JD-EE,
Possibly it was even close to start to work (decrease from 7000 fpm to 700 fpm).
We'll see in a few weeks.
But remind (as said by others) it was never in a nose-down attitude.

This was posted by fantom. I believe this to be one of the most reasoned posts in this whole thread.

He is the most capable operator of the bus I have ever seen. He is also one of the best training captains, if not the best, our company ever had. It is a great shame that he now just walks his dog!

JD-EE;

The zoom climb to FL380 described in the BEA update is fully explained by the pitch-up to 10 degrees nose-up attitude. An updraft doesn't cause an airplane to pitch up. BEA doesn't say there was an updraft, but that can be easily determined from the FDR recording.

Hi,

I'm not a 'bus driver, so please forgive my question:

Is a (deep) stall at this altitude with this AoA in the beginning recoverable in terms of aerodynamics and the plane's datum (fuel balance)?

horizontal stabilizer ineffective
 

airspeed (a/c aft/fw speed vector) almost zero

ground speed at around 107kt

I suppose that elevators wouldn´t sustain a 16º pitch-up in such conditions if the weight was in the right place.

On the other hand, I also suppose that the (fixed part of the) horizontal stabilizer would be of some help on pitching the a/c down with a 107 kt ground speed (air against the HS, c.g in the right place, center of pressure on the wings - should work like a lever)

Maybe automation is not the culprit this time. Honestly.

Many people are wondering if as is speculated why the PF pulled up as one of his initial actions. I think on Page 1 of this particular thread one explanation has already been given:

"If he thought he still had stall protection, would commanding pitch up be a way of trying to tell the aircraft: I don't want to lose altitude, and I'm relying on you not to let me stall?"

Could that desire not to lose altitude be linked due to the weather deviation,(which I think could be one of the psychological factors affecting the PF's initial reaction) in that they were just clearing the tops of a cell and were worried about the subsequent impact of losing it. Hence the application of TOGA to attempt to compensate for the pitch up.

level100
 

hi thanks for your reply. could you please tell me how the ISIS operates:ok:

Possibly a foolish question (SLF here), but why did the plane describe an almost complete circle on its descent? Is this just to do with the roll oscillations?

Why do you say it didn't work? Right after the part you highlight, it says: "The vertical speed, which had reached 7,000 ft/min, dropped to 700 ft/min". Seems to me (from the little we are told here) that it WAS working.

Problem is, the very next para goes on to say: "The PF continues to order pitch up" so at some point the PF had evidently gone from giving nose-down inputs back to giving nose-up inputs. Why? This is all within the first minute, so those pitch-down inputs cannot have lasted very long.

Now, the stall horn did go off as the A330 reached 37,500 feet, that is shortly after (at least in the narrative) the pitch down commands. Is this what you mean by "it didn't work?" More to the point, could the PF have interpreted this as indicating that pitch down "didn't work"?

But what is surprising about a stall horn going off when a heavy airplane has just climbed rapidly above the cruise altitude that the very same PF had, just a few minutes earlier, say they could not climb above, probably losing speed in the process, as well as increasing its AOA? It seems to me (admittedly from the comfort of my couch) that the reaction should have been: I haven't solved the problem yet, and need to keep at it.

Nobody has mentioned "deep stall" in any published information so far released.
The only mention seen is through conjecture on these forums.

My limited understanding of the phenomena is that this aircraft layout and configuration is not susceptible to that phenomena; my recollection of initial type rating training (A320) was that it was demonstrated (in the sim) that the aircraft could be stalled, and that recovery was conventional.
There is, in other words no high tail to be masked by turbulent flow.

The video of the Tarom A300 incident on the sister forum seems to bear this out, the aircraft stalled and recovered at a comparatively low altitude.
(credit to the cabin crew for the ice cool cabin p/a btw .. she must have been very shaken).

With the initial findings released, there seem to be many complex layers to the Swiss Cheese, hence, this will take time for the full ramifications to be distilled out.

(I take on board the comments below regarding the position of he THS, it has indeed a very powerful influence on commanded pitch vs available control Authority .. that did not seem evident in my reading of the Tarom incident)

The sad thing is PNF seemed to be more aware of what was going on. Very early on in the sequence PNF effectively declares, we are in UAS regime and we've lost protections. PF never acknowledges. I think it was so close to AP/ATHR disconnect, that PF was fixated on trying to make his own assessment of the situation. It seems it never registered with PF that they were in UAS and/or ALT2. His actions are inline with believing either he was overspeeding or was in Normal Law. (doesn't matter which one)

Close to 2 minutes later when PF finally declares he cannot believe his instruments, it was too late, he had put the a/c in a stall regime.

The stall warning coming back when they pitched nose down didn't help either. The initial response from the PF may have been wrong, but then on it was a concerted effort by PF and computer to hold the a/c in a stall.

Very sad... :{

We're not much wiser after reading the latest report and won't be until DFDR trace and comprehensive CVR transcript are released!

Because THS got 1° shy of full nose-up trim and remained so throughout the descent, all the way to splashdown.

I'll release virtual dogs of hell upon anyone who even hints that DP Davies is old-fashioned irrelevant in our day and age!

I'll assume English is not your mother tongue and you're familiar with A330 yet the intended meaning of your post got somehow lost in translation.

To set the record straight: horizontal stabilizer is very effective and it has no fixed part whatsoever.

Careful. We have obviously been given a VERY partial transcript of conversations in that cockpit. We don't KNOW that he never acknowledges.

deSitter, #402
Sorry, another unpalatable plate of tripe. If you were a professional in
any discipline, you would realise that such areas of work always have
unwritten rules that govern personal ethics and due diligence in all aspects
of the work. Such people are dedicated and to suggest otherwise, cast
aspersions etc, says more about you than any of the people that design
airbus products. Sure, they get it wrong sometimes, but that's what it
means to be human and yes, some aircraft will crash and result in loss
of life; that fact will never change. Check out actuarial data if you
want to see the reality, but also see how safe aviation is in comparison
to other modes of transport.

Try also to remember that software is mechanistic, stupid and at the bottom
of a very deep tree. For avionics, it is a machine reflection of the laws
that were designed into it by systems, aeronautics, airframe, power plant
and a host of other engineering disciplines, each of which will have a
team of specialists to decide the best approach.

As i've said before, it's easy to design a system where it's assumed
that there will never be faulty data or failures, but as
requirements get ever more complex and more systems must be connected
together, handling edge and failure cases in a predictable manner
becomes more and more difficult to provide for and to prove correct.
If you don't build capability to handle all the extreme cases into the
system, then there is no code to execute for that extreme case. By code
here, I mean overall system coordination and behaviour. Since there are
probably millions of possibilities in terms of the sequence of events
leading to an aircraft crash, it's not possible to design any system to
automatically handle all of them.

bonjour ami

takata........

Hi bear,
Quote:
Originally Posted by bearfoil
"...Many posts discuss the continuous back stick..."
Please show where in the BEA report this is stated.......

0210:05...The airplane began to roll to the right and the PF made a (ONE) left nose-up input.
0210:51...The thrust levers were positioned in the TO/GA detent and the PF maintained nose-up inputs (Plural, more than one) ...The PF continued to make nose-up input(s). The airplane’s altitude reached its maximum of about 38,000 ft...
0211:40...The PF made an input on the sidestick to the left and nose-up stops, which lasted about 30 seconds.
[French: 0211:40...Le PF exerce une action sur le manche en butée à gauche et à cabrer, qui dure environ 30 secondes.]
"en butée à gauche et à cabrer"= full deflection, stick left and nose-up (during 30 seconds)."
************************************************************ ***

AoA is sensitive to airflow in more than one direction. Initially, what appears to be a bunk move may be an aviator's attempt to hold altitude and airspeed in remarkable AIR. He has a/s to barter, and adds TOGA for good measure.

Let's for goodness' sake lose this barking dog mentality, and give the PF some credit.

I read from BEA that the PF made REPEATED inputs (NU), not sustained.....

different perspective.......

What would explain the need for constant roll left, to maintain SL?

damage? AIR ? cg? Likewise NU? cg? ICE? All we see is the response, not the stimulus.

Agreed, it's a nasty pattern developing, and nothing to do with A vs B or FBW (everything to do with higher-level automation though).

However, it isn't at all clear that 447 fits this pattern. The trim up in this case is after the a/p drops out, and in response to pilot inputs. Initially at least, auto-trim is still active, and responding to nose up (to the stops) stick input.

It remains unknown from what info the BEA choses to give us at this point whether or not other control law transitions took place which might have kicked auto-trim out later. I think if direct law had engaged it would be clear and would have been reported - but I am not so sure about abnormal attitude law, looks like at some points at least they should have been in it, but BEA does not mention, possibly still trying to determine that.

One thing that does look clear, is that regardless of what the THS did, when they put the stick forward, it sounds like the a/c responded - reducing the pitch. It would appear the inputs were never held long enough to actually put the nose down.

Or in other words, from what info we have, it doesn't look like they lost pitch authority.

Teddy Robinson
You are absolutely correct, and even though I have used the term, it was describing the attitude the aircraft was being "held" in. They were not "cast" and were capable of correcting this, but were as this Antipodean would put it, "Transfixed like a possum caught in the headlights".:sad:

Mixing up autopilot and protections/laws there. As I understand it A/P can be re-engaged in alternate law (once you've recovered stall), but normal law will not re-engage for the rest of the flight, so no protections (except g-load).

Back to some aero for the newbie posters/questioners here
 

One poster asked if it was possible to get into a stall and not be able to recover.

Answer? Yep.

So see this old post from thread 2 once we got thru all the search procedures, pinger characteristics, FDR construction, etc.

http://www.pprune.org/tech-log/44963...ml#post6432295

It is entirely possible that even full nose down elevator commands in Direct law could not provide a high enough pitch coefficient to break the stall. This could be due to the THS being trimmed almost all the way to a nose up command and the relatively small surface area of the elevators. Until I see a good pitch moment chart as the one I posted for the Viper, I'll reserve further speculation and only say that it is indeed possible.

I also point out the "golden arm" test pilot's description of the "ride" when in a fully developed deep stall. Any resemblance to the AF447 profile from 35,000 feet to impact is purely coincidental, heh heh.

Gums sends...

post seemed to be edited by "janitor" for a crass "You Tube" reference. LOL.

DFDR does record FBW law. Patience is the keyword.

ask26
 

:ok:
You know, you may be so on the money.

All the "haters" on here can't even recognise a simple human decision, a decision made in an attempt to avoid further "difficulties".

clandestino:

You are right. It is trimmable and it was 13 degrees down (pitching-up). With 107 kts ground speed it could maintain a 16 degrees a/c pitch-up attitude.

Let's get back to automation, then...

P.S.:

Somebody must have asked this before:

If the trim was not performed by the PF but by HAL would the PF be easily aware of this ?

Which is what it does, and what happened. With the addition that because speed is known-bad the speed-based protections drop out. And control gets handed to the pilots - because HAL isn't sure what the plane is doing any more.

With no control inputs, the plane should just keep doing what it was doing before, here something causes a roll and pilot responds with full back stick and all hell breaks loose.

I have to wonder if the initial thought of the PF was (after auto pilot, A/T disengage) to not let the aircraft increase its speed due to the anticipated turbulence upcoming. Remember there was a crew communication to the cabin about "it'll move about a bit more than at the moment" (2h06m04), along with the crew deciding to reduce speed from .82 to .80 a few minutes later (2h08m07) due to the anticipation of turbulence - "turbulence increases slightly". About 2 minutes later is when the A/P and A/T disconnect and the speed drops from 275kt to 60kt and a few seconds later the crew identified "so, we've lost the speeds". So now recognizing that they had invalid speeds, and knowing they needed to avoid penetrating the turbulence at too high of a speed, I wonder if the initial thought was to apply nose up inputs to ensure turbulence penetration speed was not exceeded. I also have to wonder with this being fresh on their mind, it might have been their initial concern when losing the speed indications, that we can't penetrate the weather at too fast a speed. Then while troubleshooting and dealing with everything going on and possibly being distracted, realized there was too much nose up input and went to nose down (7000ft/min to 700ft/min) You also have to wonder if through this whole ordeal, if that was something they were fighting if they were in IMC conditions and rough air for most of the 3 1/2 minutes.

Right or wrong, I just know that the weather and reducing speed was fresh on their mind. When the A/P and A/T disengaged, maybe there was zero panic and they were confident how to handle the situation and simply were going to wait for the speeds to come back. The other thing that caught my attention...was the crew briefing just before the captain left. The briefing from crew, was that they couldn't climb right now "we’re in the cloud layer unfortunately we can’t climb much
for the moment because the temperature is falling more slowly than forecast" - So I have to wonder if that is something they had discussed earlier about possibly trying to climb above the current cloud layer, but couldn't due to conditions and aircraft config at the time. When they lost the speeds, I wonder if there was a thought of trying to climb if they could to see if they could get to 1)smoother air and 2)out of the cloud layer to hopefully clear the pitot sensors.

I am probably reading between the lines, and CVR recordings would help to identify some of this. I just find it interesting that climbing was part of the crew briefing.

So did the PF try to pitch up slightly to keep the aircraft speed below .80 since they were now more than likely penetrating turbulent air? And was there a desire to see if they could get to a higher altitude (out of IMC) to help resolve the issue with the speed sensors? Again right or wrong from SOP, but it could point to one of the reasons of nose up initially. Once they entered a stall, that created a whole host of other challenges.

I haven't flown in a few years and only flew corporate jets for several years, but the mindset of the pilots will be very hard to decipher even with CVR recordings, which will help to paint a better picture of what they were thinking. I want to be able to give the pilots the benefit of the doubt and would like to think that there was some logic in the initial nose up and at other times nose up commands. As pilots, we need to be supportive of each other, and realize that many of us have been fortunate enough to not have to deal with a "hairy" cockpit in our careers. But for those that have, like this crew, we have no idea what was going through their heads.

So who has eliminated all but UAS? What was PF's initial control input, a rather robust response and result. What caused his reaction? Did a/p drop before or after, and either way, was its involuntary loss linked to the manouver? The conditions in the cell? Fixation is neurotic........and leads to accusations and unsupportable claims. Just for review, a Stall warning is not necessarily a Stall.

It depends on how you look at it. Four minutes is a lot of time for two pilots to be startled or surprised. It's not a lot of time for pilots who are confused. I think it's important to be quite clear and specific in regard to the terminology used.

In any event, I think the time issue is a red herring. What the flight crew should be judged upon is not the length of time they had but how they utilized the time they did have. Was their behavior in accordance with their training? Was it up to professional standards? The fact that there was only four minutes before the plane crashed was not a predetermined parameter set in some sim session; those four minutes were a function of the flight crew's inability to prevent and then recover from a stall.

That depends on how you define "deep stall". From BEA's Update Findings: For a groundspeed of 107 kt, the last recorded values (assuming no wind) correspond to a flight path angle of 45 degrees down, i.e. an AoA of 61.2 degrees. Deep?

mm43, nose never down notwithstanding the PF pushed the stick forward.

The plane was stable for about 35 seconds before another stall warning, which may be appropriate given speed and altitude. What happened next seems to make no sense. I also wonder why PF did not push stick forward again to initiate a descent back to FL370, which would be safe and beneficial given the speed report that returned. Of course, he may not have trusted it.

Nothing there to pull the nose up.

The nose-up input - would that be to maintain altitude while correcting the roll? It does not say how large a nose-up input was made for how long.

If the PF had not made a very assertive nose up what brought the nose up 6 whole degrees on a plane with that mass? (Mind you, I am not at all sure an updraft would lift the nose.)

(And I keep quoting because it seems some of us are not working off the same document. That way the source of my confusion is at least well delineated. I'm not trying to be a smartass - except maybe to bienville. He twisted my tail.)

Stall warning => nose down or die
 

"A formal document detailing the rationale for the revision points out: "There have been numerous situations where flight crews did not prioritise [nose-down pitch control] and instead prioritised power and maintaining altitude."
Operational experience has shown that fixating on altitude, rather than the crucial angle of attack, can result in an aircraft stalling."
Revised stall procedures centre on angle-of-attack not power


A pilot that doesn't nose down immediately when earing a stall warning has not understood what is a stall : the plane is no longer a plane, it is a cucumber.

When you ear a stall warning, you are about to die within a min => you don't even remember your name : you nose down.

The trouble is that :

" The statistical data shows that, when confronted by a stall, in 80% of cases, pilots pull back the control column, in a sort of reflex movement, which continues the loss of control.
The aircraft was subjected to a series of four full and rapid rolls. The first was attributed to the force brought to bear by the pilot on the left part of the control column; the following ones were due to pilot overcompensation on the roll then the stall. Having pulled the control column fully back and thus caused maximum nose up pitch, the pilot rectified this by pushing the control column fully forward. The aircraft dipped, with its nose going under the horizon by 32°. The roll-off from +50 to –32° in seven seconds was remarkable."

REPORT on the incident on 24 September 1994 during approach to Orly (94) to the Airb

Deep stall post referenced
 

Hazel, et al.

I re-posted the deep stall stuff an hour ago.

CogSim, good catch on the PF never acknowledging the PNF statements. It certainly does seem to match a hypothesis that PF was fixated on the unitial WTF moment.

Clandestino, the initial nose down command was way before the THS was stuck at 13 degrees. That started about 35 seconds later in the sequence at 2:10:51. And as I read it 2:10:51 was the start of THS movement from 3 degrees to 13 degrees.

{^_^}

"Transfixed like a possum caught in the headlights"
 

that, quite possibly, could be the conclusion drawn based on what has been released so far, still, until the investigation process has properly run it's course, and the full transcript released set in context, on a time line, it is all too easy to draw conclusions, when there are levels of other systemic failures that are not so easily identified.

I would expect the rate of BEA press releases to slow down from this point until the release of an interim report.

Re: deep stall, at this point, unless the term is specifically used by BEA, it remains conjecture. High A of A, high descent rate, low forward speed may fit the base line criteria for a deep stall condition, however, the term used is a recognised condition, which until officially cited by the investigation as affecting the airframe, on a type and configuration not usually affected by the phenomenon, may be a reasonable descriptive term in conversational terms ... but ...

Sorry for being pedantic.

Clipped from an earlier post..

Thats less than 11 seconds from tripping the autopilot to a stall warning. I'm not a jet pilot but that sounds quite fast. Is it?

JD-EE

From 2 h 10 min 05, the autopilot then auto-thrust disengaged and the PF said "I have the controls". The airplane began to roll to the right and the PF made a left nose-up input.

02:10:05...The airplane began to roll to the right and the PF made a (ONE) left nose-up input.

Mademoiselle, M'aider, sil vous plait? Qu est-ce que c'est? La meme chose temps?

The pilot corrects for what the a/p had trimmed out, a right roll and down Pitch.

At a subsequent time, they note the speeds are belly, and the climb commences. These events are linked, yes? I note also the similar input at the top of the climb. Do we know this aberrant non-cruise event is ICE related?

I appreciate your collating the chronologue, it is very helpful. Has anyone posted the possible encoutered verticals in a cell?

Elevator control.
 

Svarin post #237 http://www.pprune.org/tech-log/45283...ml#post6477847

In the bold is exactly what in a normal situation PRIM 1 is capable to perform, so shouldn't be a problem for PRIM 2 too.

What I can add to your intresting observation is that in this situation, due to loss of the FCPC1(PRIM1) and FCSC1(SEC1), the Inboard (Green) servos are totally lost (both servos in dampening mode) and therefore are unable to assist the outer servos(BLUE/YELLOW) in large elevator deflections.

From the Technical Training Manual:

PITCH D/O (ELEVATOR) (3)

Each elevator servocontrol is connected to two computers (one FCPC
and one FCSC).
In the normal configuration, the inboard servocontrol is in active mode
while the outboard is in damping mode.
FCPC 1 having the servo-loop control priority:
- sets its dedicated servocontrol in active mode and ensures the servoloop control,
- commands the damping mode on the adjacent servocontrol (one solenoid valve (S) energized).
For the elevator servolooping computation the computers need to acquire:
- the elevator surface position,
- the elevator servocontrol piston position.
This information is sent by servocontrol transducers (XDCRs) units and
the surface position transducer (RVDT).
In the event of large deflection demands, the two servo-controls can
become active to avoid the saturation of one servocontrol.

HYDRAULIC OR ELECTRICAL FAILURE
If a servocontrol being in active mode is either not hydraulically powered
or not electrically controlled anymore,
the faulty servocontrol falls in damping mode and the adjacent one
becomes active according the servoloop reconfiguration.
If both servocontrols of one elevator are depressurized, both servocontrols are in damping mode which prevents fluttering.
When P1, P2, S1 and S2 are no longer able to control their dedicated
servocontrol (ie: inputs missing, electrical failure, etc...), the servocontrols fall in re-centering mode

These inputs made me think of the Recovery Technique in windshear/downburst conditions (close to the ground), where the pilot is (rightly) encouraged to rely on the High-AoA protections in Normal Law (FCOM 3.04.91, but my copy may not be up-to-date:

bearfoil:

Apologies for butting in, but under what cicumstances or failure modes do these disengage, assuming not the action of the crew ?.

Trying to think logically: This is the first event in the chain. If we know the conditions under which the two disengage, perhaps we can work back from there ?...

1. that what you're referring to, sir, is in no way officially connected with BEA and it might be realistic representation of DFDR data or it might not.

2. if, and it's a big if, it's correct and accurate, trim started moving at 2:10:50 and stopped at 2:11:51. Apart from comments about giving mostly climb commands, it can't be seen what was the sidestick displacement or what sidestick was active at all during the period.

3. while we wait for DFDR traces, I'd like to once more remind fellow PPRuNers about AC Doyle's warning on theorizing without facts, the one I've quoted a couple of posts ago.

Quite
 

while we wait for DFDR traces, I'd like to once more remind fellow PPRuNers about AC Doyle's warning on theorizing without facts, the one I've quoted a couple of posts ago.