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AF 447 Thread No. 6

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AF 447 Thread No. 6

Old 7th Oct 2011, 11:46
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Dozy:
So where would they have fixed them CONF - on the apron? Even if the whole fleet didn't have to be grounded, you'd still have large chunks of it on the ground having repairs and tests done.
Your lack of knowledge of airline maintenance ops is glaring.
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Old 7th Oct 2011, 11:52
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How so, GB? Surely if they're being worked on they can't fly - the replacement schedule that was agreed was that the work would be done when the aircraft came in for their regular maintenance check. People have been arguing that the response should have been stronger than that - so me asking how that would have worked is a genuine question, which is:

Given an AD that required work before the type was allowed to fly again and the schedule that was actually agreed with the SB as extreme ends of the scale, what is there in terms of middle ground that would have satisfied those who were saying that the latter was not enough?
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Old 7th Oct 2011, 12:38
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Ecclesiasteses 1:9

The thing that hath beene, it is that which shall be: and that which is done, is that which shall be done; and there is no new thing under the sunne.


Nothing new under the Sun, but ever few years, there seems to be something new under the Apple.


One of the oldest rules in aviation remains something like this:

"You cannot defy the law of gravity, but you can break it temporarily, with lift and thrust as your accomplices."
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Old 7th Oct 2011, 12:59
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Originally Posted by DozyWannabe
So where would they have fixed them CONF - on the apron? Even if the whole fleet didn't have to be grounded, you'd still have large chunks of it on the ground having repairs and tests done.
Where have you seen those large chunks of 330/340 on the ground when finally EASA woke up in AUG 2009, after the war, to implement the AD 2009-0195 for pitot probes replacement ?
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Old 7th Oct 2011, 13:12
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That's just the old "Tombstone Imperative" in action. SBs and ADs that would have been considered overkill before all of a sudden look a lot more sensible. Before the crash, you can bet the airlines would have balked.

They may not have been willing to expedite those repairs for the sake of a few level busts - but it becomes a whole different ball game when you lose an airframe and everyone in it.
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Old 7th Oct 2011, 13:22
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Originally Posted by Turbine D
I have got to go with gums on this. The computer system, e.g., Alternate Law 1, Alternate Law 2 and subsets of Alternate laws are very confusing.
I almost agree - from an engineering perspective the gradual degradation makes sense (and Boeing must have htought so too as theirs is practically the same), but if pilots aren't trained in all the modes, they might as well be labelled "crash mode".

Only issue is that in direct (in A or B) I think you're hand-flying all the way home (or to divert). After what we've heard on training, SOPs etc., isn't there a significant risk in asking todays pilots to hand fly for what maybe a few hours, after possibly only a minor or transient issue ? Maye it is better to keep the in-between mode, which allows (in A and B I think) A/P to be re-engaged when things are stable again ?

1. Airbus failed to handle the pitot tube problems in a manner that they should have.

2. Airbus failed in their risk assessment/risk abatement to adequately cover the total waterfront, e.g., total flight envelope. They were nearly mute on flight problems at high altitudes and speeds. Guess they assumed problems couldn't happen there.

3. Airbus failed to provide complete key memorization items in their flight instructions for the A-330, leaving out for the most part, high altitude and high Mach cruise situations.
Someone made these mistakes, not sure it was Airbus in every case - some combination of Airbus, airlines, and EASA, yes. I would note that it was AF (not Airbus) who issuesd a revised UAS procedure awfully quickly after the accident...

And in one sense it is worse than above - someone (AF...) failed to train pilots at all in hand flying at cruise in alt law (and quite possibly in any law). Between SOPs and RVSM rules etc., it appears todays line pilots also get no experience of hand flying in cruise either.

Result is that if A/P drops out for any reason (and on any type) in cruise, pilot is handed an a/c he has quite possibly never actually flown at this speed or altitude. Throw in the event happening at night middle of ocean, middle of bad weather, and the result isn't that suprising. Between mfr, airilines, and regulator, no one thought this lack of training / experience was a bad idea, or at least no one did anyting about it.


As in the role of leader, Airbus must not have/didn't push the issue hard enough with EADS, or so it seems or didn't view correctly the critical nature of pitot icing at high altitude and high Mach.
[...]
What did they advise EADS to do? Airbus has the lead here, not EASA. Did EASA respond appropriately based on Airbus' strong recommendations? Did Airbus have a strong recommendation?
We'll find out on that - maybe. Currently the director of EASA is refusing to appear before the judge to answer questions on EASAs role in this event.... [ and yes I am entirely sure that this is for the best of principled reasons and not because there is something to hide ]

Now Airbus knew the AOA was a critical key component to assure safe flight, but where was the indicator to know what it was and where it was going?
Agreed [for what my opinion is worth, which is zero] - stall warning / stick shaker is way too crude, no difference between "you are nearly stalled" and "you are stalled by 30+ degrees".

Just to be clear on the Airbus role though - the indicator exists, the space on the panel exists, the airline deleted it as an option when ordering.

The final report on this accident may well say that the AOA indicator should/must be there - the sad thing is that it won't (by a long way) be the first accident report to say that, and it will probably be ignored, again.
The operational side of the industry have decided airline pilots don't need AOA, and/or they don't want the expense of training on it.
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Old 7th Oct 2011, 13:25
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Cool

Hi,

but it becomes a whole different ball game when you lose an airframe and everyone in it.
And once again the saying is true:
It is too late to squeeze the buttocks when, **** in the sheets
The sheets of Air Caraibe are clean ...
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Old 7th Oct 2011, 13:55
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Originally Posted by CONF iture
Where have you seen those large chunks of 330/340 on the ground when finally EASA woke up in AUG 2009, after the war, to implement the AD 2009-0195 for pitot probes replacement ?
Yep, have to say I'm with you on that one. The biggest problem with replaceing them turned out to be actually getting enough (decent) pitots out of the supply chain.

Since that takes "too difficult" out of the usual suspects for procrastination, it was most likely "too expensive"... as ever.
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Old 7th Oct 2011, 15:45
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Originally Posted by infrequentflyer789
I almost agree - from an engineering perspective the gradual degradation makes sense (and Boeing must have htought so too as theirs is practically the same), but if pilots aren't trained in all the modes, they might as well be labelled "crash mode".
I still don't see what's so complex about Normal Law = protected versus other laws = not protected though, which is in reality the only factor that matters at a fundamental level to the pilot.

All you really need to remember is that if you're not in Normal Law you have to be as careful with your bank and pitch angles as you would be in a conventional (unprotected) aircraft. The protections are what allow FBW Airbii to perform some pretty wild maneouvres at airshows, but even if you hand-fly the line in Normal Law it's unlikely you'll ever see the protections kicking in, because the trigger parameters for those protections are considerably beyond anything you'd normally do with paying SLF down the back.

And in one sense it is worse than above - someone (AF...) failed to train pilots at all in hand flying at cruise in alt law (and quite possibly in any law). Between SOPs and RVSM rules etc., it appears todays line pilots also get no experience of hand flying in cruise either.

Result is that if A/P drops out for any reason (and on any type) in cruise, pilot is handed an a/c he has quite possibly never actually flown at this speed or altitude. Throw in the event happening at night middle of ocean, middle of bad weather, and the result isn't that suprising. Between mfr, airilines, and regulator, no one thought this lack of training / experience was a bad idea, or at least no one did anyting about it
This is my primary bone of contention - without this factor the rest of the theorising is somewhat moot.

Saying that this was the eventual result of an insidious industry-wide pattern of laxity and procrastination is not "protecting Airbus".

Agreed [for what my opinion is worth, which is zero] - stall warning / stick shaker is way too crude, no difference between "you are nearly stalled" and "you are stalled by 30+ degrees".
Maybe so, but was it not reasonable to assume that by having a warning several degrees of AoA before the stall that a properly trained crewwould do something about it at that stage?


Originally Posted by infrequentflyer789
The biggest problem with replaceing them turned out to be actually getting enough (decent) pitots out of the supply chain.
Now I didn't know that - have you got a source for that just so I've got it on file?

Since that takes "too difficult" out of the usual suspects for procrastination, it was most likely "too expensive"... as ever.
Well - possibly, but it raises the spectre of something else that happens in mass production. Ultimately you get the contractors to bid and the ones with the best chance of fulfilling the contract at the required price will get it. If Goodrich could not provide the yields (presuming they were making them as fast as they could) then throwing money at them couldn't get them to make the things faster, so it looks like the Thales AB probes were borne out of necessity. Even if Airbus and EASA said "Replace these now" - if Goodrich couldn't supply them then the replacement work would have been slowed down anyway.

It does rather beg the question of how they worked the AD after the accident though (unless the AD was simply a political fudge to make it look like something was being done, while the replacement programme played out as it did before).

Last edited by DozyWannabe; 7th Oct 2011 at 16:04.
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Old 7th Oct 2011, 16:49
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Dozy, et al.,

What, in the end, are the differences between the Thales (AA and AB) and Goodrich probes?

AFAIK, all of them are still being qualified/certified against an obsolete standard, and so far I still have NOT seen any 'news' about the standard itself actually having been updated/improved, to take into account the environment that AF447 encountered.

I have the impression that too many people here prefer to 'blame' the UAS events and the pitots, instead of thinking the issue through.

Why weren't the standards changed, after the first UAS incidents due to hi-alt pitot tube icing occurred? Whose responsability was that?
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Old 7th Oct 2011, 17:35
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Originally Posted by ChristiaanJ
AFAIK, all of them are still being qualified/certified against an obsolete standard, and so far I still have NOT seen any 'news' about the standard itself actually having been updated/improved, to take into account the environment that AF447 encountered.
The issue is one of all engineering being a compromise to some degree - there is no such thing as a 100% reliable way to measure airspeed in all conditions (in fact one could argue that there is no 100% reliable way to do anything). Being mechanically very simple in principle, along with the fact that there have only been two fairly recent fatal accidents on the line involving failure of the pitot system - and only one where the design of the pitot tube itself is suspect - I'd wager a guess that it is simply the most reliable of the alternatives on offer.

Airbus's response to when the pitot system does fail is the BUSS module, but the way the BUSS calculates airspeed is more complex than that of the pitot system and as such it is better suited to a secondary role.
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Old 7th Oct 2011, 17:58
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FWIW.

Fuel Chemistry was never "mysterious", "Heretofore well understood", or lacking for standards.

It was a Straw man, such that RR could redesign a duff Fuel/Oil Heat Exchanger, and re-enter the playing field as though the design was not dangerous.

Qantas32? Same-O. An AD was relaxed, and an engine exploded in passenger carrying flight.

Comet and Skin? 737 Skin? Rudder? Pilots who hear the STALL WARN and PULL?

Any one see a pattern? No, Engineering is not a "compromise".

Spec. Duty cycle, Training, etc. These are compromises. There is no excuse for a Pitot Tube gnarling up at altitude.

IF that is what happened. Most people never learn, and most of those capable of learning are too easily distracted.
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Old 7th Oct 2011, 18:11
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Cool

Hi,

Again news in the press (Le Figaro)

Le Figaro - Flash Actu : Rio-Paris : de nouveaux lments

Google Traduction

And weird statements from the SNPL (the most important pilots union of Air France)
So for the SNPL .. just after the disconnection of the autopilot .. PF thought that the aircraft began to descend fast enough ... and so he reacted as we know (put the plane in a stall condition by pulling the stick for "regain" cruise altitude ) .....
Which pilot can think of such thing (important altitude loss after sudden disconnection of the autopilot while ... .. a few seconds before the aircraft was flying perfectly stable)
BEA report N°3
2 h 10 min 05 Altitude (ft) 35 024 (PA disconnection)
2 h 10 min 09 Altitude (ft) 34 664 Altitude ISIS (ft) 34 900
And I repeat these comments come from the majority pilots union pilots of Air France !
This gives again a very bad image of these .. "pilots" ? ...
It's no more "esprit de corps" .. it's foolish instead ..

Last edited by jcjeant; 7th Oct 2011 at 18:29.
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Old 7th Oct 2011, 18:35
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We have been previously chastened that the altitude discrepancy was "merely" 300 feet, and was the result of a predictable anomaly in the system.

So I won't hold my breath.

Is there more to this story than "Baby pilot kills all". FGS.

Loss of altitude without a commitment to STALL means exactly what the PF kept reporting, "I feel we have some crazy speed." If at a/p drop, his NU was to arrest descent (as he sussed it), and the 'descent' never 'arrested', this easily explains his commitment to overspeed in descent. It explains his deployment of spoilers, and his disregard for the STALL WARN; without comment or interference from his mates, it appears they all bought it.

What sort of STALL hasn't a concomitant drop of the NOSE? If his reliance (ill placed) on altimeter was driving his thoughts, the entire upset takes on a different shape.

I hadn't known the Pilots had written off the BEA. I'll admit to a bit of relief. Witholding important input from an investigation? The BEA??

Mais non, Impossible. Incroyable, n'est-ce pas?

jcjeant: If the reads were real, the descent was approximately 4,500 feet per minute. Substantial.
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Old 7th Oct 2011, 19:40
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Loss of altitude without a commitment to STALL means exactly what the PF kept reporting, "I feel we have some crazy speed." If at a/p drop, his NU was to arrest descent (as he sussed it), and the 'descent' never 'arrested', this easily explains his commitment to overspeed in descent. It explains his deployment of spoilers, and his disregard for the STALL WARN; without comment or interference from his mates, it appears they all bought it.
But fails to explain why TO/GA thrust was selected, no? Where does that fit?

And the Captain restrained second use of the spoilers right?

What of the altitude call outs/VSI?

If you selectively fit the jigsaw pieces together then may be you think you have a picture, but the box is not empty is it?
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Old 7th Oct 2011, 19:50
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Originally Posted by GarageYears
And the Captain restrained second use of the spoilers right?
Almost - it was the PNF (senior F/O). Not that we want to go around those houses again, but it looks like he had a better idea of what was going on and unfortunately didn't feel he had the authority to intervene.
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Old 7th Oct 2011, 20:16
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New element?

The drop of 300 ft in indicated altitude as a consequence of a drop in the measured total pressure is apparent in AIR CARAIBES memo dated 01-12-2008. I discussed the reason for it in my post on the AF447 thread no.1 (p.193, post #3856, 24 july 2009), and BEA explained it again in para. 1.6.11.6 'Consequences of a drop in the measured total pressure' of their Interim Report No.2 of December 2009.

Last edited by HazelNuts39; 7th Oct 2011 at 20:36. Reason: BEA rpt ref corrected
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Old 7th Oct 2011, 20:17
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GY

Hey. I'm trying to find more pieces, not reject some in favor of a bias. I am looking for reasons to explain certain behaviours? Well, yeah, since the data are thin, and there is evidence that BEA have redacted some evidence for now. Now THAT'S selective, to my way of thinking. I'd be perfectly satisfied if BEA gave you the CVR, let you suss out the deal, and report back.

You, I trust. BEA? Not so much.

TOGA? Not that it's much more than Cruise power, but couldn't he be looking for ways, alternatively, to gain NOSE UP?

We know the NOSE was already up, did he? Not if he rejected the STALL.

Let's don't assume that he was selecting TOGA to recover a STALL he may not have honored? If he was convinced the a/c was descending normally, and one has to allow him that, than TO/GA is a way to force the NOSE UP.

Just because we don't associate spoilers with TOGA doesn't mean it wasn't that way. It was a goofy night, all around. Another thing. What if he saw the TRIM at 13 degrees? With full aft stick, and still entertaining Overspeed, he's thinking the a/c is unresponsive; TOGA as a try?
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Old 7th Oct 2011, 20:22
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Does it not appear to you all that they knew they were descending, but that they thought it was an ordinary (Unstalled) descent? That the Captain rejected spoilers perhaps because he thought they were too fast? That they may not restow correctly on recovery of normal speed? That they never sussed the descent was slow (airspeed), and vertical, rather than horizontal ('normal' assiette), with plenty (too much) airspeed?

Can you see it another way?

At the end, the Captain.... "It cannot be..." Does he just then realize the ship is way nose up? Not Nose down, and (seemingly) 'unresponsive' to Pitch UP commands? They have had no ordinary sense of decel, nor a NOSE DROP, the a/c has been around one g all along, what did they have to sense the a/c's attitude? (That they trusted?) And Clearly, they were unaware of the attitude. How would YOU have known?

"Pull, Pull, Pull...."

Hazelnuts39. Yes, the indicated drop. We know. You know. Did 447 crew Know? Because at uncommanded a/p drop, the ship was descending (for real, though trending NU), rolled right, and presented 336 feet too low.

Two seconds later, a STALL STALL. Some of which were bogus. There was a simultaneous sink, so what does he do? The a/c did NOT climb readily, per BEA, in spite of PF's aft stick. His initial left roll was excessive, so with all this going on, I'm going to go out on a limb and say he............got off to a bit of a bad start. He was never given proper cues to sort that out. Lack of reference(s).

Last edited by Lyman; 7th Oct 2011 at 23:03.
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Old 8th Oct 2011, 02:37
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Originally Posted by DozyWannabe
Before the crash, you can bet the airlines would have balked.
Why would they have if it can help them to avoid a latent unsafe condition ?

Also, my understanding is, and people with knowledge will correct me, an AD is on the manufacturer’s arms, but a SB is for the airline … ?


ChristiaanJ,
The only thing is that the Goodrich model has proved to be much more resistant to ice crystals than the Thales ones.
Why weren't the standards changed, after the first UAS incidents due to hi-alt pitot tube icing occurred?
As early as 1999 the German BFU had recommended to modify the certification criteria for the pitot probes. But the EASA has been waiting AFTER the accident to go ahead.
Also Air Caraibes did an excellent job to report their events to Airbus. What did Airbus ?
Nothing.

Excellent presentation : AF 447 : l'accident expliqué selon le modèle de REASON

Last edited by CONF iture; 9th Oct 2011 at 02:49.
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