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AF447 wreckage found

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AF447 wreckage found

Old 13th Jun 2011, 06:29
  #1641 (permalink)  
 
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RWA wrote,
"So why no reason for the 2008 A320 accident at Perpignan either, opherben? In the final report? "
You are right. It isn't a complete, professional document. I say that being myself a government authorized air accident and incident investigator.
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Old 13th Jun 2011, 06:33
  #1642 (permalink)  
 
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Bearfoil

yes of course one of the f/o's is PF due to the Capt being on a break...my point being which one of the f/o's and from which seat ....if the more experienced f/o started of as PF in the RHS i find it hard to believe that he would give control to the less experienced other f/o in the lhs ...

however if the less experienced f/o was PF from the RHS then handed over control to the other F/o in the LHS one can envisage the added problems in trying to sort it all out from the LHS..

make sense?

btw i am in no way trying to blame any of the pilots for this disaster.
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Old 13th Jun 2011, 07:17
  #1643 (permalink)  
 
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In our airline normally the relief FO occupies the seat either P1 or P2 vacates. So in this case the P1 seat. It's assumed that the FO who is most 'senior' will become acting PIC.

As for flying roles: Depending on who is PF and PNF those ''roles'' stay with the seat.
eg. the P1 FO can be ''pilot flying and acting PIC''.
Whether this is what you want is another discussion and best left out of this accident.
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Old 13th Jun 2011, 07:43
  #1644 (permalink)  
 
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In our company the Acting Pilot in Command (APIC) is in the seat in which they are qualified...a First Officer would be in the RHS.
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Old 13th Jun 2011, 08:11
  #1645 (permalink)  
 
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I think I'll bow out soon as this thread is far too up and down for me.

The guy flying was in the RHS and was the least experienced of the three. The guy in the LHS was the other F/O who yes, would have little if any flying experience from that side.

RWA,

I think you might be reading too much into the THS "sticking" theory. I reiterate that the pilot must apply sufficent and sustained movement on the sidestike for the THS to move. Remember (without getting too technical) that Trim is a function of speed. A pitch change at slow speed has a different effect on Trim than at high speed.

For what it's worth. My reading of the 27th May update is as follows...

The autopilot and autothrust disconnect and the aeroplane reverts to alternate law 2 due to an ADR disagree. They are in turbulent conditions and the aeroplane rolls slightly to the right. The F/O who has been only mildly alert until this moment grabs the sidestick and makes a left nose up input. This may have been instinctive or he may have been reacting to what he saw on his PFD (apparent loss of altitude). This pitch input is enough to cause an increase in the nose attitude to 10 degrees and aeroplane starts a climb. Such an input is fairly agressive at altitude and this creates a zoom climb with a rate of climb momentarily reaching 7000'/min. The THS reacts to this significant and sustained input and starts to wind back relieving the "pressure" on the sidestick. He realises that his initial input is aggressive and slightly checks the rate of pitch reducing the rate of climb to 700'/min (is he seeking 10 degrees pitch?).

I am at a loss what happens from here but it would appear that following the second stall warning he applies TOGA and raises the nose still further, the AoA reaches 6 degrees and continues to increase reaching 16 degrees at 38,000'.

When the aeroplane stalls the AoA reaches 40 degrees and the aeroplane enters Abnormal Attitude law where auto trim ceases and the THS remains at it's previous nose-up position.

I don't know after that whether the elevator alone has the authority to pitch the nose down to what was required but I doubt it.
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Old 13th Jun 2011, 08:22
  #1646 (permalink)  
 
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Apparently it didn't enter Abnormal Attitude law, continued pitch up will keep THS trimmed esp at slow speed, small excursions pitch down wouldn't give it time to unwind.
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Old 13th Jun 2011, 13:34
  #1647 (permalink)  
 
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Pitch Trim Authority

The discussion on pitch/power has been enlightening. Guess I shouldn't be surprised there's so much misunderstanding in this group, as just now A&B are admitting power alone does not give you speed to recover from a stall.

Next will be the realization by A&B that trimming the tail to maintain altitude is wrong if your power is limited, as in the case of the Flight Test A330, TK951, etc. I expect some serious limits will be introduced to prevent trimming that presently takes the plane into a stall.
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Old 13th Jun 2011, 14:36
  #1648 (permalink)  
RWA
 
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opherben

RWA wrote,
"So why no reason for the 2008 A320 accident at Perpignan either, opherben? In the final report? "
You are right. It isn't a complete, professional document.
Great, opherben. We appear to be of one mind.

Man Flex

RWA,

I think you might be reading too much into the THS "sticking" theory. I reiterate that the pilot must apply sufficent and sustained movement on the sidestike for the THS to move.
Sorry we're disagreeing, Man Flex. We currently have only the sketchiest information about AF447 - but we have fairly full information about Perpignan. In both cases the THS went to 'full up' and stayed there, whatever the pilot did. The 'difference' is that the (full) report on Perpignan clearly says that the captain repeatedly pushed the stick forward all the way to the stop, and held it there - but the THS just stayed in the 'full up' notch........

Studi

At the end, it boils down to 4 things:
Agree that all those things are relevant, studi. But I would submit that there are at least three other relevant factors.

1. The (known to be sub-standard) Thales pitots. Just the AF447 guys' bad luck that, although these were already being replaced, Air France just hadn't got round to replacing those on their particular aeroplane.

2. The weather. Not just the icing, but probably turbulence as well. Can't have helped.

3. The instruments. The positive 'cascade' of ACARS messages shows that one instrument and 'system' after another was cutting out or in right through the crisis period. I think the most serious criticism one can levy at the BEA is that they didn't say much about that issue in their first report, and say absolutely nothing about it in their recent 'note.' Most of the malfunctioning was probably linked to icing in the pitots and ports. But we'll maybe never know what information the pilots had (or didn't have) as to the aeroplane's attitude, speed, or even its altitude at various times during the crisis. Especially, I fear, if we rely on the BEA to inform us........

In particular, we more or less 'know' that the pilots didn't have any sort of 'natural horizon' to work with. And it's only too possible that, at times anyway, they didn't have an artificial one either........?
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Old 13th Jun 2011, 14:55
  #1649 (permalink)  
 
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What would lead to the attitude indicators failling, RWA?

It has been explained to me in the various other threads on this topic that the attitude indicators are driven by ring laser gyros. I had posited that perhaps the pilots were on a "partial panel" sort of scan, and was advised with some vigor that my supposition was groundless.

There don't appear to be ACARS messages indicating Inertial Reference kicking off, so what anomaly do you think would account for both (all three?) of the "gyros" dropping off?

Or, if you think there was a single failure, the pilot flying, how would the BEA know that his failed and left seat pilot's didn't? Unless the BEA is able to find and publish evidence of an attitude indicator failure, it's hard to point to that as a causal factor.

FWIW (From a summary of how an ADIRU works on wikipedia, consider the source ...) :
An ADIRS consists of up to three fault tolerant ADIRUs located in the aircraft electronic rack, an associated Control and Display Unit (CDU) in the cockpit and remotely mounted Air Data Modules (ADMs).
The No 3 ADIRU is a redundant unit that may be selected to supply data to either the commander's or the co-pilot's displays in the event of a partial or complete failure of either the No 1 or No 2 ADIRU.
There is no cross-channel redundancy between the Nos 1 and 2 ADIRUs, as No 3 ADIRU is the only alternate source of air and inertial reference data.
An Inertial Reference (IR) fault in ADIRU No 1 or 2 will cause a loss of attitude and navigation information on their associated Primary Flight Display (PFD) and Navigation Display (ND) screens.
An ADR (Air Data Reference) fault will cause the loss of airspeed and altitude information on the affected display. In either case the information can only be restored by selecting the No 3 ADIRU.

Each ADIRU comprises an Air Data Reference (ADR) and an Inertial Reference (IR) component.
As I understand how the ACARS messages were deciphered, it was that ADR faults that stood out, not IR faults. I may misunderstand what was reported.

Last edited by Lonewolf_50; 13th Jun 2011 at 15:10.
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Old 13th Jun 2011, 15:16
  #1650 (permalink)  
 
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I think I've read every post in this thread and there are many, many comments about 'faulty' or blocked pitot(s). I've not seen (or maybe missed) comments about the static vent(s). What exactly about the pitot(s) or static vent(s) is believed to have 'gone wrong'? Surely the electric heaters were functioning and switched on?
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Old 13th Jun 2011, 15:49
  #1651 (permalink)  
 
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Lemain: in a nutshell, there is more than one kind of ice up high. Numerous posts in the three threads covering this crash discuss the micro crystals outside of usual icing environment that can be encountered and, due to size, essentially frustrate the pitot heating that usually works just find on other kinds of ice.


AERO - Engine Power Loss in Ice Crystal Conditions
Cracking a high altitude mystery - News - NRC-CNRC

While that articles discuss is a problem with engines.

What apparently happens in some pitot tubes is the ice crystals adhere, melt, then bond to the metal, which insulates following ice crystals from the heat and leads to build up in other parts of the pitot tube, heat on or not. Some months ago an early utterance from BEA seemed to support a previous industry finding that some models of pitot tube (Goodrich in this case) are a bit better at dealing with that problem than others (Thales), but numerous posters here have pointed out that until the regulating authorities (globally) create an agreed standard, it may be tougher to require/enforce a specification. This crash is perhaps a motivating factor in moving that process forward.

See this for added info ...

A330 Pitot Tube Icing Concerns Persist | AVIATION WEEK


Europeans Require Pitot Tube Modifications for A330/A340 - >> The Cranky Flier
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Old 13th Jun 2011, 15:57
  #1652 (permalink)  
 
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May I ask a dumb question?

With the Capt in his seat everyone knows who's commanding and that he had some training to be a commander.

When the Capt is resting who is in command in the cockpit?

I don't mean who is PF, nor who is more senior, but rather is the command of flight deck activity formally handed over to one of the pilots?
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Old 13th Jun 2011, 16:14
  #1653 (permalink)  
 
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I think I've read every post in this thread and there are many, many comments about 'faulty' or blocked pitot(s). I've not seen (or maybe missed) comments about the static vent(s). What exactly about the pitot(s) or static vent(s) is believed to have 'gone wrong'? Surely the electric heaters were functioning and switched on?
Hard to imagine that you've even read many posts, much less every one...
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Old 13th Jun 2011, 16:17
  #1654 (permalink)  
 
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RWA:
In particular, we more or less 'know' that the pilots didn't have any sort of 'natural horizon' to work with. And it's only too possible that, at times anyway, they didn't have an artificial one either........?
Agree.

This message is part of the 24 CMC messages delivered by the aircraft at time of accident:
02:13:14 - .1/FLR/FR0906010211 34123406IR2 1,EFCS1X,IR1,IR3,,,,ADIRU2 (1FP2),HARD
Not explained on the 1st BEA interim report and certainly not completely explained on the second one.
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Old 13th Jun 2011, 17:43
  #1655 (permalink)  
 
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At 2 h 12 min 02, the PF said "I don’t have any more indications", and the PNF said "we have
no valid indications".
This messages are from 02:11,
(Those, are presented to pilots):
2:12:10WRN/WN0906010211 341200106FLAG ON CAPT PFD FPV 2:12:16WRN/WN0906010211 341201106FLAG ON F/O PFD FPV
(These, are not)
2:13:08FLR/FR0906010211 34220006ISIS 1,,,,,,,ISIS(22FN-10FC) SPEED OR MACH FUNCTION,HARD 2:13:14FLR/FR0906010211 34123406IR2 1,EFCS1X,IR1,IR3,,,,ADIRU2 (1FP2),HARD
(and this one would be also presented to them - if ECAM was not full of previous messages):
2:12:51WRN/WN0906010212 341040006NAV ADR DISAGREE
At 2 h 13 min 32, the PF said "we’re going to arrive at level one hundred". About fifteen seconds
later, simultaneous inputs by both pilots on the sidesticks were recorded and the PF said "go
ahead you have the controls".
The angle of attack, when it was valid, always remained above 35 degrees.
The recordings stopped at 2 h 14 min 28. The last recorded values were a vertical speed of
-10,912 ft/min, a ground speed of 107 kt, pitch attitude of 16.2 degrees nose-up, roll angle of
5.3 degrees left and a magnetic heading of 270 degrees.
After that zoom climb to almost 38000ft, (and its still not clear to me if it wasn't made by/due to high speed stability, [yes HSS is available in ALT LAW], and the probable entrance into a reconfiguration provoqued by Abnormal Attitude Laws [speed less than 60kts] with the consequence of Auto Trim stoppage, their fate was closed.

Last edited by aguadalte; 14th Jun 2011 at 00:51. Reason: to correct my error HSP to HSS
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Old 13th Jun 2011, 18:46
  #1656 (permalink)  
bearfoil
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kwateow

May I ask a dumb question?
With the Capt in his seat everyone knows who's commanding and that he had some training to be a commander.

When the Capt is resting who is in command in the cockpit?

I don't mean who is PF, nor who is more senior, but rather is the command of flight deck activity formally handed over to one of the pilots?

Not dumb at all. In the same vein, I think prior to any additional money spent on training, a fourth bar will be issued to all who lack one. Phony confidence is still confidence, after all.
 
Old 13th Jun 2011, 18:56
  #1657 (permalink)  
 
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The Captain is always the guy with four stripes.
Even when he is resting.
In my company, when we have 3 or four member crews, we have the figure of the commander. Even when the augmenting crew member is a Captain, the Commander is always the one in charge of the strategic decisions. The Captain or the SFO are only allowed to take tactical decisions.
To take a nap, before crossing the Intertropical zone is of course, unthinkable...
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Old 13th Jun 2011, 19:09
  #1658 (permalink)  
 
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Lonewolf -- thanks for that full reply. It's getting hard to separate the wheat from the chaff.
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Old 13th Jun 2011, 19:21
  #1659 (permalink)  
 
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thermostat :
I will forever state that they should never have entered the CB in the first place.... Why else would trained pilots fly through the red area of a CB ? (see the satellite Wx photo)
Thermostat : please stop confusing the "red areas" on the "satellite Wx photos" with convective cells as they appear on "our" radars.
There was obviously NO "red wall" 80 Nm ahead when the captain went to rest.

thermostat :
I still feel that the radar was not working.
There is no suggestion, so far, that the radar was "not working".
Please do not forget :
1) they went through a lot of "red satellite photo Wx area" without too much problem before starting to deviate ;
2) 20' before, the LH 744 deviated only 10 miles for weather ;
3) see a post above. A 744 captain flew the same route during the same night and stated "no weather to speak about....".

IMHO, they obviously flew into clouds and encountered THE conditions leading to AA pitots freeze.
In the months before the accident, dozens of AA pitots freezes happened.
Do you, seriously, believe ALL these crews flew straight into "red wall(s)" ?
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Old 13th Jun 2011, 20:53
  #1660 (permalink)  
 
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aguadelta:
EDIT: sorry, that ought to be addressed to aguadalte

You say that high speed protection is available in alt law.
What I read from (dated) material is that high speed stability is available. Pilot can overcome that, according to my dated sources. Overspeed prot, as I understand it, is only available in Normal Law. Protection as in "won't let the pilot go that far out of the box" by making control inputs to counter a tendency/trend to get out of the box.

What am I misunderstanding about the difference between overspeed protection and high speed stability?

Last edited by Lonewolf_50; 13th Jun 2011 at 21:09.
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