@ Clandestino,

Post #477
"From the CVR report:
02.06.54 the crew say "Minus forty-two we won’t use the anti ice that’s a plus."

There are very few TAT recordings reported.
However, please see the report published in July11, page 86.
Time 0hr.09min FL. 349.92 Static temperature (°C) -43.5
Time 2hr.10 FL 350.44 SAT -38.8"
@ 02.06.54 the crew observe the SAT as -42°C
@ 02.10.00 (Interim report July11 page 86) SAT -38.8
By my maths, I make that 3 minutes and 6 seconds,
How do you make it two hours?

Edit.
The aircraft had 45° angle of attack.
Even if the nose was lowered by 25° I still make that 20° angle of attack.
Do you still think that that "aerodynamics were not enough to keep AF447 stalled"?

Thanks for these times Rudder. So using these data points, TAT was increasing at the rate of 1 degree per minute. Similar to the rate of increase with routine descent. You would expect the climate control to cope with this without the cockpit becoming uncomfortably warm.

So why did PF note at 2.08.47 that "You can feel already that it’s a lot hotter"

And why did PNF agree at 2.09.20 that "It’s amazing how hot it is all of a sudden"

It certainly doesn't sound normal or routine.

In fact, the increased temp is pretty much the last thing that PF and PNF ever agreed on.

I agree with you on their comments, but when viewing the FDR printout it is difficult to detect the change as the graphics have insufficient resolution. One possibility is not so much the temperature, but a sharp rise in the relative humidity which would have created the same feeling.

captain.
Ithink that pnf was hesitating to take over brcause he was not assigned pilot flying.and it feels like there had been personal issues that bonin was pf.Maybe we should no more about the personality of the captain.pnf had quite a lot experience,so why was he so eager that the captain comes back,instead of taking command and doing the right thing.

Hi gums,

Would you be so kind as to elaborate on the bolded sentences? Source and so on?

Why do I ask? Two things:
- AFAIK, stick free the aircraft holds its path, not "1 g". It may be that the path gives 1g (often it is!) but the law is "g demand" (i.e. stick not free) not "g holding".
- I was unable to find any credible document indicating that the stick free longitudinal behavior is different in Alternate law versus Normal law.

Thanks in advance :)


Hi rudderrudderrat,
The aerodynamics alone: you don't know. What you may notice is that the THS & elevators, commanding nose up, might have slightly influenced clean aerodynamics at that point.
What you don't know is what AoA will have been reached with thrust idle + stick full nose down and maintained there as long as needed (meaning eventually the elevators and THS would have winded down).
It can't be proven until test flights take place, and we all know there won't be such tests and why. OTOH, all indications so far show the nose would have gone down, down down, and the AoA would have followed.
Therefore I too do think that aerodynamics were not enough to keep AF447 stalled, and that this PoV ('locked in stall') is irrelevant. And it also may be used to used to divert attention BTW (this is not for you, rudderrudderrat, I'm thinking about organisations that have an agenda, out there).

Cheers.

I wonder whether the heat exchangers in the air conditioning packs could be obstructed by ice particles.

FCOM 1.27.30 Reconfiguration control laws: As I read this, alternate law pitch control is not identical to normal law.

EMIT:

"What she said is duly noted in the CVR transcription
(at times as noted by previous posters)

allo?

oui

allo?

Then no word, but a sound similar to one putting the phone back in the cradle

(word or group of words with no relevance to the conduct of the flight)?

Then no words but a sound similar to the ending of the cabin interphone communication

Needless to say that the pilots were to busy to pick up the phone."


If the pilots did not pick up their phone, how did she end up on the Cockpit voice recorder?

woodja51

"All the rest is academic , a bunch of folks died due to failure to fly the aircraft " that appears to be the case. However, failure to fly the a/c is a huge topic. Can you include some other evidence?

Lots of theory!
 

Lots of talk about lots of stuff... Facts:

Unreliable airspeed , if aircraft flight Jeopardised , ap at fd off. No more no less

Then

Stall recovery( if you put it there)...


Lower attitude

End of event.

Simple , problem solved no crash no dead people.

All the rest is academic , a bunch of folks died due to failure to fly the aircraft

And transit a temporary anomaly.

I sympathise with the loss of life , but the race to the bottom in flight training must be to blame at the core of this and is due to airline, manufacturers race to the lowest flight training cost base possible to meet min regs only.

It will only get worse with MPL.....but that is the future.

There`s one fact in this whole scenario,which is for me the most unbelievable part in the crew-captain relation.
we have 2 pilots in todays standard with a lot of experience(doing away for a moment the AF defiences in training we all konw about) flying ong haul for years no city hoppers.they were clueless,desperate,no solutions to solve their problems ,both (?) eagerly awaiting the captains return for relief.
And when that moment arrived the cpt back n cp they both are not able to give a professional briefing,the last opportunity maybe to save their lifes.What di they expect from him ? guessing ?
Can somebody pls explain that ? This can`t be explained by their mental state only.

I honestly think the actual cause for this accident is at hand. This thread has been three years analyzing incomplete and possibly inaccurate, if not fraudulent data. Stand by.

"There`s one fact in this whole scenario,which is for me the most unbelievable part in the crew-captain relation.
we have 2 pilots in todays standard with a lot of experience(doing away for a moment the AF defiences in training we all konw about) flying ong haul for years no city hoppers.they were clueless,desperate,no solutions to solve their problems ,both (?) eagerly awaiting the captains return for relief.
And when that moment arrived the cpt back n cp they both are not able to give a professional briefing,the last opportunity maybe to save their lifes.What di they expect from him ? guessing ?
Can somebody pls explain that ? This can`t be explained by their mental state only."

More than one fact. For three years this crew has been allowed to seem consummately incompetent, crazy, or impaired. Would it take much to upset the apple cart? Remains to be seen.

Capt.'s Return
 

Philip2141

This has always bothered me. When the CVR first came out, some were quick to support PNF as having some concept of the situation but limited by authority and what PF was actually doing.

BUT

PNF is desperate to get the Capt. back to the flight deck and when the Capt. gets there all he offers is:

"What’s happening? I don’t know I don’t know what’s happening"

and

"We lost all control of the aeroplane we don’t understand anything we’ve tried everything"

IMHO, he was not calling the Capt. back due to command issues, which I believe was suggested earlier--he had no idea what was going on?

Also, what had they tried?

Switch to ATT?

Well, i´m not sure what you both are getting there, therefore i try to summarize the issue about stability in my own understanding (feel free to correct).

The airframe itself is, no, must be natural positive stable, otherwise it would not be flyable in direct law.

In Nz-Law, which applies in all Laws except Direct Law Ground Law and Flare Law (did i forget one?) the flight control system creates an artificial neutral stability by use of elevators and THS trim, leading to a stable flightpath without SS input. Not the SS drives the elevators, but the flight control system using present flightpath and the demanded change from that flightpath.

Protections are there to keep this flight path stable airframe within the flight envelope, in simple terms to deviate from this ordered stable flightpath when set parameters are exceeded. There are other tasks to be fullfilled by those protections as well, but not of relevance what i try to get at.

When those protections are degraded or lost, we still have an airframe with artificial neutral stability, as the flightcontrol system still works along the demands of Nz Law, but the protections to keep the aircraft within the flight envelope are gone and have to be replaced by the skill of the crew.

In the case discussed here once on the way up to the apogee the Flight Control System was trying to maintain the flightpath with elevator deflection and THS trim blind to the fact (protections lost) that it would run out of airspeed in doing so, will finally stall, as it did. The crew, who should have compensated for those lost protections was most probably unaware of that fact too, otherwise they wouldn´t have continued to apply NU SS. This NU SS had not much influence after the stall happened, as the flight control system was beyond it´s capability to maintain the flightpath (descending already instead of continueing on the ordered climbing trajectory). The SS movement between NU and Level had no effect and showed no reaction to the aircrew, thus it might have contributed to the confusion.
Neutral SS wouldn´t have cured the problem, only ND SS would have changed the trajectory.

What BEA was getting at with the cited paragraph few posts before is imho, to show the reason for this behaviour without getting too much into details.

@ gums my friend in arms, if i remeber correct the F16 airframe was naturally unstable and a diferent beast. Your comment to blend the Nz-Law with the present (and available) AOA value for a backup in ALT laws with normal protections lost seems a reasonable consideration.

2:10:53,5 A first cabin crew or flight rest facility call (high-low chime) was heard
2:10:55 A noise on track 1 of the CVR, which may be the impact of the microphone striking a panel
2:10:55,9 Track 1: allo?
2:10:59,4 oui
2:11:02,3 allo?
2:11:08,3 noise of someone trying to park cabin interphone handset
2:11:09,8 - 2:11:27 Five call signals to the crew rest facility

Hi HazelNuts39 :)

Thanks, I maybe should have precised that I've read that too ; "limited pitch rate feedback and gains" apply to a manoeuver, i.e. when the crew commands something via the stick.
My question was about the stick free longitudinal behavior. It remains unanswered.

Maybe it's because AF culture .......

As I understand the C* control law:
C* = q + a*nz, where q = pitch rate, nz = incremental loadfactor, and a determines the 'blend' between nz and q feedback.
For side stick neutral C* = 0, hence q = -a*nz

Hi HazelNuts...

From EMIT: "Relevant
What she said is duly noted in the CVR transcription
(at times as noted by previous posters)"

What I said: "How can her voice appear on the CVR?" The "allo,Oui,allo" is from Pilot Bonin....

Thermalsniffer...

I do not mistrust PNF comment, and I believe he is correct: they tried everything to regain the flightpath. Their problem started at autoflight disable, and flight control disable. Pitch control was unavailable, navigation had been lost, and other problems emanating from a problem in the cockpit area were cascading. Neither pilot understood the scope and hopelessness of their issues. After Captain re-entered the cockpit, he immediately understood the crew were doing what they could, but him taking the controls would be not advisable, what control they had might well be lost if a transfer to him was accomplished.

PNF was reluctant to take control, that is why there was no permanent change.

There is no chance they didn't have the experience of STALL, and know exactly what was happening...To this extent: They were in trouble, and they had no control over the aircraft...the stick traces were not Bonin's. They belonged to the aircraft. Robert took the stick back as Captain returned, his input had no effect, as Bonin's controls hadn't either...in the climb, Bonin's confusion is not confusion, the a/c is not responding to his inputs.

Shortly after 447 was lost, another a/c, a 340, also lost Pitch control...

Trying to assess the human factors issues is crucial - not only to build an understanding of what transpired, but also to decrease the risk of a recurrence. Unfortunately this human factors assessment has been made more difficult as we have only been given selected extracts from the CVR. I am sure there are plenty more clues in the bits left out. In addition, we lack the all important quality of the speech - tone, volume, tempo etc

However I do understand and respect the view of BEA that some things do not belong in the public domain. All we can hope is that the human factors people that were involved in the investigation and privy to all the detail learned all there was to be learned.

Why did the Captain take more than a minute to get back to the cockpit? He was a 58 year old male. He had been in the cockpit for 4-5 hours prior to his rest. He would have had a meal and maybe some coffee. Where would he most likely go immediately after leaving the deck and before resting? I would guess that he was in the bathroom?

Despite all the talk here about the kids in the cockpit, both PF and PNF were reasonably experienced. The Captain seemed happy to leave for his rest, despite commenting that it would be turbulent during his rest.
1 h 51 min 58 It’s going to be turbulent when I go for my rest.

There was a very short handover to PNF when he arrived. Less than a minute between his arrival and Captain's departure. Despite ICTZ. Despite turbulence. Despite rising temp and a discussion only 10 minutes earlier about implications on max altitude.

So he seemed pretty confident in the other two pilots. Maybe too confident?

The guys really let Dubois down with their gibberish when he returned. If he was that confident in them and if they were essentially incoherent when he returned, then he may have been immediately overwhelmed by a perception that something very complicated must have taken place. He didn't rush in and take corrective action - because the problem was not clear to him, and no one told him what had happened. So he had to try and make sense of a cacophony of alarms, faulty data, error messages, and bewildered pilots who he believed were competent.

You can't expect someone to explain what they don't understand. But you can expect a concise account of what they did know. Look I not a pilot. But in my line of work (critical care medicine) I frequently get asked for urgent assistance when things go wrong. I don't expect solutions - that's my job. But I do expect to be given some useful information about events before I arrived. I understand this is harder for pilots than doctors - aviation emergencies are relatively rare, pilots may have concerns that their actions were somehow responsible for a problem, and they may even have concerns about their safety. Clear thinking and analytic skills go missing in the setting of unexpected stress and anxiety. But even allowing for all this, these guys appear to have dropped the ball - and possibly lost the final opportunity to recover the situation.

A couple of interesting comments from the Captain in the hour prior to his rest period:
0 h 58 min 07
Captain Try maybe to sleep twenty minutes when he comes back or before if you want
PF Yeah ok that’s kind, for the moment I don’t feel like it but if I do feel like it yeah
Is Dubois really saying he was happy for PF to have a doze while Dubois was having his rest period? Surely I am misunderstanding this.

1 h 27 min 56 How badly we see in this aeroplane with this lighting. It’s not a success
Could he have had trouble seeing the displays when he returned and was sitting behind the 2 pilots?

He was that female voice?

Gents,

If you will allow me to chip in ....

Quite so - but when people say that they are usually talking about the short period motion. CG ahead of aerodynamic centre in the classic sense for stability - that qualification says nothing about the long period (phugoid) motion

C*, by itself, is a system to shape the short period response into a form that pilots will like. When implemented as Airbus do it acts, in the absence of any further pilot input, to maintain the flight path constant as Franzl says.

But if the flight path is constrained, whether that be level flight or an approach path, the natural phugoid is suppressed because you have taken away one of its degrees of freedom. What you are left with (for the 'natural aircraft at least and apart from a stable short period) is a simple subsidence or divergence in airspeed, i.e.it becomes a speed stability issue and one where what matters is how (Thrust - Drag) varies with airspeed with throttles held constant.

Something like the A330 is speed stable for excursions above the (trimmed) cruise speed because you very soon run into drag rise. Below trimmed speed however it becomes a bit more problematical.

When one takes Mach number effects as well as the classical drag 'bucket' into account modern airliners have a drag vs speed curve that looks more like a flat-bottomed 'bathtub' than the classic parabolic shape. Depending on how thrust varies with airspeed (again at constant throttle) the speed stability is just about neutral over a fairly wide range of airspeed. It varies a bit with altitude, being slightly less stable at say FL370 than at FL350.

It is because of this neutral stability on the low speed side that 'buses' use A/T in cruise to sharpen up the aircraft response to disturbances.

Before anyone starts to yell "I told you so - the aircraft is unstable without A/T" just remember that if the aircraft is only slightly speed unstable (as seems to be the case) it will take a very long time for small initial diversions in speed to develop into serious excursions. Typically, from cruise down to Vs1g might take anything from 5 to 10 minutes but the rate of divergence escalates rapidly as one gets near that point and most of the speed divergence will be in the last say 30 secs. Once you get beyond 'stall' the rate of divergence rockets up. Hence the need for prompt recovery action.

It must also be apparent that modest speed instability, by itself, could not explain this accident. To reach the timescale recorded the aircraft divergence would have to have been 'helped' by pilot action - as it was. But once the aircraft was down to speeds at or below Vs1g the aircraft's natural speed instability would have made a significant contribution to the rate at which speed was lost.

Agreed!

I'm not so sure about this. The flight control system would still have been trying to maintain the flight path, but the flight path it was trying to maintain was that being demanded by the pilot as seen by SS movements - an increased 'g' command. So far as I can see, the continued NU SS and accompanying THS movement would have made things worse for recovery because they trimmed the aircraft into a higher AoA than it would otherwise have achieved.

Agreed.

CVR
 

Lyman,

If Bonin was the speaker, then the words "allo? oui allo?" etcetera would have been placed in his column, labeled "Copilote place droite".

As it is, the words appear in the column labeled, among others, "Autres voix".

The mystery of the voice appearing on Track 1 (Piste1) is not so mysterious - if she picks up her phone, she is on the line, i.e. will be recorded.
Compare it to the situation where a pilot pulls his headset cables from the plug and keeps his speaker off - what is received via radio will still be on the recorder track, even though that pilot will not hear it.

Another mystery solved, I hope.

I guess we have to define terms, and "flight path" is one term that may be causing us to debate a few things about the control laws and the natural aero characteristics of the 'bus.

A very good explanation of some things, Retired. But I expand...

Courtesy of some of the pilots here, I have a decent set of the manuals. And from what I see, the FBW system is strongly biased for a one gee flight, and not an "attitude hold" mode as we had/have in many jets with autopilots. It also appears to have little AoA bias, but only some "limits" to stay outta the stall regime. Body rates and gains are contributing inputs, as was also the case in my primitive system. The positive longitudinal stability most of us were/are used to is not based on AoA in this system. Let go of the stick and the sucker shoots for one gee corrected for pitch attitude. If that ain't the way the thing works or is supposed to work, please correct me.

I iterate this point because it's exactly the way our primitive system worked. The biggest difference was we could set the desired trimmed gee, and our system wasn't trying for one gee all the time, nor did it correct for pitch attitude. We had zero static stability "feel" for AoA as most of us are/were used to. Only reason the nose went down when relaxing pressure on the stick was to achieve the trimmed gee ( nominally one gee according our trim wheel, which allowed about 3.5 positive and a bit over one gee negative). If we trimmed full back, and let go, the thing would do a beautiful 3.5 gee loop, and the gee would decrease as we hit the AoA limit until we got to one gee or a bit less. AoA would be pegged at 27 degrees. Coming down the back side, and speed building, the thing would get back to the 3.5 gee trim command and finish the loop.

I bring all this to the table to help folks understand the difference between FBW systems and the conventional control systems we flew that were based on a trimmed AoA. Sure, we could build a great FBW system that was strongly biased for AoA, just like the "old days". In fact, our system did that with gear down. We biased the gee command with AoA to give us the same old feeling we had in the days of yore ( no auto throttle in the Viper, unlike the Hornet, so we could trim for an AoA and use throttle for vertical velocity). In a FBW system you can overcome all kindsa nasty aero characteristics until the confusers go to la la land. The 'bus seems to be a very benign, stable platform. So even in "direct law" it can be flown by humans. Ours was not stable until above 0.95 M or so, and if the control surfaces went to neutral due to computer failure, the thing went nose down ( 22 negative gees on one of our first computer shutdowns due to power failure).

We could build a FBW system that only used the electrons to command control surface position, just like the old days except the hydraulics didn't use a valve at the base of the control wheel/yoke/stick. We could even build one that used electrons to power the actuators for each control surface.

But we haven't done that. We use the neat computers to reduce workload and overcome aero characteristics of the platform. So we see a lot of "autopilot" functions embedded in the system. Those are the things that bother me. Those are the things that gradually destroy basic airmanship and understanding how our jet flies.

'nuf philosophy for now.

Thanks EMIT.

I thought the recording of the voice was after the lack of pick up from cockpit area. Next time I'll try to engage brain before keyboard.... Well, at least I'll try.

:O

I have no idea what Lyman has been smoking. His suggestion that the female voice was Bonin's is ludicrous. According to Otelli, the four transmissions in a female voice recorded on the CVR came through on the intercom speaker, were all made by cabin crew, and were all questioning or exclamatory (he transcribes the call at 2:10:59.4 as "Oui?" and the one at 2:11:24.9 as "Stéphanie!").
Even more ridiculous is Lyman's theory that the aircraft was not responding to Bonin's control inputs. It reacted exactly as expected. At 2:11:34.7 (ca. 1.5 min after Bonin had pulled back on the sidestick following A/P disconnect), at around FL360 and TOGA, Bonin announced that he had lost control of the plane and proceeded to pull the stick even further back and to the left and hold it there for 40 seconds.
Equally silly is the suggestion that Dubois, when he re-entered the cockpit, did not want change places with Robert for fear that all control of the aircraft might be lost. They were still at 35,372 ft, surely to God you'd think you'd still have a fighting chance to rescue the situation.
Finally, let's put at rest, once and for all, the impression that all three pilots were experienced veterans of long-haul flying. Bonin definitely was not. Before leaving the FD to take his rest and designate Bonin as PF, Dubois had to assure himself that Bonin possessed an ATPL.

My suggestion is you consider that without a complete record, posts like my last one cannot be contested without either full and naive faith in the report, or possession of substantiation that is not in the public record.

http://i45.servimg.com/u/f45/11/75/17/84/ltop_a14.gif

Prends WHAT ... ?

We can continue for months to discuss technical specific aspects of the Airbus A330 and continue to speculate about what would happen if and if ..
Nevertheless .. all of these discussions will not bring anything more than what is in the BEA report and even if one member of Pprune find the Holy Grail to solve some problems .. the final report will remain as it is .. that is to say engraved in stone
The next episode (for those who are still fortunate to be there ..) will be the trial court
It may be that short of it .. other experts (judicial) have other discoveries to argue ... and maybe some explanations will be sought from BEA and regulators and airline(s)
The debate (such as currently conducted in PPrune) will certainly be very interesting from all point of view .....

That can be anything ... a indication from a instrument or display (if this is a finger pointing to it) or even a pill to calm nerves ......

Why is the altitude alerter intermittent? Aren't they at this stage off assigned 350?

Hi Lyman,
It was sounding continuously until impact. It was interrupted by higher priority warnings such as "single chime"; "SV Stall", "cricket" etc.

No one cancelled it, no one commented on it, it's as if no one heard anything.

It was like background music, nice to have, but can be switched off sub-consciously when concentrating on something else.

I differ in that the artifact is fin C Chord if replaced by higher priority, instrument protocol would choose another word, besides "fin".

Is there no alert that signifies over ride due priority?

OK, thanks. I really should have paid more attention in math classes, back then. :8
Would that make the Alternate law stick free behavior different from that of the Normal law? q limits is different, yes, but?

Again, I may well be completely wrong, but my interpretation of "limited pitch rate feedback" would be that the alternate law value of 'a' is different from normal law.

Following from A330 Instructor Support ManualWould seem to make sense, otherwise the A/P would need to function differently in either law, and so would the pilot using the SS.:eek:

I believe I've read somewhere that the different laws only affect the flight control system interpretation of side stick inputs. The autopilot commands are processed outside of the laws. Protections override side stick as well as A/P commands.

I'll see if I can find anything else, though I must admit I have also seen what you referred to.

There are differences in Pitch law between ALt1 and Alt2b
 

@ Owain Glyndwr, mm43,HazelNuts39, AlphaZuluRomeo and all

I read the following out of the A330 technical training manual that AF447 had no high speed or low speed stability protection left (as it would have been iN Alt1), but only protection still available being the load factor protection.