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DozyWannabe
29th Jul 2011, 15:31
DOZY: As a sw boffin, do you expect much of what is needed for an understanding has a particular timeframe?

Well, from a software perspective, what you'd need to do is load up a test rig made up of the exact hardware installed on that aircraft with the exact software installed (down to point releases), apply the DFDR data to that test rig's inputs to see what the software and hardware does - then repeat this test anything up to hundreds or thousands of times to see if any anomalies appear. I suspect this would not be a small or inexpensive undertaking, but it would be do-able.

How did this START?

It's looking very much like an inappropriate response to the situation as it developed, starting with the nose-up inputs shortly after FMS disconnect, then progressing through selection of TOGA and the later aggressive and maintained nose-up inputs all the way down, and it wouldn't be the first time it has happened (as I've always said, I think this was another Birgenair-type situation).

Way back when I started commenting on these threads earlier in the year I said that unreliable instrument readings in the wee hours at night, in IMC with unsettled weather hundreds of miles from land was a nightmare situation for any pilot to confront, and that any findings of mishandling on the part of the pilots *must* take this factor into account, and this is why I got very agitated when people said that by saying software failure was unlikely to be a cause I was blaming the pilots.

Lack of training appears to be a significant issue here, along with poor CRM practice when it comes to rest periods. It would appear that the ITCZ is a known problem area when it comes to aviation, and many pilots on the thread have expressed the opinion that they would not have left the two F/Os in charge until safely out the other side.

Colganair 3407 was the wake up call that the airline industry had bred complacency in two distinct areas, one of which was the effect of fatigue and the other was poor recognition of stall conditions and application of the correct response to those conditions - but that investigation was still ongoing when AF447 crashed and the final NTSB report not released until February 2010, 8 months after AF447.

In short I think AF447 was a "perfect storm" of the problems within aviation. Birgenair and Aeroperu had shown what could happen if the pitot-static system was compromised, but both of those incidents happened in the climb phase. Not much thought was given to what would happen if something similar happened at cruise altitude, with the attendant limits on possible escape procedures. Airlines had been training pilots to respond to approach to stall and the warnings generated without getting into what would happen if you were to actually stall, how to recognise it and - crucially - how to get out of it, because it requires going against the human instinct to cram on power and pull up when the correct response is actually to get the nose down and hold it there until the speed comes back and the wings are flying again. AF also deserve to come in for criticism for failing to expedite the replacement of pitot tubes which were known to have problems.

@jcjeant - if you're honestly suggesting that airlines were training their Airbus pilots on approach to stall only and the rest of their crews were getting full stall recognition and escape training, I think you need to get some perspective.

TioPablo
29th Jul 2011, 15:42
Training for manual airplane handling
The first recommends that the regulatory authorities re-examine the content of training and check
programmes and in particular make mandatory the creation of regular specific exercises aimed at manual
airplane handling. Approach to and recovery from stall, including at high altitude.
As B4-LandingChkList , bubbers44 and others pointed several posts away: More stick time…
The question is who is going to pay for that? And… How is that redefinition of training going to look like?
Bubbers44 said gliding isn´t cheap; well prolly companies should pay that kind of training. Much more cheaper than a hull loss anyway.



Angle of attack measurement
This recommends that the regulatory authorities evaluate the relevance of requiring the presence of an
angle of attack indicator directly accessible to pilots on board airplanesWell Airbus… Begin asap with it methinks...

Man Flex
29th Jul 2011, 15:52
No conspiracy theory. The situation was mishandled by the crew leading to the aircraft departing its flight envelope.

Now the investigation will focus on the human factors involved and attempt to resolve why they did what they did.

000tfm000
29th Jul 2011, 16:14
On a very quick skim-read of the French text, two key questions are:

1. Why did it start to go wrong?

2. Why was it not corrected?

As to 1: notwithstanding the difficult conditions I am afraid it does rather look like pilot error in the sense of being a combination of ill-discipline in the cockpit and bad training. If I have understood correctly, the PF and PNF had received no training in how to deal with inconsistent IAS inputs at high altitude, or in manual flight at high altitude.

However, as to 2: IMHO the full CVR transcript shows that the systems were in large part to blame. The passage from 2:12'37 to 2:12'44 is tragic and shocking in equal measure. At the start of this timeframe (i) the PF was (for once) pushing forwards (ii) the aeroplane was in a stall but (iii) the stall warning was still silent. My poor translation is that the PNF tells the PF to "descend! descend! descend!" The PF says "That's what I am doing." The Captain intercedes "No, you're climbing". The PF says "I'm climbing [meaning - "you think I'm climbing?"], okay, I'll go down".

At precisely this point, his nose-down inputs stimulated enough speed to trigger the stall warning. The captain's next remark is "This isn't possible." His bewilderment is unsurprising.

Thus the PF's correct nose-down inputs were punished by a stall warning; his wrong nose-up inputs were rewarded by the stall warning ceasing.

The instruments thus played a cruel, Pavlovian trick on the pilots which IMHO goes a consdirable distance towards exonerating them.

I don't think this is sufficiently emphasised in the report.

levelvibes
29th Jul 2011, 16:51
Who can please shed some light on the copilot´s deficient training the BEA report states.

"The copilots had received no high altitude tr aining for the "Unreliable IAS" procedure and manual air craft handling".

I find it hard to believe this. Isn´t this training absolute standard in any simulator training of any serious airline?
Am I missing anything?

Thanks

Hyperveloce
29th Jul 2011, 17:28
Who can please shed some light on the copilot´s deficient training the BEA report states.
"The copilots had received no high altitude tr aining for the "Unreliable IAS" procedure and manual air craft handling".


The 3rd interim report says that none of the two copilots had received a proper instruction/training for
- manual A/C piloting at high altitude (see PF's large amplitude inputs in roll and pitch above 35 000 ft)(I am also very disturbed by this !)
- UAS procedure at high altitude (one of them had received a training for UAS at low altitude, where the pitch was higher, in the order of 10°)
The CVR also shows that there was no clear attribution of the roles by the CDB when he left the cockpit, and latter, that the cooperation between the two copilots was not very good

Halfnut
29th Jul 2011, 17:38
AF447 Interim Report In English -

http://www.bea.aero/fr/enquetes/vol.af.447/note29juillet2011.en.pdf

bearfoil
29th Jul 2011, 17:41
Hmmm. Claiming the a/c behaved as directed after this accident was under way is misleading, if not a direct fraud. No one to this very day knows what to expect after LOC ending in Stall, yet that is the focus of the BEA recommendations? Confusion on the flight deck? Christ, does any pilot take that as a serious critique of these guys given the circumstances?

The induction of this LOC is virtually ignored. The Public is to accept the outrageous nonchalance of this outfit, and be satisfied with a conclusion and blame prior to the finish of the investigation?

I suppose we could say that the release is intended for public and lay consumption, hence the simplistic opinion and utter lack of evidence.

But that leaves the Public with but one source of critical knowledge, a source with a financial and commercial interest in the outcome. I cannot abide "International" accords, when they are merely political, but a proper and objective source of multidisciplinary critique might be an alternative.

Who Guards the Guardians?

bearfoil
29th Jul 2011, 17:45
Hyperveloce

yes. This fact screams complacency, and negligence. If accurate, then any criticism of the pilots stops well short of the actual responsibles.

bear

Lonewolf_50
29th Jul 2011, 17:50
bear, one may make some criticisms of various members of, and actions of, the flight crew without precluding criticisms of the others whose contributions to this event, via their roles, actions, and inactions were prelude to that dark and stormy night.

Let's not raise a false dichotomy.

I estimate that the key to your objection is the way that cause factors are communicated.

The vague term of "pilot error" has so much currency, and so dubious a meaning, that it can be misleading or be no more than a fig leaf.

SaturnV
29th Jul 2011, 17:57
Halfnut, that's the link to the four page synthesis report.

DozyWannabe
29th Jul 2011, 17:58
Hmmm. Claiming the a/c behaved as directed after this accident was under way is misleading, if not a direct fraud. No one to this very day knows what to expect after LOC ending in Stall, yet that is the focus of the BEA recommendations? Confusion on the flight deck? Christ, does any pilot take that as a serious critique of these guys given the circumstances?

The induction of this LOC is virtually ignored. The Public is to accept the outrageous nonchalance of this outfit, and be satisfied with a conclusion and blame prior to the finish of the investigation?

Bear - look at the traces. This wasn't a LOC ending in stall, this was an aircraft *controlled into* the stall, because the guy with the stick in his hand had not been properly trained to deal with the set of circumstances with which he was faced.

After starting by insisting the vertical stabiliser must have separated, then moving on to various dark murmurings about the computer doing sometihng that the pilots didn't expect, or random actuation of flight surfaces taking them out of stable flight, your insistence that something must have been wrong with the aircraft (over and above the pitot tubes) in the face of all the evidence put forth has been puzzling. Why are you so sure they're hiding something?

But that leaves the Public with but one source of critical knowledge, a source with a financial and commercial interest in the outcome.

If there was anything nefarious going on, then you'd expect AF (which is a also a commerical interest of the French government) to have been given the whitewash treatment too - as it is they've come in for some pretty heavy stick here.

bearfoil
29th Jul 2011, 18:11
Nefarious? The only thing I accuse the agency of is bias. As such, I believe it is equal to manslaughter, regardless the presence of fraud or no.

Look away from this current state of affairs. The Probes? Identified as problematic, and suspected of many episodes of intake to UAS. Rejection of AHI? BUSS? An apparent and outrageous ignorance of high altitude flight with untrained Pilots (That is the charge). This is outright negligence.

It cannot be seen another way. And yet the galling (gaulling) nonchalance: "perhaps a study of the need for AoA?"

I fear I have been crying wolf for two years; since he has not gobbled our young quite yet, "I see conspiracies." The wolf's jaw is full of blood, yet I have been overreacting?

My skin is 4 gauge dermis, and critics don't bother me. I have tried, and if I cannot convince you of shortcomings in the approach (unstable?), I have given up.

funfly
29th Jul 2011, 18:17
So three 'pilots' in the cockpit, a pull back on the stick and hold it there for....how long... until it hit the deck. OK, one may have panicked but all three?
'pilots'?

bearfoil
29th Jul 2011, 18:28
If the disconnect between a/c and 3 pilots is that pronounced, why is Air France still flying?

DozyWannabe
29th Jul 2011, 18:38
adieu Doze

Wait - come back here- we're not finished.

Nefarious? The only thing I accuse the agency of is bias. As such, I believe it is equal to manslaughter, regardless the presence of fraud or no.

And I say again, would a biased agency be hauling AF across the coals for failing to train their pilots correctly?

Let's start with the technical issues you present:

Look away from this current state of affairs. The Probes? Identified as problematic, and suspected of many episodes of intake to UAS. Rejection of AHI? BUSS?

Airbus put out a service bulletin and AF implemented it, but did not expedite it. BUSS was a system developed to assist with the pitot problems, and was still very new at the time this accident occurred - I don't know how take-up has progressed since then.

An apparent and outrageous ignorance of high altitude flight with untrained Pilots (That is the charge). This is outright negligence.

And Air France will answer it. This is nothing to do with the aircraft at this point.

It cannot be seen another way. And yet the galling (gaulling) nonchalance: "perhaps a study of the need for AoA?"

AoA indications were available in the form of FPV display. Whether that usage was trained as such or not I don't know.

I fear I have been crying wolf for two years; since he has not gobbled our young quite yet, "I see conspiracies." The wolf's jaw is full of blood, yet I have been overreacting?

My skin is 4 gauge dermis, and critics don't bother me. I have tried, and if I cannot convince you of shortcomings in the approach (unstable?), I have given up.

Shortcomings in what approach? The Airbus control philosophy? I'm really having trouble understanding your point and I really want to.

Phantom Driver
29th Jul 2011, 18:44
Dozy

Way back when I started commenting on these threads earlier in the year I said that unreliable instrument readings in the wee hours at night, in IMC with unsettled weather hundreds of miles from land was a nightmare situation for any pilot to confront, and that any findings of mishandling on the part of the pilots *must* take this factor into account, and this is why I got very agitated when people said that by saying software failure was unlikely to be a cause I was blaming the pilots.

Absolutely. Which is why my favourite training philosophy has always been KISS (keep it simple, stupid), to cater for the worst case/lowest common denominator scenario.

Levelvibes.


Who can please shed some light on the copilot´s deficient training the BEA report states.

"The copilots had received no high altitude training for the "Unreliable IAS" procedure and manual aircraft handling".

I find it hard to believe this. Isn´t this training absolute standard in any simulator training of any serious airline?
Am I missing anything?


Well, I thought this quote was rather surprising from the report---
"In an interview, Eric Schramm, executive vice president for flight operations at Air France and a Boeing 777 captain, contested the need for such training. “There is not a big difference between high altitude and low altitude” in manual flight, Mr. Schramm said. “It is not a very important topic for us.” ---
Really?! Wonder how much high altitude manual flying he's done, (and I'm not talking about simply keeping the aircraft straight and level, unlike what these guys had to deal with).

In the miliitary, we had lots of practice, and I can tell you it was not as easy as it might sound. A small pitch input that would normally be of no consequence at low altitudes would quickly put you in stickshaker zone high up, especially if you had made the mistake of climbing way above your optimum (buffet margin) level.

Not that these matters concerned us at the time; (no SLF to worry about) :ok:. Different matter these days...

bearfoil
29th Jul 2011, 18:53
just this once, then I'am off for vacation

Dozy, Say I develop an intricate and efficient new line in my production shop, it will streamline my production, cut cost, and widen my market. Something I can be proud of.

I pay the enormous development costs, exercise patience, have it installed, and debugged. It has problems, as do all sophisticated technologies, and it goes on line. Some of the problems have to do with training my personnel, so an expensive and sophisticated system takes care of that.

It works flawlessly. As it happens, there is a fantastically remote chance it may malfunction, which is acknowledged, and workarounds are installed. The workarounds are not modern, and involve a bypass of the new technology onto the old (left in Place) machine.

There are now two methods of avoiding this remote malfunction.

Step One. Do nothing. The machine has a good chance of self correcting.

ALTERNATE. Cycle THIS LEVER, and the line switches to the old machine which has a phenomenally good record with this remote but systemic problem.

In my business, it is called the CRITICAL PATH. Only in my business, if the Path is lost, no-one dies.

xcitation
29th Jul 2011, 19:02
So three 'pilots' in the cockpit, a pull back on the stick and hold it there for....how long... until it hit the deck. OK, one may have panicked but all three?
'pilots'?

I agree it does fail a gut check.
I will not be satisfied unless they provide at least the same level of detail as the Colgan 3047 incident report i.e. full transcript from push back, simulated representation of flight and control inputs.
On the training issue why wait for bureaucracey. A pilot always has the option of paying themselves for extra training/sim time. Personally I would like to have basic flying experience in all the control laws including mechanical. But then I am a control freak. I detest the idea of driving an a/c and not knowing how it feels in different modes. Isn't the purpose of training to go through all the options, bells and whistles? Why hold back any training of flying characteristics from the pilots. Have we not learned from the titanic. Ships can sink and a/c can stall so we have to train for it.

4Greens
29th Jul 2011, 19:39
If you had old style fixed wing military pilots the aircraft would never have been lost. All these aircraft need a magic switch that, when it is turned on, the aircraft turns into a basic stick handling machine.

AlphaZuluRomeo
29th Jul 2011, 19:43
xcitation : Don't get too xcited, Sir ;)
The transcript cannot be "full from push back", as only 30' or 2h (depends which track) are recorded.

4greens: Really cannot see how this magic switch would have improved in AF447 case... :confused:
- If the crew (ex-military in your hypotesis, but any crew would do) had recognised the stall, there is no evidence that a proper recovery action (ND until the plane flies again) would have been prevented by the "system"
- If the magic switch was there in AF447, but the crew didn't recognize the stall, no difference in the end.

Lonewolf_50
29th Jul 2011, 19:56
4Greens, what if the pilot flying isn't "old style" military pilots, but guys who have flown mostly FBW and HUD, in planes that don't quite spin? (I suspect your point has merit, nonetheless). (gums has given us some great insights into an early gen FBW system, the F-18 is another that could compare, though I've heard it's tough to make it depart. No personal experience.) F-35? F-22? Typhoon?

What monkey skills are being imbedded in flying those birds?

The "old style" military pilots are running into some training changes. The elementary level Out of Control Flight and three dimensional upset trainers are gone. (I now speak only to US, not idea on the other side of the pond).

The Tweet (T-37) which the USAF could spin and inverted spin, is gone. T-6 has replaced it, though it still spins. Turbo prop.

The T-2 is gone, USn jet pilots used to spin, depart, cross control, and inverted spin train.

In its place is the T-45, which does not have quite the range of maneuvers one can train in that regard.

In time, the military experienced jet pilots will have had spin training, on our side of the pond, only in the T-6, which spins well enough. It isn't flown up where Eagles dare: spins tend to be somewhere in the 8-15,000 feet box. (Depends on the Op Area, they may have raised the floor in the past few years, not sure) .

What does the future hold?

DozyWannabe
29th Jul 2011, 20:07
Dozy, Say I develop an intricate and efficient new line in my production shop, it will streamline my production, cut cost, and widen my market. Something I can be proud of.

I pay the enormous development costs, exercise patience, have it installed, and debugged. It has problems, as do all sophisticated technologies, and it goes on line. Some of the problems have to do with training my personnel, so an expensive and sophisticated system takes care of that.

It works flawlessly. As it happens, there is a fantastically remote chance it may malfunction, which is acknowledged, and workarounds are installed. The workarounds are not modern, and involve a bypass of the new technology onto the old (left in Place) machine.

There are now two methods of avoiding this remote malfunction.

Step One. Do nothing. The machine has a good chance of self correcting.

ALTERNATE. Cycle THIS LEVER, and the line switches to the old machine which has a phenomenally good record with this remote but systemic problem.

In my business, it is called the CRITICAL PATH. Only in my business, if the Path is lost, no-one dies.

I still don't fully understand what you're saying. If this accident had anything at all to do with the control philosophy, automation, FBW or whatever then I could make sense of what you're trying to say.

But in this case no amount of steam gauges, big red buttons to disable the automatics or probably even interconnected yokes would have made a difference. The PF responded to the UAS by pulling back on the stick and inducing a climb to the apogee and stalled, then after a brief moment where he corrected downwards he applied full TOGA power and hauled on the stick for most of the way down to ground contact, making control inputs far in excess of what would have been considered acceptable at cruise altitude. Just the same as with Birgenair the crew were overwhelmed by a situation that ran out of their control. The PNF did not take control, despite having a much better read of the situation and the Captain's advice seemed not to register.

jcjeant
29th Jul 2011, 20:10
Hi,

In time, the military experienced jet pilots will have had spin training, on our side of the pond, only in the T-6, which spins well enough. It isn't flown up where Eagles dare: spins tend to be somewhere in the 8-15,000 feet box. (Depends on the Op Area, they may have raised the floor in the past few years, not sure) .

What does the future hold?

Well .. the miltary pilots (at least jets pilots) have a ejectable seat ... that can make the difference now and in the future

TioPablo
29th Jul 2011, 20:18
Lonewolf
What does the future hold?

Well perhaps this Wolf...

NASA - NASA Dryden Fact Sheet - Intelligent Flight Control System (http://www.nasa.gov/centers/dryden/news/FactSheets/FS-076-DFRC.html)

cavortingcheetah
29th Jul 2011, 20:30
I feel sure that this has already been posted but here it is again anyway.

http://www.bea.aero/docspa/2009/f-cp090601e1.en/pdf/f-cp090601e1.en.pdf

wallybird7
29th Jul 2011, 20:30
Back to the original concept:
With an airplane that is prone to iced up pitot tubes, which then causes loss of airspeed, which causes loss of autopilot and autothrust, and with no high altitude training in hand flying, and flying in an area of high buildups and potential turbulence, it seems to me the best course of action is to AVOID it all in the first place.
Simulator training costs money, deviations around weather costs money, hiring experienced pilots costs money --
If you can't afford it you shouldn't try to operate an airline.

before landing check list
29th Jul 2011, 20:32
You know, I have been watching this thread for quite a while as all of us have. There seems to be basically 2 types of us in here. The 1st type insists that if they were able to hand fly the aircraft with just basic instruments this never would have happened. These guys probably flew way before X-Bots came out, began in a Champ, maybe flew some ag, sweated it out flew light twins in crappy weather sleeping on an air mattress at the crash pad. They caught a lucky break to fly jets and loved every minute of it.
Then there is the other group whom I will divide into 2 subsets. Subset (1) knows they do not have 100% control of the aircraft 100% of the time since it is FBW. However they know this is a design of the manufacturer and since the manufacture has designed the aircraft to be pilot proof they know each flight is a roll of the dice but they are OK with this. They just pray nothing serious happens the system as a whole cannot handle.
Subset (2) has not only drank the KoolAid but has the KoolAid main-lined into the subclavian artery. These poor suckers pray to the god of automation almost daily, totally believing the manufacturer is all seeing and knowing. Since it knows and sees all the system has to be able to do a better job in the flying aspect and the judgment angle. I mean why would the manufacturer make something having the ability to vote out humans if this was not so?
The last group probably came from some academy and took the fast track to the airlines. Not that there is anything wrong with that.......
Anyway to make a long story short, we are screwing ourselves out of a job slowly but surely. You do not need to pay computers, they do not unionize and do not require life support.
Is this truly a step forward?

DozyWannabe
29th Jul 2011, 20:36
Subset (2) has not only drank the KoolAid but has the KoolAid main-lined into the subclavian artery. These poor suckers pray to the god of automation almost daily, totally believing the manufacturer is all seeing and knowing. Since it knows and sees all the system has to be able to do a better job in the flying aspect and the judgment angle. I mean why would the manufacturer make something having the ability to vote out humans if this was not so?

Examples of this type please? I don't see anyone around here that matches that description at all...

Man Flex
29th Jul 2011, 20:43
The French version of the Interim Report No 3 shows the complete and utter confusion on the flight deck with the crew receiving continious and multiple warnings and the PF completely unaware that his inputs have put the aeroplane into a dangerous climb.

During the descent, with the aeroplane stalled, the crew are again confused. The PF is told he is climbing by the PNF and he responds by lowering the nose only to then receive the stall warning!

I now understand why they failed to action the ECAM; because the failures were changing rapidly before their eyes.

I can only suspect that the PF was hopelessly distracted from his primary task which of course was to fly the aeroplane!

A sobering lesson to us all - fly the aeroplane, using attitude and power only if necessary.

Ct.Yankee
29th Jul 2011, 20:56
Before Landing Check List;

I heartily and sadly agree.
Seen all three types of crew members
since early glass (B757) transition from
"steam gauge" (B727) to retirement (2007).
FBW (Fly by wire) vs. FBP (Fly by pilot)

before landing check list
29th Jul 2011, 21:11
Let me further state that the group 2 people are just in for the job. They even may feel a touch intimidated by the aircraft. They really have no interest in sharpening their pilot skills (There is really no need right) however they do take great pains in knowing company SOP’s verbatim (since the SOP’s will cover your butt in all circumstances right? Also knowing them as such will give a little bit of a false sense of security) they also know every note, warning, highlighted and bold print in the FM (not a bad thing at all) however they are not only not capable in keeping the ball centered when yaw damp is taken away on short final but they do not know it is displaced in the 1st place. Tell me there are no captains and crew who do not fit this picture. I dare you.

Examples of this type please? I don't see anyone around here that matches that description at all...

That was quick, I think I hit an exposed nerve there eh?

aguadalte
29th Jul 2011, 21:42
Thanks jcjeant for the full report link. It took a couple of hours to read it. I'm impressed by the notion of confusion sorted out from the transcript of the CVR and for the pilot's actions during those four minutes before impact. But I'm much more impressed by the avalanche of contradicting feelings they went through.

I remember when I was flying "honest" aircrafts. A failure was really a "single" failure. One would continue flying the bird while PNF or FE would sort out the check-list. Today, a "simple failure" may turn a good day into an holocaust.

Those pilots never realized they were in a Stall.
It started out with poor airmanship and ended the way we all know.

All three of them were very confused and unable to "read" what was going on.
The PF, (the first-officer on the RH Seat) even stated so, at least twice: (…)
je n’ai plus le
contrôle de l’avion là
J’ai plus du tout le
contrôle de l’avion"I don't have control of the airplane, I definitely have no control of the airplane"and he is still on doubt about what was going on at time: 2h12:04..07
J’ai l’impression qu’on
a une vitesse de fou
non qu’est-ce que vous
en pensez ?"I have the impression that we have a crazy speed, what do you think about that?"(Spoilers were even deployed by this time, but the second officer told him not to deploy them).

IMHO contributing factors were:
- the decision of the Captain to take his resting period before crossing ITCZ;
- poor airmanship;
- the Stall Warning logic (intermittent behavior);
- the complexity of the FBW system
- lack of AoA information
- poor handling proficiency

Hope we all learn from that.
Hope been-counters will learn something also.

Lonewolf_50
29th Jul 2011, 21:56
Hope been-counters will learn something also.

Not likely, their actuarial tables will simply have a different entry datum. :mad:

Don't get me started ...

Mr Optimistic
29th Jul 2011, 22:11
I admit that after a couple of years observation of these threads I value the comments and discussions here more than reading the actual reports and I haven't read today's release. We have a fair knowledge of what the crew did. They did what they did because it relected their appreciation of the situation and following that, their apparently appropriate response. The important thing is surely to understand why they didn't understand the true dynamic state of the aircraft. Without that knowledge nothing that follows is likely to ever be of any use. The upshot is surely that they didn't realise they were stalled. Your question to the technologists is surely how could you design a system that would let that happen ?

infrequentflyer789
29th Jul 2011, 22:41
IMHO contributing factors were:
- the decision of the Captain to take his resting period before crossing ITCZ;
- poor airmanship;

Maybe, and yes


- the Stall Warning logic (intermittent behavior);

Not sure I agree - they original warnings appear to have been ignored or discounted. If anything, intermittency might lead to more chance of recognition. It appears they thought they were overspeed and distrusted most or all instruments and did not believe the stall warning. I think there is a good chance they would have disbelieved a continuous warning all the way down too.


- the complexity of the FBW system


Why ? As far as I can see from the info we have now, if they had done the same in conventional controlled a/c the result would ahve been the same.


- lack of AoA information


Would they have looked at it ? Would they have trusted it (remembering it would have gone invalid at some points) ?


- poor handling proficiency


System failed the pilots by a lack of training - or at least BEA seem to think so.

Zorin_75
29th Jul 2011, 23:03
Your question to the technologists is surely how could you design a system that would let that happen ? So what should the aircraft have done differently? One frequent point of criticism is the deactivation of the stall warning at low speeds. That's arguably not a very good idea, yet it should be noted that the pilots managed to ignore nearly a minute of continuous stall warning without the message sinking in...
Another point also picked up by BEA is the lack of an AoA display. Would it have helped? Maybe. But they seem to have looked at only very few indications at all and could make sense of even fewer. My hunch is those who would know what an AoA gauge was telling them in a situation like this wouldn't need one in the first place to figure out 10000fpm down + nose up = oh sh.t.

The transcript is so depressing. It reads like PF didn't only not recognize the stall, but at that moment (I'm sure sitting at is desk, browsing PPRuNe things would have been quite different) he seemed to be totally oblivious to even the concept of stall:

"Qu’est-ce qu’y… comment ça se fait qu’on continue à descendre à fond là?"

"Mais je suis à fond à cabrer depuis tout à l’heure"

"Je cabre ?" - "Ben il faudrait on est à quatre mille pieds"
:(

flown-it
29th Jul 2011, 23:29
I said it a while back and I'll say it again.
Pitch and power.
The PFD or whatever you want to call it in your EFIS aircraft is 2 separate instruments. Pitot-static tapes and IRS center. If the speed tape is telling you overspeed and the altitude is climbing what is your attitude?
If the PF had only put the thing on the horizon with cruise thrust would they not had a chance of recognising the nature of the failure?
Who needs AOA if they just understand this very basic concept?

DozyWannabe
29th Jul 2011, 23:46
Tell me there are no captains and crew who do not fit this picture. I dare you.

Apologies, I presumed by "here" you meant "on this forum". I have to say I've never encountered anyone who was, or claimed to be, a pilot on here who was completely happy with letting the automation take all the strain and letting their basic piloting skills atrophy.

That was quick, I think I hit an exposed nerve there eh?

Not at all sir. I suggest you read what I'm actually saying (and have said consistently on here for 5 years) before tarring me with that brush. I have always said it is *imperative* that basic stick-and-rudder skills be maintained and that pilots should have a knowledge base relating to the type or types they are operating that is as complete as humanly possible. I think it's dispiriting and borderline scandalous that the airline industry sometimes treats its crews with so little respect and that it is as engaged in the "race to the bottom" as any other industry you care to name - see a rant I made on this very topic here:

http://www.pprune.org/tech-log/437803-automation-bogie-raises-its-head-yet-again-7.html#post6183737

Ultimately the aeronautical, mechanical and software engineers who design and build the aircraft you fly in and the systems that make them tick have at least as much professional pride in their work as you do. The concept of computers replacing pilots in our lifetime has only ever come from press hyperbole, and I think you'd be hard-pressed to find the engineers who would want to take on that responsibility. In short, we're on the same freakin' side.

It reads like PF didn't ... recognize the stall

Neither did the Birgenair PF, who was not only a senior captain, but an ex-military jock to boot. This is all about how the human brain reacts under pressure and stress, and the truth is that none of us can know how we'll react in a situation that perilous until we're confronted with it. The hope is that training for this kind of upset will be reinforced and expedited, along with proper CRM procedures to follow.

MATELO
30th Jul 2011, 00:45
[QUOTE][The PF made a nose-up left input on the sidestick to the
stop that lasted around 30 seconds./QUOTE]

If I was in a right hand turn nose down, think I might try that.

misd-agin
30th Jul 2011, 00:50
#1 airspeed indicator was unreliable for 29 seconds.

Stby airspeed indicator was unreliable for 54 seconds.

takata
30th Jul 2011, 01:49
just this once, then I'am off for vacation

http://takata1940.free.fr/screw.jpg

TioPablo
30th Jul 2011, 02:50
Posted by Doze
This is all about how the human brain reacts under pressure and stress, and the truth is that none of us can know how we'll react in a situation that perilous until we're confronted with it. Humans… Rare entities are those… Aren´t they Doze?
Anyhow… I´m overwhelm with the grace society degrades…
We all degrade in the same graceful way. Economy degrades graceful pulling everybody in its way down, with its poor philosophy and short-minded short-term get it all, get it fast! dogma.
“Graceful degrading systems” and their redundancy have shown that they aren´t able to cope with nature… They all kicked off and gave the “bad trained pilots” the joystick… Very graceful degrade strategy indeed… A mirror of the self made, bad communication and … culture.
Radar catching-up bad weather (way before bad weather becomes an issue), becomes degraded, certainly at the moment an ETOPS ops is going on. Super Cold water? What is that? Satellites monitoring and pitot tubes designed to cope with… What? What was their task? Well, I would say awesome performance in graceful degrade!
Graceful companies and developers all the way down, which keep pilots as slaves afraid to talk?
Just give me a graceful break will you!
Nobody here is against automation and development methinks. Rather we all are seeking for an answer. The answer which came from BEA nevertheless, is more than I´d expected…
I truly hope ALL pilot unions around the world will discuss this event deeply in order to improve aviation to it best.
It isn´t only an AF issue… It seems to me a worldwide policy instead…


I´m thankful to all of you, which during this long passing years, kept their minds sharp and were seeking for an answer. Also thanks to this forum which made it possible!

before landing check list
30th Jul 2011, 03:33
Not at all sir. I suggest you read what I'm actually saying (and have said consistently on here for 5 years) before tarring me with that brush. I have always said it is *imperative* that basic stick-and-rudder skills be maintained and that pilots should have a knowledge base relating to the type or types they are operating that is as complete as humanly possible. I think it's dispiriting and borderline scandalous that the airline industry sometimes treats its crews with so little respect and that it is as engaged in the "race to the bottom" as any other industry you care to name - see a rant I made on this very topic here:


DW you are right about this and I apologize for my comment. I also do not mean to come across that the pilots on flight 447 were in anyway incompetent. That would not be fair at all since I was not there and whom am I to judge. I do not like the system nor the training department. You have to know that throughout the whole incident those pilots used every ounce of their collective knowledge and experience and this one time it was not enough.
Could I have done any better? I am 53 years old and still flying. Luckily I have reached the point to be able to say I am not as good as one time I pretended to be. I know now the system (training department) does not and cannot cover all the bases and since we know this we must try to cover the gaps the best that we can. That is our responsibility we have to ourselves, each other and to the passengers who fly with us.
No, maybe I could not or would not have done better. We are only speculating here and that is not really bad since we are learning still (whether we admit it or not) from each other. I have never been in an unknown situation (flying or not) for that long amount of time with all those insidious conflicting information, we really do not know how we would have reacted especially when you throw in the "dark and stormy" bit with several hundred people in the back. Sometimes simulators do not simulate very well since that cannot simulate real fear other then the fear of your loss of ticket. Not the same at all is it?
Until bean counters quit ruling the earth which I do not think is going to happen anytime soon we have to stick together and do the best we can with the crap we are given.

Good day gentlemen.

before landing check list
30th Jul 2011, 03:50
If you had old style fixed wing military pilots the aircraft would never have been lost. All these aircraft need a magic switch that, when it is turned on, the aircraft turns into a basic stick handling machine.

I do not think this is a totally fair statement. Fortunately I have about have my time divided between military and civilian flying. I have seen gross muck ups on both sides. The military does seem to lack in imagination (as a very general rule so don't yell at me) and the civilians (Again as a very general rule so don't yell at me) sometimes lack in consistency in training.
It is our job as individuals as we mature is to see these faults in ourselves and fix them the best as we can. We need to take recurrent (even initial) courses ourselves from outside sources, try your hand at another type of flying (not as a job mind you but with a friend or just pay out of your own pocket. We should try to see outside of our ruts and think about what we see.

Poire
30th Jul 2011, 07:33
Takata, pardon ma inexpérience: is that a flap actuator or a stabilizer one?

Merci

mmciau
30th Jul 2011, 07:43
Image at 2286

Is that screw shaft bent?

Rananim
30th Jul 2011, 09:27
The copilots had received no high altitude training for the "Unreliable IAS" procedure and manual aircraft handling BEA

I am only repeating what has already been discussed but the thread is so long,its hard to find the fundamentals and keep your bearings.AeroCaraibe suffered an almost identical incident(s) just prior to AF447 and a lengthy report was issued.Same Aircraft,same pitots,same icing encounter,same language.Why then was it not disseminated,digested and trained on?

The key line in the AeroCaraibe report(French language only) says:
"En effet,le 'PF' est intimement persuade que les deux alarmes 'STALL' sont inappropriees.C'est volontairement qu'il ne tient pas compte de la phrase 'RESPECT STALL WARNING AND DISREGARD RISK OF UNDUE STALL WARNING STATUS MESSAGE IF DISPLAYED ON ECAM."

The AeroCaraibe pilot used a KNOWLEDGE-BASED response to loss of airpseed and spurious STALL warning associated with pitot icing.Fly pitch and power,2.5 deg ANU and 82% N1.My question is that even if the AF PF was unable to disbelieve his instruments and ignore any spurious warning,why did he pitch the aircraft to 10deg+ ANU?At FL350???Would not the instinct be to fly TOGA and 0-2.5 ANU pitch?And then find himself in overspeed after the icing clears(only 50 seconds)?This is very confusing.Someone said that FBW pilots apply TOGA and full ANU on the stick in response to stall.Now he acknowledges ALT LAW(ie.a/c can stall unprotected..is that right?) yet goes for 10+ANU pitch at 35000 feet?
Pitot-static anomalies are not easy for pilots;you have to ignore your instruments affected by the blocked sensor and maintain concentration on pitch/power through a cacophony of aural/visual alerts,some valid,some not.Experienced crews have been flummoxed by conflicting information as seen in Aeroperu and Birgenair.Use a rule-based response at your own peril.But those crews did exactly that.And there was a Captain sitting in the left seat on both flights,although an umbrella of suspicion is certainly cast over the quality of the Birgenair crew(he continued the takeoff with an AS disagree).

The two Airbus anomalies here(THS stuck at 13ANU and stall inhibited below 60),although contentious,should never ever have come into play.Lets assume that we cant expect two co-pilots to apply a KNOWLEDGE-BASED response to a high altitude unreliable airspeed event at night over the Atlantic.They are fooled by the conflicting information despite the fact that they knew they were flying at M.8 just moments prior.They now believe they're in a stall.They believe whats presented in front of them.Then there should not have been any ANU pitch command and hence no auto trim to 13 degrees,no speed(real) decay and no possibility whatsoever of stall inhibit.They should have found themsleves in an overspeed condition after the pitot unblocked which may/may not have led to inflight break-up.This would have been plausible,even forgiveable.All they had to do was do what the AeroCaraibe crew did.Set 81% N1 and put the nose just above the horizon.It was flying before with those settings,it will continue to do so.

Mimpe
30th Jul 2011, 09:51
Please look at the BEA website.
There is a new press statement/synthesis of the accident. There is also some recommendations regarding pilot training for high alt stalls, and a recommendation that all aircraft display A of A data.

Personally, I'm concerned at the absence of comment on pilot/aircraft interface factors- in particular, regarding the loss of speed data resulting in a situation where correct stall recovery actions appear to have led to a reactivation of the stall warning. At that moment, it seemed to be the last chance for these poor people.

My friends in the industry none the less assure me that fyling attitude strictly, with minimal changes to any control inputs, would have saved the day.

I would also be interested in any comments as to how the alarm/alert system may interact with a disorientated pilot to produce responses that generate additional risk in emergency situations.

takata
30th Jul 2011, 10:31
Hi Poire,
Takata, pardon ma inexpérience: is that a flap actuator or a stabilizer one?
THS screw and actuator... and it was a test in order to verify that Bearfoil was really off for vacation. (He could not have refrained from posting as he is quite obsessed with this piece of metal).

Loose rivets
30th Jul 2011, 12:57
I also do not mean to come across that the pilots on flight 447 were in anyway incompetent.


Seems you don't have to. But, it's so, so easy to fly those last few minutes from the comfort of one's armchair. It must have been enough to throw a good mind into chaos for a moment or two, but for those with very limited time handling real hardware in extreme conditions, it seems what they had in front of them was more than they could unravel. It takes a lot of willpower to shut out a vista of sophisticated equipment and concentrate on one small and comparatively primitive device.


BBC News - Air France Rio crash: Pilots 'lacked training' (http://www.bbc.co.uk/news/world-europe-14342877)

Mac the Knife
30th Jul 2011, 13:57
Sorry, very ignorant person confused here.

Did they not have an attitude indicator/artificial horizon working (I thought that they did)? Would that not have shown that they were markedly pitched up and given them a clue to what was going on?

Loose rivets
30th Jul 2011, 14:30
As far as I know after some weeks torn from the internet, the standby horizon was unaffected by the computer derived errors. Although the main systems were probably okay, the idea of the standby is that its power supply should be maintained and its internal workings unaffected by the plethora of information inputs. If in doubt, check that little unit.

Just a video of a random 330. Start just after a minute in. Worth looking at the scan of first the standby horizon, then captain's screen, then it goes through standby to the right. A bank has been started.

Even the standby is electronic. I would love to see a gyro in there somewhere.


‪A detailed flight deck view of A330‬‏ - YouTube

Probably a translation plus press-speak, but some of the dialog must be from the transcripts. Totally horrifying.


Cockpit terror of jet's 38,000ft death plunge - News, Frontpage - Herald.ie (http://www.herald.ie/news/cockpit-terror-of-jets-38000ft-death-plunge-2835832.html)

Mark in CA
30th Jul 2011, 15:49
Just reading the NY Times report on this (http://goo.gl/IKmQy), which ends with a paragraph that says:

Since the accident, both Airbus and Boeing have modified stall-recovery procedures with guidance from safety regulators in the United States and Europe. Safety experts say those procedures now instruct pilots to first lower the nose of the aircraft, regardless of altitude, and, if necessary, reduce thrust to avoid excessive acceleration. Previously, the standard procedure when nearing a low altitude stall was to raise the nose by around 5 degrees and maintain thrust.

First, this just so elemental it seems to be rediculous. But that last sentence really surprised me. In my extremely limited experience as a GA pilot, I was always taught that the first thing you do when approaching a stall is lower the nose. Can someone explain why the "standard procedure" has been to raise the nose?

ChristiaanJ
30th Jul 2011, 16:04
As far as I know after some weeks torn from the internet, the standby horizon was unaffected by the computer derived errors. Although the main systems were probably okay.... So far there are no 'hints' either that the main attitude displays were affected at all.
...the idea of the standby is that its power supply should be maintained and its internal workings unaffected by the plethora of information inputs. If in doubt, check that little unit. Not relevant here, but the "old-fashioned" electro-mechanical standby AH would remain stable and reliable (because of the high gyro rotor speed) for minutes after everything else went "kerplunk". It's still credited with saving a Caravelle when the entire electric systems went belly-up.

----

Just a video of a random 330.Not quite random, since it has an independent 3-inch standby A/I. The AF A330 that crashed had an "ISIS", a bigger standby 'instrument cluster' on a separate screen (there should be a photo somewhere on this or the other AF447 thread). Hence I assume the video was not of an Air France A330.

Even the standby is electronic. I would love to see a gyro in there somewhere.I don't know what the type/manufacturer of that particular standby A/I is.
But I think that you'll discover the old and well-known fully electro-mechanical SFENAs have now left the stage, but that behind that electronic display there's still an independent gyro. Switching to an electronic display just made the mechanical bits simpler....

Probably a translation plus press-speak, but some of the dialog must be from the transcripts. Totally horrifying. The dialogue that the Herald quotes is indeed based on translated excerpts from the transcripts.

Two's in
30th Jul 2011, 16:06
Can someone explain why the "standard procedure" has been to raise the nose?

I believe the (flawed) training analysis is along the lines that if you learn to recognize the onset of the stall early enough, then an increase in thrust (and hence airspeed) will fly you out of the stall threshold WITHOUT any reduction in altitude or requirement for a nose down attitude.

The flaw in this training philosophy is that it assumes you will always recognize and react at early stall onset, so the full stall never develops. If you never couple this training with full stall recovery techniques, eventually pilots end up not knowing what to do if a full stall develops.

This originates in flawed training analysis where the fear of losing any height at all during stall recovery on an approach has the effect of removing the basic skills required to recover from a fully developed stall.

Loose rivets
30th Jul 2011, 17:41
Yes, I think it is based however, on a full compliment of engines running at say, cruise power, and an attitude that wouldn't be that much of a change when hurriedly pulling to +5. The power increment could then be metered out by erm, skilled judgment.

The crew were perhaps dealing with not only vigorous turbulence, but also more than a few man-made excursions from the horizontal. Also trying to recognize a stall with massive lifting and down-droughts would certainly be very much more difficult. Stalled one moment, and flying with reduced wing loading the next.


What I find hard to understand is the 'Deep Stall' nature of this decent. There does not seem to have been a succession of conventional stalls, yet the aircraft is not one of the T tailed types that could lock one into such a decent. I can only conclude a lot of time was spent with the systems blurring the issue, indeed applying power with vectored thrust 'shaping' the angle of stabilization to some deceptive angle.

Is there a clear recording of the flight-deck ambient noise? Once height was reduced enough to give a good gap between stall speed and overspeed, the ambient noise would have been quite different. The silence should have been deafening.

Capt Turbo
30th Jul 2011, 19:07
The previous recovery procedure was based on the fact that all widebody aircraft with hi bypass engines is capable of stall recovery with minimal altitude loss due to quick engine response and massive thrust. If slats is extended at the same time the aircraft can be flown out of the stall without altitude loss if at low level.

An A330 in degraded law at high altitude stalls at 7 degrees AoA (vs 15 degrees at low altitude), max thrust = climb thrust, and the recovery pitch is somewhere between 0 to -5 degrees and requires 4000´if done correctly. If you do not initiate recovery promptly, but hold the stick back, lack of elevator response will cause the THS to trim nose up, just as the report suggest.

In this situation, if the AoA becomes extreme, you may have to use rudder to get the nose down, and it takes a very low nose down attitude to unload and regain airflow.

Now, with this attitude (more than 20 degrees n.d.), once the airflow is back, the acceleration is huge - especially in manual TOGA - and you must[B] start a smooth recovery immediately while avoiding over-stress ( fortunately the Airbusses have g-meters), secondary stalls and Vmo excursion. Vd excursion with structural failure is a distinct risk.

Recently, we have done the AF profile a number of times in a very good CAE SIM: recovery is possible at 37000´if done properly. After holding the stick back and letting the THS trim aft, the ensuing deep stall is IMHO not recoverable for the average line pilot, and that brings up a new question:

[B]To which extreme situations shall we select and train commercial line pilots?

Oh, we all want to keep our cosy straight-and-level job, and the operator just want to fill a seat, so the mental break point SIM assessments has gone out of fashion, and no one knows if the co-pilot is really up to it, if the poop hits the fan.

What is left is training, and while some operators are doing a great job, some are not, partly because proper high altitude recovery training takes time, and the allocated training time is already full of NPA, V1 cuts, ECAM work, Evacuations etc. etc.....

Hopefully this tragic event will trigger some thoughts in the training departments and among the regulators, so we can swop some of the endless checklist reading with some hands-on training. Getting extra time....? In your dreams.....

And BTW, 25 years ago I initiated a hi-level training program for the old captains; many of them didn´t have a clue of what was going on up there unless they had survived a tour on one of the "interesting" fighter types of the day, and only a few of them had actually recovered from a stall in the Starfighter, the Phantom, the Lightning or the Mirage.

Greek God
30th Jul 2011, 21:23
Correct me if I am wrong (I'm sure someone will!) but I thought the revised stall recovery was as a consequence of the 737 stall on approach into Bournemouth and similar incidents which application of TOGA could cause an uncontrollable pitch couple especially if out of trim?

TioPablo
30th Jul 2011, 22:47
B4-Landing said:
Until bean counters quit ruling the earth which I do not think is going to happen anytime soon we have to stick together and do the best we can with the crap we are given.

:D Thanks B4

Clandestino
30th Jul 2011, 23:21
The crew were perhaps dealing with not only vigorous turbulenceVertical acceleration trace is not consistent with flying through turbulence. There is +1.6 G spike as the aeroplane starts its climb, after that, it remains between +1.25 and +0.7G for the remainder of the flight.

What I find hard to understand is the 'Deep Stall' nature of this decent.Trimmable horizontal stabilizer went to maximum nose up deflection. For most of the upset, both elevators were at their maximum nose-up deflection, too. Twice they start moving towards nose-down, first prompted by command from RH stick, second time by LH, but they only get halfway to neutral before new pull on the sidestick sends them back to their NU stops. Seemingly FBW was in Altn law so elevators were trying to satisfy G demand from pilot controls. It goes to show that even when there's no direct stick displacement to control deflection things work out in quite conventional way.

misd-agin
31st Jul 2011, 00:55
Have to wonder if the FB(in the left seat) and CA(jumpseat after returning to cockpit?) could tell that the FO had the stick in the full nose up position?

With a sidestick, especially at night, I wonder if anyone could see the FO's sidestick inputs?

larssnowpharter
31st Jul 2011, 01:39
I work for a major oil/gas and petrochemical company and a fair amount of my job involves investigating what we call catastrophic events. For this reason I follow investigations into civil aviation accidents as they are probably the best investigated accidents available and, generally, set a standard for other industries.

I have a background in military and sport aviation although not commercial flying.

This interim report from BEA has resulted in headlines in the press that basically lays the fault/blame on the crew. Indeed, it would seem that errors were made and I can see at least 6 of DuPont's Dirty Dozen raising their combined heads above the parapet. No doubt the cockpit transcript will provide excellent training in Human Factors in the future. Sad but true.

I have no idea of the BEA's remit in terms of how far it can go in a proper RCA of this event. So far we seem to have a good idea as to the WHAT and the WHO. However, when we get to the WHY we have the all too common finger pointing at the training system. Sure, a failure in training can be rectified relatively easily if the will and money is there. However, my view is that this is an easy cop out and that the true root cause can be disguised all to easily by following this route.

So, let's ask ourselves a further WHY: Why had the training system NOT identified the need to train pilots to deal with inaccurate IAS indications at high level especially in the light of previous events as well as known reliability issues with the pitots.

I would like to see this next step taken. There was clearly a decision making (or, more likely, a lack of decision making) process involved here that may be the real root cause of this tragic event. Was complacency also a factor here?

Lastly, I find AF's comments re the lack of AoA indications (is not the stall warning an AoA indicator?) specious and more likely made in what will no doubt be a blame game between Airbus and AF decided in the courts.

TioPablo
31st Jul 2011, 02:11
Sure, a failure in training can be rectified relatively easily if the will and money is there.

Do that! Don´t dare to doubt please! It will pay out in time... It is just a question of time... Dare to invest in the future, but... Don´t be afraid... You have a lot of good ppl going around.... You are one of them :)

before landing check list
31st Jul 2011, 02:45
Thanks B4

De nada dude.:ok:

MountainBear
31st Jul 2011, 05:26
I deleted my prior post because frankly it was hot-tempered. Let me try to be more civil and to the point.

At this stage in the aviation industry's development it is clear that airline accidents have become nothing more than blame game with software designer/engineers on one side, hardware manufactures on the other, and the pilots stuck right in the middle. Rather than either of the primary culprits taking responsibility the industry's response to every accident is to trot out PILOT TRAINING as the grand panacea that will cure all the ills.

This accident is the poster child for pilots taking the heat when the real culprits are (a) poorly thought out software design decisions and (b) flaky hardware. That doesn't mean that I think the pilots performance was mistake free. But it's obvious that they were set up to fail and MOAR TRAINING is not the answer to the problem.

before landing check list
31st Jul 2011, 05:38
Bear, maybe the (or A problem) is software is needed for basic functions. I do think that if there were some real instruments requiring hardware such as a tube that was relaying ram air pressure from the outside DIRECTLY to the inside to an instrument which would translate that to a circular scale and call this an IAS dial, and somewhere close to it have a real gyro to give attitude information with a battery back up and another one with another tube DIRECTLY reading the pressure outside the aircraft to another circular dial and call this an altimeter. Then SOMEWHERE on the panel mount these where the computer operators can see them and before they climb into the cockpit give them training on how/when to use them. While you are at it have a freaking big red button between the seats that when pushed there is no right stick did this, left stick did that and if the moon is at a certain light level and it is Tuesday the software still may or may not give you what you ask for and in doing so the computer operators now turn into pilots. :ugh:

Face it, the freakin system as a whole was designed to eliminate pilot mistakes. It was not expressly designed to lighten workload, was already had all we needed for that. Not only was it to eliminate our possible mistakes but to also cover up our lack of basic flying skills with designers and software engineers who thought they knew more then we did on how an aircraft is supposed to be operated. We were sold a wagon full of crap now we must do our best to operated within this absurd criteria.

Dudes you need to rise up with your unions and take your positions back, this is not working.
Now let us hear the bitching from the My god is my software and I shall covet no other people.

Zorin_75
31st Jul 2011, 06:19
While you are at it have a freaking big red button between the seats that when pushed there is no right stick did this, left stick did that and if the moon is at a certain light level and it is Tuesday the software still may or may not give you what you ask for
I had already asked you this earlier, but now that we have a much more detailed record of 447s final minutes maybe you're ready to answer - at which point didn't "the software" give them what they asked for?

before landing check list
31st Jul 2011, 08:10
Zorin, hold on a sec. I did miss your prior question to me. So here goes an answer flown an AB aircraft;
Flight 296 in Paris. I do not think the pilots flew into those trees on purpose.

Quoted from misd-again

Have to wonder if the FB(in the left seat) and CA(jumpseat after returning to cockpit?) could tell that the FO had the stick in the full nose up position?
With a sidestick, especially at night, I wonder if anyone could see the FO's sidestick inputs?

So if you were to jump into the right seat and pushed forward on the stick whom would the computer attempt to obey? Either way somebody would not be getting what they asked for and worse that person would never know because there is no feedback. They would just be assuming for whatever reason the inputs they were trying to give were not working now it is time for plan B, C, D etc. All of this happens in seconds adding to the confusion. So you end up with the left hand not talking with the right hand and the computer through lack of feedback not talking with either of them.

Do you think the pilots wanted the THS to go full ANU or do you think the computer assumed one (not both) of the pilots wanted it? I say both because who really has command when the side sticks are displaced in different locations? I really do not know.

In fairness to the PF (whichever one it was) the only 'nose-up input' he (The PF) applied at the onset of the accident was immediately after the sign-off. The BEA states that the 'zoom climb' started at least 11 seconds after that - and there is no mention of the PF moving the stick either way until he applies 'nose-down' to counteract the climb. Does this mean the PF did not cause the climb but it takes several seconds for the AB330 to respond to control movements?

Hand Solo
31st Jul 2011, 08:12
The software gave them what they asked for at all times, but what they asked for was dumb. Regrettably to me this boils down to the fact that if you lose your airspeed instruments at altitude, close to your performance ceiling, initiating a 7000fpm zoom climb is about as wrong a response as you can have. Having done that if you then find yourself descending rapidly with the nose high you should recognise the stall for what it is. Its no good blaming the software or the system. If you did the same things in a 737 you'd get the same result.

Edit: if you have dual inputs on the sticks it will tell you, and you can override the opposite stick with the priority button. This accident was not caused by confusing dual inputs but by inappropriate and sustained solo inputs. The computers don't make assumptions, they follow commands. What the THS is doing is largely immaterial so long as the aircraft retains the capacity to deliver the commanded load factor, which it did throughout. Pulling and holding full aft stick in an Airbus is akin to pulling full back stick and holding full aft trim on a Boeing. There is no mystery or confusion about it, it's Airbus FBW 101.

IcePack
31st Jul 2011, 08:57
Someone mentioned a 1.6 g spike at the start of the climb. Doesn't sound like much but would feel quite violent. It also probably mean they had just clipped a quite strong updraft. Personally I believe that no pilot would maintain a pitch attitude of 16 deg at height intentionally it would look too weird.
Also if you go hands free from straight & level, neutral stick, the a/c tends to climb at high level due it trying to maintain 1 g.
Methinks too much blame is being metered out to the pilots. But then again it is ever so.

Capt Turbo
31st Jul 2011, 09:08
OK465 : When I say that the "average" line pilot cannot recover from a deep stall I actually mean that very few of us have any training and experience in recovery from a departure in a swept wing jet.

While the majority of my trainees will have to follow some (very loud) commands from the old man behind, there are a few ones around who has the aggressive, composed attitude to keep fighting and who knows what it takes.

No doubt an airline, who would only employ Imperial Flight Test School graduates, can expect that this particular field of operations is covered (and the salaries will again be "up, where they belong" :E ), but we live in the real world, and my question remains:

When is enough (training) enough?

As I see it, a good many operators have a long way to go before reaching "enough"; just the fact that in the Mach-region pitch attitudes outside +5 to -2 degrees is risky business comes as big news to quite a few fellas.

So if a majority of pilots in a given airline has inadequate knowledge of the environment in which they fly, is that to be blamed on the individual pilot or is it a "system failure"?
If the pilot corps cannot deal with a 1/10.000.000 probability failure, is that to be blamed on the pilot, the airline or the manufacturer?
If you add severe weather, night, black sea, does that make it "natural causes", pilot error, system failure or design failure?

Which one will be the cheapest verdict for the huge economical interests involved here? And how do you make interim reports pointing in that direction in a subtle way? :*

Kalium Chloride
31st Jul 2011, 09:12
Personally I believe that no pilot would maintain a pitch attitude of 16 deg at height intentionally it would look too weird


"Look"?

In darkness at altitude over an ocean, possibly in cloud, I suspect there was no visual reference to "look" weird. I suspect that was part of the reason for failing to realise the attitude of the aircraft during the stall.

BOAC
31st Jul 2011, 10:18
Also if you go hands free from straight & level, neutral stick, the a/c tends to climb at high level due it trying to maintain 1 g. - with your training experience, I'm sure you could could you explain this statement to we non-AB folk? It seems a little odd.

cwatters
31st Jul 2011, 10:19
As I understand it the aircraft (if not the pilots) knew the AOA was too high. So perhaps changing the audible warning to announce the AOA would be benificial.

At the very least change it so that the warning isn't the same pre and post stall.

It seems they never realised they were fully stalled so can you really blame them for they way they responded?

The other possibility is that one or more did realise they were stalled but assumed the PF realised it and had tried to get the nose down. There is a lot less discussion of the situation than I expected.

EGPFlyer
31st Jul 2011, 10:45
BOAC, I believe it's because 1G is acceleration due to gravity at sea level. The same acceleration at 40000ft might be 0.9999G (I'm sorry, I'm not clever enough to work out what it is) therefore to maintain 1G the aircraft will slowly pitch up.

BOAC
31st Jul 2011, 10:52
Hmm! So the clever software is not clever enough to know its altitude, and will eventually command a loop to maintain 1g?:) Don't forget it will also need GS in order to compute centripetal acceleration.

iceman50
31st Jul 2011, 11:29
ICE PACK

Sorry where do you get this from Also if you go hands free from straight & level, neutral stick, the a/c tends to climb at high level due it trying to maintain 1 g.


ALT 1
PITCH CONTROL
Ground mode
Identical to normal law ground mode.
Flight mode
The flight law is a load factor demand law similar to the normal law with limited pitch rate feedbacks and gains depending on speed and configuration.

FLIGHT MODE
The normal law flight mode is a load factor demand law with auto trim and full flight envelope protection.
It provides control of elevator and THS from the side stick controllers to achieve a load factor proportional to stick deflection, independent of speed.
With the side stick at neutral, wings level, the system maintains 1 G in pitch corrected for pitch attitude, and there is no need for the pilot to trim with speed or configuration changes.


ALT 2
PITCH CONTROL
Identical to ALT 1 law.

So it will not go into a gentle climb trying to maintain 1G.

Kalium Chloride

In darkness at altitude over an ocean, possibly in cloud, I suspect there was no visual reference to "look" weird. I suspect that was part of the reason for failing to realise the attitude of the aircraft during the stall.

Not quite, that is why we "pilots" have to fly on instruments, namely the PFD, on most new A/C (artificial horizon), with reference to an ATTITUDE. I would certainly never expect to see 14 degrees plus at 35,000'. You also start to see big red arrow heads which show you where the horizon is as you go further from level and they get BIGGER the further you move away from level.

Clandestino
31st Jul 2011, 11:57
therefore to maintain 1G the aircraft will slowly pitch up. That's an urban legend. Releasing stick to neutral in pitch in normal and alternate laws results in pitch hold, not 1G hold.

I do think that if there were some real instruments requiring hardware such as a tube that was relaying ram air pressure from the outside DIRECTLY to the inside to an instrument which would translate that to a circular scale and call this an IAS dial, and somewhere close to it have a real gyro to give attitude information with a battery back up and another one with another tube DIRECTLY reading the pressure outside the aircraft to another circular dial and call this an altimeterMost probably all 3 pitots were affected by icing. Everything between probes and instruments was in perfect working order until aeroplane was smashed against the ocean. Static pressure system was totally unaffected. There's no indication that any of four horizon references toppled during final minutes of flight.

When I say that the "average" line pilot cannot recover from a deep stall Per definition of deep stall, no pilot can recover unless aeroplane is equipped with antispin parachute and it's used properly and timely.

Do you think the pilots wanted the THS to go full ANU or do you think the computer assumed one (not both) of the pilots wanted it?
Flight controls computers acted in accordance with sidestick inputs.

In darkness at altitude over an ocean, possibly in cloud, I suspect there was no visual reference to "look" weird.There were instrumental references, three of them to be precise. Two EADIs and ISIS. It is mighty certain that two of them agreed and so far there's no reason to believe that third toppled.
Personally I believe that no pilot would maintain a pitch attitude of 16 deg at height intentionally it would look too weird. Page 109 of BEA 3rd interim report refers. Pitch is "assiette" in French. would you believe pilot attempting to take off without clearance? Trusting only instrument that has failed and stalling the airliner on climbout? Failing to control speed and stalling on short final?

In fairness to the PF (whichever one it was)Initially it was the youngest pilot, sitting in RH seat. Control was later transferred to older F/O in LH seat. Sidestick traces clearly show who made which input and when.

The BEA states that the 'zoom climb' started at least 11 seconds after that - and there is no mention of the PF moving the stick either way until he applies 'nose-down' to counteract the climb. Does this mean the PF did not cause the climb but it takes several seconds for the AB330 to respond to control movements? BEA has thoughtfully included sidestick and control position plots in its report so anyone able to read them should not depend on BEA's wording only. A330 is big aeroplane with powered controls. Both of it spell: i-n-e-r-t-i-a.

So perhaps changing the audible warning to announce the AOA would be benificial.I am sorry sir, but I fail to see how replacing FWC shouting "STALL-STALL-STALL" with one saying "Your AoA is ten... it's twelve now... whoops there goes fifteen... boy, you've hit 25 degrees AoA" would be benefical.

Me Myself
31st Jul 2011, 12:20
What really upsets me is that everybody seemsto concentrate on what happened once the aircraft stalled : Who Cares !!!!!!!????

The central question is : Why on earth did they get themselves into this and how ?
BEA has pretty much nailed it : the least experience pilot pitched a whopping 10 deg up without applying power !!! and the most experienced, instead of keeping his eyes on attitude and whatever was left, chose to turn his gaze elsewhere to call the captain to the flight deck.
The failure was never recognized, therefore the adequate checklist never called for.
How could anyone of these 2 ever realize they had stalled when awareness was at its rock bottom from the start ?

Of course they did everything they could to get out of this.................not having a clue about the problem they had to solve.

All this comes to basic airmanship, plain and simple.
Wether this airmanship is training related is open to debate.
Once stalled, I too, would have never been able to recover.

larssnowpharter
31st Jul 2011, 12:49
Me myself:

Your post tends to illustrate the good sense stated in Two's In post:

I believe the (flawed) training analysis is along the lines that if you learn to recognize the onset of the stall early enough, then an increase in thrust (and hence airspeed) will fly you out of the stall threshold WITHOUT any reduction in altitude or requirement for a nose down attitude.

The flaw in this training philosophy is that it assumes you will always recognize and react at early stall onset, so the full stall never develops. If you never couple this training with full stall recovery techniques, eventually pilots end up not knowing what to do if a full stall develops.

This originates in flawed training analysis where the fear of losing any height at all during stall recovery on an approach has the effect of removing the basic skills required to recover from a fully developed stall.
Two's in is offline Report Post Reply

In short, a basic misunderstanding of what a stall is.

aguadalte
31st Jul 2011, 12:54
My Boeing aircraft experience ended in the early ninety's. Since then I have flown A310/320's/330 and A340.
Must tell you that I still miss the yoke and the (artificial feeling) feed-back that I used to receive from it, as well as from the Auto-Throttles.

Let me ask you this:
If the PF co-pilot was "feeling" a sluggish yoke, would he ask his crew mates:
J’ai l’impression qu’on
a une vitesse de fou
non qu’est-ce que vous
en pensez ? "I have the impression that we have a crazy speed, what do you think about that?"

EGPFlyer
31st Jul 2011, 13:12
Clandestino,

To be honest I don't know how the A330 differs but if you disconnect the autopilot in level flight at altitude the A320 will pitch up slowly. I know, I've done it.

From my FCOM

"With the sidestick at neutral, wings level, the system maintains 1 g in pitch"

I've never heard of 'pitch hold'

predictorM9
31st Jul 2011, 13:14
[Static pressure system was totally unaffected.]

Mhhh... I may be wrong, but if the static pressure system was totally unaffected, why does the vertical speed graph (page 109 of the report, second graph from top) looks so weird, with huge jumps?? They may also have excluded the vertical speed info because of that.

I think the responsibility of the pilots in this case is pretty limited. They failed to identify a stall, but the fact that the stall warning appears only when you put your stick would make me believe (if I was pilot) that the stall warning is also wrong, as everything else.

I don't know who got the idea of excluding AOA measurements based on speed. If I had designed the system, I would have kept this data all the time (except possibly during the take off and landing runs. For knowing that you just use the landing gear sensors as input and that's it) .While in flight, I don't see any configuration where the AOA measurement would be too bad because of low speed. Was the A330 designed to fly at 60 knots anyway?
I cannot understand the logic behind this design. If somebody can, that would help me.:ugh:
For me, this bad logic is a driving factor of the crash. Had the stall alarm sounded *permanently* during the fall, I would have expected the pilot decisions to be different.

dewoitine520
31st Jul 2011, 13:23
1/ the report is a factual description of what was happening
2/ it never says it is a crew fault.
3/ as in many other domain, from facts, in view of your own experience, you make your mind.

1/ the crew never recognized they were stalling. (would I had ??) It is a fact, the report is clear in that matter.
2/ a fault is when you do purposely something you should not do. I do not see any crew fault in that report.
3/ some occurences air data references losses because of freezed probes were reported on the same aircraft type several times in Air France and other companies.
.
3/a Airbus was aware of the problem, and a probe replacement campaign was scheduled.

3/b in the time frame the probe replacement campaign was ongoing, they have never been trained to cope with that kind of major failure. in fact it looks like the training in "pure" aircraft handling is very poor in the training syllabus.


I hope this accident will help the aviation international authorities to rethink the pilot training syllabus, but also to improve the " field experience feedback" processing in aircraft safety.

I am afraid... it will lead to discharge the responsibility of all accumulated mistakes from all parties onto the three crew members.

before landing check list
31st Jul 2011, 13:25
I don't know who got the idea of excluding AOA measurements based on speed. If I had designed the system, I would have kept this data all the time


That is because a lot of operators believe that with high speed you cannot stall thus no need for AOA indicator. These poor souls believe that the answer is ALWAYS to point the nose down which is the answer MOST of the time however not all the time. In reality an airplane can stall at any attitude and airspeed (within structural limitations of course.) The IAS and ATT are subordinate and supporting to an AOA indicator in relation to what the wing is actually producing. Even if the pilots were clueless the on board computers would know this (tongue in cheek)

So does the 330 have an AOA indicator and if not do you think that if it did and if the pilots were trained to interpret it would it have helped? After all it is giving a true condition into what the wing is doing.

predictorM9
31st Jul 2011, 13:41
Yes but this goes even beyond that... even if you don't want to display the AOA info to the pilot (which I can admit), I don't understand why you would start to exclude what one sensor is saying using the data from an unrelated sensor.
As long as the plane is in the air, the relative airspeed cannot be less than 60 knots, I think everybody will agree about this. So why was this logic implemented?

hulotte
31st Jul 2011, 13:47
To POIRE

Its THS screw shaft
(Are you expat in Middle East)
Take care

Rob21
31st Jul 2011, 15:09
Based on the principle that automation came to minimize pilot error, I foresee the following flight crew formation:

One pilot and one computer specialist. The computer will have a new "law", the emergency law. The computer will be able to quickly identify the nature of the emergency and take proper action. Auto pilot will disengage only when the pilot decides to do so. Of course, he will check first with the SS (System Specialist) if the computer will be able to solve the problem.

If computers are able to fly a crosswind ILS, with gusts, I don't see why not the computer can't "read" the checklist on, for eg., procedures for unreliable airspeed.

To train a computer is cheaper.

The pilot will be a "flight consultant" to aid the computer with the "gut feeling".

bearfoil
31st Jul 2011, 15:14
With you until the "gut feeling" :ugh:

funfly
31st Jul 2011, 15:22
What would have happened if none of the pilots had been there?

DozyWannabe
31st Jul 2011, 15:31
So here goes an answer flown an AB aircraft;
Flight 296 in Paris. I do not think the pilots flew into those trees on purpose.

I'm not willing to go into that one again in public so I'm putting together a PM for you, but I will tell you it wasn't in Paris, it was at Habsheim/Mulhouse airfield, which I think is in the Alsace region. I will also tell you that a lot of second and third-hand information on that incident came from poorly-translated, largely inaccurate and occasionally sensationalist press articles. :)


Also if you go hands free from straight & level, neutral stick, the a/c tends to climb at high level due it trying to maintain 1 g.

To be honest I don't know how the A330 differs but if you disconnect the autopilot in level flight at altitude the A320 will pitch up slowly. I know, I've done it.

It's a quirk of the A320 which was corrected in the later models (A330, A340 and A380) from the outset. It may have even been corrected in later A320s.

Most of the time you're at cruise - i.e. at an altitude where this becomes noticeable - in an A320 which exhibits this quirk (or indeed any other modern airliner for that matter) will be spent under FMC (autopilot) control with altitude hold engaged anyway, so it rarely comes up.

jcjeant
31st Jul 2011, 15:52
Hi,

The central question is : Why on earth did they get themselves into this and how ?
BEA has pretty much nailed it : the least experience pilot pitched a whopping 10 deg up without applying power !!! and the most experienced, instead of keeping his eyes on attitude and whatever was left, chose to turn his gaze elsewhere to call the captain to the flight deck.
The failure was never recognized, therefore the adequate checklist never called for.
How could anyone of these 2 ever realize they had stalled when awareness was at its rock bottom from the start ?I think the answers to your questions are in the BEA N°3 report ...

The PF made a announcement to the cabin personnal about turbulences to come
The PF was not belted on his seat (nothing .. completely free)
Are this a normal or professional behavior of a responsible pilot ?
My answer is no
What you can expect from such seriousness pilot in case of an emergency situation ?
The AF447 tragedy

Mac the Knife
31st Jul 2011, 16:03
Apologies, me again.

"There's no indication that any of four horizon references toppled during final minutes of flight."

So why didn't they look at the attitude indicator/s, which would have shown them to be steeply pitched up?

Isn't that a primary flight instrument when you have no external horizon reference?

before landing check list
31st Jul 2011, 16:12
I think a little humor is needed right about now.


1. A flight computer may not injure a human being or, through inaction, allow a human being to come to harm.
2. A flight computer must obey any orders given to it by human beings, except where such orders would conflict with the First Law.
3. A flight computer must protect its own existence as long as such protection does not conflict with the First or Second Law.

ChristiaanJ
31st Jul 2011, 16:55
I think a little humor is needed right about now.
Nice to see somebody else here likes Asimov and has been reading "I Robot".

But no, the Airbus FBW flight control systems are not 'robots' and don't 'think'. They were an evolution of the basic AFCS (automatic flight control systems) that existed well before the A320.
Whether the designers should not have taken more authority away from the pilots (as they did), is an interesting question.

I can't remember the "Three Laws" being pinned up in our design office... maybe they should have been.

But even Asimov's robots were not programmed to deal with every aspect of human stupidity, and neither is the Airbus system (Habsheim comes to mind, again....)

bearfoil
31st Jul 2011, 17:07
For the record, I am certain no one is inferring that one or more of the 447 drivers were stupid. For if so, it would be a blanket condemnation of Aviation as it exists today. Something's wrong, but I would hope no one is trying to polarize........ Condemnation prior to investigation is truly.....stupid.

aguadalte
31st Jul 2011, 17:28
My Boeing aircraft experience ended in the early ninety's. Since then I have flown A310/320's/330 and A340.
Must tell you that I still miss the yoke and the (artificial feeling) feed-back that I used to receive from it, as well as from the Auto-Throttles.

Let me ask you this:
If the PF co-pilot was "feeling" a sluggish yoke, would he ask his crew mates:

J’ai l’impression qu’on
a une vitesse de fou
non qu’est-ce que vous
en pensez ?
"I have the impression that we have a crazy speed, what do you think about that?"

jcjeant
31st Jul 2011, 18:21
Hi,

This is the reaction of Air France on the report No. 3 of BEA
I remain astounded by the words of the spokesman for Air France
This is a position of denial concerning the recommendations of the BEA
In french of course ........
‪Vol Rio-Paris: réactions au rapport du BEA sur la catastrophe‬‏ - YouTube

Neptunus Rex
31st Jul 2011, 18:35
Rob21
If computers are able to fly a crosswind ILS, with gustsHowever, the landing is a different matter. For the A330, max crosswind for Autoland is 20 kts. For a manual landing it is 32 gusting 40.

DozyWannabe
31st Jul 2011, 18:37
I think a little humor is needed right about now.


1. A flight computer may not injure a human being or, through inaction, allow a human being to come to harm.
2. A flight computer must obey any orders given to it by human beings, except where such orders would conflict with the First Law.
3. A flight computer must protect its own existence as long as such protection does not conflict with the First or Second Law.

You may consider it humour, but the fact is that Asimov's laws were indeed considered as a baseline by the engineers. In fact I believe they were considered as a baseline by the engineers responsible for all the advances in flight automation made over the last half-century.

BOAC
31st Jul 2011, 18:42
Well, that's Rule 1 bust then - Stall Warning logic?:ugh:

Shame the 'engineers responsible' didn't READ the wallpaper.

MountainBear
31st Jul 2011, 18:52
I had already asked you this earlier, but now that we have a much more detailed record of 447s final minutes maybe you're ready to answer - at which point didn't "the software" give them what they asked for?

Although this question wasn't addressed to me I'm going to answer it.

The question you ask is disingenuous. The complaint is not that the software didn't do what it was supposed to do but that what the software was doing was not communicated to the crew in an intelligible way.

It's simple.

(a) When the airplane is within the flight envelope the stall warning provides an aural communication to the pilots: SILENCE.

(b) when the software decides the airplane is outside established parameters it provide an aural communication to the pilots: STALL STALL STALL

(c) when the software decides that the airplane has so drastically exceeded established parameters that the data should be considered invalid it provides an aural communication to the pilots: SILENCE.

Now, if you think that the pilots were confused and failed to recognize the stall for what it was then you have to ask yourself how the above represents good software design. Because it does not. It's horrible software design. It's horrible software design for the software to communicate the exact same aural message (and silence is an aural message) to the pilots both when things are 100% good and when things have gone totally to hell.

DozyWannabe
31st Jul 2011, 19:35
@MountainBear : I'm sure that will be addressed.

bearfoil
31st Jul 2011, 20:09
A question......

I generally associate OZONE aroma with electrical issues.....


Fair?


(WRG)

Jando
31st Jul 2011, 20:11
I believe the whole discussion about the stall warning inhibited below 60 kts is a red herring. The stall warning on AF447 sounded continuously for 54 seconds without any indication that the crew acted on it. In my opinion it would have made no difference if it had sounded 30 seconds longer.

Once the aircraft was falling down with an airspeed less than 60 kts they probably had no way to unstall the plane anyway, they were miles away from any reasonable flight envelope for a commercial airliner, even miles away from test pilot territory. Terra incognita.

(As far as I know the stall warning is inhibited because the AoA vanes do not work below 60 kts. You cannot sound a stall warning when you have no working sensor to detect a stall.)

ChristiaanJ
31st Jul 2011, 20:34
A question......
I generally associate OZONE aroma with electrical issues.....
Fair?
(WRG)
Negative.... ozone is associated with (usually high-voltage) arcing.
This WRG issue was associated with an avionics bus communication between two computers.
The voltages on such a bus are in the order of about 10V, and the electronics are incapable of producing an electric arc (short-circuit currents inthe order of milli-amps)

captainsuperstorm
31st Jul 2011, 20:42
keep in mind AF has their own checklists, own language (french) and all book are in french.

which is not in the Airbus philosophy.

example: the cockpit is in english, ECAM, FMGS are in english, and at airfrance they think , talk, and eat in french.

"vitesse de fou!!", did he mean high speed or low speed?instaed of "woow, we are fast", or "damn, why are we so slow?"

pure mistake from the begining for one of the best airline.
they should review their pilot training, it seems to me they have a bunch of incompetents pilot who think a stall is a "crazy speed".

any aeroclub pilot, know what to do when they have the little red warning light flashing...plus on the 330, it s printed 'STALL' on the PFD.


golden rule:
1:nose down
2:full power, or TOGA

if you can not get out of stall, there is nothing you can do!

only idiot keep nose up during a stall, flat stall, deep stall, whatever you call....by chance they won't kill more people!

wait for the next crash done by a low trained LCC P2F pilot... we will have a good laugh when one these planes will crash on a school or hospital in the middle of LONDON killing thousands.. :ugh::ugh::ugh::ugh:

jcjeant
31st Jul 2011, 20:42
Hi,

The stick of PF busy making mayonnaise ..

http://i.imgur.com/X3HIW.png

Ranger One
31st Jul 2011, 20:46
MountainBear, Jando:

I think you both have good points. I've questioned the stall warning logic before.

Irrespective of whether or not it would have made any difference to the outcome of this accident, it seems bad and wrong to me.

I don't think anyone could reasonably have foreseen that it might be necessary or helpful to warn the crew of a civil aircraft that they were so far outside the envelope the AOA sensors were no longer giving useful data.

Until this accident.

MountainBear, with the benefit of hindsight the aural progression should perhaps be SILENCE -> STALL STALL STALL -> FLY THE F**KING AIRCRAFT

It's not something that was considered before, but if you're below 60kts and in the air, those computers should be screaming at you, under (Asimov) Laws 1, 2, and 3.

SaturnV
31st Jul 2011, 21:07
Ozone smell probably came from the Cb overshoot they were flying near. I believe the top of the Cb was estimated by Meteo France as 52000 feet, and by Vasquez as 56000 feet. Ozone is present in significant amounts near the tropopause and the Cb overshoot reached into the ITCZ tropopause by 6,000 feet according to Vasquez.

The PNF seems to have recognized what it was.

pedrobaltic
31st Jul 2011, 21:35
@ Jando - was the real aircraft airspeed < 60kts or was this an erroneous reading due to icing? It is a pity if it is the case that when airspeed is unreliable, or all 3 ADC disagree or are out of range, the stall warning computer decideds that the aircraft is not in a "real" airborne situation and decides not to play ball when the situation actually may be recoverable.

It would appear the absence and presence of the stall warning may have added to some of the confusion on the flight deck, though on some aircraft and dependent on pilot technique, the stall warning or stick shaker can be activated during recovery from the stall. But maybe these guys had never experienced this and of course its always easier from the armchair.

In system design, probability is regularly used when deciding how safe a system needs to be or how complex the logic should be. It may be that loss of all air data was of a suitably low probability to not be considered in the stall warning inhibit logic. As someone else said earlier maybe this is one of those 1 in 10000000 events.

Clandestino
31st Jul 2011, 22:18
From my FCOM
"With the sidestick at neutral, wings level, the system maintains 1 g in pitch"
I've never heard of 'pitch hold' My apologies, I've oversimplified it into "untrue" category. I've only described what it looked like to me when I'was flying the beast. It isn't pitch hold, rather it's flight path hold yet with no speed excursions or no vertical windshear, it will result in maintaining constant pitch.

I've flown 320/19 with MSNs in low 1000s and never spotted the tendency to pitch up while handflying high. As DozyWannabe mentioned: this quirk was ironed out of TA FBW Airbuses. Difference between gravity on the Earth's surface and at FL390 is about 0.4%, between the equator and poles is 0.5%, I don't think that having constant 1G value of 9.81 ms^-1 in your FBW was good idea, if it ever was used. Could be miscalibration of vertical accelerometer and that there are some Airbi that pitch down slowly, instead of up. We'll have to turn Mythbusters' attention to the issue.

I may be wrong, but if the static pressure system was totally unaffected, why does the vertical speed graph (page 109 of the report, second graph from top) looks so weird, with huge jumps??Because aeroplane is so out of flight envelope that AoA, VS, speed, mach, flightpath angle constantly switch themselves off and on. Could be flight/ground logic that gets them but my french is not that good to understand the whole report. However, baro altitude is constantly recorded from top of descent to end. No spikes or surprises there.

was the real aircraft airspeed < 60kts or was this an erroneous reading due to icing? It was real. Pitot 1 unblocks at 2:10:35, pitot 3 at 2:11:08. After that they agree until AoA goes above 30° and everything becomes mess.

It is a pity if it is the case that when airspeed is unreliable, or all 3 ADC disagree or are out of range, the stall warning computer decideds that the aircraft is not in a "real" airborne situation and decides not to play ball when the situation actually may be recoverable. Fortunately, it's not true. Stall warning worked just fine after all airspeed was lost. It has thrown in the towel after AoA exceeded 30°. That's area where no flight test was done before - for a good reason.

They failed to identify a stallDespite FWC shouting "STALL STALL STALL". 54 seconds.

So why didn't they look at the attitude indicator/s, which would have shown them to be steeply pitched up?If we ever get the answer to that, it won't be very palatable.

IcePack
31st Jul 2011, 22:23
Well Airbus manuals would say that wouldn't they.(about pitch attitude & height)
However if you take the guidance out (Autopilot) at 40,000ft on a 332 and wait.. The a/c TENDS to climb. Tried it a few times on different days as was interested after I knocked the disengage button on the side stick button with our ungainly hard plastic tech log.. Noticed the a/c was STARTING a gentle climb.
Whatever, I still believe that an attitude indicated indicating 16 deg NU. At height would look weird to any heavy jet pilot. If that 1.6 g spike is true that probably explains the INITIAL climb.
Again think too much blame pointing at the pilots..(all dead men who can not defend their corner)

DozyWannabe
31st Jul 2011, 23:31
Again think too much blame pointing at the pilots..(all dead men who can not defend their corner)

Really? I read it as the airline taking the most stick - their training and procedures were either not followed or were clearly a dreadful mess at the time.

aguadalte
1st Aug 2011, 00:15
Quote:
I had already asked you this earlier, but now that we have a much more detailed record of 447s final minutes maybe you're ready to answer - at which point didn't "the software" give them what they asked for?
Although this question wasn't addressed to me I'm going to answer it.

The question you ask is disingenuous. The complaint is not that the software didn't do what it was supposed to do but that what the software was doing was not communicated to the crew in an intelligible way.

It's simple.

(a) When the airplane is within the flight envelope the stall warning provides an aural communication to the pilots: SILENCE.

(b) when the software decides the airplane is outside established parameters it provide an aural communication to the pilots: STALL STALL STALL

(c) when the software decides that the airplane has so drastically exceeded established parameters that the data should be considered invalid it provides an aural communication to the pilots: SILENCE.

Now, if you think that the pilots were confused and failed to recognize the stall for what it was then you have to ask yourself how the above represents good software design. Because it does not. It's horrible software design. It's horrible software design for the software to communicate the exact same aural message (and silence is an aural message) to the pilots both when things are 100% good and when things have gone totally to hell. The question here is not " at which point didn't "the software" give them what they asked for" (Airbus - and BEA - were very quick to answer that).

The problem here is that, FBW Airbuses are flown differently from conventional airliners. They purely don't give you any feed-back on the side-sticks (and on ATS). And when confronted with a situation of multiple failures, pilots tend to fly by their pants...that is why the PF Co-Pilot voiced his impression about going with a crazy speed.
They were in a turbulent area (no sense of posture), they had no correct speed informations (no complete visual clues) and no feed-back on the side-sticks.

jcjeant shows it all...
The stick of PF busy making mayonnaise ..

http://i.imgur.com/X3HIW.pngRemember when you went to your first flying lessons? What were the first clues our instructors told us about identifying an approach to stall? The reduction on the forces needed to move the stick, the lack of reaction and amplitude required from the controls, the buffeting, etc...
The lack of feed-back (and interconnection between) the side-sticks was IMO a major factor, on the inability of the pilots to properly identify the stalling conditions.
One can always argue about the stall stall synthetic voice warning, but we must remember also, the number of gear-up landings that have been made in the past with the horn ON, all the way down to the tarmac...

Now put that voice coming on when you put the nose down and turn that madness situation into an accident...

Yes, the systems behaved exactly as designed.
Yes the situation was poorly handled by the whole crew.
But when we take away from the man/machine interface such an important clue (feed-back) we are forgetting that those aircrafts are ultimately flown by men and that men revert to basics when in face of an outstanding dangerous situation.

Mike X
1st Aug 2011, 00:25
those aircrafts are ultimately flown by men and that men revert to basics when in face of an outstanding dangerous situation.

No offence, but your statement is unqualified.

Computer pilots are handed an unfimiliar situation when the AP drops out (remember Roselawn ?).

With less hands-on training for the "men", what do you expect ?

Graybeard
1st Aug 2011, 00:54
(As far as I know the stall warning is inhibited because the AoA vanes do not work below 60 kts. You cannot sound a stall warning when you have no working sensor to detect a stall.) You obviously haven't been following these threads.

According to many prior posts here, the Stall Warning shuts off below 60 kt IAS. Why they have IAS input to SW is beyond me. The DC-10, for example, uses only AOA for SW.

Regardless of IAS, the plane was moving through the air fast enough to keep the AOA vane aligned with the relative wind, even as they were falling like a brick.

DozyWannabe
1st Aug 2011, 01:03
@aguadalte - Tactile feedback will come into it, yes - but it's worth remembering that the same thing happened to the Birgenair 757 which had interconnected yokes, and the psychological impact and tragic result was much the same.

@Graybeard - As I said, I suspect that Airbus will be revisiting their logic over this one. However at the same time I think Ranger one was right when he said:

I don't think anyone could reasonably have foreseen that it might be necessary or helpful to warn the crew of a civil aircraft that they were so far outside the envelope the AOA sensors were no longer giving useful data.

Until this accident.

Remember that the stall warning was sounding for 57 seconds before the values went out of usable range and it shut off. How in the hell did that happen?

Mike X
1st Aug 2011, 01:11
Remember that the stall warning was sounding for 57 seconds before the values went out of usable range and it shut off. How in the hell did that happen?

Unfortunately, that points to the pilots.

DozyWannabe
1st Aug 2011, 01:21
Mike X, welcome.

Rhetorical question, my apologies.

Mike X
1st Aug 2011, 01:44
Dozy, we're following this on two threads.

I believe that no-one wishes to put forth an opinion that may bury them in the future.

Off for some shut eye. Later.

PEI_3721
1st Aug 2011, 01:58
Some posts conclude with aspects which tend to ‘blame’ the crew.
I suggest that before coming to any conclusion a wide range of ‘human’ aspects should be considered.
The crew were faced with a sudden failure of an airspeed display: This is not obviously an unreliable airspeed – there is no display; thus, no demanding thought of using an UAS checklist. Remedial action might focus on reinstating the display or using an alternative source.
With all airspeed displays failing, again there is no obvious link to anything being ‘unreliable’. The priority action has to be to fly the aircraft, but without any specific checklist, basic aero / control concepts have to be recalled from memory and used in an aircraft where the control characteristics might not be best suited for a ‘novice’ pilot.
Add a stall warning to this scenario, which initially and logically, might have been disregarded as false: – Technically, an inappropriate association of stall with airspeed, but ‘stall’ is shown on the airspeed scale and everyone talks about stall speed, thus without any speed display why believe a stall (speed) warning. This was a mindset which unfortunately was not reversed later even with a valid warning, but there were no other stronger cues to trigger a change of view, particularly in a rapidly developing and very confusing situation.
These humans – the crew, may not have deduced that the aircraft had actually stalled until very late in the event, if at all.

Why did the aircraft climb: The loss of airspeed affects the ADC in a way in which the indicated altitude suddenly reads low (see FDR and previous events). In this instance, the crew focus on altitude recovery – avoidance of an altitude bust – they are ‘the juniors’ responsible to the absent captain and thus have responsibility for a safe and accurate flight. Did they deduce turbulence or another affect of adjacent Cbs. Add this to the developing scenario as above, then apparently inattentive control may not be surprising.
Possibly both crew focused too much of their ‘cognitive resource’ on deducing the ‘technical’ situation and problem solving, flying the aircraft was no longer #1 priority. This might not have been a result of a conscious choice, but due to the surprise and confusion of an unfolding complex event in a timescale incompatible with an ability to think, understand, and act.

glhcarl
1st Aug 2011, 02:46
The question is what were he control surfaces doing while the PF was practicing his signature?


The stick of PF busy making mayonnaise ..

http://i.imgur.com/X3HIW.png

jcjeant
1st Aug 2011, 03:10
Hi,

The question is what were he control surfaces doing while the PF was practicing his signature?


Page 115 french report N°3
http://i.imgur.com/176xQ.jpg

rubik101
1st Aug 2011, 04:04
IMHO, and FWIW, I lay the blame for the crash into the sea on the shoulders of the pilot, for not doing the correct stall recovery drill, i.e. unload or drop the nose to recover the airspeed and at 30'000 ft, hang the altitude loss. The fact that the aircraft was descending rapidly is not a valid reason to pull back on the side stick.
The reason for the stall I lay squarely on the shoulders of Airbus/Air France for not fixing the pitot problem years earlier.

predictorM9
1st Aug 2011, 05:10
"According to many prior posts here, the Stall Warning shuts off below 60 kt IAS. Why they have IAS input to SW is beyond me. The DC-10, for example, uses only AOA for SW.

Regardless of IAS, the plane was moving through the air fast enough to keep the AOA vane aligned with the relative wind, even as they were falling like a brick."

I completely agree. As long as the plane is in the air there is always 60 kts of relative wind, even if the angle of attack is so high that the pitot measure wrong speeds. The fact that they certified the logic behind this is for me a huge mistake. As long as the AOA is not insane it doesn't matter. But if the aircraft is capable of 45 degrees AOA, they should do a logic that also works in this case (irrespective of the issue of displaying the AOA info to pilots).

Also, what matters is not the fact that it sounded for 57 seconds straight. What matters is the fact that pilots push the stick forward and then the stall warning sound. If you were piloting this plane with all the other faulty sensors, wouldn't you start to think that the stall warning is faulty too?

This kind of behavior of the stall warning is only caused by the faulty logic, and the BEA does not seem to want to address this...

predictorM9
1st Aug 2011, 06:45
It was real. Pitot 1 unblocks at 2:10:35, pitot 3 at 2:11:08. After that they agree until AoA goes above 30° and everything becomes mess.

No, the speed of less than 60 kts wasn't real. The relative wind speed was always above 60 kts, just by looking at the vario and ground speed it is actually above 100 kts.
So the AOA data shouldn't have been "rejected" at all. The system worked as designed, as stressed by the BEA. But the design on this point is bad, and adds unnecessary confusion during emergencies.

I don't see why we should blame the pilots for discarding a warning system that is behaving erratically and against your intuition (nose up= stall, nose down=no stall).
Agreed it sounded 54 seconds straight and they should have done something way earlier. But they were about to fix the stall problem multiple times, when they pushed the stick forward (and the stall warning sounded again at that time... preventing them from continuing in this direction).

britfrog
1st Aug 2011, 07:26
Having read report 3 and the CVR transcript I am no longer surprised by the ineptness of the handling crew and the crash, more so the fact that they actually managed to get the plane airborne in the first place.
they overlooked just about every lesson that one learns within the first few hours of primary training, simply a horrific testament to modern training and modern electronically flown a/c where manual flying is not so much a requrement but actually discouraged. I hope the whole flying community learns from this crash.

britfrog
1st Aug 2011, 07:38
what faulty logic? the only faulty logic was the pf who looked at the vsi which was pinned to the bottom, and he couldnt deduce that they were fully stalled out. a very elementary mistake

mastercaution1
1st Aug 2011, 07:58
My question!
What was the WX-Radar showing? How big was the cell there going thru? Green, yellow or red? Is there anywhere a reconstruction of the picture?

predictorM9
1st Aug 2011, 09:13
what faulty logic? the only faulty logic was the pf who looked at the vsi which was pinned to the bottom, and he couldnt deduce that they were fully stalled out. a very elementary mistake

Actually if you look at the variometer data from the BEA report, it is not pinned to the bottom, but also flickers too.

Conclusion:
- failure from the pilots to realize that the variometer data was almost right even if it flickered
- failure from the pilots to realize that the lack of stall warnings was wrong because they flickered

that's it! pilot failure. case closed.

DozyWannabe
1st Aug 2011, 09:20
Also, what matters is not the fact that it sounded for 57 seconds straight. What matters is the fact that pilots push the stick forward and then the stall warning sound. If you were piloting this plane with all the other faulty sensors, wouldn't you start to think that the stall warning is faulty too?

The only faulty sensors were the pitots, and then only briefly, so to say "all the other faulty sensors" is a bit disingenuous. At this point I believe a competent pilot should disregard all other annunciations other than the thrust settings and the pitch as displayed on the ADI (double-checking the ADI with the standby instrument if you're unsure). Once you've got those in the right ballpark you should know you're going to be OK.

This kind of behavior of the stall warning is only caused by the faulty logic, and the BEA does not seem to want to address this...

If they didn't want to address it, they wouldn't have mentioned it in the report, but the important point (which goes back to your first paragraph) is this - simply teaching stall warning and avoidance, as had been done prior to this accident, simply isn't enough. Stall recognition and recovery procedures should be a mandatory part of recurrent training, which you'll notice has become something of a hot topic in the industry over the last couple of years.

I don't see why we should blame the pilots for discarding a warning system that is behaving erratically and against your intuition (nose up= stall, nose down=no stall).

Again, only the press are saying that the report is "blaming" the pilots. If you read the report itself, it becomes pretty clear that the BEA considers this an industry-wide issue that should be clarified and adopted by manufacturers and airlines alike.

I'm beginning to wonder why the press are unilaterally oversimplifying the interim findings this way - you only have to look at the report itself to see that it is a very dry document that does not apportion blame as such, but does criticise the apparent lack of CRM and flying knowledge exhibited in the flight deck. It isn't blaming the pilots, it's saying there's likely a systemic problem that needs to be addressed - unfortunately that doesn't make for a "sexy" byline.

carlosgustavo
1st Aug 2011, 10:53
Flying high is a new experince. High altitudes stalling is not very frecuent To practice.Has anyone here done it¿ I wonder how low density of the air and the inercia of the stall due to the long time stalling affects the recovery tecnique.

STALL WARNING MUST ALWAYS WORK. Its unveliable that on the Airbus with that pitot probe on icing condicions doesnt.

Its funny for me how people blame the pilots because the stall warning sound for 57sg and they didint recognize the stall. Dont you understand that when the stall warning stops means NOT STALL, but the aircraft wad actual stalling.

This is what should be:
Sound of the stall warning should mean STALL
Not sound of stall warning should mean NOT STALL


If you relay on stall warning when the sounds stops should be that you are out of stall. I think they pilots of the Airfrance understood that the stall warning was not working right, but I think they probably felt overspeed due To de strong turbulence and icing they were in.

timpara
1st Aug 2011, 11:31
Apologies if this article is already familiar in this domain, but
The Case For An Angle Of Attack Indicator | Air Safety Week | Find Articles at BNET (http://findarticles.com/p/articles/mi_m0UBT/is_8_14/ai_59664858/?tag=content;col1)

seems to summarise quite well the conditions under which an AOA indicator available to the pilots is useful. Good to see it the the BEA recommendations.

aguadalte
1st Aug 2011, 11:37
DozyW: Tactile feedback will come into it, yes - but it's worth remembering that the same thing happened to the Birgenair 757 which had interconnected yokes, and the psychological impact and tragic result was much the same.Was there a UAS procedure training in force at that time? (I honestly can't remember) As I said before, my experience with Boeing ended long time ago in the early 90's and I can't remember training UAS at that time.

before landing check list
1st Aug 2011, 11:49
Timpara, I agree with you 100%. That is exactly what I was saying in an earlier post. Attitude and speed are secondary to the AOA in relation to the performance of the wing.

ross_M
1st Aug 2011, 12:05
From the BEA report:

Until impact now the stall warning activates when the nose is lowered and silences when the pitch angle increases. FDR data suggest that as soon as the stall warning activates the pilots react with nose up inputs which cause the stall warning to silence again.

I can hardly blame the pilots. If something you do silences a warning there's a natural temptation to keep on doing it.

Horrible systems design I say.

RansS9
1st Aug 2011, 12:06
One of the problems highlighted by the investigation was inadequate pilot training.
Why don’t the various National Pilot Unions alone or better still in concert devise their own Standards of Simulator Training for different categories of commercial flying; then use this as a benchmark to judge the quality of training given by companies. In this era of transparency publish the results on the web, with a section for the company to reply to any criticism if they wish, and give the Public / Journalists more information to make their Carrier decisions.
Perhaps this is already done; perhaps not. It would at least open the area for more debate and scrutiny.
Just a thought

Feathers McGraw
1st Aug 2011, 12:24
Anyone know if an English translation of the 3rd interim report in French (the 117 page pdf) is going to appear?

Difficult to grasp the details when my technical French is not up to the job.

Loose rivets
1st Aug 2011, 12:31
Sim training will only take you so far. I refer again to Davis' impassioned plea to get ordinary airline pilots some extraordinary training - in real aircraft.

My original edition does not include this - has anyone got one of the later editions they could copy a quote from? (I read an F/O's in about 1999)


While flying in a 'retirement job' I found myself in a twin Turboprop with a full load of passengers, hopping from Aldergrove to City, at night, in rough and rainy conditions.

The stall warning went off, with shaker and siren.

It's hard to describe how that 7 mins or so of that beaten-into-me-brain pair of warnings affected me, even after thousands of hours in command on Turboprops, and really steeling myself against what had become an almost certain false warning. For a very long 60 seconds, it was almost impossible to believe the instruments.

Apart from the fact we were near lumpy ground, the 447 crew's sensory inputs and scrolling data were I would think, much more confusing. I feel deeply sorry for them, but do feel that they should have nailed attitude and power within a band appropriate to that aircraft as an absolutely fundamental part of aircraft handling.

sebaska
1st Aug 2011, 12:34
According to many prior posts here, the Stall Warning shuts off below 60 kt IAS. Why they have IAS input to SW is beyond me. The DC-10, for example, uses only AOA for SW.

Stall AOA is ~7deg when high&fast and ~16deg when low&slow.
Besides, AOA vanes are designed and calibrated for situations when air comes from generally front direction, not side or bottom. AOA was severe enough to cause Pitot readings off, variometer indications got flaky, etc.

I completely agree. As long as the plane is in the air there is always 60 kts of relative wind, even if the angle of attack is so high that the pitot measure wrong speeds.

Nope. It's perfectly possible, as evidenced by previous accidents, to get airspeed below 60kts in a large plane (some poor guys happened to get negative airspeed before they crashed). But I agree that the real airspeed was above 60kts in this particular case.

The fact that they certified the logic behind this is for me a huge mistake. As long as the AOA is not insane it doesn't matter. But if the aircraft is capable of 45 degrees AOA, they should do a logic that also works in this case

Certification does not bring much attention to situations so far away from flight envelope. Many airframe designs are considered totally unrecoverable even by heroic measurements when stalled so severely, yet they get certified.

failure from the pilots to realize that the lack of stall warnings was wrong because they flickered

The stall warning was on for long enough to take proper action. It's debatable if the airplane could be recovered if they initiated proper action after stall warning continued for the whole minute.

You, and many posters here concentrate on what happened after the plane has severely stalled. But from a flight safety PoV things were already critically bad. Dealing with problems during "falling out of the sky" phase won't improve safety much (if at all).

What is really important is how it entered the stall and how there was no immediate proper attempt at unstalling it. Aural stall warning was active then, attitude indication was good, vario was good, even speed was good at least on PM's display and backup (ISIS) display.

So, if even, there is some human interface problem pertaining to that phase of flight ain't aural stall warning silencing itself when attitude gets so far away from flight envelope that pitot probes stop working.

DozyWannabe
1st Aug 2011, 12:35
Was there a UAS procedure in force at that time? (I honestly can't remember)

Yes, because there had been several UAS incidents with the Thales AA pitots. There was a specific bulletin on the subject if I recall correctly.

@ Feathers, it's due later this week.

ross_M
1st Aug 2011, 13:21
some poor guys happened to get negative airspeed before they crashed

What exactly is negative airspeed? Plane flying backwards? :confused:

So, if even, there is some human interface problem pertaining to that phase of flight ain't aural stall warning silencing itself when attitude gets so far away from flight envelope that pitot probes stop working.

Did the pitots stop working because of the snow or being away from envelope?

Denise Moore
1st Aug 2011, 13:43
Unfortunately the BEA's report isn't available in English yet.

But from the discussions here it seems to still be silent on many things.

Did the pilots say nothing during the last three minutes? Because I have not seen anything mentioned.

The BEA did, apparently, say the plane was fully and completely responsive throughout, so how did they explain the THS being apparently stuck up, ignoring the
down instructions (of which there were at least a few).

takata
1st Aug 2011, 13:54
Hi ross_M,
Did the pitots stop working because of the snow or being away from envelope?
At first, because of ice crystals. This issue #1 lasted a bit less than 1 minute and it was cleared before they were actually stalled (but stall warnings were not affected by this fault).

Later in the sequence, alpha went so high (above 35°) that both pitot and alpha probes were out of boundaries (hence, Stall warnings stopped). issue #2 happened 40-50 seconds after the full stall developed.

The main confusion is due to #2 starting too closely after #1, the crew being not able to deal with any of them (neither UAS nor Stall).

camel
1st Aug 2011, 13:59
it does seem weird that the PF in the RHS was not wearing any kind of seat belt,having warned the cabin crew of turbulence ahead.. i understand Airbus provide a nifty table where the yoke sits on most other aircraft

is it a possible scenario that he had the seat pushed back and was tucking into his dinner? so that when the Auto Pilot/Auto thrust clicked out he had to reach out further than usual to grab the side stick ...plus maybe with a tray full of food in the way ... apologies if this has been done to death before.. just a thought .

Mimpe
1st Aug 2011, 14:03
at least the Airbus engineers now know an AoA of 35 degrees positive is possible in commercial flight, and it shouldnt pose a condition for the silencing of a stall alarm......:ugh:

I bet there are lot of other limiting software conditions that pose create additional risk at the very edges of the improbable flight envelope , where one needs the info the most.

mach2.6
1st Aug 2011, 14:14
I was watching French TV 5 Monde last week, and they aired the actual conversation of the last few minutes of the flight, narrated by an announcer with text superimposed over a graphic of the cockpit. All three crew members were present in the cockpit. It was clear that they were confused and, in fact, could not believe what was actually happening. One crewmember (maybe the captain, but I'm not sure) repeated several times "pull up" and "pull". My French isn't very good, so I was concentrating more on the speech rather than which crewmember said it. Maybe some of our friends on the East side of the Pond have some contacts at TV 5 Monde and can get the video. I can't find it on their website.

SaturnV
1st Aug 2011, 14:32
Feathers McGraw, the English language version will supposedly be available on Wednesday.

Denise Moore, the pilots said a lot. There is a transcript of the conversation and a translation of the French in the Tech forum.

aguadalte
1st Aug 2011, 14:41
Yes Dozy, thanks for the reply. I meant a procedure training, (already edited my post) i.e., was it common to train the UAS on Flight Sims, at that time.
I just went to my old (1987) version of B737 QRH and looked at the procedure of that time, the basics are the same of course, but this was what was written then, (compared to A330/340 three pages checklist...):
AIRSPEED UNRELIABLE
AIRPLANE ATTITUDE/THRUST.......ADJUST
Adjust attitude and thrust to maintain airplane control. Attitude and thrust information is provided in the performance chapter.
PITOT STATIC HEAT.....................CHECK ON
MACH/AIRSPEED INDICATORS......CROSS CHECK
Pretty simple, hen?

Feathers McGraw
1st Aug 2011, 14:45
Saturn

Thanks for that, hadn't noticed the Tech Log thread, off for a read now.

I shall read the translated report ASAP.

Graybeard
1st Aug 2011, 14:47
SebaskaStall AOA is ~7deg when high&fast and ~16deg when low&slow.
Besides, AOA vanes are designed and calibrated for situations when air comes from generally front direction, not side or bottom. AOA was severe enough to cause Pitot readings off, variometer indications got flaky, etc.Again, I'm quoting DC-10 SW from AOA, because I have the data handy. Its SW from AOA is modified by position of flaps and slats, not "low&slow and high&fast."

According to a prior poster, the mechanical limit of the AOA vane is something like 110 degrees NU. BEA reported FDR trace of >30 degrees AOA, a region where the SW was silenced.

I cannot understand the logic of inhibiting Stall Warning based on low airspeed, unless it's meant as a redundancy to squat switch (WOW) discrete. It would be better to make the WOW more reliable, than add complication to SW logic, but that was an engineer's decision not vetoed by the AB pilots nor certification authorities.

jcjeant
1st Aug 2011, 14:49
Hi,

Since the publication of interim report No. 3 .. all comments are about the training of pilots and also pointed discussions on more technical subjects as well as word by word analysis of the known parts of the CVR
This is all very well and certainly contributes a better understanding of the BEA report.
One thing that seems to be masked by these tests .. and this is the problem of pitot tubes
In its report No. 3 .. BEA speaks very little about the pitot tubes and in its conclusion ... he says that "probably" the Pitot tubes are at the origin of the loss of signal indication and thus the transition from the normal law has alternate
So the BEA does not formally recognize that the pitot tubes are the cause of a loss of airspeed indication.
These Pitot tubes are a very important issue and no training even extreme will solve it ....
Pilots must not have a mission to supplement by their actions a construction defect.
Imagine:
You own a car whose brakes do not work starting from a certain speed.
You can see .. and having escaped the accident you request an explanation from the manufacturer.
It will answer that this is not a problem .. It will give you a free training so you can effectively use the parking brake to help you stop in the abscence of main brakes operation
Are you satisfied with that answer? is what is normal?
Something else ... BEA notes that there is a problem with the crews point of view is .. qualifications .. reliefs on the flight deck... etc..
Why BEA in its recommendations does not require an immediate review by AF (and also other companies) of the composition of crews for this type of flight .. and to be applied immediately.
Possible to immediately implement and do not requires extensive feasibility study.
Afterwards .. regulators may make laws ... but why to wait?

DozyWannabe
1st Aug 2011, 14:53
I cannot understand the logic of inhibiting Stall Warning based on low airspeed, unless it's meant as a redundancy to squat switch (WOW) discrete. It would be better to make the WOW more reliable, than add complication to SW logic, but that was an engineer's decision not vetoed by the AB pilots nor certification authorities.

I suspect it was not a deliberately designed-in behaviour so much as a point so far outside the envelope that it was not considered. >60kts, in a heavy, at cruise altitude?

Lonewolf_50
1st Aug 2011, 15:35
A previous quote ...Personally I believe that no pilot would maintain a pitch attitude of 16 deg at height intentionally it would look too weird
In darkness at altitude over an ocean, possibly in cloud, no visual reference to "look" weird.
It also looks weird on your artificial horizon if your intent is to be flying level.
Really, it does.
The dark side (bottom circle) or the AH isn't visible, all you see is the light semi circle ...

PEI 3721, post 2367: http://www.pprune.org/rumours-news/447730-af447-wreckage-found-119.html#post6610842
Nice post, food for thought. (And no mayonnaise, on that, thank you! :) )

carlos: disagree
This is what should be:
Sound of the stall warning should mean STALL
Not sound of stall warning should mean NOT STALL
Stall warning is a very handy tool in preventing a stall. It lets you act while you still have control of all of your flight surfaces. You get to make a correction while you are still flying, rather than once you have started not flying, but more or less falling ...

Loose Rivets, in re spurious warnings.

I bet your instrument scan was working, since you were flying ... :)

Denise Moore:
Did the pilots say nothing during the last three minutes? Because I have not seen anything mentioned.

Head over to tech log, a poster (gpc62) did a best effort English translation of what the BEA have released from CVR. It is as he says "unofficial CVR transcript translation - plus VS" (Stall warning)

http://www.pprune.org/tech-log/456874-af-447-thread-no-5-a-58.html#post6610403

It is some chilling reading.

Mr Optimistic
1st Aug 2011, 16:09
'Extracts' from the CVR start on page 91. It does say 'extracts' so there is more, but not released.

jcjeant
1st Aug 2011, 16:18
Hi,

I suspect it was not a deliberately designed-in behaviour so much as a point so far outside the envelope that it was not considered. >60kts, in a heavy, at cruise altitude?

Well .. when a aircraft stall .. ,he can go anywhere .. and certainly fare outside the envelope.
It's not something discovered after the AF447 crash ... it's known from ages....

DozyWannabe
1st Aug 2011, 16:45
@jcjeant - Fair point, but you're forgetting that engineering is the art of compromise in order to achieve specified goals. As far as I know this particular A330 is pretty much the only aircraft of its size and configuration to end up in that situation, and right at this moment I don't see many pilots queueing up to test a similar envelope excursion in a B767, B777, DC-10, MD-11, A300, L-1011, or Il-8/96 to see how those systems fare in such a predicament.

britfrog
1st Aug 2011, 17:16
pitot failure is known to have occurred but this has no effect on the vsi , the pitot has two sources impact which can get blocked and static the vsi uses the static side
However this could all have been avoided had the crew a handheld gps to crossreference with as this wouild have given them an accurate speed readout as well as height. I have always carried one when i fly along with a handheld icom radio, as long as i have them I will never use them but you can guarantee the day I leave them at home something will go west. However it doesnt get away from the fact that the crew were not up to the job sadly

MountainBear
1st Aug 2011, 17:29
DW

@jcjeant - Fair point, but you're forgetting that engineering is the art of compromise in order to achieve specified goals.

True enough. But with the authority to make compromises also comes the responsibility to take the heat and bear the costs when those compromises come back to bite you on the ass. Your recent responses in this thread are the perfect illustration of what critics of the airline industry mean when they refer to "engineering by gravestone."

I think the flight crew made compromises; I think Air France made compromises; I think Thales made compromises; I think Airbus made compromises. All those compromises seemed, I am sure, rational and logical and reasonable compromises to the decision makers at the time the decisions were made. The problem is that those rational, reasonable, logical compromises aligned with each other in a way that produced an outcome that was not rational, not logical, and not reasonable. AF447 should not have crashed....but it did.


While the final report is not out yet and so my mind might change, as events stand now I think that in 20 years AF447 is going to be studied as a classic case of system failure. Everyone shares part of the plane from the pilots to the airline to the the manufacturer and its subcontractors. Regrettably, no one really cares about that at this stage; all they want to do is point fingers and shift blame so that when all is said and done it is not they by some other sap who bears the financial cost of this disaster.

lomapaseo
1st Aug 2011, 17:57
While the final report is not out yet and so my mind might change, as events stand now I think that in 20 years AF447 is going to be studied as a classic case of system failure. Everyone shares part of the plane from the pilots to the airline to the the manufacturer and its subcontractors. Regrettably, no one really cares about that at this stage; all they want to do is point fingers and shift blame so that when all is said and done it is not they by some other sap who bears the financial cost of this disaster. While the final report is not out yet and so my mind might change, as events stand now I think that in 20 years AF447 is going to be studied as a classic case of system failure. Everyone shares part of the plane from the pilots to the airline to the the manufacturer and its subcontractors. Regrettably, no one really cares about that at this stage; all they want to do is point fingers and shift blame so that when all is said and done it is not they by some other sap who bears the financial cost of this disaster.


This is a surface perception gleened by reading too many discussion posts by people not in the actual chain

You can call it what you will ... even gravestone mentality .. citing a few fatal accidents over the years.

Engineering is not an exact science. Trades are made and lessons learned. But more importantly measuments are applied to avoid worsening our lives and to ensure that we are taking more steps forward than backward.

The confusion about who to blame for the accident du jour is in your mind. It has nothing to do with the learning process and the search for corrective actions that ensure more steps forward than backward. The regulators, the designers, the operators will look to the engineers to effect this process.

So ignore the rhetoric in discussion boards and blogs and look for immediate results in Service buletins, FCOMs, Training, product upgrades and maybe in 10 years a regulatory change.

The fact that you might not recognize the progress has a lot to do whether you are part of the process or not.

DozyWannabe
1st Aug 2011, 18:28
Your recent responses in this thread are the perfect illustration of what critics of the airline industry mean when they refer to "engineering by gravestone."

My recent responses are of the who what now?

I don't know if I've given the wrong impression hanging around here for - what is it - 5-6 years now? But if you think I'm for automation über alles, airmanship being a thing of the past and an enthusiastic supporter of the race to the bottom then I clearly haven't been expressing myself properly, so please allow me to disabuse you of that notion.

I think that pilots should be pilots. I think that stick and rudder skills are an important thing that should be maintained and checked on a regular basis even if your day job involves flying a FBW airliner that has protections up the wazoo. I think that the current state of affairs in some airlines - and particularly regional US airlines - is worrying bordering on scandalous.

But I am also a software engineer. Not of the calibre that makes the software that runs the systems on aircraft, but I studied with and under the ones that were and are capable of that, and I cannot *abide* the false dichotomy that is frequently presented here blaming the evolution of automation and technology for the decline in piloting skills.

I love flying - have done since I first boarded a BCal BAC 1-11 at the tender age of two on a family holiday and every time since - I still get a buzz when I get on an aircraft even now my line of work makes it happen a few times a year, and nothing - but *nothing* compares to the first time I was taken up as an Air Cadet in a Chuckmonk and the friendly middle-aged guy in front of me said the magic words "you have control". I only wish I had the money to continue that pursuit and hopefully one day I will. Don't think for a second that I don't consider this a privilege.

This here, what we're talking about is an accident that could and should shake up a complacent industry - some good forward steps have been made but we must keep up a basic knowledge of airmanship among pilots. The advances that FBW brought forth are there to assist, but cannot be thought of as taking the place of proper piloting skill. Everything I've seen indicates that the PF did not even begin to understand the problem, let alone work out a way to solve it and if his training was deficient in that regard it needs to be fixed. I'm seeing failures of CRM, failures of communication and major gaps in basic aeronautical knowledge and I've got to say, I'm concerned - because I want the people in front to know what they're doing when I get on the thing and I wonder how many hours of stall recovery training could have been bought with the money used to furnish the airline executives' houses. This isn't just about Air France (although it would appear they have some major work to do), this is about the industry in general.

BOAC
1st Aug 2011, 18:54
the false dichotomy that is frequently presented here blaming the evolution of automation and technology for the decline in piloting skills. - your last para was 'spot on' in my book.

Regarding the 'quote' - I think most of us, when we take that 'view', mean the way it has been trained for and implemented by operators rather than the 'luddite' postion to which I think you refer. I, for one, do see a definite 'decline in piloting skills'.

DozyWannabe
1st Aug 2011, 20:05
Regarding the 'quote' - I think most of us, when we take that 'view', mean the way it has been trained for and implemented by operators rather than the 'luddite' postion to which I think you refer. I, for one, do see a definite 'decline in piloting skills'.

Thanks very much BOAC, and I'm honoured. But if what you say above is really the case, why is this ire not more clearly directed? I know it's only a minority that jump on every Airbus incident or accident with tales of conspiracies and concierges - but at the end of the day if the airlines are abusing the tools that the engineers are giving them in order to cut costs then it is the airlines who deserve to be in the firing line - not the engineers!

There is so much that could be done with the co-operation of all parties to make it crystal clear to the industry that while the technological advances can improve safety and can keep costs down - this should not come at the expense of knowing how to deal with things on the rare occasions that things go pear-shaped, but so often on here I see such discussions break down into lamenting the fact that things aren't like they were in the '70s. Lord knows I wish we could undo a lot of what happened in the '80s but we have to work with what we've got.

ChristiaanJ
1st Aug 2011, 21:07
I think the flight crew made compromises; I think Air France made compromises; I think Thales made compromises; I think Airbus made compromises.
In defense of Thales.... and possibly Goodrich.
(I worked for SFENA, then Sextant, now Thales, but in a totally different sector, so I've no axe to grind).

One thing that seems to have been neglected in recent discussions, is that engineers design to standards, and in particular certification standards.
(When Concorde was designed, an entire new "SST certification standard" had to be written, and I think much the same happened when the all-digital FBW came along.)

Todays certification standards for pitot tubes still date from the Stone Age.
Unless a real job is done to update those standards, and re-define the certification testing with regard to potential present-day (icing etc.) circumstances, "we" (the engineers) just try to do our best.... which, because of the lack of clearly defined design data, may not be good enough.

Both Thales (the 'AB' probes) and Goodrich seem to have tried to do "better than specs", but in the absence of new and more stringent specs and design data, how do you decide what is indeed "better"?

So maybe some of the "blame" should go to the regulators, or rather, there should have been a recommendation in the BEA report for the certification standards for pitots to be "brought up to scratch"?

bearfoil
1st Aug 2011, 21:26
The blame is so diffuse it must be borne by everyone. EVERYONE.

To say this was 1/10.000,000 is the height of ignorance. At every step in the denoument, and mark my words, there will be maths aplenty to show it to be far more likely than that.

Throw in the certain knowledge that the PITOT tubes were a problem, and that AF crew(s) are shown to be lacking in some skills re: problems aloft, AF deferral of R/R for Thales, and their lack of concern about hand flying at altitude, and one gets a better picture.

As for the Engineers, due to their mode d'emploi, I would say the best (and longest) odds are with their work. So Bravo? Mais NON.

It is precisely this assignment of RESPONSIBILITY that is traditionally lacking in an honest approach to safety,

Should I read AD's, SB's, and MEL's to my satisfaction at this point before boarding?

I will if no one else will. The industry is full of pretense and marketing.
As before, and again, mark my words:

The PROBLEM is SYSTEMIC. As such, I look everywhere.

"Bear, don't be ridiculous". Most will be satisfied with BEA FINAL.
It is 'tacit satisfaction' that killed 228.

jcjeant
1st Aug 2011, 21:32
Hi,

Another dumb question (and maybe already asked .. no remember .. and the search engine of this forum kill my nerves :8 )

Why the AP must absolutely disengage when the system detect incoherent speed datas ?
And consequently ..why the procedure for IAS can't be take in charge by the AP for some time ... (pilots alerted) and give to pilots the time to put their gloves before touch anything ?

The fact that you might not recognize the progress has a lot to do whether you are part of the process or not. Sad to tell .. but methink the 228 victims are part of the process .....

TCU
1st Aug 2011, 21:36
DW as a footnote to your post 2402, this extract from the L1011 website...also in memory of a certain much missed poster:

"Another interesting British Airways certification requirement that came up during TriStar production was FAA Stall Certification - in the US, the FAA requirement for the manufacturer was to only take the aircraft to stall warning (that is, when the stall warning horn sounded in the cockpit) and then recover. For European certification however, the requirement was to take the aircraft to full stall and then recover. So, Lockheed took the 1011 out and full stalled it - then it invited the FAA along and demonstrated to them that the TriStar could enter a deep stall and recover safely - then the FAA pilot tried it and in the deep stall the wing dropped and he could not recover it - film taken in the chase plane showed that the 1011 rolled inverted during the recovery attempt and finally was pulled out at around 10,000 feet - and the test started at about 25,000 feet! During recovery the aircraft pulled an excessive amount of G loads - the No. 1 test ship had to be hangered until it's structure was completely inspected before returning it to flight status.


On later British Airways training flights, I was an Instructor Flight Engineer and sat through some of these deep stalls in the actual aircraft - in the deep stall the aircraft shook so much you could not see clearly - the pilots just had to hold on to the control wheels and push forward to recover - it was quite a wild ride to say the least."

....push forward to recover

BOAC
1st Aug 2011, 21:40
I know it's only a minority that jump on every Airbus incident or accident with tales of conspiracies and concierges - as I see it, there is a long-term 'whiff' of 'conspiracy' - that will take time to blow away. The 'Concierge' is something that has created enormous damage and will take even longer, since it has appealed to many - those who wish to learn to fly airliners without lots of effort, those who see the advantages of a 'cannot go wrong' system (namely insurers and accountants - the latter also seeing the savings in training) and management who can insist on no-one touching anything thereby making their jobs easier. There is no doubt that the FBW technology is the way forward. It offers big savings in economy with 'relaxed' stability and enhanced safety in normal operations.

As I have said on t'other thread, the industry needs to claw its way back to a sensible middle ground. Not all pilots agree, of course. As I have also said elsewhere, it is not the fault of the engineers/software writers - they can only work to the best of their ability to produce what the industry asks for.

My last 'elsewhere' quote is that I hope all AB pilots are having quiet contemplative thoughts about the way it works, or doesn't. I also believe this accident will be a big shake up to both AF and to a lesser extent AB

I still like your (oldish) idea of dropping straight to Direct Law in the 447 scenario, by the way - with a concomitant shift in training, of course...............

Zorin_75
1st Aug 2011, 21:44
Zorin, hold on a sec. I did miss your prior question to me. So here goes an answer flown an AB aircraft;
Flight 296 in Paris. I do not think the pilots flew into those trees on purpose.I think Habsheim is a different discussion, one that's been had exhaustively. Let's stick to AF447 (of which there's plenty of data now to discuss).


Do you think the pilots wanted the THS to go full ANU or do you think the computer assumed one (not both) of the pilots wanted it?I think they made it pretty clear they wanted nose up. With active autotrim, the bus could indeed deliver a lot.


I say both because who really has command when the side sticks are displaced in different locations? I really do not know.
When both sticks are used the values are added and you get a "Dual Input" warning. If the not flying pilot starts making unannounced simultaneous inputs you're probably having problems that can't be solved by software, though...


In fairness to the PF (whichever one it was) the only 'nose-up input' he (The PF) applied at the onset of the accident was immediately after the sign-off. The BEA states that the 'zoom climb' started at least 11 seconds after that - and there is no mention of the PF moving the stick either way until he applies 'nose-down' to counteract the climb. Does this mean the PF did not cause the climb but it takes several seconds for the AB330 to respond to control movements?Just to be sure what we're talking about - have you seen the FDR traces in the new interim report? Stick input and climb seem to correlate quite nicely.



Although this question wasn't addressed to me I'm going to answer it.

The question you ask is disingenuous. The complaint is not that the software didn't do what it was supposed to doActually that was precisely blcl's complaint, hence my question.


(a) When the airplane is within the flight envelope the stall warning provides an aural communication to the pilots: SILENCE.

(b) when the software decides the airplane is outside established parameters it provide an aural communication to the pilots: STALL STALL STALL

(c) when the software decides that the airplane has so drastically exceeded established parameters that the data should be considered invalid it provides an aural communication to the pilots: SILENCE.
I think we all agree that turning off a stall warning as the stall gets worse is not really a good thing. But was it a main factor? Wasn't the bigger problem probably not that the stall warning stopped, but that there had been no proper reaction to it for nearly a minute before?

DozyWannabe
1st Aug 2011, 22:13
I still like your (oldish) idea of dropping straight to Direct Law in the 447 scenario, by the way - with a concomitant shift in training, of course...............

That was never my idea, I'm not sure how it ever got started that it was. My position is and has always been that the alternate laws satisfy a design requirement and should stay.

Sorry about that! :)

TioPablo
1st Aug 2011, 22:14
CJ said:
Todays certification standards for pitot tubes still date from the Stone Age.
Unless a real job is done to update those standards, and re-define the certification testing with regard to potential present-day (icing etc.) circumstances, "we" (the engineers) just try to do our best.... which, because of the lack of clearly defined design data, may not be good enough.Thanks CJ, that is the kind of communication I like to see.
It shows dignity...

Maybe is the wind tunnel as it is outdated as well... Maybe some kind of Cb sim could be developed for AFCS and/or IFCS testing... Improving weather satellite links in place of (or assisting), poor local radar systems may be helpful as well...

Graybeard
1st Aug 2011, 22:41
Quote:
Originally Posted by Graybeard
I cannot understand the logic of inhibiting Stall Warning based on low airspeed, unless it's meant as a redundancy to squat switch (WOW) discrete. It would be better to make the WOW more reliable, than add complication to SW logic, but that was an engineer's decision not vetoed by the AB pilots nor certification authorities.

DW replied: I suspect it was not a deliberately designed-in behaviour so much as a point so far outside the envelope that it was not considered. >60kts, in a heavy, at cruise altitude? AB added to the complication of SW warning logic by adding the airspeed input. Couldn't they have kept it simple?

bearfoil
1st Aug 2011, 23:17
If AB disabled SW< 60knots, would they have likewise programmed no WARNING at OVERSPEED? Seems logical?

In a spin, one can have forward A/S, and negative G/S. Fact is, it will always be 'negative' save for still air.

TioPablo
1st Aug 2011, 23:27
BOAC said:
I still like your (oldish) idea of dropping straight to Direct Law in the 447 scenario, by the way - with a concomitant shift in training, of course....See the clear announcement in front of you: USE MANUAL TRIM (blinking red if possible), you aren´t protected!

Speed prot wasn´t possible anyway... The system has no idea of speed... It seems...
So... Alternarte Law...?
Oldish or not, i like the idea too...

bearfoil
1st Aug 2011, 23:31
Tio Pablo

How is "Use Manual Trim Only" a Protection? It is a command. BUT, theoretically, it is unneeded for even STALL recovery if zeroed. Elevators are enough. It is a command also to CHECK THS' deflection, and zero it immediately? So, if THS is not necessary for Manual flight, (IT should not be- per certification?) How is THS allowed (commanded) to deploy to max NU in less than NORMAL LAW? And if in other than NORMAL, shouldn't the return to zero be auto as well? Remember, if PF needs its authority, it is available? "Use THS with Caution, Roll Direct, Pitch not protected")

Perhaps, rather than a big red Button to DIRECT, the button should be to ut back neutral the THS. Would not that have been enough in 447' case?

bear

wiggy
1st Aug 2011, 23:39
They could have looked at ground speed and it would have helped.
So if you lost IAS and then you scanned GS and see it drop from >400kts to <50kts you would not worry?

Trouble is you (and others) are looking at this with the benefit of hindsight, aka "Monday morning quarter backing".

These guys were on the edge or beyond it and they had very little time to decipher WTF was going on. Nowhere, to my knowledge, is keeping the Groundspeed, even if displayed, a requirement of a basic instrument scan. I'm sure, if the AF447 crew had unlimited time then they may well have noticed the G/S and made the connection.

I'll make the point I made a while back: unless you have experience of an aircraft coming "unglued" around you have no idea how idea how difficult it can be to comprehend (a) how little time you've got left and (b) how bad things have got. I suspect if we could listen to the CVR that would be very clear.

xcitation
1st Aug 2011, 23:39
@bear

If AB disabled SW< 60knots, would they have likewise programmed no WARNING at OVERSPEED? Seems logical?

In a spin, one can have forward A/S, and negative G/S. Fact is, it will always be 'negative' save for still air.


I would expect overspeed warning to only disable if IAS was invalid or somewhere beyond Mach 1.0 (no wings then anyway).
My point is that cross referencing ground speed at the onset of lost IAS they would see it reducing during the bizarre zoom climb. Either way if ground speed gradually from 400kts to close to zero it would indicate more an underspeed than an over speed. Giving a profoundly different perception.

aguadalte
2nd Aug 2011, 00:48
me:those aircrafts are ultimately flown by men and that men revert to basics when in face of an outstanding dangerous situation. Mike X:No offence, but your statement is unqualified.No offense taken. But what has Roselawn to do with what I have said?
My line of argumentation has to do with feed-back and interface between machine and pilots. Of course pilots have to be proficient.

The question I am highlighting is a different one:
We fly FBW Airbuses in a different way from other aircraft. Although the same laws of aerodynamics apply, the "orders we give" to Airbus Flight Controls are: "You fly this way". We really "don't care how" the aircraft is going to "fly that way", but underneath that "order", a number of systems will try to cope with that "order", and will move all the necessary flight controls surfaces (including THS) in order to cope with that "demand". The protections are used to prevent pilots to "order" unrealistic or stupid demands, when in normal law. But when those protections are lost in alternate law, pilots must be very careful when "asking" for unrealistic "orders" (from a degraded FBW aircraft). Unfortunately, the fact that pilots are now used to "ask" for what they "want" from FBW aircraft, without having to actually "fly" the aircraft, has lead them to a false sense of safety. Moreover, the fact that pilots now have no feed-back on the sticks has turned them senseless and complacent. We, FBW pilots have left ourselves tend to be taken by the Principle of Least Effort. And the only way to cope with that, is to try to keep proficient on basic flying skills. I have the fortune of having my own Pitts (together with a couple of friends). Others, just take some spare time in the local aero club. But most think its just a waste of time. I would advise them to think again...and get back to basics.

TioPablo
2nd Aug 2011, 01:33
How is "Use Manual Trim Only" a Protection? It is a command. BUT, theoretically, it is unneeded for even STALL recovery if zeroed. Elevators are enough.Direct Law is a protection Bear... The trouble is... It relays on flying knowledge. I said: it would have been the best state change inside the system given the situation... Which is something quite different as what you did interpreted...

I hope nobody needs to explain that elevators autorithy is directly related to THS position...

bubbers44
2nd Aug 2011, 02:31
Seeing a +10 nose up with decreasing airspeed and obviously ground speed decrease should have told them something. I guess they were just bad pilots. What other explanation is there? They probably were never trained to hand fly at altitude. I don't understand why a pilot has to be trained to handfly an airplane. Is it a European thing? I thought hand flying was taught in the first five hours. That is how we do it here.

bearfoil
2nd Aug 2011, 02:52
Tio

A protection to me means a limit, something is prevented that could conceivably cause a serious problem, and not up to the Pilots in Normal Law. With Alternate Law, Protections are less, though some remain.

My point is that what occurred, for whatever reason, found the a/c climbing and peaking with a "trimming" HS, not a protection, a flight path mitigation re: elevator reduction of effort.

Of course elevators authority are related to PITCH of HS. That is my point, to the extent that it eases elevator pressure in one direction, it fights it in another. One of the reasons the a/c climbed so well, was the THS deflection NU. At apogee, and Stall, it remained full NU, making recovery either problematic or impossible? So it autoed in ALTERNATE LAW all the way up, and since the PF input little nose down, it remained in that position? What inputs he made ND he did not have the boost of the THS.

Now he should have recalled the flight LAW, and pushed (and held?) ND, to recover level flight. He did not.

So, whether he was cognizant of the trim NU or not, he was not cognizant of THS when he "tried" to drop the nose. Only in Direct does the warning appear "Manual Trim Only"? Add in that PITCH is not protected in ALTERNATE LAW, and whatever solution any PF would attempt is hampered with the THS' Position, yes? My simple point is that an annunciated migration of the THS back to neutral would make possible an elevators only solution, just that. That IS a protection, taking THS deflection out the problem. The THS is for continued flight at a certain PITCH, and it is not a maneuvering device, per se. In fact, it is anti maneuver, this time anti LOWER THE NOSE. Favoring the ship Nose Up is not a good thing in a Stall? Is it as simple as connecting the THS drive to STALL WARN? Auto return? Is that undoable? Too expensive? Hurt someone's pride? Or am I throwing Pooh?

Rananim
2nd Aug 2011, 08:18
unless you have experience of an aircraft coming "unglued" around you have no idea how idea how difficult it can be to comprehend (a) how little time you've got left and (b) how bad things have got. I suspect if we could listen to the CVR that would be very clear.

This is 100% correct.Just fly the plane in UAS event.Pitch/power.Keep a cool head and ignore(try to)alarms/bells/whistles.The old adage about sitting on your hands for 10 seconds when anything happens up there holds true.Fly the plane.KISS.It helps in a Boeing/MD as PNF can see and feel inputs of PF on the stick.

Good memories
2nd Aug 2011, 08:23
Bearfoil,

How will we find out weather the elevator had enough authority the bring the nose down at such a low speed and that immense sink rate. For me a test in the best simulator is no proof it has enough authority. It has to be simulated on the acft. , same weight, same altitude, same CG, 5000 kg in the stab tank. I think EADS is obliged to make a test like that with a test pilot and some normal line pilots with no aerobatic experience.

If this it not possible, maybe full rudder could have helped to bring her nose down, I think the air force pilots call it top rudder. I never heard of this until l was 50 and skipper on a 747. There was a video demonstration from a AA Captain about unusual attitudes. Only after my retirement flying gliders here in the Provence I did these maneuvers real time.

We are not all gifted like Scully and I was certainly not, still I was able to fly 21000 hrs accident and incident free.

It is therefor that I find the conclusion on this matter by the BEA very premature and greatly unfair towards the pilots.

I like Aquadelta's questioning and view on the matter in post nr. 2423.

To me it seems there is more knowledge and serious doubt in this forum than there is with the BEA or is it EADS?

JJFFC
2nd Aug 2011, 09:17
Either the PF was insane either he could have commited the perfect crime if AF, AB and the BEA had not spent millions to recover the boxes :

The PF managed - volontarly - to :
1/ Preparation of the action
- not to use the anti-icing;
- send the captain to rest yet the capt had a nasty feeling : "Do you (really) have your licence ?"
- unfasten his seat belt;
- disconnect from Rio;
- Not connect to Dakar;

2/ Action
- nose up to stall
- lost the plane
- when the PNF wants to take the command : disconnect his stick without telling him;
- when the PNF understand that the problem lies with the PF: he ask the Captain not for his skills but for his authority ;
- when the captain arrived, the PF had this incredible phrase : "we have the speed of a "fool"" so the captain can't understand the situation;
- when the PF his asked to put the wing "à plat" (horizontal) that clearly shows that the PNF had identify the stall, the PF seems to agree but lie and continue to nose up;

Conclusion : Air France is one of the company where the salaries are the higest in the profession and therefore, the selection is really severe. It is just impossible that a 32 years old qualified pilot had not the skill and the training.

In the contrary, many smart people have tried to kill their wife and suicide... ???

The conclusion of the BEA is to undertake a "psychological" inquiry. Then, the case will go to the Court.

sebaska
2nd Aug 2011, 09:37
Another dumb question (and maybe already asked .. no remember .. and the search engine of this forum kill my nerves http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/nerd.gif )

Why the AP must absolutely disengage when the system detect incoherent speed datas ?
And consequently ..why the procedure for IAS can't be take in charge by the AP for some time ... (pilots alerted) and give to pilots the time to put their gloves before touch anything ?

I answered that question some time ago (post #2067):

http://www.pprune.org/rumours-news/447730-af447-wreckage-found-104.html#post6582987

NASA is running a project to address that by prototyping "inteligent flight controls" which would adapt to particular degraded conditions whatever they might be. But this is for now just research project. And it's not finished yet, while it started in previous millenium. It's findings will probably first find their way into military UAV (meant to fly over enemy territory, so if one falls off the sky and hits someone on the head it's enemy who's hit so damage is acceptable), then into manned military equipment and only much later into transport category planes.

IMHO, what is conceivable now, not in some distant, undefined future, is making "staged" (or "preanounced") AP disconnect in some (but not all!) situations. I.E. have two thresholds for various parameters. When first threshold (let's call it warning threshold) is crossed there is a warning that AP "feels uneasy" about particular parametr(s) (which crossed that threshold). And the second threshold is exactly what is now AP disconnect threshold and causes the very same effect - disconnects AP.

That would not change current AP logic at all, it would add another system with logic similar the one which rules AP disconnection, but with lower preprogrammed thresholds.And that would help that guys and gals in front to bring themselves fully into the loop before airplane is handed to them.

Loose rivets
2nd Aug 2011, 10:51
How will we find out weather the elevator had enough authority the bring the nose down at such a low speed and that immense sink rate . . .

Again, we see a suggestion that the aircraft is capable of locking the pilots into a true deep stall. Some posts back, a flight engineer monitoring the pilots referred to deep stalls.

I again ask - is there any evidence one can be locked into an unrecoverable deeps stall in this aircraft type?


Good memories goes on to say:


For me a test in the best simulator is no proof it has enough authority. It has to be simulated on the acft. , same weight, same altitude, same CG, 5000 kg in the stab tank.

Amen to that, but . . .


I think EADS is obliged to make a test like that with a test pilot and some normal line pilots with no aerobatic experience.


The suggestion funds might be diverted from executives luxury homes to advanced training is not going to - dare I say, 'fly.' But I'm left wondering just how much of Davis' handling training could have been bought with the costs of years of recovery and even more years of inquiries and the implementation of even more confusing workarounds and fixes.

BOAC
2nd Aug 2011, 11:14
How will we find out weather the elevator had enough authority the bring the nose down at such a low speed and that immense sink rate. - NB I am still waiting for Wednesday to download the (English) report, but as I understand it the 'nose down' SS DID move the nose down? Did the stall warning not 'restart' as the IAS increased? Had the input been continued recovery (from the stall) would probably have been assured. Any reduction in AoA is going the right way and would then rapidly reduce AA further as 'forward' IAS increased.

sebaska
2nd Aug 2011, 12:20
- NB I am still waiting for Wednesday to download the (English) report, but as I understand it the 'nose down' SS DID move the nose down?


It was rather weak (just bit beyond neutral -- see that post: http://www.pprune.org/rumours-news/447730-af447-wreckage-found-118.html#post6610311) and short timed and it reduced nose-up attitude.

Did the stall warning not 'restart' as the IAS increased? Had the input been continued recovery (from the stall) would probably have been assured. Any reduction in AoA is going the right way and would then rapidly reduce AA further as 'forward' IAS increased.

Well, some poster just few pages up said that recovery was not assured, and in fact very hard. He said that they tried that situation is sim and flight allmost allways ended in the ocean anyways. The word is that for typical line pilot recovery would be pretty impossible. As I understand even if the stall was recovered then there was overspeed shortly thereafter and that could not be recovered.

bearfoil
2nd Aug 2011, 13:58
BOAC

Agreed, emphatically. The NOSE lowered (to 6?). Was that all the further it would drop? Or did the STALL warning frighten the PF into a reprise of hie "approach to STALL recovery" in vogue at the time?

I am not agreed that this 'approach' (to Low altitude STALL) is completely unwise. From cruise, any STALL WARN (if correct) means controlling power and velocity (NOSE DOWN, keep power as selected?). Just gently.

I don't feel a go to DIRECT is wise. And certainly not with a touchy a/c. Absolutely not with a trimmed state other than cruise, the elevators are plenty for recovery.

I am trying to understand still how it is acceptable for the THS to go 13 NU withn or without the PF' knowledge. Then to remain there with a new control added to the scan and the control mix, and that a slow one.

I still do not understand the Pilots' behaviour. Perhaps never. Surprise? Distraction? Ergonomic? Fatigued? A Battle of "wills"?

It is not logical to consider more training here, though it would always be well advised and have a safety payoff.

Why? Because the engineers do what is asked of them, and some questions are not asked. The trend is toward more and better automation.
BEA have spoken, they have a great deal "invested" in the state of the discussion at present.

1. The accident was caused directly by a poorly known event, one that requires high level performance, and quickly.

2. How was the cause addressed prior to its first fatal entry? Badly.

3. From the outset, any act that had been properly addressed by those responsible, would likely have had a good result.

a. New Probes
b. High level manuevering skills
c. Restricted cockpit, Sterile? (For conditions)
d. Addition of kit.

KIT: Airbus has an RTLU. Rudder Control Limiter. Speed sensitive, it prevents damage to the Rudder from overdeflection.

THSTLU. Speed and Altitude sensitive, it might prevent damage to the people? Do we care about control loads management at cruise? It does save money, there's the Rub.

Good memories, at low speed and with a hobbled Rudder(RTLU), top foot may not have been helpful. With ROLL oscillations, the NOSE may have bobbed down a degree or two, but from the way the PF was piloting, he may have been trying to PREVENT the NOSE from dropping. Hence the "STOP the lateral movements" from PNF. A Tunnel test of 447's attitude would be interesting. At her AoA, the spill from the fuse and HS/elevators may have been flowing up and into the Rudder causing reverse action.

DozyWannabe
2nd Aug 2011, 15:00
It helps in a Boeing/MD as PNF can see and feel inputs of PF on the stick.

I say *again*, it didn't help the Birgenair 757 crew (PNF could see and feel the Captain's input and seemed to know it was inappropriate, but was unable/unwilling to take control).

poorjohn
2nd Aug 2011, 16:01
(sebaska):IMHO, what is conceivable now, not in some distant, undefined future, is making "staged" (or "preanounced") AP disconnect in some (but not all!) situations. I.E. have two thresholds for various parameters. When first threshold (let's call it warning threshold) is crossed there is a warning that AP "feels uneasy" about particular parametr(s) (which crossed that threshold). And the second threshold is exactly what is now AP disconnect threshold and causes the very same effect - disconnects AP.

That would not change current AP logic at all, it would add another system with logic similar the one which rules AP disconnection, but with lower preprogrammed thresholds.And that would help that guys and gals in front to bring themselves fully into the loop before airplane is handed to them.

My comment from a long-ago thread was a bit different - I think the a/p software should actively monitor trends, project the a/c state x seconds into the future, and thus warn the crew x seconds before disconnect. Being a big fan of situational awareness, as that prediction began to suggest bad things were in the future, I would have it clearly enunciate its concerns to an as-yet alarm-free cockpit.

Software complexity might be vaguely comparable to TCAS, although given the large number of parameters that might be an underestimation. And the counter-argument might be that many/most disconnects come from a sudden exceedance, not a slow degradation.

Off-topic here in any case.

MountainBear
2nd Aug 2011, 18:40
I have the fortune of having my own Pitts (together with a couple of friends). Others, just take some spare time in the local aero club. But most think its just a waste of time. I would advise them to think again...and get back to basics. This is exactly what I mean by burden shifting.

In response to my comment about stall warning logic several posters claimed that the situation AF447 found itself in was a set of facts that simply couldn't have been anticipated prior to this accident. But part of the job description of engineers and designers in all fields is to use their imagination, not just their reason. It's not a defense to say "We failed to anticipate" when part of your professional and ethical duty is to anticipate.

AF447 shouldn't have crashed. It did. The men who are responsible wear white shirts, trim their fingernails, shave their facial air. All of them have some type of advanced training and most of them have professional degrees. If there is a poster child for "white collar manslaughter" AF447 is it.


It is not logical to consider more training here, though it would always be well advised and have a safety payoff.

Why? Because the engineers do what is asked of them, and some questions are not asked. The trend is toward more and better automation.
In the big picture I support this trend towards more and better automation. But it comes at a cost, not just for pilots but for engineers and designers. With greater authority comes greater responsibility. If you want the power to fly the aircraft from a cubicle (via software) you have to be willing to accept the responsibility when it crashes. No dodging the ball of blame when it comes your way.

jcjeant
2nd Aug 2011, 19:07
Hi,

Vol Paris-Rio : le rapport d'enquête a été caviardé (http://www.latribune.fr/entreprises-finance/services/transport-logistique/20110802trib000640317/vol-paris-rio-le-rapport-d-enquete-a-ete-caviarde.html)

Reportedly, a recommendation on the stall alarm of the Airbus provided for in the final report almost BEA, 48 hours before its publication, is not the official version. Air France took the European Aviation Safety.

The controversy over the crash of the AF 447 Paris-Rio is not going to go out. The shadows glide on the third progress report of the Investigation Bureau Investigation Analysis (BEA) released on Friday pointed to the responsibility of the pilot of the Airbus A330-200.

According to several sources, a recommendation on stall warning device, which was in a near-final version of the report 48 hours before its official publication, has not been published. Envisaged under the precautionary principle, this recommendation was to immediately begin a process of analysis and reassessment of the logic of operation of such alarms.

When asked by The Tribune, the BEA said "he did not comment on the steps that led to a recommendation or not." BEA internally, some did not appreciate and even threaten to resign.

According to our sources, Air France has sent a letter to the EASA (European Aviation Safety Agency) requesting that the matter be reviewed quickly. When questioned, Air France has confirmed that he took the EASA on August 1 about the failures of the stall warning.

For pilots and Air France, these problems have played a major role, since "the multiple activations and stops unwanted and misleading, contrary to the state of the aircraft, have greatly contributed to the difficulty for the crew to analyze the situation, "stated the airline in a statement released Friday in response to the report of the BEA.

Between 2:11 minutes and 45 seconds, the night of the accident on 1 June 2009, and the crash, the alarm has reactivated a dozen times with durations ranging from 2 to 8 seconds. The reactivation of the alarm the longest took place when the crew goes into action to restore the unit to a normal position. Clearly, the alarm can stop when the aircraft stalled and recur if recovery of a valid speed. Experts speak of a "case of reverse operation of the alarm."

Indeed, it stops when the speed is less than 60 knots, because it was considered that there was no reason why the aircraft can be found at this speed. But every time the driver gave the order to bite (the correct order) and ironed it on top of 60 knots (rearing, its speed had slowed considerably), the alarm goes off, making believe that his action was wrong.

They therefore had no comprehensio the actual situation of the aircraft. This explains why the actions of the pilots of flight Rio-Paris appeared incomprehensible by their colleagues.

xcitation
2nd Aug 2011, 19:08
@moutain bear

I think it is over simplification to say it is the engineers fault.
IMHO there are plenty of areas for improvement i.e. training, systems, QRH and procedures, CRM, weather data, weather avoidance policy, satellite comms for emergency, FDR and visual recording.

SkyITL
2nd Aug 2011, 19:34
Hello all,
AF is a company where operational culture is supposed to be much better than in any other airline... Well, french people tends to beleive so, as well as many, if not all, AF pilots.
This is another story, but french pilots will certainly understand what I’m trying to point here…
Anyway, here is what upsets me :
Some of you try to explain the crash buy many factors but pilots’ responsability. Ok, why not.
But who can seriously here say that AF447’s PF did his job during the final 3’’30’ of the flight ? Didn’t he receive a partial instrument panel training during his instrument rating ? Every pilot here knows (and has to know !!) how to deal with an airspeed loss during IMC : keep thing staight an level, move the levers with extreme care (especially on high altitude flights) and focus on the altimeter and ADI trying to keep what was good before failure…
Anyway, aren’t we paid for applying strict procedures during failures in flight ? Does anyone here can say that this PF ever called for the appropriate procedure ? NO, never.
Now try to imagine, you have 3 minutes to answer this question: the aircraft is 15° nose up, with a VSI of -10000ft/min (confirmed by the altimeter) ; in wich configuration do you think your aircraft is ?
Who the hell was this PF ?? What did he do in this passenger aircraft ?? Who or what allowed him to be able to fly this aircraft ?

Kalium Chloride
2nd Aug 2011, 20:10
Does anyone here see how the THS was broken?

Frankly, no, I don't. From the FDR trace it looks like it functioned exactly as designed.

Lonewolf_50
2nd Aug 2011, 20:34
Regarding jcjeant's leak from the press:

If it's legit, I'd tend to agree with the Air France position that the stall warning system is found to be unhelpful in a particular condition.

It's a problem, and a design decision that makes me scratch my head.

Air France must face the training and operations question on why the pitch and power response to UAS didn't take place very early in the event.

Mountain Bear: the part of the team in white shirts you might want to add is those who fund and establish, and then execute, pilot training requirements.

It makes my heart ache to put myself in the position of the PNF, with the PF chasing/fighting the aircraft pitch and roll once in alternate law ... he seems never to have been in a position where PJ2's "do nothing" guidance (really, fly level and then methodically work one's way through the UAS procedures, memory then checklist) could be applied to its conclusion.

Ergonomics question: if you have flown both tapes and circle gauges, who besides me wonders if the unwinding of the altimeter, or the needle pegged down in the VSI, might have provided a different cue to the scans of PF and PNF. (OK, call me a luddite, I know that people crashed on steam gauges too ... )

When speeds went quickly bad, it appears that the pilots identified airspeed going bad, but what isn't recorded is whether or no UAS procedure was called for. For the moment, absence is evidence that they never got that far.

Training issue?

xcitation
2nd Aug 2011, 20:40
@bearfoil

If the THS was broken how do you explain no errors from its feedback control. If there is a mismatch between motor control to move it and its position then an error is generated. How do explain the abscense of errors? Also the a/c appeared to respond to the flight controls correctly (see the theoretical vs actual lines in charts in report #3). Also when the a/c nose down the attitude responded demonstrating elevator authority over THS.

One could argue that the SS was broken with a nose up bias. However the PF explicitly stated that he had be giving it stick back the whole time. Clearly this is more consistant with him thinking overspeed (nose up, deploy spoilers).

MountainBear
2nd Aug 2011, 20:44
I think it is over simplification to say it is the engineers fault.

Yes, that is what I said in my post #2404. I understand quite clearly that this is complicated matter with many different players involved. My post was primarily directed at the specific person I quoted who seemed to imply that the best solution was simply to have pilots practice more in their own free time, a simplistic solution itself.


I think we all agree that turning off a stall warning as the stall gets worse is not really a good thing. But was it a main factor? Wasn't the bigger problem probably not that the stall warning stopped, but that there had been no proper reaction to it for nearly a minute before?

I'm sorry I missed this comment in my first read through of recent posts because I think it is an excellent question.

In order to understand the importance of the stall warning logic in this case we need to understand the way human beings responded to accidents. When faced with changing circumstances the mind forms a mental picture or mental model of what is happening to it. This mental model is predictive in the sense that it takes not only the data it knows but fills in the gaps with guesses about data it doesn't know. The mind's response is also a process in the sense that the mind is constantly taking in new data and, if necessary, changing its mental model of events as it gets new data.

In this situation there are two separate and distinct questions. The first question is why did the pilots form a wrong mental model of events to begin with. To answer this question it's wise to look at things like training, CRM, etc. The second question in this case is why did the crew maintain that wrong mental model right up until the plane went into the ocean. It is possible that the stall warning logic was a key factor in why the crew maintained the wrong mental model for so long.

I hope the distinction between a person making a mistake and a person continuing to make a mistake is clear. I don't think that the stall warning logic had anything to do with the initial mistake the crew made; I think it's possible it had something to do with why they persisted in their error for so long.

Now some people will take the position that the real focus should be on the initial mistake but I think that a robust system cannot be predicated on the fact that a human being is going to be perfect every time. There has to be more than one line of defense.

Other people will claim that even if the stall warning had operated differently it still would not have made any difference in this specific situation. That's no defense either because (a) that's hindsight bias (b) whose to say it won't make a difference in some future accident.

So do I think that the stall warning logic was "the main factor"? No. But that doesn't mean it's not a real area of concern.

DozyWannabe
2nd Aug 2011, 20:53
STALL WARNING MUST ALWAYS WORK. Its unveliable that on the Airbus with that pitot probe on icing condicions doesnt.

Its funny for me how people blame the pilots because the stall warning sound for 57sg and they didint recognize the stall. Dont you understand that when the stall warning stops means NOT STALL, but the aircraft wad actual stalling.


This is exactly what I mean by burden shifting.

In response to my comment about stall warning logic several posters claimed that the situation AF447 found itself in was a set of facts that simply couldn't have been anticipated prior to this accident. But part of the job description of engineers and designers in all fields is to use their imagination, not just their reason. It's not a defense to say "We failed to anticipate" when part of your professional and ethical duty is to anticipate.

If you'd like to have a look at this post in the other thread, courtesy of thermalsniffer. This post does not (IMO) have the definitive translation from the French, but it is the first I've seen that syncs the CVR details up with the facts in the BEA note released in June :

http://www.pprune.org/tech-log/456874-af-447-thread-no-5-a-67.html#post6614845

Then please check your prejudice at the door and listen carefully.

The Stall Warning sounded initially, at 2:10:10.4 and at 2:10:13. This was in response to the drop in IAS caused by the blockage of the pitot tubes. This is likely a false warning and stops. I would suspect (though I have no proof as my notes don't go into the required detail) that the IAS component of the stall warning logic is disabled when an ADR DISAGREE status is in effect - at least, if I was designing the logic, that is how I'd have it work.

(Note, this is not how the software is actually written, being instead generated from a graphical representation of the logic paths, but I hope it will suffice for demonstrative purposes)


if (STALL WARNING && ADR DISAGREE)
then
STALL WARNING INPUT PARAMS = AoA ONLY

else
STALL WARNING INPUT PARAMS = AoA AND IAS


The reason for this is because it was discovered from the Birgenair and Aeroperu crashes (and it had been suspected but impossible to prove from as far back as BEA548 at Staines in 1972) that aural warnings can be filtered out by the human brain under stress conditions - therefore it is prudent to determine which of the aural warnings is valid and only present those.

I don't believe that IAS would be considered a valid input to stall warning for the sake of it, as stall warning is purely a function of AoA, which is the way stall warnings have been implemented for a very long time. The only logical reason I can see for introducing an IAS parameter would be to filter out false warnings.

Now, back to the transcript. The second time the stall warning starts is at 2:10:51, which as I understand it was around the point of the apogee of the zoom climb and the point at which the aircraft approached and then began to fall into the stall regime. This stall warning is the real thing, and it continues for just under a minute. During this time the nose-up inputs are aggressively maintained and the aircraft starts bleeding off even more airspeed. If I've understood correctly, for at least the first 10 seconds the real stall warning was sounding, if not slightly longer, all the pilots had to do was push the sidestick forward and the aircraft would have come out of the stall. They were, however, not trained in this escape maneouvre, having only been trained on the approach to stall.

The stall warning stops at 2:11:45, and during this time the stall warning has been sounding for almost a minute, during which time the inputs have been almost universally nose-up (i.e. incorrect and making the situation worse). Also during this time, the pitots have become unblocked and crucially the speeds are once again valid and ADR DISAGREE is not longer in effect. What this means is:


Stall warning is inhibited due to a *genuine* IAS reading of less than 60kts
At this point the aircraft is falling at or near terminal velocity and is unrecoverable


Therefore, while with 20/20 hindsight, the Stall Warning logic should be reviewed (potentially by adding air/ground mode detection as an input to the logic if this is not the case already*), the inhibition of Stall Warning at 60kts and below had no causative effect on this accident, because by the time the aircraft had reached this point it was already too late. That the initial false Stall warning triggered (and was quickly silenced) at the same time as the PF made his initial (and only significant) nose-down input was an unfortunate coincidence, but the fact remains that the stall warning system was doing it's job correctly from the point at which the actual stall began to the point at which the aircraft was way outside the flight envelope, nearly a whole minute later.

I apologise for the bluntness of this post, but I wanted to make it as crystal-clear as I could.

[* - after all, you don't want a stall warning blaring at you during initial takeoff roll and landing rollout... ]

Lonewolf_50
2nd Aug 2011, 20:55
Why is a pilot more worried about overspeed than stall? (I am going out on a limb, presuming more than a problem with body sense of speed.

Is that due to high speed buffet/stall at the fast end of the "coffin corner" triangle's legs being a severe event (and potential damage to airframe?)

I am at sea on this one.

Can someone who flies heavies explain this? There may be more to what the PF was worried about, in re high speeds, based on the conventional wisdom of that specific detail of the occupation.

Is FOQA (worry about being written up for an overspeed) a contributor to bias in this regard?

Think about this, and about how rules influence people: "You must not overspeed because ... (____ fill in the blanks for reasons not to overspeed)"

Davies: "If you have a choice between stall and somehthing else, try something else."

Was PF predisposed to be worried about overspeed?

DozyWannabe
2nd Aug 2011, 21:12
Why is a pilot more worried about overspeed than stall? (I am going out on a limb, presuming more than a problem with body sense of speed.
...
Is FOQA (worry about being written up for an overspeed) a contributor to bias in this regard?
...
Think about this, and about how rules influence people: "You must not overspeed because ... (____ fill in the blanks for reasons not to overspeed)"
...
Was PF predisposed to be worried about overspeed?

This is something of a conundrum - I think I might have read somewhere in the Tech Log thread that the PF was also a glider pilot. I don't think the fear of overspeed was due to fear of a write-up, so much as an overspeed can and will cause structural damage (and thus potentially render the aircraft unrecoverable) if allowed to persist, whereas with a stall you should have plenty of warning as you approach stall speed and perform the corrective actions (which at the time were effectively maintain altitude and increase thrust).

The conundrum then becomes "If he knew enough about aerodynamics that overspeed concerned him so much, why then did he then fail to realise he had stalled the aircraft based on what was being displayed in front of him (unresponsive lateral control, rapidly unwinding altitude, nose-high attitude, TOGA power, stall warning sounding)?". We're *well* into the realm of the hypothetical here, but could confirmation bias have played a part? It's generally accepted that the Birgenair PF remained fixated on overspeed because that was the first warning he got. It would appear that the AF447 PF was concerned about overspeed without any prompting whatsoever, but is it possible he was still focused on worrying about overspeed to the detriment of his scan and situational awareness?

mm43
2nd Aug 2011, 21:26
Originally posted by DozyWannabe ...

The Stall Warning sounded initially, at 2:10:10.4 and at 2:10:13. This was in response to the drop in IAS caused by the blockage of the pitot tubes. This is likely a false warning and stops. I would suspect (though I have no proof as my notes don't go into the required detail) that the IAS component of the stall warning logic is disabled when an ADR DISAGREE status is in effect - at least, if I was designing the logic, that is how I'd have it work.The SW sounded because the allowable AoA had been exceeded - see:-

Post #1160 - AF447 Thread No.5 (http://www.pprune.org/tech-log/456874-af-447-thread-no-5-a-58.html#post6610567)

It was in response to the initial pitch-up, and nothing to do with IAS.

DozyWannabe
2nd Aug 2011, 21:32
The SW sounded because the allowable AoA had been exceeded - see:-

It was in response to the initial pitch-up, and nothing to do with IAS.

Cool beans, thanks for the correction. I'm pretty sure that it doesn't invalidate the rest of what I was saying though - the stall warning worked when it was possible to make a difference and only stopped working long after anything could be done.

bearfoil
2nd Aug 2011, 21:33
Doze

There is nothing in your last posts to disagree with.

The STALL occurred after the aircraft died. No argument. The mayonnaise stirring is far more important than the Stall, or even the climb, imo.

One way to recover is to fly to a heading. Oblivious of heading, apparently, and unwilling or unable to correct ROLL, plus a fixation with a dumb distraction are the reasons this crew failed?

The "Committee" approach to recovering a dangerous flight Path won't work, ever. And if in the simulator, one can "do-over".

One of the most egregious blunders was the calling back of the Captain.

A bad situation became impossible. The highly trained division of Labor took a holiday, and troubleshooting is for mechanics at the base.

What was broken about the THS? You mean mechanically, operationally, or theoretically, oh, or Philosophically? All of the above.

Nothing about what happened to 447 should be seen as being sacred. Including kit, ego, and compassion.

DozyWannabe
2nd Aug 2011, 21:36
Bearfoil, please tell me you're not now back to arguing that the THS screw broke during the event?

bearfoil
2nd Aug 2011, 21:49
xcitation

the actual trace shows the THS pinned, with elevators deflected Nose Down, at a time when ACARS were overloaded with other unreported data, and BEA have not explained the mechanism for controls integrity.

Let alone: What was he seeing? On a PFD that was not recorded?

My mention of two identical inputs, one at the start of, and one near the end of the episode? NOSE UP, with LEFT ROLL to the stop!

That nagging and chronic descending turn to the right that cost them 270 degrees off course? You might say, well, who has time for Heading? Level wings provide a constant heading. No mention of this from BEA. Who remembers recovery from Unusual attitudes or steep banks: "Roll out on heading xxx, please"........

Doze. I have way short of enough to say anything definitively. Others might consider they are also in the same position. Look at the traces Elevs v THS on the right (later) tracks.

thermalsniffer
2nd Aug 2011, 21:53
Dozy said:
"It would appear that the AF447 PF was concerned about overspeed without any prompting whatsoever, but is it possible he was still focused on worrying about overspeed to the detriment of his scan and situational awareness?" In some defense to the PF, the PNF and the Captain apparently had SA issues as well.

PNF briefing to the Captain when he returns:

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

Later:

PNF: What do you think ?what do you think ? what do we have to do?

Captain: I don't know we're going down

Later:

Captain: It's not possible

DozyWannabe
2nd Aug 2011, 22:05
the actual trace shows the THS pinned, with elevators deflected Nose Down, at a time when ACARS were overloaded with other unreported data, and BEA have not explained the mechanism for controls integrity.

Doze. I have way short of enough to say anything definitively. Others might consider they are also in the same position. Look at the traces Elevs v THS on the right (later) tracks.

Given that you're now using phrases like "the aircraft 'died'" I suspect that would be a "yes", then. I still think it incredibly unlikely, and hopefully the final report will include a metallurgical analysis of the THS jackscrew assembly that will determine whether any fractures are consistent with ground impact or otherwise (I suspect that is the reason the assembly is one of the things they raised).

I also suspect the only way it could be proven to your satisfaction with the information we have at this point would have been if the PF had made an input sufficient to move the THS in the opposite direction and not got a response, which he did not do. The traces of what you describe as "making mayonaise" prove it.

@thermalsniffer - Sure thing. I was not intending to single out the PF for censure over and above the other crew members, just stating what could be a possibility based on the information we have. That said, the PNF queries the PF's actions several times ("Why are you going up?" "Descend, descend descend!"), but never seems to reach the point at which he has had enough and takes control. By the time the captain reaches the flight deck, they are past the pont of no return in any case, but it does appear that he did work out what had happened seconds before impact ("No, no, no don't pull back up").

bearfoil
2nd Aug 2011, 22:12
Not the mayonnaise end of the traces, the other end. Distinctly show the elevators going NOSE DOWN, The THS trace remaining flat.

The "aircraft died" I used after seeing "PULLED UP like a madman"....



I'll be more careful. Hyperbole is my enemy. Especially amongst the true tracking adherents!

Mr Optimistic
2nd Aug 2011, 22:16
I admit to being a merely SLF, but I think you guys are making a meal out of this. I do not see how it is so difficult, given the evidence now presented, to come to some fairly straightforward conculsions.

First, it is clear that the investigation has been well handled and no expense has been spared in gathering evidence in order to understand what happened.

There is no evidence that BEA or any other party is manipulating the evidence to promote, or protect, any other party.

It is clear that in a modern cockpit, when things go wrong, the independent software streams are capable of presenting the human beings with an cachophony of instructions, advice and warnings.

There is no evidence of unwarranted presence on the flight deeck.

Training, and modern concepts of technology, give a basic belief in the security of systems.

It is easier to explain, by way of repetition, the capabilities of a system designed by humans than it is to explain the workings of the physical universe.

If circumstances project you into the gap between your training and reality, you need a more fundamental understanding than your training provided.

JJFFC
2nd Aug 2011, 22:17
1/ " 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."

you can read this in the REPORT on the incident on 24 September 1994 during approach to Orly (94) to the Airbus TAROM

http://www.skybrary.aero/bookshelf/books/680.pdf

It means that 80% of the crews in the sky couldn't recover from a stall except by chance.

The reaction to a stall warning should become a reflex => weekly practice.

Therefore, for the industry, it is safer to prevent the pilot from being out of the flight enveloppe than to train the pilot to recover, what would need a continuous training as some have proposed here.

This accident is only within the statistic.:{

2/ Don't forget that neither the PNF nor the Capt. ever knew that the PF made an initial huge nose up => how many of us could have imagine that ?

In the TAROM incident, the crew could identify that a human action made the stall.

In AF447, the PF never confess his mistake and it is logical that the PNF and the Captain were looking for any cause except a human mistake

fireflybob
2nd Aug 2011, 22:18
Am I right in saying that on this type if inputs are made on both sidesticks the system will take the algebraic sum of those inputs?

In which case if one pilot was maintaining full and up and the other full down this would equal neutral - not what you need for stall recovery.

wozzo
2nd Aug 2011, 22:39
Not the mayonnaise end of the traces, the other end. Distinctly show the elevators going NOSE DOWN, The THS trace remaining flat.

At which time exactly go the elevators ND? I see two instances where they reach -15 (2:12:45 and just before 2:14), but never 0 (after 2:11:00) or ND (>0).

DozyWannabe
2nd Aug 2011, 22:41
Not the mayonnaise end of the traces, the other end. Distinctly show the elevators going NOSE DOWN, The THS trace remaining flat.

That could equally easily be explained by the lack of time for the nose-down inputs to take effect. Looking at the traces (if I understand them correctly), the elevators never return to neutral completely, but begin to move towards "nose-down" twice - once in response to the PF's brief nose-down input at about 2:13:32, and again when the PNF begins pushing nose-down at about 2:13:45 (which correlates with the CVR). This begins with a full-authority push, but gradually tends back towards neutral over the next 15 seconds ("I'm pitching up?") - not enough to move the THS.

During this time the PF returns his stick to neutral, but then begins pulling again at 2:13:52 or thereabouts. At 2:14:05 he makes the statement "We should be pulling, we're at 4,000 ft", at which point the PNF gives up pushing and starts pulling - by this point they are seconds from sea level.

At no point is there a commeasurate nose-down input capable of counteracting the full-authority nose-up command made by the PF at around 2:11:40 (or thereabouts) and subsequently held for over a minute.

bearfoil
2nd Aug 2011, 22:54
Thanks, Doze. I sense some hesitancy there, just a bit. I see the traces as elevators commanding NOSE DOWN, and the THS not moving even a bump off the dead bottom (Closed, NU). Now you say that this "relaxation of NOSE UP" is insufficient to pry the slab off its perch. How about this. The Pilot does not know the THS is NU max. His "Nose Down", when THS is planted, may actually cause the THS to nestle even further into its stop.

Aerodynamically. Now the sensor does not do "Aerodynamically", so shouldn't the slab start to inch its way back ND? Do the elevators have to reach past 0 degrees (mechanically) to encourage the THS to migrate? Because moving the elevators "Less NOSE UP" does not move it?

If this is so, I can see where the case can be made that the THS caused the crash, with some help from a PF who was unaware of its importance in its position working against him. His "Feedback", via his instruments, would tell him "Up is working fine". "Nose Down is not working all that well", with overspeed on his mind, he's thinking (wrongly) the aircraft is aiding the "recovery from OS". Nose UP is what he wants, and the a/c seems to agree, and he is taught to trust the a/c. (Not that there is anything wrong with that).

BTW, and I'm sure you have thought of this: In a too fast condition, one instrument will tell the truth the same way as in a deep STALL, the VSI.

High rate of descent, on the panel, in his belly, ("We have crazy speed, Non?" etc.). Just another hole in the stinky cheese? And another reason to hold "Back stick for a long while".

The points I am trying to make are not substantial, they are made in an inquisitive way, and not to irritate. We may be left forever with a non registration of #2 Panel, and the pilot making use of it locked in a seemingly personal battle with demons he imagines, or may actually see in evidence on his screen. I have suspicioned Overspeed, or its mimic, or its position in PF's thought process, for some time. His initial input, repeated at the last with one identical, is troubling. For you?

I am exceedingly curious about these three Pilots. There is much complication on this flight deck, and soon the engineers will be satisfied.

The upshot of this accident is neither simple, nor is it in any way suggestive of progress. Yet.

jcjeant
2nd Aug 2011, 22:55
Hi,

AF447 shouldn't have crashed. It did. The men who are responsible wear white shirts, trim their fingernails, shave their facial air. All of them have some type of advanced training and most of them have professional degrees. If there is a poster child for "white collar manslaughter" AF447 is it. Mountain Bear: the part of the team in white shirts you might want to add is those who fund and establish, and then execute, pilot training requirements.Maybe for the sake of safety and ease the investigations and find origin of faults .. it will be better to install cameras and OVR in the offices of the decisions makers and beans counters ...... :8

MountainBear
2nd Aug 2011, 22:59
@DW

the inhibition of Stall Warning at 60kts and below had no causative effect on this accident, because by the time the aircraft had reached this point it was already too late.

I have not held in any post in this thread that the stall warning caused this accident. I have held that (1) the logic of the stall warning system is flawed (2) that this accident illustrates the nature of those flaws (3) that these flaws are one possible explanation for the pilots behavior doing one specific phase of the accident (4) that the professionals who designed the system should be held accountable for those flaws to the extent they played any role in this accident (a point which I believe has yet to be conclusively determined because the final report is not out yet).

That is all I have held and anyone who asserts anything else fails at reading comprehension.

Mr Optimistic
2nd Aug 2011, 23:10
Re stall warning inhibit. You do not know. I disagree.

DozyWannabe
2nd Aug 2011, 23:10
Thanks, Doze. I sense some hesitancy there, just a bit. I see the traces as elevators commanding NOSE DOWN, and the THS not moving even a bump off the dead bottom (Closed, NU). Now you say that this "relaxation of NOSE UP" is insufficient to pry the slab off its perch.

Look very closely at the THS trace (as in zoom in to at least 300%). Unfortunately the PDF render is in too low a resolution to see much more than a couple of pixels difference, but there is movement from the THS actuator trace towards the end of those nose-down inputs. Unfortunately in both cases, the nose-down input was not applied long enough to make a significant difference.

...and the pilot making use of it locked in a seemingly personal battle with demons he imagines, or may actually see in evidence on his screen. I have suspicioned Overspeed, or its mimic, or its position in PF's thought process, for some time. His initial input, repeated at the last with one identical, is troubling. For you? r

I think an overspeed warning would require agreement from all speed sources, and therefore would have been annunciated to the PNF at the same time. The use of emotive words like "madman" and "demons" has come from you, not me. I'm trying to remain in the realms of dry language and logic. :)

[EDIT : I haven't backtracked at all - I merely gratefully accepted a correction on the part of why the initial stall warning events happened. I also know that "madman" originated from a post on the other thread, but I certainly never used it. ]

@MountainBear - I agree that the logic needs revisiting, but to say that the stall warning inhibit may have contributed to the pilots actions is to go directly in the face of the FDR traces. Stall warning starts at the apogee of the climb and persists for almost a minute. The correct response to stall warning is to lower the nose until the stall warning goes away and then level out once stable. The *trained* response to stall warning was to maintain a level attitude and increase thrust. The PF's response to the stall warning was to continue holding the stick halfway back (with two blips of nose-down lasting less than a second each), and then, 30 seconds into the stall warning holds the stick in the full nose-up position for more than 30 seconds, then returns to hovering around the halfway back position. At *no* point is there any sidestick input which correlates to the end of the stall warning at 2:12:57.

bearfoil
2nd Aug 2011, 23:20
NO. Madman is not mine, and demon is in my view a descriptive worthwhile. I explained this before, you missed it?

It goes to style, and I am working against an old habit of vocabulary.

Can you relent ever?

As above, and before, you have had to backtrack. The STALL WARN inhibit may have played a crucial role in the accident.

Even with the VS, I did not use Bold! No grades, no promotions, no degrees. This is conjecture and informed discussion, in good humour. I take my lumps with the rest, as I get carried away also.

From a legitimate investigatory standpoint, there is not one creature present who exhibits credentials sufficient to convince me that this thread is take it to the BANK........ I try not to take my self too seriously. Forget my threadbare credentials. They are evident, I am sure. This is how I do not take personally the insults and derision. Water off a duck's back.

JJFFC
2nd Aug 2011, 23:27
As a result, (TAROM accident see my post above) the Bureau Enquêtes-Accidents recommends:

that a study be launched so that the pilot’s priority over all Automatic Flight Systems is
maintained in all circumstances.

This could be done :

a) by the disconnection of Automatic Flight Systems (automatic pilot and auto-throttle
lever or auto thrust) in the event of conflict between the pilot’s actions and those of the
Automatic Flight System or Flight Director.

b) and/or by clear information in the cockpit (possibly an alarm) warning the flight crew of
such a conflict.

The stall started with the nose up by the PF.

Did the PF started this nose up BEFORE the autopilot disconnected ?

xcitation
2nd Aug 2011, 23:31
JJFFC

Ok I understand an incorrect reflex action by 80%.
However this incident went way beyond reflex with 4 minutes of stick back, with PF saying he has been sticking back is not a reflex. It is some evidence of a conscious action i.e. observe, analyse, take action and communicate. Also 2 others in the cockpit also agree with the nose up attitude and resort to focussing on keeping the wings level.
Under your hypthesis we say they correctly identified stall, did a bad reflex for 4 minutes. All 3 failed to communicate stall. In fact they all appear to say they have no idea what is happening.
IMHO the facts as they stand do not back this hypothesis up.

bearfoil
2nd Aug 2011, 23:32
Or was it the "lurching elbow" hitting the ss when he turned back to the front after chattin his wife? Do not say this is impossible.

Turbine D
2nd Aug 2011, 23:55
Or was it the "lurching elbow" hitting the ss when he turned back to the front after chattin his wife? Do not say this is impossible.

This would be typical of one of the TV network's daytime dramas,e.g., "Soaps".:suspect:

Best to forget the drama and stick to the technical stuff.

The THS didn't break...;)

DozyWannabe
2nd Aug 2011, 23:56
@xcitation : It was at a much lower level, but remember ColganAir, where the reaction to a Stall Warning was a pull-up to the stops that was held for the duration of the subsequent stall, spiral dive and crash.

DozyWannabe
3rd Aug 2011, 01:02
OK, so here's the best I can manage given the limited PDF resolution :

http://i1088.photobucket.com/albums/i331/turricaned/fdr-munge-2.png

The only point at which I see a possible positive correlation between stall warning stopping and relaxing of nose-down input is at approximately 2:12:35, but this doesn't then explain why he holds the stick around neutral when the stall warning returns a 2:12:40 and holds it *back* when it returns at 2:12:50.

One of the things I noticed as I was munging this graphic is that the traces on pages 110 and 111 are not scaled t oprecisely the same size, so I had to re-scale the graphics to match up. Be very careful when flicking between the pages and trying to draw correlations.

oldguy42
3rd Aug 2011, 01:12
When the AP disconnected the PF pitched up, which eventually caused the plane to stall. Not sure why he did that, he should have just essentially left the controls alone and flown the pitch attitude at auto pilot disconnect.

But, I have no idea why the programming of the aircraft flight control systems silenced the stall warning system when in fact the aircraft was stalled. Whatever stall warning system is installed in that aircraft should have been active while the aircraft was stalled period, no excuses.

bearfoil
3rd Aug 2011, 02:02
Doze

Whilst in Autopilot, notice the oscillation of the THS, it varies 1-2 degrees very consistently, and smoothes when PF inputs NU. It also flies at three degrees NOSE DOWN during the same time frame. Stick obviously caged in spring tension.

Am I seeing some "Weather" reactions? Or an anomalous "Buzz"? Of course it is not flutter, but flutter does present that way.......

jcjeant
3rd Aug 2011, 02:03
Hi,

DW
Thank's for post here the graphic.
In the timeline transcript the BEA write:
Between 2H10min07 and 2H10min18 the vertical speed increase to 5200 ft/min
That's indeed true .. and when you put it in correlation with the graphic you see immediately it's a vertical speed to down (loss of altitude)
Vertical speed used by BEA in transcript is misleading less the down qualification (as in the timeline the BEA don't give the difference of altitude during the time gap)
So I can at least understand a little more why the PF give a up command (stick back) as a vario of 5200 ft/min down is not a negligible vertical speed ...

http://i.imgur.com/uYwUs.jpg

DozyWannabe
3rd Aug 2011, 02:17
@jcjeant

Sorry, but not so - look at the altitude trace. From 2:10:07 to 2:10:18 the aircraft is climbing. It reaches the apogee of the climb at about 2:11:15 and then begins to fall.

xcitation
3rd Aug 2011, 02:20
DozyWannabe

ColganAir: I do recall that incident. They said that he had been recently trained to stick up because under certain circumanstances. So he had both the reflex and some training indicating it was the right thing. Like you say it was lower so they had no second chance after the initial nose up stall response. Clearly the problem with a stall is that you must do the opposite of normal flight i.e. a/c drops so I nose up to get back up whereas a stall - i have stalled, nose down to get my wings flying and generate lift.

It makes me think that stall recovery is ripe for automation, so long as above a certain height, AoA sensors valid, etc. We want the pilot to do something counter intuitive, quickly. Stall recovery is not practiced often enough to become familiar let alone a reflex except for special pilot categories.

Thanks for the graphic and scaling. Has anyone figured out why the speeds spike up and down between 400kts and 50kts. Looks really odd. If the PFD showed radical jumping then it confused them even more.

jcjeant
3rd Aug 2011, 02:21
Hi,

@jcjeant

Sorry, but not so - look at the altitude trace. From 2:10:07 to 2:10:18 the aircraft is climbing. It reaches the apogee of the climb at about 2:11:15 and then begins to fall. Look better at the altitude line (blue first up table) .. it's a step down ... sorry but it's very evident .. with my spectacles or not :8

http://i.imgur.com/aOtC5.jpg

DozyWannabe
3rd Aug 2011, 02:32
It's an initial step down, for sure (at 2:10:07 or thereabouts), possibly due to turbulence - but from that point onwards the aircraft is climbing, and at 2:10:18 the climb is well established.

@bearfoil - I reckon that's the autotrim trying to ride the weather.

bearfoil
3rd Aug 2011, 02:36
jcjeant....... (vertical Speed)

And it can be understood at a gut level to be consistent with an overspeed dive. (As well as STALL). More so than a STALL, actually. Nose first, she slips quickly down. Butt first, less logical for the reads they saw.

I have never been in a Stall long enough for it to get loud. Were they all thinking "Dive", at one point?


A-6 guy. See up here. I think no bumps on the ss? That would accede way too much control to the Pilots. The control is like the one on the 402, a big bakelite frisbee that gives elbow cramps on short final. A WHEEL!

Intruder
3rd Aug 2011, 02:37
Does the Airbus have a stab trim button on the sidestick? If it does, there is absolutely NO sane reason why, in almost 3 minutes, at least one of the pilots would not take control and push both the stick and the trim button forward to try to break the stall. There is also NO sane reason to explain why those pilots would expect the plane to NOT be stalled with the excess pitch attitude they had.

Regardless of any control laws or design flaws, there was PLENTY of time to get the airplane out of the stall, and they failed to even make a reasonable attempt to do that. THAT is sad!

jcjeant
3rd Aug 2011, 02:44
Hi,

It's an initial step down, for sure (at 2:10:07 or thereabouts), possibly due to turbulence - but from that point onwards the aircraft is climbing, and at 2:10:18 the climb is well established.

@bearfoil - I reckon that's the autotrim trying to ride the weather. Well it's a nice turbulence .. 5000 and more ft/min at vario and the plane stay at a down altitude for 7-10 seconds and in the same time the PF made nose up stick command
So .. and despite stick up commands (nose up) .. the aircraft still not climbing all this gap of time ..
Speak of little turbulence .. lol .. it's a downdraft for sure .. and a good ..
And I repeat .. the BEA transcript is misleading .. until you put the graphic in correlation ...

http://i.imgur.com/YECUr.jpg

takata
3rd Aug 2011, 02:46
Look better at the altitude line (blue first up table) .. it's a step down ... sorry but it's very evident .. with my spectacles or not
The contrary (increase or no change of altitude) would be much more curious as there is a (false) loss of about 300 ft (recorded) at the start of each UAS event. (due to loss of mach correction for static pressure). -> See BEA reports #1 & 2 for explanations, including projected table of loss of airspeed effects on the other flight parameters.

Second, the change of pitch (reduction) that was recorded after 0209:58 is due to the crew reduction to Mach 0.80, followed by a change of N1 of -16% in 8 seconds. Pitch decreased from +1.8° to 0° in three seconds (0210:00-0210:03).

2 h 09 min 58
La gestion de la vitesse passe de
managée à sélectée. Le Mach
sélecté est 0,8.

2 h 10
L’assiette longitudinale diminue de
1,8° vers 0° en 3 secondes.
En 8 secondes, les N1 commandés
et les N1 passent de 100 % à
84 %.

bearfoil
3rd Aug 2011, 02:47
Funny, that "staccato" buzz on the trace. Weather is that short term, and Consistent?

Another opinion, before I go all VS?

DozyWannabe
3rd Aug 2011, 02:54
http://i1088.photobucket.com/albums/i331/turricaned/fdr-vs-munge.png

That's the Vertical speed trace. The slight drop at 2:10:07 is nowhere *near* -5000ft/min.

jcjeant
3rd Aug 2011, 03:00
Hi,

That's the Vertical speed trace. The slight drop at 2:10:07 is nowhere *near* -5000ft/min.

Indeed this is best understand with this graphic !

bearfoil
3rd Aug 2011, 03:05
Is Vs calculated on anomalous readings? Or raw data?

The drop looks like less than 700fpm. The vertical speed trace is beyond my meager comprehension, are those fluctuations due UAS, or are those, they're not actual, are they?

That THS graphic is (they all are) full of bit rash, but the zipper trace is not bit rash, what is that dang deal, dozy?

Turbine D? Stop me. What is that? Because if it is real, the THS was oscillating 1+ degrees once per second. Right up til it quit. It looks at least noisy, if not mechanical.

A one second wave generated by the one second sampling/trigger that repeated? How long? The aft cabin must have shook like a wet dog.

DozyWannabe
3rd Aug 2011, 03:15
@bearfoil - The graphic is too far zoomed-out and too low-resolution to draw any conclusions from anything other than large and significant trends. I don't think you're seeing quick fluctuations in THS angle so much as you are seeing the graphics renderer trying to cope with displaying the data at that granularity.

I'd say the extreme AoA was probably fouling the static data from 02:11:47 onwards.

bearfoil
3rd Aug 2011, 03:30
I think that is reasonable, and thanks for your patience. What makes it suspicious to me is its connection with a mechanism that exhibits that precise artifact in rare though actual circumstances. We'll see.

Statics? Quite agree. especially with the ROLL coupling the AoA. For that matter, the airframe was in very untrod territory, all bets off.

Just to be clear, I am noting the zipper trace at prior to ap loss. I do not take that to be AoA fluctuations, there isn't time enough between 'cycles'.

takata
3rd Aug 2011, 03:41
In the timeline transcript the BEA write:
Between 2H10min07 and 2H10min18 the vertical speed increase to 5200 ft/min
That's indeed true .. and when you put it in correlation with the graphic you see immediately it's a vertical speed to down (loss of altitude)
Vertical speed used by BEA in transcript is misleading less the down qualification (as in the timeline the BEA don't give the difference of altitude during the time gap)
So I can at least understand a little more why the PF give a up command (stick back) as a vario of 5200 ft/min down is not a negligible vertical speed ...

No, no, no... V/S increased to +5,200 ft/min between 0210:07 and 0210:18 !!!

But sure, right before this point, two seconds before precisely, it decreased, say at -18,000 ft/min in one second... (or you can even make a 10 times much bigger number if you use 1/10th of second), because it was the false loss of about 300 ft due to UAS at 0210:05.

. ADR 1 (altitude, ft)
0210:00 -> 35,044
0210:05 -> 35,024 (UAS after this point, barely no mach correction of static pressure)
0210:09 -> 34,664 (ISIS: 34,900)
0210:11 -> 34,636 (lowest altitude recorded)
0210:17 -> 34,976
0210:25 -> 35,856

Explanations, BEA report #2 p.48: (they should have anticipated that far the cover up of those tracks "issues")

http://takata1940.free.fr/static.jpg

jcjeant
3rd Aug 2011, 04:08
Hi,

Explanations, BEA report #2 p.48: (they should have anticipated that far the cover up of those tracks "issues")

I wonder if the PF had knowledge of this phenomena ..

hulotte
3rd Aug 2011, 04:46
When a french pilot said GAUCHISSEMENT he speak 's about ROLL

That common sense

takata
3rd Aug 2011, 04:47
I wonder if the PF had knowledge of this phenomena ..
Well... I have said, some time ago, that this sudden drop could be a factor for a reflex imput; adding the possibility of seeing the MMO bar going down to current speed (if it wasn't removed immediately). When one switch to Alternate law, MMO is reduced from Mach .86 down to Mach .82 while they were flying at Mach .81. If PF is at first catching only those indications, with speed dwindling = unreadable... who knows?