Level100

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.

gatbusdriver

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!

HazelNuts39

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.

iwrbf

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)?

augustusjeremyreborn

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.

ask26

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.

foster23

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

overthewing

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?

spagiola

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.

Teddy Robinson

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)

CogSim

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...

Clandestino

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.

spagiola

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

syseng68k

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.

bearfoil

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.

infrequentflyer789

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.

mm43

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".

infrequentflyer789

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).

gums

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.

Clandestino

DFDR does record FBW law. Patience is the keyword.