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 ...) :
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.

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?

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

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?

Hard to imagine that you've even read many posts, much less every one...

RWA:
Agree.

This message is part of the 24 CMC messages delivered by the aircraft at time of accident:
Not explained on the 1st BEA interim report and certainly not completely explained on the second one.

This messages are from 02:11,
(Those, are presented to pilots):
(These, are not)
(and this one would be also presented to them - if ECAM was not full of previous messages):
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.

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.

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...

Lonewolf -- thanks for that full reply. It's getting hard to separate the wheat from the chaff.

thermostat :
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 :
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)" ?

aguadelta:
EDIT: sorry, that ought to be addressed to aguadalte :O

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?

As there was MachLimit on ACARS, and there is evidently no overspeed mentioned thus far, The Protection was obviously there. Have Faith.

Seriously, the warning could have been a "sensed" event, due only plugged drain. They were @ .82 (limit for conditions) No?

bear, maybe I misremember, but didn't the reconstruction so far show that the crew choose to slow to M 0.8 in anticipation of entering turbulent air?

More to the point on this item, bear: once the crew verbalized "alternate law" they are aware that they aren't in Normal Law. That tells me that the crew are aware that they no longer have overspeed protection. The crew would thus be aware that they need to be mindful of avoiding an overspeed, since the robot won't be doing it for them.

High speed stability, as I read the chart, would "assist" if airspeed approaches (is close to?) overspeed, but a pilot could override that and make it go too fast. So it isn't a protection, by design, it's more of an assist.

In the Protection mode in Normal Law, my understanding is that the robot would do considerably more to resist the pilot trying to increase speed beyond the threshold value. (Airspeed as sensed by the infamous pitot tubes and massaged vigorously by the various flight control and nav computers. No cigarette afterwards, sorry, this is a no smoking flight! :p )

With High speed stability still an available function (presuming that Alt Law was as far as things degraded ... the possible Abnormal Attitude law excursion remains "unproven")
IF erroneous or valid airspeed at the "too fast" limit is sensed,
THEN high speed stability would be expected to make an input to reduce airspeed a small amount. Not sure what that value is.

That's how I read the chart. If I'm wrong, so be it.

I vaguely remember that on the report. However, I think it is not affirmed as actually occurring. Similarly, they were about to enter warmer air, perhaps they changed their (his) mind, and retained their lift instead. This occurs at the "FROM 2:10:05" time stamp, where events are reported without their attendant time point, and thus even the sequence loses credibility (though not all of it) imo.

Hi,

Someone here know who was the PF and if yes .. if this PF was complying the European law and Air France crews laws regarding licenses for be the relief of the captain on AF447 ?
Can a AF pilot post the AF law for flight deck crew management for flights like the one of AF447 (long flight) ?

I am fairly certain, but I know who knows for absolute sure, BEA. This will without question be in the Final Report.

Bear,

If you were trying to remember Mach number, this is it:
From the BEA May Update:

Previously at ORARO they were level at 35K and Mach 0.82

TurbineD

Hey, how are you? Thanks for the post. I have no reputation other than partisan nitpicker, so why should I change?

"..the crew decided to reduce the speed to about Mach 0.8 ..."

Did they?

At that point, the change would be dialed into the AutoPilot, and we know the a/p was a shortimer from here on in....No?

Lonewolf_50
Yes you're absolutely right, I meant High Speed Stability.
Thanks for the correction L.

Edit: correction made:ok: