Could it be dependant on the fact that Abnormal Attitude Law is active or not, probably in relation to the 30 deg value for the AoA ?

Option 1: don't disturb anything.
Option 2: in that fully developed stall tell the Captain what happened, put the nose to 40 degrees down and throttles to idle and fly from there.

Any chance of a summary in English for us linguistically challenged anglos?

Can we have this renamed to "AF447 thread No12" please? ................. Done .. JT
 

That would explain why 320's cockpit is smaller than 737's except for the fact it isn't.

..then you are discussing something which has never happened, is unlikely to happen and has no relevance to AF447.

In aircraft with traditional instruments and controls there is procedure for pitch + power flying when all air data gets shot up. Position of controls never comes into play. It's the same with A330 and was the same at the time of AF447. Surprise, surprise.

The system is certified and very well proven, both in everyday use and in unreliable airspeed situations. There might be some hilarious stupidity around but not within FCS designers' circles.

Yup, it ignores marketing.

That would explain why other 40-something 330/40 crews (including AF ones) faced with loss of airspeed indication in cruise, AP trip off and degradation to ALT law ended up similarly to AF447 except for the fact they did not.

Both pilots lacked it... at 4:00 AM in cruise. If you could travel in time an tell them (or any other pilot that never put down his last flight in the logbook) about the way they would meet their demise, I'm pretty sure the least reaction you would get is offense at the suggestion they might be so dumb to do that. Discussing aerodynamics and performance here is pretty easy exercise. Remembering any of it at 4AM when scared witless is not quite so.

And there I was thinking that the proper simulation is about getting inputs as close as the real ones. Real turbulence was pretty well recorded so this is:

...untrue and massively ignorant at the best.

That would explain why the roll wasn't following pılot's inputs except for the fact it did.

Horrible PIO! Convergent and with maximum pre-stall amplitude of 11 degrees! That would explain why Bonin didn't change the pitch except for the fact he was steadily decreasing it from 12 to 6 degrees ANU as soon as he got roll under control but pulled to 17.9 when stall warning fired again.

The first and foremost thing about IFR flying is attitude! Who gives a PPRuNe about how much one displaces stick or yoke with what force! One uses it as much as needed to get desired attitude - which can be easily read out from big EADIs on PFD.

How did THS behave in real world FBW Airbus stall incidents and accidents?

Nope. See here:

As RetiredF4 has correctly observed, Airbus FBW gains are related to G/pitch change, not controls deflection.


Not just that, up to some bank (33 IIRC) it has roll compensation too! So how does this super-duper-complicated-magic work? By programming FBW to keep stable vertical flightpath. What is commonly and wrongly referred to 1.2 G demand is actually 0.2 G demand superimposed on current normal acceleration. So how does average Joe the pilot cope with super-duper-complicated Airbus FBW and its reconfiguration laws? Well that's the beauty of it; he does not need to know anything about it to fly. No matter what law one is in, stick forward brings the nose down, stick back brings it up, stick left brings left wing down and right stick brings it up - unless one has stalled his Aırbus, that is.

It has never done it nor there is any need for doing them.

THS gubbins...
 

Hey all - sorry, been a bit unwell the last few days.

Anyhoo - I found A33Zab's post from back in the fourth thread, which I hope can shed some light on the THS question. Link here:
http://www.pprune.org/tech-log/45465...ml#post6532375

It's worth having a look at the whole thing, but the interesting bit that I recall is this:
So, near as I understand it the PTA override mechanism detects mechanical resistance to the electrical motion and disengages the electrical system via a clutch mechanism. I would imagine that both holding the wheel (static resistance) and rolling the wheel (dynamic resistance) will disengage the electrical system until the resistance goes away - i.e. the wheel is released.

As to the other question - i.e. what the FCPC is doing with the various inputs (elevator position, stick input etc.) while the trim is being controlled manually - either it continues computing where it wants the THS to be while the wheel is under manual control - in which case the electrical system will attempt to re-acquire that on release, or it does not - and simply starts calculating from the point the wheel is released. In either case it will not attempt to roll it back to the last known position, and in the former case it will not roll it all the way NU unless the sidestick has been commanding that position while the wheel has been under manual control.

@Winnerhofer - appreciate the enthusiasm, but it might be worth checking to see if the subject of AoA gauges has been brought up in the previous threads before posting it again (for the record, it has)...

Human error, human factor
 

Errors, mistakes, faults, or success have all an origin, a reason, a cause.
John Tullamarine's excellent document about human factor, or part of the USAF KC-135R report refering to human factor (excellent too) are going to the deep of human factor definition, very far from the pseudo-philosophical and pseudo-scientific readings i.e. that quotation and other VF!

Clandestino:
Good to see you back in the scrum. :ok:

Just a thought here ...
Based on the limited evidence available to us, which is some of the CVR transcript, I'll suggest that neither Bonin nor Robert ever got to the "frightened" stage. They remained in the "what is going on?" stage, though Robert seems to have been more aware of the aircraft's flight condition than Bonin, coupled with frustration and confusion.
Captain DuBois may have been indicating fear with his "it's not possible" remark, but he just as likely to have been in a different mode of problem solving as he tried to get a grip on what those two had done in his absence ... and correct it. His instructions to Bonin on using his rudder to help his roll control strikes me as being in a problem solving mode, not in the "I am scared" mode as he tried to get the situation back to something like normal.

The above considered, we can't be sure since we can't read minds through a CVR, and can't read minds beyond the grave. We'll never know if they were frightened or not. I don't think they ever got to that point.

FBW auto trim implementation
 

Wrong, Winner. The pitch law is not for an attitude. The attitude resulting from a stick input and then neutral is due to the pitch gee factor that the engineers programmed.

Our primitive Viper law was all AoA limit and gee command. At 45 degrees of pitch, a neutral stick had about 0.707 gee thru your feet, but the jet kept trying for one gee Nz, and you kept getting more nose up attitude and the dreaded THS autotrim. The 'bus corrects for that in "normal" law ( and maybe one of the sub-laws). It also puts in a gee command for pitch when rolling into and continuing a turn.

My opinion is too many protections and "aids" once the primary law is gone. Sheesh. Put a big light up and say "you are in back-up flight control law, and fly stick and rudder!"

We don't need to go to "direct law" willy nilly. But trying to keep all the "protections" until finally in "direct" seems to create confusion for we pilots.

That's kind of what it's doing anyway. There are some folks working on translating the second Judicial Experts' Report, particularly with reference to Section 2, which covers the flight tests performed to assess aircraft capability in that scenario:

Interesting stuff...

The translation's rough and ready, admittedly - but it gives a reasonable overview for the most part. I think they actually physically blocked one of the pitot tubes before departure.

This was an A330-200 aircraft, and the report makes reference to using it to make certain that any claimed differences between that and the A340 previously tested would be nullified.

I'm afraid Dozy rather jumped the gun there - my unpolished translation was a PV not intended for general consumption - well not yet anyway.


The complete, relevant French version is this: native French speakers feel free to correct my approximations!

2.1.3.1 Vol sur l’A330-243 MSN 1496 F-WWTP, le 10 février 2014 à Toulouse, en partie de nuit.

Configuration particulière avion:

(photo of blocked pitot)

Tube de Pitot no2 bouché et son dégivrage inhibé pour tout le vol

Configuration systèmes:

ATA 27: FCPC P7/M16
ATA 31: FWC T1

La loi ALTN a été activée en coupant l’ADR3 et en activant l’ADR2 qui est boucheé (double panne d’ADR). La loi ALTN2B s’active alors lorsque la vitesse vue par le Pitot 2 (via les orifices de drainage) dépasse un certain seuil et que les 3 ADR deviennent incoherent. Cette transition en ALTN2B étant irreversible, on retrouve des informations de vitesse valable au PFD2 pour le bon déroulement des essaises, en réactivant l’ADR3

2.1.3.1.1. Essais principaux réalisées et commentaries



2. Prise en mains, evaluation des Qualities de Vol en loi ALTN2B, autour de M=0.81, entre 35000 and 38000ft.

Commentaires pilotes: <<La loi de vol ALTN2B ne présente aucune difficulté majeure de pilotage. Le contrôle en assiete est pratiquement identique à celui de la loi normale. Le controle en roulis semble étonnament plus précis qu’en loi normale et l’avion fait preuve d’une bonne stabilité proper. Lorsque des impulsions plus aggressive en roulis sont effectuées, il en résulte une perception d’accélerations laterals pouvant etre interpretées comme des mouvements de lacet. En résumé, cette loi ALTN2B n’est pas un facteur pouvant justifier une <<vision tunnelisée>> accaparant toutes les resources du pilote,>>

<< Je n’ai ressenti aucune difference s’agissant du contrôle longitudinal, la réponse à la demande est correcte; sans action sur le manche, l’assiette reste stable.>>

Nonsense
 

If Bonin had that perception we can imagine his trouble : Yaw is heading change, not lateral acceleration perception.
Bonin was discovering that unknown law and that sudden law change and that behaviour dissimetry of the plane in pitch and roll. He was not informed -unlike the pilots of Toulouse's february 2014 flight- before the facts happened and was not a test pilot.
Did anybody found objection in AF447's FDR/CVR?

Exact in the test conditions (the pilots know what will happend .. and they knows the BEA final report and more)
In the reality ... over the sea at night in the AF447 .. the conditions were not the same .......
If you take all the events separately ... it's not so busy workload ...
When you mix all the events in a short lap of time ... this is different .....
If you make a reenactment of the battle of Waterloo (with all the insight) maybe Napoleon will win !

I've pointed this out before, but how could any law change have caused Bonin problems, when he didn't even have any experience of how the aircraft handled at high altitude in Normal Law?

Sounds like making excuses to me...

@DozyWanabee
The situation was lost after :
-1 high altitude stall
-2 wrong pitch-power used
-3 inability to decide action after UAS
-4 Autopilot missing
-5 Captain leaving
-6 Puzzled brain in a complex situation
-7 Crew's Robert/Bonin bad coordination
-8 Bad health/rest before the flight
-9 ITZ
-10 Missing stall test of airliner
-11 etc.
-12 Cadet training

From my experience as airline pilot in a french airline, I would like to point the second and the fourth items. Really I only met people giving no importance to knowledge of some important ref pitch&power, included chief-pilot, instructors, etc. One of our CPL lost his ATPL check after being unable to continue safe MD83 ILS flight after he had to fly with Pitch and Power. It showed a gap of our pilots' team, but nothing was done. It was not only in high altitude. It is then that I revised for my own the page full of numbers and discovered the MacDonnell mistake N2% dicreased from 76 to 66 at 3000 Ft...
It seems the wrong figure existed since 13 years, for 165 airlines... Happily nobody needed it. Perhaps the fact that the need of Pitch&Power seldom happens explains the deny of needing acurate knowledge, despite it is taught in old time french IFR BASICS ...

@roulis:

Perhaps I should clarify. When I say "making excuses", I don't mean for the crew - I mean making excuses to blame the aircraft and systems.

Of course being handed control via AP disconnect in cruise at night over the ocean and in turbulence is going to be a fairly difficult scenario for the pilot - even more so if that pilot has never been trained in or experienced handling the aircraft manually at that altitude. But that would be true of any aircraft type you care to name - whether the control layout is conventional or not, or whether the systems are electro-hydraulic or FBW (or indeed what control law one is in, in the latter case).

The practice whereby pilots were routinely put into the flight deck in this phase of flight despite neither of them having any experience of manual handling in that scenario absolutely deserves close scrutiny - in real terms, it shouldn't really have been allowed to happen.

What I was getting at was that it doesn't make sense to claim that the change in control law had any effect on the way he handled the aircraft (particularly in roll), or the way in which he perceived the aircraft to be handling - because he had no experience of what it was like normally with which to compare it and thus be "confused". Yes, it was probably frightening and yes it was difficult - but that was because of the scenario in which he found himself, not because of the change in control law.

Does that make sense?

Dozy;

Re, "Of course being handed control via AP disconnect in cruise at night over the ocean and in turbulence is going to be a fairly difficult scenario for the pilot"

The following actually goes to your point regarding scrutiny, etc...

Regarding being handed the airplane when the autopilot disconnects, no, it is not difficult at all, not even a bit. I've had the autopilot disconnect, (over both oceans...didn't seem to matter) and the first thing one does is leave it alone and do nothing, but (for those who desire to know what "do nothing" means), by all means maintain altitude and keep the airplane stabilized - most of the time it does that on it's own for a half a minute or so which is way more than one needs to assess the situation and get comfortable. Then try to re-engage the AP and if no joy, fly the airplane...tiny, gentle squeezes on the stick or column to correct little divergences.

Hand-flying the aircraft in cruise IS difficult for anyone who hasn't done it or who doesn't have a lot of experience, and therein, as you say, is what needs scrutiny. In fact they shouldn't be in the cockpit but I recognize that I'm growing older and automation, (which I always thought was wonderful) is here to stay. I heartily agree that putting inexperienced (cadets?) people up front needs scrutiny - it's a money thing and is today somehow an acceptable risk).

BTW, "...over the ocean" makes no difference, neither should night-time if one is an instrument pilot; the Airbus handles turbulence well when hand-flown in Normal law, (in fact you don't move the stick at all, really, until the airplane diverges from what one wants), and in Alternate law one is gentle with the airplane as a pilot would be with slightly more sensitive roll and at high altitudes. I have to say I've hand-flown the A330 & A340 in cruise, sometimes for an extended time, (not in RVSM airspace of course) and it's a delight aircraft to fly.

The DC8 was a bit more of a handful in the sense that one was always "working the control column a tiny bit to maintain one's altitude, but it was just another airplane, difference was these aircraft have a lot of mass so they're slower to change, slower to return - one has to wait, then make a change, wait...

They're all very stable and not difficult at all to fly. Flying them has less to do with training than one's experience - you can't "train" everyone to fly...that I know from experience, but if they can fly, then "training" would consist of little hints here and there regarding handling because you'd be expected to be able to fly an airplane. DP Davies was superb in the advice he offered.

I tend to agree with you - an autopilot disconnect for someone without experience would be disconcerting and distracting. I think this is where the rubber meets the road, so to speak, in the way the industry has gone, and its already addressing the problem.

@PJ2:

We're basically "singing from the same hymn-sheet" here. What I was getting at was the modern condition - that even a pilot with some experience of manual handling at high altitude may initially balk if it hasn't been practiced in a while. A pilot who has no such training or experience has every reason to feel genuinely scared.

WRT "over the ocean/at night" etc. I was referring to the complete lack of outside reference for attitude, which I would imagine is a big deal in the event of an apparent instrument failure because it erodes trust in all the instruments, even those which are working.

Anyways - all good... :ok:

Not sure it's a "big deal" - it doesn't necessarily "erode trust in all the instruments" [my italics], especially not in those that are working - reason is, if you know they're working it is reasonable and probable that they can be trusted so you use them.

We experienced steadily diverging airspeed indications on a B767, (winter, in cloud, night, in the climb above FL200). We had to decide whether it was the captain's ASI or mine, as mine was getting lower and lower while he was maintaining a steady climb speed. Mine agreed with the steam-standby; the hiss of air noise wasn't normal. I wasn't flying at the moment so I don't know how the airplane felt - he began using the standby and as his ASI increased past the barber pole we waited for the overspeed warning - it never came, but an EICAS message came on regarding the ailerons and a speed limiting function, (I can't recall it now - it was amber). We took a look at the IRS/FMC groundspeed. He gave me control and we finished the flight uneventfully - the ASI returned to normal in warmer air during descent.

No one here should mistake this for a hero story because it isn't - it's what's done very likely hundreds of times a day around the world in commercial transports- not this of course, but certainly something. It isn't thought of as "scary" or "difficult" - it's a problem to solve and with both good training and lots of time in, it usually works out. One should rarely if ever be scared in an airplane when s. happens but deeply respectful of what it may do to one if one provides it with an opening.

When someone would ask how much airline pilots make, the joke was $100,000 a minute but you'll never know which one. Thing is, airlines aren't paying this anymore and now it's showing up, only occasionally so far, but as the cadets move to the left seat and the other seat is a 250hr guy or gal who's never just about killed themselves at least once, they're not up to snuff when things really get difficult.

We live in an age that I call the "illusion of technique" because people who run things at airlines can be buffalo'ed into thinking technique is everything and neither experience nor intuition count for much anymore. I prefer to think of automation as the greatest assistant I've ever had except my First Officer and the two Relief Pilots - the machines are brilliant, but the guys and gals have eyes and got time in the old fashioned way and when their time comes they'll make great captains. I care very much about this profession and I don't like the trends; been writing about them for about twenty five years now - spit in the wind, and I'm a pilot who I loves automation.