should have assumed control within 15 seconds of AP disconnect based on the PF's failure to apply basic airmanship and fly "pitch and power" stabilizing the airplane while the PM worked to sort out and prioritize the fault warnings.

This is a scathing indictment of AF's safety culture and CRM training. For a seasoned pilot to sit there and watch a colleague kill not only himself but the SOB they are responsible for is criminal....literally. This comment is not aimed at the poor pilot involved but at the airline itself. At this point they need to be slapped down hard...and hopefully will be.
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Old 11th Aug 2011, 14:26
  #2798 (permalink)  
 
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I fully agree

good firm clear non democratic CRM could have saved this situation...

none of this liberte fraternite egalite stuff.

We sound like a bunch of 50 somethings...
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Old 11th Aug 2011, 15:21
  #2799 (permalink)  
 
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Cool

Hi,

Some article interesting to read .....
Current Issue | Flight Safety Foundation
Flight Safety June 2011
Current Issue | Flight Safety Foundation
http://flightsafety.org/download_fil...asw_june11.pdf
Read from page 24 to 27
"Drappier, the Airbus representative, added, “Airbus does not recommend encouraging airline pilots to fly the airplane manually [during line operations] because the airline passengers have
paid to get the maximum level of safety
.
Most of the time, the autopilot is the best route.”
Ironic ?
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Old 11th Aug 2011, 16:26
  #2800 (permalink)  
 
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Mr jeant
Perhaps a translation problem, but Monsieur Drappeur has just cost his company some billions of eurosd. Mr. Lawyer has already copied these comment, and is drooling down his chins.
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