thermostat said:
One can always hope!

Thermostat, Having been a more than competent pilot, If you won't agree that there wasn't enough airspeed for the elevators to work, once AF447 was stalled, would you agree that the 3 pilots involved were incompetent?

Simplicity
 

I've read most of the AF447 threads and I am quite surprised by one thing:

Regardless of complexity of the situation with crew been hit by many confusing alerts, flying in the darkness without visual reference, did they doubt about indicators of altitude and vertical speed? (I don't think so, CVR revealed it).

What else than lack of lift => lack of speed can cause falling that bird so fast from the sky? Did they believe that they are in a dive/overspeed situation?

It seems to me that flying modern a/c (plus training) went too far away from simplicity. There are some senior data applicable to airmanship and if they are forgotten then gross piloting errors are the result.

It seems to me that the very basic principles may be neglected in training and too much attention is given to various particular issues which are rendered unimportant once basic skills are out.

"What else than lack of lift => lack of speed can cause falling that bird so fast from the sky? Did they believe that they are in a dive/overspeed situation? "

well, like by many times written above- basicly nothing other than a stall, with high nose up and this sink rate you can exclude a dive. basicly a PPL owner would answer this question.

one thing ist that it was night, possibly IMC and there was turbulence. they probably had not any visual reference to the natural horizon outside and maybe they did not believed the pitch indication on their instruments.

i think the big question we had at the day of the crash WHAT happened is fully answered, it may be of interest to read the thread no1 what kind of speculation there was made. the question WHY it happened will never be answered because the people who know why they pulled until impact will not tell you.

On another tack, given the criticism leveled about the captain taking a break at that juncture, was it because he was especially tired and could that, exacerbated by the consequent very short sleep, have left him a bit dazed/sleepy headed ? Is the inquiry looking into the previous 12 hour activities ?

- in fact probably around 15 minutes between leaving the cockpit and being summoned back.

Coagie,
I agree with you 100%. Since the day of the crash there has been endless speculation on why the A330 failed. From theories on the VS snapping off to uncontrolled dives to engine failure, computer malfunction/interface etc...
But as we know now the pilots were helpless in trying to figure out the situation they helped create. The blame is with Air France and there procedures...
This was the "perfect storm" scenario, the result of a chain of misguided decisions starting with flying through bad weather, the captain leaving the flight deck at a critical stage of the flight and leaving the least experienced pilot in control, the failed Pitot tubes (weather related) and then of course the pull back on the SS. It all wreaks of poor training and procedures...

I guess the selective CVR out-takes should advise caution but there seems an odd lack of energy and activity about the whole thing. Hardly a time for quiet contemplation and one would expect the Cptn to become suspicious (rightly or wrongly) of the PF actions when things didn't go as expected and then forcibly intervene. No evidence of heads down activity as computers are re-configued or re-booted, not even a distracting light-bulb failure, so what were they doing - sitting largely in silence ? Were these men exhausted ?

Stability and Control at high AoA and post stall
 

Bit off-topic but related to discussion on stability and control of transport aircraft - have recently seen presentations and videos related to recent research between NASA and University of Illinois.

A pretty impressive remote control model:-

NASA AirSTAR Testbed - YouTube
Nasa - AirSTAR (HD) - YouTube

and safe way of testing approach to stall and recovery

NASA AirSTAR full stall with subscale large transport - YouTube

NASA AirSTAR testing L1 adaptive control for post-stall control - YouTube


In none of the tests I have seen was there a stable post stall, but maybe due to scale it was just beyond the ability of the auto controls/remote pilot?

I think the stability of a swept wing fully stalled airliner has amazed many. Most of us would have expected a departure, I'm sure.

I should imagine some of you will be surprised to read these excerpts from an RAeS Upset and Loss of Control document.

Mr. Optimistic.

"An odd lack of energy..." You have concluded what BEA have assumed all would conclude. These are not ill informed boffins who do not know how to create a foundation in the public for conclusions that support a pov. The MEMO was at the behest of Airbus. Foundation for a PR from the company that exonerated the a/c of any "new" fails.

Feigned inexperience at Press functions is de rigeur here. Selected and parsed data is a calculus, my friend. Are you not curious as to why BEA will not release more information? Lack of funds? Fear of creating the wrong impression? "It's too soon...." Why, exactly, would that be?

Why does the Judge demure at further release of FDR? Surely, more data is in the public interest? It is, and that is why it is not released. The Public Interest is not the driving vector, here. Nor is safety, at least the kind that costs money and shows Principals as criminal in their lack of mitigation of current problems.

Spread your wings, my friend, and partake of public buzz elsewhere. It is a battle, ther one trying to access, the other trying to prevent.

In which condition is the lack of disclosure predominant?

Financial, or Criminal? Erm, Both.

Lord Spandex Masher.

And hence, unrecoverable. I follow. I have been gifted with some Airbus data re: THS. Who's up for a discussion? It seems there are other conditions that defeat autotrim beside Overspeed. Some other conditions that subsequently reinvigorate it are included.

BOAC

Define STALL. Then define FULLY. Thanks.

Departure
 

Sorry to object here.

Imho with the term "departure" we adress the point, where the aircraft leaves the region of controlled flight (i.e. departs the flight regime).

There is no doubt, that the aircraft was outside this controlled flight region, was uncontrolled and therefore had departed. It stalled and departed with a high sinkrate and some minor roll oscilations.

Unaccelarated stall and departure like we had here (1g-stall) is less liable to violent maneuvers / g-loads / rolls/ oscilations and therefore hard to discover from the aircraft behaviour alone (without reference to the instruments or to the outside). First sign might be a gentle nose drop in a conventional aircraft, but not in AF447 case, as the FCPC´s where acting to maintain the demanded load factor. This stall has besides the AOA problem (AOA too high) also a speed problem (speed too low for 1g flight). To recover it is necessary to reduce the AOA and increase speed up to flying speed again.

Accelerated stalls (normal asociated with turning) are more sudden and more violent. The flow separation over the wings is not equally distributed and therefore yaw, roll and pitch changes in any random combination are induced. There is a primary AOA problem (g-induced too high AOA) but lesser or no speed problem (speed too low for acelerated flight, but not for 1g flight) and relaxing of g-load does the trick to solve the problem.

The entry into the stall of AF 447 was very smooth, as the speed decay below the stall speed occured in the timeframe, where the PF tried to correct his pitchup by some ND input (g load around 1 g). But the mass of the airframe in combination with the pitch upward vector smoothed the airframe close to the stall (second stall warning). It was initially no AOA problem, but a speed problem (running out of speed in the climb with not enough power applied). At that point speeds where already unreliable. The aplication of TOGA at that critical phase delayed the departure and held the AC in the pitch and in a little bit of climb (for further 500 feet) while further shedding vital speed. But finally the AC just departed by picking up a high descent rate and some roll oscilations.

The slowing during the climb might also have caused some SI (if you slow, you feel tilt forward) and induced doubts about the validity of the pitch information, as airspeed was unreliable already. That would also explain the missing ND inputs (as he felt already ND pitch) and the thinking of the PF at some point later, that they where fast and thus descending fast (not believing the pitch information), not falling / stalling downward fast.

All three pilots saw their problems obviously in the roll oscilations not in speed and AOA. Otherwise primary concern should have been the reduction of AOA and rolling wings level later on, when AOA reached an non stalled value.

Later on when it came to their mind that they are not in some high speed descent, that commanding climb with the SS did not work, they couldn´t get their mindset squared to "being stalled" and the apropriate recovery procedure.

Alternate Law 2 - Reduced Yaw Stability
 

After reading and re-reading a number of A330 documents and checking the FDR traces (p.112), I have tentatively deduced that the aircraft's tendency to a RH roll was directly related to the rudder Yaw Damper inputs.

It seems to me that the Yaw Damper applied left rudder as a LH roll was being recovered and contributed to the next RH roll.

The PF started applying RH rudder at 02:13:03 and over the next 45 seconds kept a RH bias on the rudder which helped to reduce the roll amplitude and the RH roll bias. In the last 40 seconds he left the pedals alone and the RH roll bias returned. It also appears that PF pedal inputs (up to the maximum allowed by the RTLU) were algebraically added to the Yaw Damper inputs.

Airbus documentation indicates that the Yaw Damper is probably compromised in ALT-2 outside the Normal Flight Envelope, and it seems that most of the fight with the rolling could have been prevented if the Yaw Damper was OFF. With low IAS, the lateral stability was undoubtedly compromised.

@CONF iture; I've not been able to find any documentation that indicates that the Outer Ailerons are unavailable in ALT-2, but it certainly appears to be the case.

Thanks mm43 for your research, I was expecting some inputs from Svarin A33Zab PJ2 takata ... but none of them seem to be around lately.

There is still so much to analyze on the little FDR data we've been given ...
Is it possible, the captain, after suggestion from the PNF, did switch OFF both PRIM and SEC 1 ?
Was it done in an attempt to force Direct Law or something ?

The other, you did post something of interest from the Instructor Manual ... By any chance, would you have a link for that manual ?

CONF iture;

Thanks for your comments.

The following link to the A330 Instructor Support Manual will provide some more insight into the design/operational criteria additional to the FCOM.

The on page Search facility in the document works well.

I have been reading something on AOPA online that may relate to what the PF on AF447 experienced.
AOPA Online: Technique: The 'Panic Pull'
I would expect any pilot who has never flown a slow roll might easily succumb to this reflex. (Not referring to barrel rolls here.)

It might not take a very extreme roll on a black and turbulent night to trigger the pull reflex in an already surprised and anxious pilot.

I don't expect everyone to embrace this concept immediately. Just an idea to kick around.:)

Mbird - what is more deep-rooted and more difficult to eradicate is the natural instinct to pull back hard when you see the ground/altitude zero rapidly approaching. Sometimes it works and sometimes.....................

AF447 never got to really 'extreme' bank angles and the 'pull' was rooted in a different mental process.

Rather generic, but . . .
 

via 'Layer 8', a few days ago:

"(United States) Air Force wants studies impact of human reliance on autonomous systems

at http://www.networkworld.com/community/blog/air-force-wants-understand-impact-automated-s"

I wonder how long the planning for the study has been in place?

Please resume normal conjecturing.

Hi all! I don't understand why everyone seems to ignore that even the conversation between two pilots ever since the start of the event didn't resemble a conversation between pofessional pilots? No call outs, no attempt to analyse the situation professionally, no checklists mentioned, no procedures. How badly were they trained exactly and how average were they? I find it frustrating that so many people seem to be reluctant to accept that what was found so far was more than enough to bring down the plane. Two FOs that couldn't fly complemented by a capitain that couldn't command put in one cockpit and as a result an event of frozen pitot probes that is not terminal by nature developed into a catastrophe. 228 dead. What is so surprising that other factors are needed? That modern planes still require pilots to know how to fly? After all, that's what happened. Pitot froze, obscure UAS procedures - this is on the surface, but if you scratch it, it's the case of A/P disconnect and the pilot's inability to fly the plane - as shocking as it sounds. Add unfamiliarity with plane's features. Multiply by two, add the capitain who failed to take responsibility, command and control when called to interfere (it's academic that it might have been too late by then). 228 dead. And insistance on an aviation forum that modifications to the plane are due to prevent this. I am a lay person, but I understand that a pilot without flying skills and solid knowledge base is a dead man walking, 100% at the mercy of the plane (automation) and his colleagues and a liability in some situations. And this is what happened. No addditional causes are needed.

Why there is insistance that the "plane did something" or that it caused the crew to do what they did? How can anyone take seriously AF's bull**** about "complexity of man-machine interface" after the converstaion in this cockpit was revealed and the latest report published? There is no and shouldn't be any interface in any sophisticated technology equipment that allows unproficiency. What's next then? Kids-friendly nuclear power stations? Interface didn't play any role in the event and for this crew any different interface could be just another thing not to know. To believe otherwise one would have to ignore all that was said and also what wasn't said in this cockpit. We have pilots that demonstrated that they knew and understood their plane - the one they were working on - badly. There is no reason to conclude logically that if plane was designed differently they would have known and understood it any better. They ignores stall alarm for almost a minute without saying a single word about it and then it was stopped by design, it's a pure conjecture to say that if design was different they wouldn't ignore it.


I disagree with recurring theme "something must have been wrong with the plane even if the investigation doesn't say it". In the light of what is published so far I don't understand where this conviction comes from. I saw failures on many levels but they are not technology-related. Does anyone blame technology when using it without reading the manual and breaking it? If you have a piece of equipment but only ever know one button there will be problems. And IMHO any debate about technology in the context of this crash will mean that these failures won't be properly addressed. It is clear that advances in technology no matter how big don't mean that professionals skills can be allowed to deteriorate especially when they are meant to complement and in times to compensate for this technology. Not a rocket science to understand. However I will agree that debate is due on why this is still allowed to happen. And please lets not try to make plane manufacturers responsible for pilots skills. Maybe instead airlines should be made to EARN their share of profits and prevented from attempting to take a free-ride on the back of manufacturers by manning new planes with untrained crews? Free-riding is unfair competition, and because as the result of poor training events like frozen pitot are turned into fatal, this is also a murder.

BOAC,
Been there, avoided the temptation to pull right back. Still here to pester you.:}

It may not just be ground proximity that triggers the pull reflex. Think about some of the accidents you know where the guy flying pulled the wings off.

Were they all at low level? Doesn't "when bank angles exceed their comfort levels" factor in?

Hi,

Methink .. the best training (for pilots) for self control will be a training for deep scuba diving
There .. 1 second of panic = immediate dead

WRG message
 

Thanks a lot for the document mm43.

In paralele to the outer ailerons inaction, another point of interest :
This is in page 126 and relates to Alternate Law.
If I get it right, the THS should NOT have moved ... but it did !?
What was happening in that aircraft ?
This reminds me the WRG fault message ... only Svarin was interested to discuss.

I was interested as well, but the discussion petered out through lack of useable data.

You get it wrong. In ALT2 with loss of 2 or more ADRs low speed stability is lost.

You should have continued readin thru page 127.

@Hamburt Spinkleman:

Correct - the important paragraph is on the following page:

There's a reason that Alternate 2 is marked with a very clear "(NO PROT)" on the ECAM.

Hamburt,

My point of interest here is NOT the low speed stability or the roll control ... but the autotrim.
I think the autotrim activated as it did not have to.

Now, if it's normal by conception to autotrim under stall warning, it is aberration.

CONF iture; ChristiaanJ;

I raised the THS auto trim matter by PM with another poster a couple of days ago, and for the benefit of all, the excerpt from the A330 Instructor Support Manual follows:-
http://oi54.tinypic.com/k96jyd.jpg
The ALTN 2 provision clearly indicates that the longitudinal static stability cannot be "automatically" restored.

This is a serious question, I promise I'm not being facetious here... Why do you consider it an aberration?

Would you not use manual trim in a conventional aircraft if elevator authority was not enough to help you escape the stall, or indeed if the elevators jammed? Autotrim is simply a way of providing trim function through the sidestick, and in the Alternate Laws the pilot has full trim authority through the sidestick. Alternate 2 removes some or all of the soft protections (soft meaning that sidestick input can override them, so in this case there would have been negligible difference had Alternate 1 latched, because the PF did not let go of the stick throughout the sequence).

The very reason for the existence of Alternate 2 is because with certain sets of failures, the FCU is programmed to recognise that it cannot manage the flight, and so full authority is given to the pilot. This is entirely in keeping with the Airbus engineering philosophy, which acknowledges that the last line of defence is the pilot, but could potentially cause problems in an operational sense if the airline concerned has used the existence of the FCU protections in approximately 99.9 (rec) of flight time to under-train pilots in manual handling.

In terms of systems architecture, Stall Warning is part of the notification subsystem and is not connected to the FCU protections in any way. The purpose of the notification subsystem is to tell the pilot, who in Alternate Law has full authority, if the aircraft is in a non-normal/dangerous state. The design relies on the pilot to heed that warning and take appropriate corrective action, as is the case in any other airliner. The notification and protection systems are complementary rather than co-operative or consequential - if the protection systems are functioning then the severe notification logic (e.g. overspeed warning, stall warning) should sound either briefly while the protections compensate, or not at all.

One of the fundamental misunderstood perceptions of the Airbus (and I suspect Boeing) FBW systems is that they are seen as a monolithic system in which everything is tied together - they are not. FMS/AP is distinct from FCU is distinct from reporting systems - they interoperate, but they do not form a cohesive whole from an engineering standpoint - nor should they lest they risk creating single points of failure. The protections are part of the FCU architecture, and the reporting systems are part of the avionics.

The design of the FCU states that absent specific parameters (in this case ADR data), then the pilot should have full authority - the safe limits will be notified via the reporting subsystem to which the pilot is expected to respond in a timely and correct manner, just as has always been the case before the days of FBW and the FCU system.

I don't see anything inherently wrong in retaining autotrim in Alternate Law, but the ramifications of retaining it must be trained for and understood.

Doze,

THS: It was not retained, it resumed, having stopped at ALT LAW2 Latch.

You gonna leave your post as is?

mm43

we had this discussion in thread 3 ages ago. I think it was TAKATA who explained it there.

The stopping of the THS trim is a function of the static longitudonal stability protection and is only available in Alt1, not available in ALT2.

In certain failures like 2 ADR which was the case with AF447, the longitudonal static stability cannot be restored, which means imho that THS trim remains available.

I would be cautious with the reference anyway, the instructor support manual is from 2001 and has been replaced by the FCTM some years ago. In the FCTM the wording is similar, but the part with the trim is missing. That is for the A320 as well as the A330 /340 family.

Also the Technical Training manual states, that in ALT2 only Load factor protection would be available.

RetiredF4;

I actually agree with you!

The ALT2 proviso "kills" further discussion on it.

This is what BEA #3 (p.41) says about it:

worried SLF: Because it's unbelievible that none of the three pilots knew what they were doing. Admitting that these three were incompetent is difficult, because their incompetence tarnishes a historically heroic profession. Air France would have been better served by actors. At least the CVR would have sounded like professional pilots. Now Air France has no place to hide. Maybe some of the other carriers will learn, and if they don't hire competent pilots, they might, at least, try to train them to be competent pilots.

@Lyman - just this once I'll respond. You show me where it stops and resumes, and then I'll contemplate taking you seriously, otherwise I assure you that trying to engage me further will remain an exercise in futility.

@Dozy;

Think you'll find that Lyman will leave it alone.

Have been back and highlighted the ALT-2 proviso in the graphic a few posts back. As HN39 has carefully pointed out, the BEA have had Airbus prove the aircraft behaved as expected.

Is Interim Report#3 still available at the link in the first post ? Tried to download it but no luck. Looking for extracts of the conversation to see the extent of cross communication of SS actions. May be one thing to not see what was happening, surely not deaf as well.

@Mr. Optimistic:

Both links (FR and EN) working fine for me. PM me if you have further issues and I'll send you my local copies.