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AF 447 Thread No. 9

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AF 447 Thread No. 9

Old 15th Jul 2012, 19:07
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Originally Posted by Dozy
....when one pilot pushed and the other pulled, the result was split elevators and immediate departure from controlled flight.
Is that strictly correct? Seems to me that shutting off the engine master switches followed by loss of electric power had a lot to do with the loss of control. (Which way is up?)

Be careful about half truths.
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Old 15th Jul 2012, 20:21
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Snoop Law about automation, hand-flying and Captain's autority

Originally Posted by Lyman #312
In my view, the ball is in the regulator's court
Lyman,
You often evocate law problems. You are right. But they are hard law in aeronautics, and near nothing in the young science of automation.

In my interpretation, some Court have to say what "hand flying" means for the airline, as everything is still secret, or proprietary knowing (to verify!), as no Justice enquiry has been done.

That situation started with the Habsheim case : the lawiers, judges, experts, did never spoke about the definition of automation, responsibility of the engineers who hide important information to the Captain of the flight. They just do not know what it is !

The law (Code de l'Aviation Civile for instance, enforced by the Chicago convention, their annexes, and a lot of Court decisions) give all the rights to the Captain. Compared law exist, and is important, between Captain of an Aircraft, and Captain of a Ship : nearly the same.

The french Code l'Aviation Civile protects the Captain in the independance
of his decisions in flight.

The french Code pénal (criminal code) protects everybody against blackmail, when the airline intimidates the Captain. But HE HAS TO SAY "NO" !

Last edited by roulishollandais; 15th Jul 2012 at 20:23. Reason: add: they just do not know what it is
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Old 15th Jul 2012, 20:37
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Originally Posted by Machinbird
Is that strictly correct?
Sorry I can't find a better source more quickly than Wikipedia, but here:

EgyptAir Flight 990 - Wikipedia, the free encyclopedia

Originally Posted by Wikipedia
The flight data recorder reflected that the elevators then moved into a split condition, with the left elevator up and the right elevator down; a condition which is expected to result when the two control columns are subjected to at least 50 lbs of opposing force.[1] At this point, both engines were shut down by moving the start levers from run to cutoff.
It looks like the split condition happened at around the same time the engines were shut off.

Admittedly the departure from controlled flight as a result of the split condition is conjecture to some extent, but given the authority the elevators have it's got to result in a serious upset very quickly.

At any rate, the point I was trying to make was that in modern airliners, yokes aren't simply attached to a big metal bar like they were in the days of yore, they are complex electro-mechanical devices that can behave in unexpected ways when put into unusual configurations.

Last edited by DozyWannabe; 15th Jul 2012 at 20:47.
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Old 15th Jul 2012, 20:55
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EgyptAir 990 - NTSB Report
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Old 15th Jul 2012, 21:01
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roulis

"That situation started with the Habsheim case".

You probably have a lot of automation in your car, but the manufacturer doesn't explain in detail how it works.

It remains your responsibility to not to drive it negligently into the trees, killing your passengers. Something which Capt "Rambo" Ass-line never understood.
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Old 15th Jul 2012, 21:17
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Originally Posted by roulishollandais
That situation started with the Habsheim case : the lawiers, judges, experts, did never spoke about the definition of automation, responsibility of the engineers who hide important information to the Captain of the flight. They just do not know what it is !
This isn't about Habsheim - which is a 24-year-old case!

The engineers "hid" nothing from the Captain - he simply didn't appreciate the consequences of the actions he performed when trying to rescue a botched approach rather than go round and try again.

As I said before - by trying to make it about pilots vs. automation his lawyers actually made things more difficult for him in terms of the criminal proceedings - the report basically threw the book at Air France for poor procedure and implied that the mistakes made by the captain were understandable, but by making a media circus out of it his legal team made him more of a target.

Sadly what it's also done is propagate a lot of misunderstanding about the case - and some of those misunderstandings are still repeated by the media today.
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Old 15th Jul 2012, 21:29
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Admittedly the departure from controlled flight as a result of the split condition is conjecture to some extent, but given the authority the elevators have it's got to result in a serious upset very quickly.
That is a lot of conjecture on your part. Split elevators are going to result in an average of the two pitching moments and a roll moment. Since the elevators are very close to the aircraft's roll axis, any roll moment generated by the split elevators can be countered by the ailerons and spoilers which are much further away from the roll axis and therefore have a much greater moment arm, which is conjecture also, but results from the application of simple physics.

The core problem on Egyptair 990 had to be the active sabotage of the flight.
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Old 15th Jul 2012, 21:33
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@bubbers
Isn't the checklist saying 5 degrees nose up and climb power until at a stabilized altitude which they were at at FL350 and use UAS and thrust charts to continue.
If only they would have identified UAS and started the procedure.

BEA speculates about, that PF might have thought, he was in an "overspeed situation".

Wasn't he trying to extend spoilers? Who would extend spoilers in any other situation than overspeed?
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Old 15th Jul 2012, 21:56
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Originally Posted by Machinbird
Since the elevators are very close to the aircraft's roll axis, any roll moment generated by the split elevators can be countered by the ailerons and spoilers which are much further away from the roll axis and therefore have a much greater moment arm, which is conjecture also, but results from the application of simple physics.
I have no doubt that a pilot briefed on the behaviour should be able to counter it, as you say. I still wouldn't rate the chances of countering that if such behaviour was not widely known.

In any case, we're digressing here - the point is that modern yoke designs are more complex than Lyman suggested.
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Old 15th Jul 2012, 22:05
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I guess if he did the 5 degrees nose up with climb power he would let the higher altitude static port because of the lower static pressure but blocked pitot tube cause an overspeed warning. Then he increased attitude to around 15 degrees when the overspeed warning happened.

This happened in the dominican with a taped over pitot tube on a 757.
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Old 15th Jul 2012, 22:09
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@bubbers44:

There was no overspeed warning - nor did the aircraft approach an overspeed condition at any point.

The PF queries whether the PNF and Captain suspect "crazy speed" (which we're assured by our Francophone colleagues means he was concerned about overspeed), but the PNF at least seems convinced this is not the case and rebukes the PF for trying to extend the speedbrakes.

It has been suggested that the PF may have suspected overspeed due to abnormal wind noise (possibly due to stalled air).

[FYI : The Birgenair 757 crash you refer to was suspected to have initiated from an insect nest inside the pitot tube - the "taped over" incident was the Aeroperu 757, and in that case it was the static ports. ]

Last edited by DozyWannabe; 15th Jul 2012 at 22:14.
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Old 15th Jul 2012, 22:23
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Probably not but why would a pilot pull up 15 degrees unless something startled him into doing it. You can't do that at FL350. The scenario I told is the only one that made sense, trapped pitot pressure and a climb with real static pressure would give an overspeed. None were heard on the CVR that I know of but why did he pull up into an impossible climb?
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Old 15th Jul 2012, 22:29
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@bubbers44:

...why did he pull up into an impossible climb?
I suspect that question has a lot to do with why there are nine threads on this incident!

Unfortunately the only man who can provide a definitive answer is dead, and so the report suggests several potential reasons. The one that makes the most sense to me is a sustained startle response of the type that afflicted Captain Renslow of ColganAir 4805.
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Old 15th Jul 2012, 22:35
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@Dozy

rebukes the PF for trying to extend the speedbrakes.
According Interim 3 CVR transcript:

2:12:04 to 2:12:07 "The airbrakes are controlled and deployed" and PF comments "I have the impression that we have some crazy speed..."

That has occurred at about FL300 descending. What else than thinking of overspeed makes a pilot deploy airbrakes?

Last edited by Flyinheavy; 15th Jul 2012 at 22:40.
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Old 15th Jul 2012, 22:39
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@Dozy...

"It has been suggested that the PF may have suspected overspeed due to abnormal wind noise (possibly due to stalled air)."

1. Suspect nothin'...the spoilers were deployed, see the traces of the devices. There is no record that I could find that however they stowed, they all stowed completely. That is the genesis of my guess that the chronic right roll, yaw was damage related...

2. You have not considered the wind shear as the source of the Belief in crazy speed? There could easily have been an apparent accel/decel due to this type of turbulence, and changing air mass/noise...

Erm..... Thanks Flyinheavy, great minds think alike...

@Dozy... I think their respective TT and TiT are very similar, and I concur re: Renslow, Bonin. Good catch.

@Dozy...PNF: "do not extend....etc." So yes, the PNF was assertive, here, and if I might, I'll use this bark to introduce a possible problem.. To now, I have been reliant only on what I read in PPRuNe and the officials to found my remarks. Recently, I have ventured off the reservation, and have read some interesting discussion re: CVR content. The BEA have heavily witheld crew remarks if they are profane. They euphemistically use the Catchall: "not related to flight". I think there might be some interesting rhetoric in the CVR that is witheld due it's colorful nature. There is also so much to understand from volume and tone, notwithstanding profanity, that I'll bet you a kidney the CVR has much more to tell us than what we are given...

Last edited by Lyman; 15th Jul 2012 at 22:58.
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Old 15th Jul 2012, 22:58
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@FlyinHeavy:

The speedbrakes are only partially deployed, as the PNF immediately selects them back in.

The PF may have suspected overspeed, but the point is that the suspicion was incorrect. There was never an overspeed warning because the aircraft was never in an overspeed state.

@Lyman:

The roll problem is an artifact of stall, nothing more. The indicated spoiler positions after the attempt to deploy correlate precisely with the sidestick roll inputs made by the PF, and there was no obvious sign of damage to the spoilers on the wreckage found. Is it that hard to accept that - besides the pitot tubes - the aircraft behaved normally? The report does not damn the crew, and outside of scuttlebutt neither does anyone else. Why this quixotic crusade to prove a mechanical failure?

Re: CVR - while the BEA sought to spare unnecessary detail, that book published earlier this year claimed to have more of the unexpurgated content - in fact I'm pretty sure it used all of it, while leaving some of the more relevant stuff out. I'd be very surprised if there is any more useful information that we don't already know about.

Last edited by DozyWannabe; 15th Jul 2012 at 23:02.
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Old 15th Jul 2012, 23:09
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Recheck your spoiler response....What the pilot considered, created their collective reality. That you do not understand this is what keeps us miles apart.

What the CVR has in the way of usefulness is lost on you when you use it only to qualify a mechanical log... It is the human version of the DFDR.

I can't discard your take on the CVR contents, but it is half full.... Their is more to spoiler operation than roll, and drag, likewise deficiencies in position sensing that you do not consider. Position of spoilers can be correctly displayed without the spoiler being attached to the actuator. For example only, not a statement of support for any theory...
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Old 15th Jul 2012, 23:15
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@Dozy

There is no doubt about that there had been nor a warning neither real overspeed. Sadly enough did this crew not realize what WAS their situation.

I found it remarkably though that BEA cared to mention it as a POSSIBLE reason for the otherwise very strange maintaining the SS in nose up.

Sorry to post again, but just as a reminder:

2.1.3.3.1 PF’s reactions

On the other hand,
in the absence of airspeed information known to be reliable, it is possible that the
PF thought that the aeroplane was in an overspeed situation, notably due to his
interpretations of several clues:

ˆ The aerodynamic noise,
ˆ The buffeting, that he might have interpreted as being due to high speed,
ˆ The speed trend arrow on the PFD, which at that time indicated acceleration.

He reformulated his impression
a*few seconds later, combined with an attempt to extend the speedbrakes.
Other factors which may have prompted the PF to fear an overspeed situation were:
ˆ The display on the ECAM (max speed 330/.82) combined with the reconfiguration
to alternate law which may have been read;
ˆ The fact that, in cruise, the upper red strip on the speed tape (MMO) is about ten
knots above the current speed, whereas VLS is barely visible at the bottom of the
tape (thirty knots less);
ˆ The dangers associated with overspeed situations embedded in the collective
consciousness of pilots.
May I add, that I did also exams for ATPL in France and I do recall that they were putting a lot of emphasis to the problem of overspeed in Aerodynamics. Much more than FAA or some other European ATP exams would. So I would understand a French pilot thinking of this getting into a subjectively high stress situation.

Last edited by Flyinheavy; 15th Jul 2012 at 23:23.
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Old 15th Jul 2012, 23:21
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Dozy. you continue to misuse the report. Again, what the PF was thinking and doing, you reject because it does not fit what happened.

That is absurd, when you consider that what he thought and did created what happened, otherwise known as 'what happened'....

Flyinheavy....by "Possibly" do you refer to its misuse, when it is quite clear the PF was convinced enough to select speed brakes? Is there a doubt?

Last edited by Lyman; 15th Jul 2012 at 23:29.
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Old 15th Jul 2012, 23:33
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Originally Posted by Flyinheavy
I found it remarkably though that BEA cared to mention it as a POSSIBLE reason for the otherwise very strange maintaining the SS in nose up.
It's not that remarkable really - as I said, because there is no way to be definitively certain about why the PF handled the aircraft the way he did, the BEA are therefore compelled to examine all potential reasons.

Originally Posted by Lyman
Recheck your spoiler response....What the pilot considered, created their collective reality. That you do not understand this is what keeps us miles apart.
The point is that they were supposed to act as a crew, and what we instead see is a significant difference in perception between the two FOs. From the start of the sequence, the PF seems completely out of his depth and it looks very much like he was throwing possible conclusions out there -almost at random - to see if anything would stick. The PNF on the other hand seems to be trying to work from the evidence in front of him, and gets increasingly frustrated with his colleague.

What the CVR has in the way of usefulness is lost on you when you use it only to qualify a mechanical log... It is the human version of the DFDR.
You're levelling assertions at me that don't fit my actions. If you recall, I was one of the first to point out the PNF's growing sense of uncertainty and irritation with the PF - I've used the CVR transcript for far more than qualification of the DFDR!

Position of spoilers can be correctly displayed without the spoiler being attached to the actuator.
I'm not so sure of that. I'm pretty sure that a "position" trace requires confirmation from the systems that the position was actually achieved.

Dozy. you continue to misuse the report. Again, what the PF was thinking and doing, you reject because it does not fit what happened.

That is absurd, when you consider that what he thought and did created what happened, otherwise known as 'what happened'....
I'm not "rejecting" anything, and I'm certainly not "misusing" the report. The evidence suggests a sequence of incorrect diagnoses by the PF, and that's all there is to it.

Without wanting to sound harsh, you've attempted to advance theory after theory for over a year, and every time the evidence has disproved those theories (which have included vertical stabiliser separation, THS jackscrew failure and structural failure of the spoilers among others), you come back with another one.

Now it seems you're trying to argue that the PF's assertions were actually correct and it is the data gathered that is somehow wrong. What makes this incredibly unlikely as far as I'm concerned is that on the CVR, you can hear the PNF in the opposite seat repeatedly making assertions and suggestions which *do* fit the data and which in all likelihood would probably have helped. If the PNF had even the slightest belief that the PF had a point, then you'd have heard co-operation between them. Instead, we hear the PNF openly wonder where the Captain is, while at the same time trying to get the PF to snap out of it and approach the problem logically.

Last edited by DozyWannabe; 15th Jul 2012 at 23:58.
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