Nose-up?
 

How shure are we that the "nose-up" was made by the pilot flying. I have been thinking about a possible sudden malfuntion of his side-stick, like a broken spring or failing position transducer.
Could this be a real possibility of would it have generated another ACARS mgs?

Did they loose the IR`s or only ADR`S?

Hmmm, no. If the AP kicked out because of unreliable airspeed, he was already in Alt law -- even though the PNF didn't verbally state this until 11 seconds later.

Baling till the interim report is published.
 

I'm not qualified, nor interested in the level of speculation, informed or otherwise on this thread, next report issued, we can look again perhaps.

My parting shot is this : leave it alone it will still give 1g / zero roll rate .. hold it in ALT law, the THS will trim back to support the input, to reverse this requires a sustained push as the THS re-adjusts .. so without over complicating matters, and without having access to the full picture .. there we, or at least I have to leave it until we have further.

The aircraft does not (in my recollection) have a true AP / OUT mode, call it CWS if you prefer, until you are at the absolute level of reversion, it says what it will do on the packet. Aggravated stalled condition perhaps .. deep stall no.

all yours.

Something that is apparent to me, is that once the aircraft was in the fully developed stall, the right roll was effectively a side-slip/bank as the direction of flight changed and became stabilized once the wings were leveled.

No mention has been made of any rudder inputs, and it looks as if there was no spin element in the descent. The final roll to the right may have been in the process of being corrected at the time of impact, and hence the left wing low and the tail yawing to port. The same could have happened if someone planted their foot on the right pedal shortly before impact, i.e causing the yaw and left wing low.

What was causing the roll to starboard? Some symmetry problem, or payload/fuel out of balance and no flyable airspeed to compensate?

@Minorité Invisible
Cher cousin, it does not sound ambiguous to me: "en butée" (full stop) applies to "gauche" (left) and "à cabrer" (nose up).
Otherwise it would be: "à cabrer et en butée à gauche", or "à gauche et en butée à cabrer". :)

Change in training needed?
 

I have been looking at statements by posters from various parts of the world regarding use of the manual pitch trim and there appears to be a dichotomy of views.

Posters from Europe seem to believe that you will never touch the manual trim wheel while airborne. And if you do use the trim wheel during a training session, you will not pass.
http://www.pprune.org/6476909-post77.html by Svarin and http://www.pprune.org/6477104-post106.html by Svarin
http://www.pprune.org/6476888-post72.html by Narval

A poster from Hong Kong says, yes you don't use it often, but there are times when its use is highly appropriate, and he remembers using the manual pitch trim during training.
http://www.pprune.org/6479397-post419.html by cxhk

There is one of those little rules that we all know to be true. It is use it or lose it.
It appears that non-use of the manual pitch trim is dogma in European training centers. The Hong Kong poster's statement highlights a more pragmatic view.

We have now planted two European Crewed Airbus aircraft in stall related situations where timely use of manual pitch trim would have been the fist step in saving the day.

Under the pressures of the moment, it never occured to the crews to lay hands on the manual pitch trim, or apparently even to look down at it to see where the trim was.

It would seem that Airbus drivers everywhere need some training reminders on the use of manual pitch trim.
The old training dogmas regarding manual pitch trim use need to be thrown into the dustbin.

TLB - TO/GA was not asserted until the second stall warning. At about the time of the first stall warning, perhaps before it upon AP/AT disconnect, the PF simply raised the nose a little and left the CLB default throttle setting.

A-3TWENTY, all the lost was the ADRs. The IRUs did not have any reason to drop out. They're more like a reference for everything else with some tweaking via the navigation system Kalman filter, presuming there is one.

TurbineD, in your post #596 you asked about possibile similarities betwwen AF447 and the airprox incident over North Atlantic (AAIB bulletin 6/2001).

Looking at appendix B of the report showing P1 sidestick controller inputs it is a bit puzzling that the majority of the inputs are upwards during the zoom climb (while TCAS was calling "descend") and even during part of the recovery phase of the event.

I have no idea what to conclude.

> TLB - TO/GA was not asserted until the second stall warning. At about the
> time of the first stall warning, perhaps before it upon AP/AT disconnect, the
> PF simply raised the nose a little and left the CLB default throttle setting.

JD-EE,

Thanks. But this is exactly the point I am trying to raise. If the PF initially thought his main problem was an unreliable airspeed situation, then his initial response (raised the nose a little and left the CLB default throttle setting - your words) was exactly the right thing to do, according to the C/L.

JD-EE,

With due respect, but I fail to see how having a bad day can be an excuse. If a pilot has a so bad day that it can impairs his/her judgement, he/she has the option of staying home, sparing the lives of a lot of people. In fact it´s not an "option", is a moral obligation.

And in fact it seems that the less experienced pilot was commanding the airplane. This raises some interesting questions beyond his own hipotetycal culpability: for example, is it considered to be good practice for a captain to let the less experienced pilot drive the thing during the crossing of the ITCZ? This is a fair question, you see, even if in the end BEA investigation proofs that the pilot received erroneous information from the system.

Hi,
Yep, I concur with your explanation, hence also this English translation.
Alternate law should pop up on each pilot's PFD at 0210:05, with several amber flags (3). The PNF talking about the "speed lost" and "alternate" are more sounding like a cold statement than a timely warning. The THS certainly did close to nothing at and right after this point as it was still at +3 deg (close to normal) 46 seconds later until much more sustained stick NU. It took about one minute to reach +13 deg but it was between 0210:51 and 0211:51 (more likely 0211:40). More than very likely, this trim rate was caused by pilots NU imputs alone.

From 0211:40, she would not be anymore in Alternate law as all speeds and AoAs were invalidated => abnormal law: THS is frozen at +13 deg and autotrim become inactive (like the RTLU was at 0210:05, remember? we told you that it was its last valid airspeed before ADRs faults).

About the roll, it looks like an oscillation (left and right) and I'm wondering also about what caused it as she seems unbalanced at its right from the time AP went off. From 0210:05, yaw and roll axis were in direct law without any PRIM control and to not overshoot bank corrections might be tricky even in light turbulence.

Some questions I'm asking myself:
1. was the first stall warning "real" when AP went off?
2. what caused this roll just before AP went off?

Would be nice to see a plot of the aircraft attitude rather than just a few AoA data points.

At one point they say the AoA reaches 40 degrees. It's tempting to think this means the nose is pointing at the sky but that's probably not the case. I mean if they are descending at 100kts vertically and flying horizontally at a similar speed what would/could the attitude be to achieve a 40 AoA ? Could the attitude be close to level?

Which Version of Alternate Law
 

Since this was an A330, there are two Alternate Law reversions possible.
Per BEA, the aircraft reverted to Alt 2 Law.

Per my understanding of the flight control system:

Alt 2 is a roll direct law. This means that the aircraft is in direct law on the roll channel and Alternate Law in pitch.
Direct law is a 'you fly it' law. Control displacement causes proportional control surface displacement very much like any non-FBW aircraft.

This means to me that keeping hands on stick was not optional, particularly if the aircraft was a bit right wing heavy. There is no lateral trim on Airbus. About all you might hope to do is throw in a bit of rudder trim to compensate and move fuel around to adjust lateral balance. The PF could not have let go of the stick with a wing heavy aircraft. Under this situation, he could very easily tense up and apply unintentional nose up input.
Now, would some real A330 pilot tell me if I am reading the Flight Control FCOM properly. :confused:

What position was the rudder in? Or, where was the vert. stab. Was it still on the airplane. Just wondering. A lot of indications the sitck was moving from up to down, and left to right. What were their feet doing?

Certainly not in the real aircraft. The sim is likely accurate enough that you will need the stick forward to recover from stall (not approach to stall).

See post 498, (http://www.pprune.org/tech-log/45283...ml#post6479876) by jcarlosgon for someone who appears to have actually done such training.

@jcarlosgon
thanks for the informative post,I, for one, would be fascinating to know if there was any debrief on why it took so long and whether any reason for slow control response was discussed.

They are freakingly correct! Under no circumstances is the trimwheel to be used while the autotrim is operative. It's not a dogma, manual trim in normal and altn law is useless as autotrim will return it to what it thinks is correct setting and 99.9999% of the time, it is right too.

What the poster from HK was referring to is loss of autotrim in alternate abnormal and direct laws or in mechanical backup. Then you have to use manual trim. As A320 was my first jet aeroplane ("You reek of propellers" was one of milder estimates of my capabilities I received from established jet jockeys), powers that be decided I should be given 20 hrs of sim time in direct law to get used to oh-so-enormous-speed-of-320. To my utter disappointment, 320 turned to be much easier and more comfortable to fly than ATR-42 even in direct law with all protections off and no autotrim.

I've never, ever heard of sidestick going haywire in real life, except for DLH's roll polarity mess up - courtesy of maintenance.

There are hundreds, if not thousands, flights through ITCZ every day. Somehow, they manage to get to their destinations safely. Go figure.

CONFiture has made an excellent question: why does autotrim doesn't stop when stall warning is activated? I hope that final report will have equally good answer to that.

As for the rest of speculation around, it seems that my neural centre for disgust over completely unfounded conjecture has overloaded and popped the breaker.

Hi Machinbird,
Well, I think that's a bit jumping too early at those trim wheels.
I do believe that posters from Europe and Hong Kong would agree that:
1. You need first to aknowledge the stall situation;
2. You need next to apply full nose down before starting to think about moving the wheels, reduce thrust, or rolling to nose down pitch.

Airbus seems pretty confident about its elevators authority, even with a jammed THS between +8 and +14 degrees, as it is said to be an issue mainly above 180 kts.

The way I read the BEA info, the nose was raised more than "a little" and pitch much more than 5 degrees.

But on the C/L, buried in a postscript to a post a few pages back by Hyperveloce is this little bombshell:

Now, is that a "reminder to follow the procedures", or an urgent message that the previously advised procedures were wrong ???

If it is the latter, then AF found probable cause in training / SOPs only 5 days after the crash - who did they tell ?

What caused the roll just before the AP went off....?
 

Excellent question after following this terrible event for two years-----where exactly was the VS at this point in time?Does anyone know for sure as yet?
What would the flying characteristics be----if any?
Just a thought from a low-hours person...which I am sure all of you guys,and the BEA,have already considered?

infrequentflyer789,

We had to wait for the THS to move forward and regain flying speed, longer than I had, wrongly, anticipated. Nose down pitch had to be maintained pushing the stick. Usually, once pitch is set, the stick may be released, but not that time, until THS was in position. Nothing wrong with flight controls, loss of altitude because we delayed recovery on purpose.

Takata
Could be, but, "Use it or lose it" still applies. It shouldn't be a stranger.
You need to train a few exercises where you have to find out where the darn thing is set, preferably in response to a scenario, and thereby get it into your scan and thought processes.

Don't you think if the AF447 crew had seen the trim position - the light bulb would have come on? And the Perpignan crew also?

Hi Loerie,
Beside few die-hard tailsuckers, everybody seems fairly convinced that the VS was still planted exactly where they put it at the factory.

Let me clarify: the way the French version is written, the term "en butée" could either apply to both the left and up inputs, or to the left input only, the up input not being to the stops. The English translation implies full left AND full up input (both to the stops)

The answer is undoubtedly related to these:-

2:11:49 FLR/FR0906010210 34111506EFCS2 1,EFCS1,AFS,,,,,PROBE-PITOT 1X2 / 2X3 / 1X3 (9DA),HARD
2:11:55 FLR/FR0906010210 27933406EFCS1 X2,EFCS2X,,,,,,FCPC2 (2CE2) /WRG:ADIRU1 BUS ADR1-2 TO FCPC2,HARD

The first opportunity for these FLR messages to be transmitted.

TLB;
With respect TLB, no, this is not "exactly the right thing to do" for an Unreliable Airspeed event in cruise.

Please reference post #2269, and the First BEA Interim Report, Page 69 and Appendix 7.

The UAS drill has two sections - the memorized items are to be executed when the safety of the flight is at immediate risk, which is primarily at and just after takeoff, (as the Birgenair and Aeroperu accidents demonstrate). When to apply the memorized items is stated in the expanded training documents for the A330 and so should be no mystery to those who know their stuff. It's how drills and checklists are run.

After the qualifying conditional, (is the flight at immediate risk, yes/no), and the AP/AT are disengaged etc, there are the three conditional statements which refer to the A330 acceleration altitudes, stating pitch and thrust settings which provide an immediate "safe zone" until the aircraft is at a suitable altitude.

The qualifying conditional statement at the bottom of the memorized drill, is actually the second statement in this drill IF the flight is not in immediate danger.

The statement requires that the aircraft be leveled off for troubleshooting. Troubleshooting means, while stabilizing the aircraft (essentially "doing nothing"), getting out the QRH for the pitch and power settings for the weight and altitude, (in this case, FL350), and then calling for the "ECAM Actions" when the aircraft flight path is stabilized.

This guidance is in a number of Flight Crew Training Manuals and has been the SOP for a UAS event since around 2005, perhaps earlier.

Whether the pitch-up is this particular response, or a response which is entirely unrelated to the UAS event remains to be determined and we cannot determine this with the information we have. But there are documents cited here which tell us that such a response was a concern. As I have said a number of times when discussing this scenario, one way or another, it needs to be confirmed or dismissed as part of the overall investigation as to why such a response was executed.

mm43;

I know that you will know this but, for the benefit of those who don't, the ACARS messages do not capture any information about a stall, nor the associated warnings or indications, just as the CMC does not record Overspeed warnings. It is, after all, a maintenance system, not a diagnostic flight data tool as some have tried to make it.

Agreed
 

bubbers44 said!

Like I said in my first and previous post, I´m not a pilot, I´m a
doctor. But something tells me, bubbers44 has it figured out!

Inexperienced pilot for that kind of complex machine, flying in a corrupted
environment, faced with a dual challenge (what´s going on outside, and what´s going on inside), miss-reacted maybe naively (expecting) thinking all the protective envelopes would prevent the a/c from a high altitude stall - just as he might have been told in training for that type of a/c!

Who knows? In my line of work, we´re sold a lot o BS for truths! And many inexperienced doctor just buy the idea; never question, do as your told. I figure in the aviation world similar approaches are used to sell you erroneous info!


Don´t mean to offend anyone here, but the sum of circumstances is
building up to this unfortunate reality.

At least this is my two cents worth!

PJ2,

Thank you for your informed and detailed response.

In hindsight, with all these informations available to us, they would certainly have acted differently. But it looks like a tunnel vision issue up to this point, like if something took all the PF attention: it is not even sure that a giant red warning "THS +13 degree" painted on his PFD would have made the outcome different if he was believing to do exactly the right thing.
This THS information would have been paramount only if he had tried to pitch full nose down but lacked from elevators authority. Now, was this even attempted before it was too late?
If not, the main issue about what crucial information didn't reach the PF in time lie certainly elsewhere.

Hi,

About the BEA paper: A little time after BEA read VCR, it appeared in the news (a leak?) that the Captain gone back and was heared "shouting orders to his pilots". This phrasing ("crier des ordres" in French) appeared curious to me and I remember thinking was it "shouting orders from the other side of the locked cockpit door"? Inaccurate thinking, but why BEA tells nothing about what the Captain said. It would be very interesting to know what was his perception of the situation, no? Especially after "the PNF tried several times to call the Captain back" was written by BEA (which could mean "between the lines" the PNF was dubious about PF actions).

In very different domain, about the Pitots icing problem: many, here, have given ideas. But there is very simple one, imho. Have one or two "inversed" Pitots, ie Pitots "looking" backward. The precision would be less accurate, as the extent of the measurement scale would be reduced between true pressure and zero, but this would be better than nothing. Why this would be not possible?

PJ2
Welcome back, and thanks for the timely reminder!

There is something about the AP/ATHR OFF that may be related to the questions takata is/was posing. Svarin has also shown keen interest in this area, and ultimately time will tell whether it was warranted or not.

TLB;

You're welcome...not picking on you but impressions become realities for those who don't know any better and believe everything they read. The passengers and crew and their families and friends deserve as accurate a telling of these things as possible. If you dont' know, don't write it and don't make it up. Some here don't do the hard research, most don't fly these aircraft or know anything about the A330, some just plain don't know and write anyway and some actually go on the internet for "information"...Like George Carlin said, "it's all bull!!!! folks and it's bad fer ya".

Sorry. Grumpy.

Thanks Tanaka....
 

Just asking---no need to get all bent out of shape about the question...something clearly went wrong and if it was not the chaps flying the Aircraft it must have been the Aircraft or their training in relation to that Aircraft,right?Or perhaps their training to deal with the situation....which was placed on their laps at some unexpected time.......don`t things always go sideways at 0200 or therabouts?
I am so sorry to have upset your sensibilities.From your address you are clearly a serious person close to the heart of everything,which is great.
I guess we will soon see who and what happened to cause such a catastrophe.
It would be nice to see some more information from the French Investigative people upon which to work by all you guys who fly the Aircraft,day to day.
Regards.

Originally Posted by Machinbird
Don't you think if the AF447 crew had seen the trim position - the light bulb would have come on? And the Perpignan crew also?

Takata
Well it certainly looks like they made nose down inputs, in a tentative fashion, and got stall warnings back for their efforts:

From the BEA statement

PJ2, nice you're back.

I've noted the PF's reaction to the AP/AT drop out. As written in the writeup:
The $64,000 question that moment in time poses is whether that all happened at once or smeared, in the order stated, over 11 seconds. If it was smeared over time in the order written, I'd presume that would be uncertain airspeed. If it isn't what would be the PF reaction taken as he says he has the controls?

If they all happened in a slightly different time sequence the PF might have a whole different chain of actions initiated.

Another question is how good the simulator training is for cascade failures, which certainly appears to be what happened here. PF starts uncertain airspeed knowing he's going 275kts CAS. And a stall warning hits, a sure disruption to his chain of thought. Is training good enough that there is a smooth transition to realizing it's false and the pitots are out or does it start a whole new chain of trained reactions or does it leave the pilot rattled?

(I'm rather fastened on that spurious stall warning that seems to have happened more than just this once and left pilots transfixed trying to solve the impossible. This seems like one obvious change required in the flight control systems. If kCAS indication drops dramatically and that is not matched by a similar reaction in the inertial reference unit, suppress the stall warnings even if they might be real as might be the case with 10 degree AOA and 268 kts. It a pilot knows he won't get spurious stall warnings (or its far less likely) then a real stall warning will be heeded properly. I'm simply relying on my computer training here. You can overwhelm systems with conflicting input. In fact it's a known hacking technique. I also think this problem may well have already been dealt with in the flight controls for the new fully autonomous drones.)

Hi mm43,
In fact, I have no doubt about what caused AP/ATHR OFF (UAS/ALT). But there is no detail in BEA note about the weather as there is no reference to turbulence level, g variation, etc. Hence, I wonder about what could have caused this roll beside the weather or any uncontrolled pilot imput when AP went off.

On the other hand, I'm wondering also if there is not a mach correction of the AoA function -at high mach numbers- that could change the resolution of the displayed alpha and could cause a Stall warning following an unreliable airspeed. This happened many times during past UAS events and it is far from clear if those warnings were "real" or only caused by the change of AoA resolution. Another possibility would be that AoA probes could be affected by ice in some way (TAT probes seeems to be) at the same time as the pitots are clogged.

PJ2,

Totally agree. Hopefully, when all of the data points are eventually released (along with the full transcript of the CVR superimposed), we will have a much better understanding of what actually occurred during this tragic flight and - more importantly - what might be done to prevent it from happening again in the future.

Don't forget that this procedure is new from December 2010 and therefore was not in force at the time of AF447.

That is not exact. Thrust is frozen until thrust levers are moved, so it could be anywhere between idle and climb thrust depending how was the thrust level at the time of the malfunction.

With all due respect, the richness of this forum (and others for that matter), stems from the tension that exists between the 'ignorant' and the 'knowledgeable'. I for one have learnt a great deal from this forum and would like to thank every single one who has taken the time to post here. If only the 'knowledgeable' posted here, we'd all be the poorer for it. That doesn't mean there is no bull!!!! posted here, there is; lots. But if there was no bull!!!!, a lot less of the 'knowledgeable' folks would post to counter the bs. So please keep posting. If you don't know, do your research, use the search function to look at what has already been discussed. Ask in the Spectator's Balcony first, if you are not sure. Strive to make an informed contribution and help maintain the quality of this thread and of the forums in general.

Now back to topic.