The very basics that we get to discuss here...
 

United Nations.

There is no evidence at all, that such system behaviour can be evaluated in a simulator outside the designed envelope, therefore your test proves nothing. If BEA would be as certain as you are, they would have made the same test and would have come to the same answer.


There is no evidence, at what point your simulator would behave different to the actual A320, despite the fact that we are talking about an A330 here. It´s no difference wether we talk about somewhat stalled or sustained stalled, as the simulator has no validated database for either one to do that.


It was an interesting experiment when no other values where available and BEA had its cards still hidden, but now the final report is out and i see no sense in supplementing the report with own non proofed experimental data like they are real hard facts. .
BEA clearly states that the aircraft was not tested outside its normal flight envelope and that no data are available, period. We have to accept that and work from there.

"In the begining ..."
 

Lyman;ICAO Convention Annex 13 provides that mandate to the State of registration for an aircraft lost in International waters. The BEA is the designated responsible entity in French law.

Any Search and Rescue response is that of the State in who's SAR AREA the accident occurred; in this case Brazil. The BEA was able to consult with Maritime experts and put together an initial TPL search for the ULBs without impinging on the Brazilian SAR efforts - be they misplaced or not. But in like vein, the BEA was able to enlist the naval and air resources of the French state to work with the Brazilian Military.

The BEA was always ultimately the legal custodian of any bodies or items recovered during the SAR phase or later. Not having the resources in the initial stages to handle/store recovered bodies, that task was left to the Brazilians. Once the Brazilians declared the SAR operation to be complete, the BEA was left unfettered to proceed at its leisure to instigate its own Search and Recovery plan. One small complication was the criminal investigation proceedings commenced in France, which gave the court the power to place evidence under seal.

Perhaps it depends whether an accident report is there to allocate blame, or to reduce the chances of a recurrence.

I for one would hope the report is there for the latter reason.

DontHangUp, I added the {brackets} for ease of reference
I'll nitpick slightly here and point out that while {A} looks to be true, {B} may not be so clear cut. Point being, if stall was at any point recognized, by either pilot he may not necessarily have said anything. All that they said is not all that they saw, experienced, and decided. It seems well established that the CRM and crew synergy wasn't at its best in this mishap, nor that the pilots were other than task loaded early on. There is also the impression I get of a frustrated PNF calling the captain back, perhaps thinking " I can't work with this guy!" but I am on thin ice with that.

Early on, you get the PNF asking, in re the crickets, "what's that?"

Is that an indication that at least one of crew was concerned with a stall, or approach to one? We can't be sure. Verbalization of that concern is not recorded, or if recorded was redacted. (<--- very unlikely)

Another tidbit shows us that early in the event, the PF set TOGA and the nose up (12-15deg?). He may have been trying to avoid a stall (crickets chirp finally gets through?) by using a low altitude response to stall warning, or he may have been applying a response to low altitude UAS, which procedure is tailored to landing and approach environment.

We don't know what was going through his mind.

I agree that best estimate is {A}, then {B}.

Given some of the actions taken, we are left in some doubt as to what was actually going on in two brain housing groups in the LH and RH seats.

Lonewolf - I'm having difficulty with the concept of pulling the nose up to 'avoid a stall'??

Hi Lonewolf 50,
The above quote actually came from me in a post I made to Lyman. It was my words echoing what the BEA Final Report stated in the Synopsis:
and, in the CONCLUSIONS - 3.1 - Findings:
To the best estimates of {A}, then {B}, I would add a {C}. As the BEA stated:
The FDs were not turned off as they were supposed to be. You can read the discussions of this on pages 188 & 190, BEA Final Report. Also, you can read the discussion regarding the application of TOGA thrust on pages 180-181, BEA Final Report.

Lonewolf: "Early on, you get the PNF asking, in re the crickets, "what's that?" "... I don't think so.... I submit that is not a conclusion made by BEA. Though close in chronology, (I think "what's that..." is too close to the sound to allow for PNF's processing it. If he did mean to link it to the SW, I would think it was rhetorical, of course he knew what it was...Don't you also attribute a comment "it is impossible" to Captain on his return to cockpit? I think that is PF, late, after,"we are going to crash..."

Recoverability from a DeepStall Condition
 

One of the apparent "unknowns" is whether a deep stall is recoverable once an A330 is embedded in the condition. It was never flight-trialled by Airbus (i.e. neither the possibility nor the high altitude ballistic entry conditions with various trim states and engine powers). There would be many variables including weight, CofG, pitch attitude and pilot control inputs.

One paramount determinant would be the relative airflows once stabilized in a descent at greater than 40 degrees angle of attack. The effectiveness of a tailplane is a function of its lever arm and (even more vitally) the airflows across it. The Lever arm is its distance from the wing's Centre of Pressure (which "moment arm" itself changes at 40 + degrees angle of attack,
particularly with underslung engines at high power). Wind that trimmable horizontal stabilizer into a fully nose-up deflection and its chord-wise airflows are very adversely affected. At 40 degs AoA those chordwise flows would be minimal and so the tailplane's efectiveness would be greatly compromised.

In fact the whole Lift/ weight /thrust /drag relationship becomes significantly distorted for pitch-control, once "stuck" in this aerodynamically distorted flight regime. Elevator and tailplane pitch control authority are no longer a "given" at that excessive angle of attack. The "forward flight" model has now become a "falling leaf" model.... and the wind-tunnel is now an elevator shaft. A feather on a bird works well aerodynamically. A feather falling has no aerodynamic qualities whatsoever.

Something that seems to be lacking in the BEA report is the sensory deprivation of the pilots in respect of what they'd normally expect from a stalled flight condition. Uppermost in that category would be airframe buffet. Because that would be quite absent in a deep stall (there being no bathing of the empennage in turbulent flows from the wings), the resultant eerily smooth flight would induce an atmosphere of "unreality" and nothing conducive to any perceptions (whatsoever) of stalled flight. A similar sensory deprivation occurs in a super-fast lift ascending or descending in the bowels of a skyscraper. The impression of vertical speed is quite lacking once acceleration stops. However, unlike the skyscraper analogy, in AF447 the initial downwards acceleration into the deep-stall was subliminal and undetectable. That was partly due to the inadvertently optimized pitch attitude at entry caused by an inexperienced pilot's unintended or incompetent sidestick input (as well as high power, thin air and a fully deflected THS).

To sum up, as I have said before in Pprune, the pilots were suddenly operating well beyond their experience in a very alien flight regime. It's unsurprising that they ended up non-plussed and quite out of ideas. The cutback-in of the aural stall warning amidst the cacophony of other alerts and alarms only served to confound them further. It was not conducive to any concerted (or even continued) attempts to lower the pitch attitude. In fact, it was a straight-out deterrent to doing so. That was one of the few tangibles that they had to work with, but it was lethally misleading and working 180 against the (otherwise) logical solution.

If you ever wanted to construct a labyrinthine, bizarre and Byzantine conundrum for an unprepared coterie of fat, dumb and happy long-haul cruise pilots, you'd have to go a long way beyond this pitot-ice induced nightmare of countervailing automation.

That is a very well said piece. I have one question. Since the return of Stall Warn may have seemed to alert to Stall entry why did the pilot Pull Up when it first came in through the "back door"? May be a nit pick relative to your choice of wording, but rather than confused, wasn't his response confusing?

In other words, he may have been confused, but his actions were wrong either way the Stall Warn fired? In a way, it did not matter, whichever way the SW appeared, he acted similarly.

At 60 knots IAS, or at actual Vsw, the horn should mean "reduce incidence"?

AF 447
 

I have been avidly and carefully following this thread since the fateful,terrible loss of AF 447 between Rio and France,with all of her crew and passengers.Shocking.
The posts seem to go on and on ad inifininitum,but one fact is clear----the crew screwed up through lack of training combined with the (slightly) lesser malfunction of the pitot tubes which were unable to cope with the ice incursion.
There seems to be little wrong with the Aircraft---it seems to be a "fly the Aircraft" situation which was not followed in real time.....surely its now time to put this to rest?On and on by armchair scientists.....it was an "accident",which are certainly never intentional!Move on everyone and let the Litigators sort it out money-wise,as sharp as they are....There is nothing wrong,it seems,with AB or Boeing or whoever.Lets put this to sleep.....

Loerie:
B-but......then.....what would we do all day???

Here's an idea! let's all chip in and buy Loerie a space bar for his keyboard. :cool:

TheShadow;I don't believe the tailplane was as compromised as you posit. AF447 - Thread No.6 will provide you with an alternative viewpoint.

They did. Local police did. Nothing to do with Asseline's lawyers.

What makes the difference between the average quality company and aircraft engineering? Holy Spirit? Provocation aside, I been there, done that, got the t-shirt: I can confirm that there *are* "vegetable engineers", including higher ranked positions, including supposed-to-be-decision making individuals. Sorry to bring the illusion of the all-too-perfect aviation back to the level of mortal beings.

You are correct, I mixed that.

The FDR was not in BEA's possession all the time. It was never officially clarified where it had been for a couple of days before BEA begun its investigations. Missing data where some should exist, wrong lead tape in the FDR, etc... Too much to be all accidental, no need to have a hang for conspiracy theories. You could object that it wasn't exactly the fault of BEA for not handing over the FDR to them etc., but then I extend that to the French government who was setting the rules for them, for the police, the federal prosecutor, the manufacturer. It is imperative to avoid any doubt in any such investigation, even the distant possibility of forging must be excluded.

Now we have nearly the same constellation for the AF447 investigation. But as I said, I see absolutely no indication for any irregularities this time.

I spoke about known incidents - so *known before* AF447. Why did Airbus extend their internal requirements against the ones from the authorities? Because they knew better and were even more careful than the authorities. EASA obviously never adapted, at least that's my understanding.

First: When stating that somebody could handle something this does not imply the statement that others don't - by the laws of logic.
Second: The other crews did not face the same situation, so not 100% comparable anyway.
Third: I referred to the captains abilities as opposed to the ones sitting in the front row during flight AF447, not opposed to other crews.

So: My point was that being a potentially great pilot (knowing intuitively how to get out of the situation once at the controls) does not automatically imply to be a good captain who has to actively regain control. Pilot in command (captain) should be ultimately in command, not just watching / advising. The fact that he still let the controls to the least experienced crew member when it was obviously already screwed up was bad crew management in itself.

My personal conclusion is something like that the PF indeed messed it up. But he was left alone by his captain (give comments is not enough), by his training, by crew structure, by checks, by PNF not insisting more to break his mental deadlock, by SOP (like only AP on if possible, never hand flying even in severe CAVOK), by almost everything.

BOAC:
Given that I used to teach stalls and spins in smaller aircraft, I am as well.

What I understand is that, if you are in the low altitude/terminal environment, on approach, and you get a warning of approach to stall, the response isn't typically trained in AB 330 as "lower the nose" but instead (and I think the assumption here is in Normal Law) to set an attitude (nose above horizon) and max power and fly out of it and away from the ground.

With Normal Law, the protections would usually help you not stall in the process. That habit pattern, likely trained, and possibly even the most recent in terms of a sim event, would heavily inform the response of a pilot being surprised by a stall warning. But then, we are not so sure that "stall warning" even penetrated, and as BEA finds, it is not shown that it ever did.

Granted, more of the folks discussing this take the PF's actions as a sort of remedy to UAS ... but did the crew ever really declare and establish that they assessed UAS as their condition? That isn't clear either.

If I misunderstand the general response and actions action taken to avoid a stall when stall warning goes off, my apologies to AB pilots.

It is obvious the PF was oblivious to what was going on but the PNF getting the captain back to the cockpit instead of taking over the aircraft puzzles me. Did he not have enough confidence to say " Ive got it". Take over the aircraft and worry about his job on the ground if it didn't follow company procedure?
I understand the left seat can push a button and the right SS will disengage.

A maneuver the Airbus flight system performs is Escape from CFIT. I do not recall the part, if any, Stall Warn played...

If CFiT is imminent, in Normal Law, The stick can be pulled .back to to the stop, throttles to TOGA, and if a turn is needed, the stick moved to the stop either right or left.

The aircraft will fly on the edge of STALL, at maximum bank, and climb, turn at max allowable as determined by the a/c, not the pilot. It nibbles at STALL, and the a/c Escapes, or not, depending on the proximity of the obstacle.

It is an emergency maneuver, and since PJ2 was involved in the discussion, I take it to be accurate, as I can remember it...

I am assuming Approach to STALL can be taught in similar manner, (or confused with it), but I am unclear what effect the Warning has on the performance, or the LAW. I think this was one of the drills Asseline was going to perform. The a/C cannot suss obstacles, and at the time had issues with sequencing inputs when RA and wow became operant....my assumption is that the a/c, if healthy, can be flown at any AoA short of Stall, and will simply sink if thrust is not increased. Seems like a pretty impressive system...theoretically, I think, had there been no trees, the 320 would have sunk onto the runway, had there been one, or if throttle had been advanced sooner, the aC would have performed as advertised.

Please take this at face value, it is from memory, and may contain errors.

CFIT is not the same as a stall, nor is response to stall necessarily related to stall near the ground, though it can be. A colleague of mine died thanks to an OCF condition that was recovered but then ended up not so nice due to an accelerated stall during recovery. :{

I was in no way relating a CFIT escape with an approach to stall response. I suppose that both would be related in that you'd tend to approach the limit of AoA for the condition during both maneuvers, but it would vary with situation.

I have also lost friends to CFIT. Two were on low level nav missions. Each hit something, which was not part of the plan for that mission.

I lost another friend in an A-6 that Stalled low over the ocean when he overcorrected a high closure rate on his lead, low altitude rendezvous. :{ Not CFIT either. Ejection not in time.

Typical CFIT scenario is an unstalled aircraft hitting the ground due to any number of errors that get it there unintentionally. The Escape maneuver you refer to, robot assisting or not, has as its purpose to FLY away from the terrain using the best performance the aircraft can give you.

A stall ends your flying and begins your plummeting.

It may also end up with aircraft meeting terrain, unintentionally, but the C part is no longer in application, as you are no longer in Controlled Flight when stalled. You could call it OCFIT (Out of Control Flight into Terrain) or simply a crash. Dead no matter what you call it, absent an ejection seat.

Thus, if you are WARNED that you are approaching a stall, you FLY your plane at an AoA and attitude and power setting that both
a) avoids a stall (because as soon as you stall you begin to fall, more or less, and are not really flying)
b) gets you away from the ground (which you wish to encounter under more frienly circumstances a bit later on)

Are we clear on the difference? :) I didn't drag CFIT into this, and would like it to stay out. Plenty of post for that over in the thread regarding the Islamabad crash recently.

@Lyman,

You are asking questions that are part of training for Airbus pilots as well as how the aircraft (A330) performs and is controlled. Perhaps this Airbus A330/340 Flight Crew Training Manual will help you understand more and answer many of your questions:

http://www.dream-air.ru/new/pilotam/FCTM_ENV_LR-1-.pdf

Thank you TD, that's very kind of you...

What did they do?

You do know that the "switching /altering flight recorders" accusation was a lie, don't you?

Nothing ...
But ... the DGAC take the recorders (with no judicial seals) and keep them 1 week :* and this was outlaw
After that .. they were requested by a judge ... :ok:
That's a good point for launch any "conspiracy theory" :)

Myself .. to today .. I don't know ..

@jcj:

It seems to be a truism that when regulators get themselves involved in accident investigation and resolution, things go wrong (e.g. UK CAA with the BA 747 approach incident, US FAA several times - but notably with the DC-10 'Gentlemen's Agreement' post-Windsor).

The point is that because journalists frequently can't be bothered to learn the difference between the investigatory body and the regulator, on that occasion the BEA were unfairly tarnished.

Re: that incident, the apparent "time discrepancy" that the retired AAIB investigator noted turned out ot be a misreading of the data. The photo sent to the Swiss for analysis proved nothing, as the only person to suggest that the boxes in the photo and the ones from the crashed aircraft should have been one and the same was a journalist. Generally when you've got non-technical people searching for something, you have another example around to show them what it looks like.

And things can go more wrong when those regulators make illegal actions :)
And things can go wrong when those regulators are not punished in any way for those actions ....

Black helicopter, grassy knoll, moon landing was the Mojave, YAWN.
Please take your stupid conspiracy theories to an appropriate forum.
:=

Not talking of "stupid conspiracy theory" here .. :=
Just talking about the fact (not theory) that DGAC detained (illegally) the recorders (and under no supervision of any) during one week (no judicial seal on ... as required by the law)
Normally the recorders had to be detained by the BEA (the lone official body in France, allowed to make investigations) .. and had to be sealed by judicial supervisor (like in the AF447 case)

Fundamental question- Why not a requirement to stall commercial ac?
 

Hello all-
Long time lurker, GA type who has learned so much from this thread and everything else on PPRune- Thanks so much for an excellent forum.

Of course full stalls are never trained in the real world, but I can't imagine why there isn't a requirement for commercial pilots to have regular sim experience? I understand that current sims can't model stalls because no one ever spins and stalls commercial AC in testing, but whey don't they?

In a FBW environment, wouldn't it be easy to wire up a prototype and remotely pilot it beyond the envelope? This should generate data for design and efficiency that didn't exist before and give sims accurate data for stalls and spins?

Test pilots increase the odds of total failure incrementally, so I would imagine that a lot of data could be collected before the airframe is lost and planning on loosing the airframe would be the same as wing bending and pressure testing- You just factor the loss into the total cost of the program.

Perhaps the AC will provide great data in approach to stall and recovery after a spin or two. Maybe great data can be obtained falling off the high and low ends of the coffin corner- It might have the opportunity to be recovered after a high altitude stall, and if it makes it this far, the holy grail would be attempted recovery from a deep stall (assuming the AC can be deep stalled)-

If you get good data from that, maybe a high speed dive until the wings come off, but if I understand modeling correctly, everyone of these data points should allow better sim modeling for unusual attitudes.

Am I missing something? Is the cost of an aircraft the only thing stopping an approach that seems like common sense from the outside?

Much appreciated, and sorry if this was an insane question.

The perseverance of the French authorities in the location and examination of the wreckage is to be applauded though I expected nothing less.

My idea is that the authorities were certainly driven specially by Airbus for further research
In fact ... by analyzing ACARS report and preliminary reports before discovery ... Airbus certainly had the certainty that (exept pitot tubes) .. his plane was not implicated technically
This required that the wreck (and recorders) was discovered at any price that leaves no room for doubt or speculation about the quality of their product

Airbus FBW in AF447
 

To quote a paragraph on Page 187:

However, positive longitudinal static stability on an aeroplane can be useful since it allows the pilot to have a sensory return (via the position of the stick) on the situation of his aeroplane in terms of speed in relation to it's point of equilibrium (trim) at constant thrust. Specifically, the approach to stall on a classic aeroplane is always associated with a more or less pronounced nose-up input. This is not the case on the A330 in alternate law. The specific consequence is that in this control law the aeroplane, placed in a configuration where the thrust is not sufficient to maintain speed on the flight path, would end up by stalling without any inputs on the side stick. It appears that this absence of positive static stability could have contributed to the PF not identifying the approach to stall.


If I were a lawyer looking to blame Airbus I believe this would be my "smoking gun" so to speak. However also in the report the paragraph prior states:

When there are no protections left, the aeroplanee no longer possesses positive longitudinal static stability on approach to stall. This absence specifically results in the fact that it is not necessary to make or increase a nose up input to compensate for a loss of speed while maintaining aeroplane attitude. This behaviour, even if it may appear contrary to some provisions in the basic regulations, was judged to be acceptable by the certification authorities by taking into account special conditions and interpretation material. Indeed, the presence of flight envelope protections makes neutral longitudinal stability acceptable.

So the certification authorities have allowed a "relaxation" of certification standards. Airbus themselves designed a flight control system that contributed to this accident.

Again if I were a lawyer, I would love to examine the "special conditions and interpretation material".

The certifying authorities and Airbus still have many questions to answer. This final report has no doubt marked the beginning of some serious legal process

@bonernow

The stability question is being bounced around quite a lot in the most recent Tech Log thread on the subject. I'd suggest having a peek in there to get a better idea of what those paragraphs state.

The idea that standards were "relax[ed]" is a contentious one - they were simply changed to accommodate changes in technology, as they have been for every iteration of airliner design from the beginning.

While the design removes the traditional signs of feeling approach to stall through the primary flight controls, the other signs (including buffet) can definitely still be felt, and because thet's not enough, there's a very loud aural "STALLSTALL" warning. What the design made obsolete with one aspect was replaced with others - the change in design did not make it harder to recognise approach to stall in real terms.

What other usernames?

Only today you have managed to insult a few posters with your attitude. On various threads. Go play golf or something.

DW, it always seems you are making excuses for a bad design. This is a travesty of engineering - an airplane that can't be felt, only interpreted.

@ svhar,

This is a legitimate question. Although you show only 23 posting, you are actually credited with a total of 466. Most coming on JB, "Where in the world?"

Suggest you log on, click on your name on one of your posts and then click on "See more posts by svhar", and see for yourself. Are you the only one or is there another? Who is the real svhar? :confused:

Ridiculous design
 

Quote:

---

The report suggests
Diagnosis : the pilots never diagnosed "unreliable air speed". Analysis of the dozen or so similar incidents where pitot tubes froze suggest that most of those crews did not diagnose it either.
Stall warning: did they comprehend it? The report provides references suggesting that in a confusing environment, humans can be cognitively deaf to aural stimuli, and tend to prefer and respond to visual stimuli much better.

---

Technically it is VERY EASY to detect and report IMMEDIATELY and PRECISELY to the crew the UAS. Airbus SAS prefer delegate it to the crew. :} (A paper from Airbus SAS designers, etc. shows that):E

It seems Airbus SAS don't consider important the GIGO concept. The non trained crew were presented with ABSURD data mixed with consistent data.

IMO F-GZCP had a ridiculous design (WRT to Air Speed) AND An ABSURD man machine interface.


In earlier posts i wrote on AS ridiculous design. After final report i include ABSURD man machine interface.

Who can tell the truth? BEA? Airbus SAS? :)

Do you pilot at all? And if so what experience of Airbus fbw do you have?

@glad rag
Let me ask another provocative question:
How much "piloting" is there in "airbus FBW expierience", not to mention on a long range job?

Most of us abandoned the concept of aviation as terminally unique ages ago. For the simple reason that those who wished high profit could claim "complexity" to hide their greed and demands for special treatment from regulators and the public.

Airbus and BEA insult all of us who are capable of understanding not only flight, but controls and failures, with this entirely unsatisfactory report.

Concierge? Thus started the patronizing and fallacious nonsense....

Turbine - I assume he/she is still going on about it. As I said, I don't see his/her posts. I did exactly what you posted a while back but could find no post where I had put 'svhar down' (oh to be a vet:)). I have a vague memory that some way back he/she claimed exclusive evidence that AF447 had been struck by lightning to which I replied (I think I may have mentioned the 'O' bird, but got away with it), but I assume a mod sensibly deleted the post. Hey ho. Time to move on, I think. Bigger fish to fry.

Special Conditions and Interpretative Material
 

From the FAA Regulatory and Guidance Library: Special conditions are often a precursor to later general rulemaking proposals. Although originally specific to an airplane make, other manufacturers in a similar situation may elect to use them for their projects.

Interpretative material is published by the regulatory authority to illustrate one or several ways to meet a requirement that have been found acceptable in past certifications, for example FAA Advisory Circulars or EASA ACJ/AMJ material.