Almost every crew nowadays is fed 8000ft air. That most flights end uneventfully and large majority of emergencies are dealt with properly completely rebukes your theory but thanks for the entertainment.

Nice argumentation there. Not.

How about impartial?

Who cares who you are! Amateurs or non-aerospace professionals did contribute significantly to discussions here.

However, this is plainly false.

Inertial data. Per design. Write to EASA if you want to have it changed.

Need to fly pitch and power and disregard the host of false alarms, perchance? How complicated is that?

Here: G-THOF serious incident at Bournemouth. A lot of force, thou sayst? No force could lower the nose and the crew didn't remember to use the manual trim.

The way many a PPRuNer glosses over the fact we need to have very powerful THS in modern turbofan transports and that when mistrimmed they can be lethal on any aeroplane, not just on Bus, would have me worried about the knowledge level in today's cockpits if it weren't for the red warning at the bottom of this page.
It was. Conclusion was it behaved as expected and no recommendations to change it were made. Something wrong with it?

...until you zoom through your initial altitude and then bust it by 2500 ft with rate reaching 7000 fpm? Wouldn't you agree that we may call such a feat "overreaction"?

They had no clue what to do.

At it's best, AF447 was measly 72.1° short of vertical, which is quite a bit of stretch to call "not far short of". Aeroplane never stalls in properly executed hammerhead and is only briefly stalled at very low speed during during tall slide, thence no buffet. Thank you for putting forward this entertaining and quite false theory.

Something just isn't clicking here Clandestino. I'm well aware of the need for a powerful THS, as I suspect most every other pilot is also aware and that is PRECISELY the reason I find it disturbing that the Airbus THS operates without pilot awareness so much of the time. As this trim discussion continues, I find myself questioning the system more and more.

The PF took the controls and announced such. That was correct. The PM announced the state of protections. That was correct. Yet you state that they had no clue.

If "they had no clue" is the cause, why haven't we seen a program immediately placed in our training to ensure that we all have a clue?

Hello,

I am reading the CVR from AF 447 and I wanted to know if anyone knew what the two letters P L meant when the Captain says "t'es P L toi" at 1h56 into the flight.

Thanks

You can download the english version of CVR transcript here:
http://www.bea.aero/docspa/2009/f-cp...nexe.01.en.pdf
Hope it's help !
Note:
Asking if he have the right license for make the job of PF (pilot flying) when the captain is not in the cockpit

I think I can see now where we don't seem to understand each other :
No autotrim means no alternate law no more Nz demand.
Direct, just direct law, where 20% displacement of the sidestick will produce 6 deg up of elevators.

No pilot I know couldn't have flown this aircraft or any aircrat by just using pitch and power. How about using what it had when the auto systems cut out. Why do we hire these pilots with minimum time that can't do simple tasks without autopilot? This is the future unfortunately.

The Perpignan report told us that the A320 THS has an electric pitch-up stop at 11 deg for a maximum THS deflection is 13.5 deg nose up.
For the A330, according to A33Zab, there is no such electric limitation.
After re-reading his post, I can see he had already produced a possible reason for which the THS did not reach the max deflection.

But once again, it was the BEA job to develop that stuff ...

If I understand A33Zab post (read between the lines ... ) maybe he think at the law (another!) "Unusual attitudes" who inhibit the autotrim system
Nevertheless .. nowhere in the FDR extracts of the BEA is show a trace of this law been triggered ......
I can be wrong ...

I don't disagree with that. But you miss the point, or you are evading the issue, so we still don't seem to understand each other. Maybe we should leave it at that.

EDIT:: One last try: If the system had been such that in Alt2B from the onset of stall warning the THS setting had been limited between setting at stall warning onset and 2° nose down (i.e. no further uptrim would be applied), but otherwise as is, i.e. Nz law without high-AoA protections, then the elevator trace on FDR would have been as shown by the purple line on the graph up to the point where the elevator reaches 30° at 02:11:41 (101 seconds after 2h10). Up to that point the airplane's trajectory and the stickforce felt by the PF would have been identical to those in the accident.

Might be there does also imply that they might not be there? Wouldn´t it be more usefull to know that they are there or to know that they are absent? Would it be comforting to have an antiskid system built into your car, but not knowing wether it is active or on leave? I can´t see any sense in your position.

Last try, then i give up. What kind of certain protections besides the mentioned load factor limits does it offer you are talking about? Would you please name them and describe them, that i can understand what kind of protections you are talking about? You also can PM me.

The longer the flight, the greater the accident rate
 

EXENG AF337 had been in the air for over four hours.

The longer the flight at altitudes like 35,000 feet, (at a cabin altitude of 8000 feet) the greater the likelihood that pilots will screw up - see J H Goode (Journal of Safety Research "Are pilots at risk of accidents due to fatigue?" Issue 34: Pages 309–313).
The pilots may feel fine - but they're not. It's not their fault. They haven't got enough oxygen in their bloodstreams. Their problem-solving capacity is degraded. Not a lot, but enough to make a difference in a complicated emergency.

Korrol

Obviously you wrote your post at the incapacitating altitude. AF337???

Well, the 337 is a twin. And also has to do with 02.

All things considered, O2 is of course a factor. Pilots get used to it, and it will not likely change. Saying it is no factor is simply simplistic.

You simply cannot obtain a similar trajectory with an identical stickforce with 2 scenarios as different as one with a THS set at 3 deg and another one with a THS moving from 3 to 13 deg.
A simulator experiment would clearly point the difference.

Trimming in a stall is an unknown procedure. It is dangerous stuff.
We need to ask Airbus why they think differently.
As the BEA avoids asking the tough questions, we need to do it.

That is just not correct. At FL350 the cabin altitude would have been around 6500 feet. I note that in the passenger forum you repeated the same incorrect information over and over, despite being corrected by several people who's correct information you chose to ignore. Now you do it here as if repeating it makes it correct.

If the premise your conclusion is based on is wrong, and you know that it is wrong, what does that say about your conclusion or you?

What a strange statement!

Airbus don't think differently - they simply never countenanced the idea that a pilot would pull into a stall, keep pulling through the stall warning and pull *again* once the stall was established.

Limiting the trim movement under stall conditions would be simplicity itself in terms of implementation - but the secondary implications (of which there are several) need to be thought through.

It's not a "tough question" - not even every contributor on this thread believes it's a *relevant* question.

As I say, at this point if you don't get the difference on a theorical ground, you would certainly get it through the practical experiment - If you ever have the opportunity to put your hands on a simulator, just try it, the word 'strange' won't have the same meaning.

HN39:

If I may make an input regarding CONF's statement...

The manual (hand flown) stall QTG's for the simulator are specified to be done in Direct Law with a specific stop manual trim speed. As you decelerate below this speed, without benefit of trim, SS movements tend to be exaggerated to some extent in both directions to maintain a stable flightpath, with varying levels of spring force to deal with.

If the entry is done in Alternate Law, as the rate of airspeed decay progressively increases with the drag buildup, the autotrim input essentially outpaces any necessary SS commands and allows a more 'relaxed' SS input, with less awareness of any spring force.

I think this what he is getting at, but I could be wrong, and don't want to speak for him.

(CONF: Thanks for the reference to the A33Zab post)

I need to borrow the formula of HN39 here :
What a strange statement coming from you !
Dozy, you keep coming back on how crews have been pulling back on controls all the way during stalls, but Airbus 'simply never countenanced the idea that a pilot would pull into a stall, keep pulling through the stall warning and pull *again* once the stall was established'.

So you know about it but Airbus don't ... Give them a call.

OK465:

Thank you for your post #1392. I understand most of what you are saying, except when you say "a more relaxed SS input". A valid experiment would compare the two cases at exactly the same entry conditions and exactly the same pilot inputs. On 'theoretical grounds' I remain convinced that the resulting airplane trajectories would be identical up to the point where the elevator reaches the stop.

That flys in the face of everything published about Airbus C* control law. It is supposed to be path stable, make an input and then the path will be held until you change it. If you point it up and don't have enough thrust then it will continue to pitch up to try and do what you asked, even to stall. The BEA make exactly that point in the report.

Sidestick force is not relevant because you could have let it return to neutral and it would do the same.

THS is not relevant either, until you reach elevator limit, because the control feedback loops will simply command elevator deflection to achieve the path. If the THS helps then they will use less elevator, if not then they will use more. None of that changes sidestick force as there is no feedback.

How are you programming in a 3deg THS limit in your sim when there is not one on the a/c - are you using a THS-failure setup of some sort or are you physically holding the trim wheel to override the autotrim or what ?

Stall is part of a procedure (outside test flights) ?:confused:

Trimming in stall recovery (if that's what you mean) damn well should be part of the procedure (if it's got to the point that pilots need a SOP for stall recovery:sad:) and definitely should not be unknown. Failure to trim in stall (and approach to) recovery has killed or nearly killed a lot of people, on bus and other types.

BEA doesn't ask because they have excluded autotrim as not relevant to this accident. I can see why: elevators alone would have got them stalled, kept them stalled (see OG and HN39 posts here, but BEA will have access to similar data), and autotrim did not hinder recovery because stall was never diagnosed (BEA conclusion) so no recovery was even started (BEA conclusion).

If BEA find something relevant but then fail to ask the tough questions of the mfr / regulator then you might validly criticise [actually I think they have on at least one point, but no ones really picked up on it here yet...].

You might also disagree with their conclusions, just as some think that their conclusion that the fin stayed attached is wrong (or at least not sufficiently investigated).

But what you are doing is the same as criticising BEA for not asking hard questions about the composite fin and its attachments - there might well be hard and interesting questions still to be asked in that area, but they aren't for this report because they didn't cause this accident.

Have to agree. Not only did AB countenance it, but they built the normal law protections to counter exactly that possibility.

Alternate laws are a failure condition, and 447 was several failure conditions down to the point that the protections were gone. At that point AB system designers didn't lose sight of the possible pilot behaviour, just that without valid airdata they can't build a system to help.

"a more relaxed SS input" was a veiled reference to once the desired trajectory is established it can be maintained "hands off".

With exactly the same entry condition, as a practical matter, I don't think maintaining identical trajectories could be accomplished with 'exactly the same pilot inputs' to the elevator limits.

I understand what you're saying, that in ALT LAW with a somehow fixed THS setting, the FCS should 'theoretically' reposition the elevator as necessary, even hands off, to maintain the flight path up to the point the elevator reaches 'full travel'.

In practice, in ALT LAW, if the THS is somehow stopped at any position, when further movement would be commanded, the FCPC treats this as a jammed stab and will only exercise about 1/2 of the remaining elevator movement automatically, leaving the pilot about 1/2 of the elevator movement for manual control.

And of course to make the comparison in DIRECT LAW (non Nz) requires a whole different series of pilot inputs.

So I see what you're saying. I guess it would be correct if one considered the limit of elevator travel to be 1/2 travel. :)

FCPC's are wonderful things.

FWIW I think you are right too. The key issue is probably how is CONF getting his 3deg THS limit in the SIM session. If he is using direct law then we're not even comparing apples and oranges, more like mayo and fruitcake. Might as well say a 737 would have felt different...

The comparison should be: pitch-alternate law with normal THS behaviour vs. pitch-alternate law with 3deg THS limit. With same sidestick inputs, is the trajectory the same (up to elevator stops) ?

CONF - is that what you are saying you have done in SIM and if so, how ?

Who's talking about C* ?
DIRECT LAW all the way since data are diagnotized as unreliable.
Why keep trying to patch on dubious data ?
Keep it simple and straightforward - No ambiguity.

As said earlier, protections and and autotrim can well wait for the next flight, what's the urgency ?

No. If you follow the thread and the accident patern it was all about further trimming into the stall - Where is it desirable ? Please explain.

That was in fact a side-effect of the intent. The reason the hard protections are primarily there is to allow the pilot to make control inputs at the limit of travel without getting into difficulty.

The fundamental aspect of manual control as it applies to the FBW Airbus flight deck is that the pilot makes inputs, observes behaviour and then corrects if necessary. Slamming the stick against the backstop and holding it there runs counter to this methodology no matter what law you're in.

Now - first rule of Alternate is that there are no hard protections. If the AF447 PF had heard the PNF's call of "Alternate Law" he had no business making inputs that aggressively.

Except that Direct Law throws the crew into a situation where the aircraft handles differently in *every axis* compared to what they are used to, which would likely be more risky than the current design.

In this case, what you're glossing over is that while autotrim in Alternate Law may have extended the duration of the stall if the correct recovery action had been taken, the fact is that autotrim will *help you recover* from stall by the simple action of pushing the sidestick forward and holding it there.

You're also avoiding the fact that holding the stick back like that at cruise is a thoroughly inappropriate response no matter what you're flying.

Sorry
 

Yes, inexplicably I did get the flight number wrong. Sorry about that. As I can't possibly live this down I'm now withdrawing from Pprune.

Even on your AF337 flight, the cabin pressure in an A330 on a flight of greater than 2.5 hours duration is set at 7,350 feet.;)

That seems counter intuitive. Do you mean other than a manual input to the Trim Wheel?

BIG deal BIG risk Dozy come back when you got some experience.

I have never made a secret that the attitude control was inappropriate.
It is not before the THS was at 13 deg that 'the stick was hold back like that'.
And thank you for reminding that holding back a flight control is inappropriate. I'm sure the PNF and the CPT would have loved to know about it when the PF was doing it ...

That argument might hold water if every (or even a majority of) line pilot(s) on here agreed with you, but they don't.

It should never have been held back at all!

The attitude on the ADI would have been a pretty big hint.

CONF iture

After all the debate over the unknown position of the other pilots SS, I now suspect that you would be happy to accept the "Iron Cross" display of the SS position on the PFD following an A/P disconnect and law reversion in flight mode.

I don't mean to be critical here but why would you find the THS movement disturbing? It is part of every Airbus FBW aircraft and quite successful if recognition and acknowledgment of it, by the crew flying, acts in a reasonable manner. In the flight control operation section of the FCOM, the THS is described in Normal Law as to what it does. Then in Alternate Law (ALT 1), it is implicit, similar to normal law with limited pitch rate feedback and gains, depending on speed and configuration. ALT 2 is the same as ALT 1. Only in direct law does the auto trim stop when manual trim is required and noted by an amber message. The auto function/THS movement is the result of whatever is commanded by the PF in sidestick movement, back or forward.
I've thought about what took place after AP/AT disconnect on AF447. It quickly became an unorganized experiment in flight ending with the comment "We've tried everything". In reality it didn't have to be this way.
From an earlier PJ2 posting in the AF447 Final Crew Conversation:
I don't think it can be said any better. The primary decision point was, "If the Safe Conduct of the Flight is Impacted" For AF447, it wasn't but the crew thought it was and they went set off in the wrong direction.
Aside from this on a more general note, there was an interesting revised book requested by the FAA and assembled by Airbus, Boeing, Flightsafety and various participating airlines and others. It issued prior to the AF447 accident, AF was not a participating airline but distribution of this to their flight crews could have been helpful. If you have not seen it, you can view it by going here:

http://flightsafety.org/files/AP_UpsetRecovery_Book.pdf

That's the precise period when the attitude got to 10 deg ND ... what a hint Dozy !

That is not correct either. The cabin altitude is limited to a maximum of 7350 feet, it is not set to it.

No please - Too many data already on that PFD.

And the period during the zoom climb where it was way in excess of what would normally be accepted? In any case, if the ADI is showing evidence that pitch stability is a problem then stall definitely moves towards the head of the table as far as probable reasons go.

Agree totally. If you can't see a yoke move look at the ADI.

And let's be honest, it's likely that most pilots tend to look *through* the yoke by default anyway...