Gatbusdriver
Gatbusdriver, welcome to the fray. During your training, have you flown in ALT 2 law, or are you on the little Airbus? We are drafting all able bodied bus drivers to try to answer this question.

My personal experience with the USNavy peg, cone and vane type AOA sensors is that they would come alive in a definite breeze, perhaps 10 knots. A vane type that needed 60 knots to be reliable would be a sticky one in my book.

True -- once the rate of descent stabilized at some -10000fpm. But shortly before that, they'd actually been climbing, so at some point there was a heck of a vertical acceleration, and for that period the description would likely hold true.

I can only hope that that moment passed quickly, because it must have been terrifying.

Well if gaining vertical speed the seat will push beyong 1g to accelerate the Pax. When the vertical acceleration becomes negative the seat will push up at less than 1g. If the vertical acceleration exceeds 1g down, and only then, will Pax leave their seats and be pushed down by the seatbelt.

In French assister means to witness or be present at an event.

In referring to the Speigel article.
Hüttig is not without bias in that he provides technical assistance to the victim's families and thus probably has economic interests at play.

The description of the conditions inside the aircraft on the way down are a bit overblown. Although the nose did get pretty high in the air, the maneuvers suggest that cabin environment was close to 1 g. Probably more unsettling would have been the wing drops that the aircraft experienced. Not so bad as a roller coaster ride though.

Biggest fault with the Spiegel article is that the aircraft was "doomed" when the trim ran up to 13 degrees. If the crew had run it back down to near normal, this long thread would probably not exist and there would likely not exist a victim's family group.

There are a lot of training issues sticking out of this mess, and not all of them appear to have originated with AF.

The meaning of assister is related to context.
1. être présent (participer) = to be present at something
2. aider (seconder, secourir, concourir, dépanner) = to help someone.
Where it is quoted from?

"Entre 1 h 59 min 32 et 2 h 01 min 46, le commandant de bord assiste au briefing entre les deux copilotes..."

from the BEA interim report

The comment in the BEA statement which was translated into English as "the Captain attended the briefing between the two co-pilots" - maybe trying to read too much into the wording - would expect the Captain to lead the briefing? As JD-EE pointed out above maybe this statement just confirms there was a formal handover as required, nothing more.

Absolutely. :D

Machinbird:
Agree entirely. If it's true about the Captain recognizing that the airplane was stalled, then everything comes down to that trim wheel -- unless, of course, the A330 turns out to have an unrecoverable deep stall mode, which I very much doubt. But if he said that as reported by Spiegel, why did the PF not react with an AND command? Oh, maybe that's where the AND command does occur -- but is aborted because of the stall warning. What a mess!

Does it? How about a system where if it is not giving a reading within 16°AoA, it signals a stall? Say it is pointing "to the ground" whilst the aircraft is airborne. What do you reckon the crew needs to know? That aircraft isn't flying ie it's stalled. It doesn't matter where the vane is actually pointing.

But in this case, just when the crew needed the most "reminding" (and who would have not been confused: VSI off the clock going down, but with speed tapes on nothing, "knowing" that only a couple of minutes before they were giving duff gen), the stall warning silenced. Had it kept screaming at them, maybe their confusion would have eventually been overcome and one of them would have stuffed the nose down to recover the thing.

For lots of detail on the AoA vanes see the Perpignan crash report. The vane may indeed generate a "local angle of attack" but "As the fuselage disturbs the flow of air, these measurements
have to be corrected to obtain the aeroplane angle of attack." I wonder if its the compensations that limit the use at lower speed, but then where does the speed come from?

This does not look like good logic: if they have evidence that the ac is stalled while there is no stall warning, they should ignore it when it sounds again.

Abnormal Law Warnings or Messages
 

I previously asked the following questions:

1. If/when the plane kicked into Abnormal Law, what warning or message would have been visible or audible to the pilots?
2. Why was there an ACARS message about the transition to Alternate Law, but no ACARS message about any other change in Law (e.g. Abnormal or Direct)?

mm43 directed me to A340 / A330 Control: flight & laws
but having read through that, I must be blind because I don't see the answers to my questions!

It seems that whether or not the plane was in Abnormal Law (and hence had no autotrim - making the THS "frozen" at 13 degrees unless manually adjusted) is important in understanding whether the pilots had a chance of pulling out of the stall once they started putting the nose down (after the captain returned to the cockpit).

So far, it sounds like we are inferring that it was in Abnormal Law, owing to the AoA and speed crossing the specified thresholds, but can this be shown explicitly through a message or recording? And if not, why not? It may be an important point, so it would be nice to have certainty. There appears to be no ACARS message about any law other than Alternate - does that mean that Abnormal Law doesn't generate an ACARS message...?

The other question, which some others have touched on, is whether the pilots knew they were in manual trim mode. From the "flight & laws" link above, if in Direct Law the pilots will see "USE MAN PITCH TRIM" on the PFD. Is that also the case in Abnormal Law (it doesn't explicitly say in that link)?

Sensor validation:
Th 60KT limit may also be an almost arbitrary "safe" limit withe the rational that if airspeed is that low you are not flying anyway?
This would also help eliminate spurios alarms durinfg landing.

Right. In this context, "assister" only means that he was present during the briefing. He could have either contributed to it or remained totally passive, it doesn't tell it.

You guys are again focusing on press "leaks" which doesn't look more "informed" than all the previous ones. The statement that FO2 (Pierre-Cédric Bonin) was the PF is clearly doubtful.

I've got to say Garrison, I feel that's likely true.... especially if less than TOGA thrust was also selected.

It is a very remote possibility I suppose, that the PF was under 'some impression', at a base response level, that recovery from a stalled condition does not require a consistent and nose-down pitch .

If so, it's highly unlikely that Captain M. Dubois would have followed that course of action, and must have realised having made his way to the cabin, pretty well what sort of situation they were in, irrespective of instrumentation

howdy. PF gets Stall Warnings; a warning is not the same as the real deal.
His training (prior to AB "Stall Warning Recovery" "modification") was to fly through the warning losing little if any altitude and use power to accelerate.

A warning given at the break would not be a warning, it would be an annunciation. Having never experienced a full stall, he would likely not anticipate it by definiton, as he has had no training how to recover it, so all that would happen is an unanchored 'anxiety'. In other words, one flaw in "Display" is a gotcha without recourse. Not very nice, Miss.

I have thought from the beginning that a deep stall was very unlikely, but it appears that the pilot flying managed to unknowingly stabilize the airplane in a very similar flight condition. I don't know why he changed from a perfectly good pitch and power setting to get so slow, but at that low a speed, the engines were probably providing a goodly amount of nose-up pitch (along with the stabilizer trim automatically coming in to "help" him keep the nose up) so the normal pitch down occurring at stall might not be evident. Other than airspeed, which he has reason not to trust; angle of attack, which isn't displayed?; and an aural stall warning, which is apparently inhibited, how else does he know that he's stalled? What he knows is he has the throttles pushed up, the airplane pitched to 15 degrees or thereabouts (16.5 degrees) which is a familiar number for powering out of a problem, and his rate of descent is at the bottom of the tape and the altimeter is a blur, both high-order attention getters. Who among us wouldn't be confused as to why the airplane was descending instead of climbing and desperately pulling back on the stick to make it climb like it always has before?

So his forward stick and decrease in AoA may have gotten him on the way to recovery, but do we know the decrease in AoA was not just the a/c dropping her nose after stalling?

If the Captain did re-enter and shout, or command, likely it would have been something along the lines that precipitated a "just about" recovery.

You know, this discussion, read with patience, will eventually get to within 90 per cent of the actuals.

That is the bit that seems to have got them totally confused.

The AoA vane plus IAS provides the stall warning. Only problem is that the IAS must be greater than 60KTS for the combo to provide the SW. The SW stopped because the IAS had dropped too low, and when they attempted nose-down and got an IAS over 60KTS, the SW started again.

Their logic told them it was the wrong thing to do, hence the persistence with nose-up on the side-stick. I wonder if the actual AoA had been available, what they would have made of it?

Stall recovery
 

It's reasonably simple, actually.

The stall warning system would only work within a specific range of parameters.
( An educated guess here)

The aircraft went though the range, to the "other side", ie excessive AoA, low fwd speed. When the pilot tried applying nose down, the a/c would have re-entered the operative range, hence the stall warning sounding again. Proves he was moving in the right direction, be it elevator input, or THS, (except that it sounds like the THS had not started to wind back the other way, before the ND was discontinued)
Had the ND input continued, the rollover would have continued, (with the stall warning still sounding,) until AoA reached or passed through, the "onset" parameter. We now have control.

That's the next problem! Once the IAS has dropped below 60KTS, the aircraft is in Abnormal Law and the THS must be adjusted manually.

Or that their AoA exceeded 30 deg (same effect = abnormal Law).
Reduce AoA, airspeed will increase, she will return to Alternate Law and the auto-trim will work again.

My read of the above is that the plane was flying fine when the autopilot/thrust kicked out due to unrelaible airspeed. No power changes are mentioned by the BEA so the thrust required for level flight at FL350 and 0.8 must have been set and being produced. The initial control input is nose up (and left roll) and a climb begins. The plane isn't stalled at this point as a) it's capable of a climb and b) the BEA confirms that the last 3m30s were in a stalled condition which puts the start of the stall at about 2h11m (the stall warn triggers again at 2h10m51s). There are some nose-down inputs mentioned at this point and it seemingly controls the climb but is still probably in a climb (and bleeding airspeed) due to the pitch and VS indicating +700ft/min.

It appears that there was a trade of speed for altitude but no actual stall until 2h11m.

Once the stall begins, all BEA references are to nose-up up inputs and the THS rolls to full nose-up. Some references to nose-down are made later but as others have commented, with full nose-up THS it's a good question how recovery would be made at that point.

Hi,

Is this "Abnormal Law" dispatched for the PF?
Doesn't be curious BEA note doesn't not mention this?

One more question:
Why ISIS speed display goes down? Isn'it inertial? I don't understand how they can truly loose all that speed before ascending.

mm43, if it got them totally confused it's a software specification design problem. If the airspeed is less than 60kts, suddenly and the plane is 10k feet above ground for the plane's estimated location it's "obviously" stalled. It cannot fly that slow. So why isn't it continuously telling the pilot he IS stalled? (None of this about to stall warning nonsense.)

Methinks the damn good system software for the A330-200 can be improved, as can all software. And this is one good improvement. Enshrine the knowledge early so that when we DO get to autonomous SLF carriers this is one fewer problem the aircraft will face. (The communications problems should be covered as well with a "guaranteed" work around.)

All indications of AIRSPEED are based on air passing into the pitot tubes, processed by ADIRUs for output to the PFD or ISIS. Inertial is not used, and not usable, for airspeed.

One is not "dispatched" in alternate or abnormal law.

He must have asked and they will have explained
 

BEA knows exactly what the PF and PNF thought happened.

'At around ' 2h11min40 (why say 'around'?) the 'Captain re-entered the cockpit'

Hard to imagine him saying other than "What happened?"
And the PF and PNF will tell him and us what they perceived and their actions.

Mind you
The background stall noise on the CVR will be sounding like 0m55sec into this Tarom ROT381 AB incident:
perhaps it said 'At around ' because only then did he speak

matthewsjl, let's add one more "fact" to your discussion, The 60kt drop in speed is very close to what calculations show the plane would lose simply trading horizontal velocity for altitude with very high efficiency.

That's a good argument for there not being an updraft. And 215kt at FL375 is almost certainly qualifying as a legitimate stall, especially considering the angle of attack registered. (That's if I've read graphs right.)

Hi,

As many commented here ... the CVR transcript is not the complete one.
On the other hand ... Air France (in a press release statement) tell they were proud of the professionalism of the crew .. it's certainly for some reasons.
Sure Air France had access to the complete CVR transcript or sound version.
So I'm in the waiting of the words of the captain (no one word of the captain after the upset in the actual BEA release)

29% CG
 

To me, 29% makes more sense than the 37% as initially estimated by the BEA in their interim report #1
Due to the heavy cargo load, it is probable that the fwd cargo hold was also fully loaded, which explain the fwd CG of 23% at take off. Considering the initial fuel distribution, the trim tank had normally 2400kg at take off time.
During the climb, an additional 2400kg was transfered to the tail for a total of 4800kg which was still there at the time of the event.

The 37% target is an ideal that can be reached only if the initial loading would allow it.

The CG was pretty much centered, at least it was not especially aft.

data access
 

At the present time, who has, or momentarily had, access to the full or partial data ?

• some people at the BEA
• then who ... ?

CONF...

Here is a link to ICAO Annex 13. If you look at Chapter 5, specifically sections 5-3 to 5-5, you'll find the criteria for who can be, who should be, and who must be part of the investigation, including who can have access to all or part of the investigation material.

http://www.airsafety.com.au/trinvbil/C619icao.pdf

Hi,

It's just for the organization between states ..... it's not realy instructive about who have really access to the data .... IMHO

JD-EE
Undoubtedly! It would appear that no-one anticipated an approach to a stall that wouldn't under normal circumstances be dealt with correctly. In this case it wasn't, and degradation of air-data was such that the SW operated in a negative sense, i.e. letting them think they were about to stall again, whereas if they had persisted they would have gone through the warning with a chance of recovery.

As takata has rightly pointed out, IAS greater than 60KTS AND/OR AoA less than 30 degrees are required to prevent the Abnormal Law activating. It is while in this AND/OR regime that a very clear warning needs to be given that the aircraft is stalled. IAS is useful, and AoA is useful, and it would be preferable to know each rather than being left in the dark because one or the other, or both wasn't deemed valid.

"This is a stall. Reduce power and nose down!"

If this quote from the Der Speigel article is true, it seems a puzzling omission from the BEA report given the other quotes and seems to purposefully lead one astray(by omission). It was a definitive acknowledgement by the captain of their situation and how to react.

Pitot Physics
 

http://upload.wikimedia.org/wikipedi...tic_system.JPG

Wiki has some info on pitot-static, but does not explain. I don't think I've seen this explained elsewhere in a long time, so I'll take a stab at making it simple.

The pitot tube captures impact air, which is sensed by an Air Data Module in the A330, and converted to airspeed. The drain tube allows water to pass without clogging the pitot. To do that, it passes air all the time.

The pitot opening is a specific size, say 5mm dia, and the drain is maybe 2mm. That makes the pitot about 20 sq. mm area, and the drain about 3 sq. mm area, for a ratio of about 7:1. This means the impact pressure at the sensor is about 14% less than actual impact pressure.

When it comes to clogging at high altitude, there are these possibilities:

Pitot clogged, drain clogged at same time: IAS, Indicated AirSpeed, will not change with change of aircraft speed, but IAS will increase with increase of altitude.

Pitot Open, Drain CLogged: IAS will increase 14%. 14% excess IAS will remain regardless of actual airspeed or altitude.

Pitot Clogged, Drain Open: IAS will decrease toward zero as the drain bleeds off the impact pressure to ambient. Increased altitude will not affect IAS.

This last situation: "On 28 October 2009, an Airbus A330-202 (A330) aircraft, registered VH-EBA (EBA), was being operated as Jetstar flight 12... (IAS decreased to about 60 Kn). The airspeed disagreement was due to a temporary obstruction of the captain's and standby pitot probes, probably due to ice crystals. A similar event occurred on the same aircraft on 15 March 2009."

The AeroCaraibe incident showed much the same behavior, so it can be expected AF447 was also the same type failure.

Comment?

Hi,

Seem's a little bit ironical ... but modern military jet fighters planes have an HUD with many interesting datas just in face of pilot eyes .. all this for assure the safety of one soul .. and some tons of metal and weapons .. and airliners have not this for assure the safety of hundred of souls and some tons of metal.

FPV?
 

Just a general thought - does the Flight Path Vector display use air data at all or is it just inertial? Would this have helped the pilots' SA in this situation?