Air France 447 - On topic only!

[Evan]

Originally Posted by VANGHELL

It seems to me that you have taken the interim report for granted, and are convinced it is the truth about what happened, that is stated in it.

Interim report(s). There are two of them. What is stated within them are truths about what happened. These truths alone do not explain the resulting crash, thus the mystery remains unsolved. Your post reveals that you have a very poor understanding of the revelations of the reports, a very poor understanding of the technologies and science involved, a very poor level of historical knowledge regarding similar unreliable airspeed events, and a very poor level of research relative to the members of this thread with whom you are disagreeing.

This is not to say that you don't have a right to post here. It is saying that you have an obligation to read this thread and (more importantly) the previous one before taking up the discussion. Once you have done this, you will see the event in a clearer light and understand the value and quality of the findings of the interim reports.

Particularly on this thread, opinion without a certain in-depth technical understanding is a useless nuisance to the rest of us.

[Fear_of_Flying]

Originally Posted by Evan

Particularly on this thread, opinion without a certain in-depth technical understanding is a useless nuisance to the rest of us.

The arrogance reaches new heights. On whose behalf are you speaking, exactly, and what level of technical understanding do you, Evan, deem sufficient for someone to rise above the level of mere nuisance with their petty ideas?

[Gabriel]

Originally Posted by TeeVee

Gabriel, to the best of my recollection, you and I have never argued. please re-read my post that set evan off and tell me where i said there were equal chances. here is the post(with emphasis added):

"how so? the interim reports are filled with a lot of nothing. a few acars messages, the results of the examination of a paltry number of jet parts, the post-mortem on a few bodies...not to mention that it was drafted by potentially biased folks (haven't the french quite clearly showed the world how biased they are with their deplorable actions and rulings re the concorde crash??? yeah, i thought so!)

this tells the world what exactly? that the "authorities" have ZERO clue as to what really happened.

now mind you, i'm not defending vanghell's theory, but from what i recall from reading the "interim report" (which will most likely be the final report) i'm not sure that you can say the "evidence" contradicts his theory."

TeeVee,
I've already replied to you in my post #214.

You are right, the interim report doesn't absolutely contradicts the possibility of a light ball as much as it doesn't absolutely confirms that an unreliable speed event was a necessary link in the chain of events that led to the accident.

In the interim report, there is no evidence at all that gives the slightest hint about a ball lighting (which is not the same than absolutely contradicting), and there is strong evidence that leads to an unreliable-speed-related event (which is not the same than absolutely confirming).

[Deadstick]

Originally Posted by Evan

Particularly on this thread, opinion without a certain in-depth technical understanding is a useless nuisance to the rest of us.

Um, scuse me Evan, but as I recall you don't hold any type of airman certificate.

[Gabriel]

Originally Posted by Fear_of_Flying

While I agree that we have a "most likely candidate" for the AF crash,

I don't agree. IMHO opinion, what we have is:

- A strongly likely candidate (beyond any reasonable doubt, if you wish) that one necessary link was an unreliable speed event.

- A very likely candidate that ice was the cause of the above.

- A lot of suspicious candidates of why the plane was lost after that, since the unreliable speed alone shouldn't bring a plane down. One or more of these candidates may be guilty, and there may be other guilty links that are not even candidates yet.

- Ball lighting doesn't fin in any of these categories.

We were told repeatedly by authorities during the early investigation that there was indeed a missing piece still to this accident, but conveniently that piece seems to have fallen into the distant background over time, to have become incidental, as we become more inured to the notion that of course it would have been extremely difficult - nearly impossible in fact - to save the aircraft once the speed data was lost in those conditions.

What on Earth leads you to that? I think that even Evan has shown to be very aware that the unreliable speed is just a necessary, but not sufficient, link.

Yet is it not reasonable to speculate that subsequent to the initial crisis, a secondary event occurred that ultimately led to the aircraft's demise? Perhaps it would turn out that the plane could have and should have been saved, except that some other terrible mistake was made.

Reasonable to speculate? Perhaps it would turn out?
What are you talking about?

That's one of the most certain things here. Other A-360 have suffered an unreliable speed event and were not lost. That proves beyond any reasonable doubt that something else, in addition to the unreliable speed alone, was necessary to bring the plane down. Whether we will ever learn what it was is another story. And chances are that we will not. If the information from the black boxes is not retrieved, the best we'll ever have will be several speculative scenarios of how things could have been to end as they did.

But, when one doest know something, it's not only Ok but necessary to say simply "I don't know". "I can't explain it hence it's an alien starship (or a ball lighting for the matter)" is not acceptable.

[Gabriel]

Originally Posted by Fear_of_Flying

Yes, but in life, "probable cause" is usually the best we can hope for

Exactly. That's why saying "the report doesn't abslotuely confirm (or excludes) something" simply makes no sense.

[Evan]

Originally Posted by Fear_of_Flying

The arrogance reaches new heights. On whose behalf are you speaking, exactly, and what level of technical understanding do you, Evan, deem sufficient for someone to rise above the level of mere nuisance with their petty ideas?

"a certain level of technical understanding"

Not an airmanship certificate. Not a technical degree.

Where does one get this understanding?

By carefully reading the reports and both threads in their entirety.

Beyond that, by taking initiative to find and research other technical publications and reports related to the incident.

Is that arrogance, or just a reasonable request for anyone interested in contributing anything valuable to this forum?

[Evan]

Originally Posted by Fear_of_Flying

But "probable cause" fulfils the same need that certainty did in eons past. People want that explanation, and if all we have are a series of error messages, a food cart, several bodies and a tail fin to provide us with a probable scenario, we will ultimately be satisfied that we can do no better in reaching an understanding, and we will accept the conclusion that the iced pitot tubes, in those circumstances, led inevitably to disaster.

One of the most immediate things a crash investigation must focus on after an accident like this is isolating contributing factors which might cause a recurrence before the final report can be completed. ACARS told us right away that pitot failure was highly likely, and this, combined with a known pitot issue, prompted the fleetwide replacement of pitot tubes with more robust probes of a different manufacturer. Another thing which became immediately clear was the presence of intense CB activity. Questions were raised about the possibility of supercooled water in these systems, and precautions were raised.

THESE TWO ACTIONS will probably prevent a reoccurrence, even while we don't yet know why these factors resulted in a crash. That is the value of what is currently known.

While we need to understand how, and in what sequence, these factors can lead to a catastrophic loss of control, we have reduced or removed two of the initiating factors in the sequence. So on the one hand we have learned a great deal, and on the other we have an enduring mystery that needs to be solved.

[Gabriel]

Originally Posted by VANGHELL

Although important to aviation, a discussion about the human character, and about human bias when purely discussing possibilities, and making a brain storm about what could have happened, is a little bit too far, for the subject at hand. Need I remind you Gabriel: “discussion is being taken mainly on-topic, with respect, constructively, with technically sound discussion, where everybody is learning”!!!!!!!

Mind you, I consider myself one of the most respectful, constructive, and technically sound members of this forum.

This was your first post on this thread, and you are way off the topic.

Mind you. I STARTED this thread!!!
And this threads follows another closed thread on the same subject where I posted dozens of "constructive, respectful and technically sound" posts.

As far as I know this is a public forum, and everybody has the right to post his/her own opinion!

Everybody, including you, is welcomed, and your opinion is accepted and respected, which doesn't mean agreed upon.

Of course that "everybody" includes me too. If I don't agree with you, I feel entitled to tell you that and, because I'm constructive, to tell you why too.

Further more: even though you have started this thread (a very laudable initiative, given the fact that the previous thread had somehow disappeared, or whatever…), you are not entitled to ownership of this discussion

We agree on that.

and opinions which don’t fall in your understanding of what might have happened to AF447, aren’t necessarily wrong.

Give me one evidence that a ball lighting might have been involved and will start talking.

It seems to me that you have taken the interim report for granted, and are convinced it is the truth about what happened, that is stated in it.

No, but the interim report is about all we have. Leave at a side, and we don't have much beyond that a plane went down.

The use of such clichés as: “conductive thunderstorm”, “severe icing conditions”, “area of extreme turbulence”, “EICAS messages confirming a speed disagree problem”, and so forth are nothing but biased attitude on your part! It fits snuggly into what you consider as being the cause/causes of this accident,

It's not me. It's the official professional investigation team. And they and I don't know what are the cause/causes of this accident, beyond that an unreliable speed event was one necessary but no sufficient link.

Let us consider what is already known as hard facts:

Now we are talking.

ACARS messages transmitted to AF HQ about speed inconsistency! This only tells you about the effect of whatever happened; leaving everybody to speculate about what is the cause of such a conflict.

The ACARS messages were not only about speed inconsistency. There were many others (I don't recall exactly, but more or less AP off, AT off, error messages in the pilot's PDF, reversion to alternate law, freezing of the rudder limiter, and others) that are what one expects AFTER an unreliable speed event. That doesn't says a thing about the cause of the unreliable speed event, but it's as much proven as it will ever be that there was an unreliable speed event with it's cascade of related failures at the beginning of the sequence.

• The weather at the time was fierce, and could have harbored icing conditions! But this doesn’t mean that a thunderstorm or “severe convective thunderstorm system typical of ITCZ conditions in that time of year” (to be more precise), couldn’t also harbor the following conditions: severe updrafts and downdrafts, hail, intense electrical activity (in the form of lightning), super cooled water, intense turbulence, zero visibility, and the list can go on… of which every single one can be a “killer”.
• “The aircraft hit the water at a significant rate of vertical speed, relatively flat”.
• Few parts of the wreckage, and human remains were found, which includes the captain, as I recall! This could mean a lot of things, but most probably that he was not in the cockpit at the time.
• AF knew about several speed inconsistency incidents, which is shown in an Internal AF memo NT 34-029 issued 20 August 2008, page 4/5, but the “OPERATIONAL IMPACT:” was deemed “NIL”

Well, it looks you are taking the french reports as "hard facts" after all.

Other than that, very few elements are known, and can only be guessed at. This leaves us with a myriad of possibilities, of which I could (or anybody else for that matter) deduce that AF447 collided with a UFO, in the middle of a thunderstorm from which it was taking power because of the intense electrical activity going on at the time… or maybe not! Maybe it was a missile from a Brazilian battle ship, mistaking AF447 for a jet fighter!

And how is any of that compatible with an unreliable speed event with no sudden loss of pressure, electrical power, hydraulics or other system failures, and with the plane hitting the water essentially intact? (oh, you forgot to include that part of hard fact, or are you choosing what parts of the report are reliable for you and which aren't?)

I’m not picking a fight… but this is already too much! Let’s just talk about possibilities, not about what the human condition is, about the human character, or about bias, or whatnot!

I’m sure those directly involved in the flight’s history, be it those who lost their lives, or the families involved, or the industry as a whole, would appreciate a technically sound discussion, from which those involved can draw conclusions, or come up with solutions, so everybody can benefit from them, and to make sure nothing like this ever happens again. I’m sure that’s what we all want!
>>
Thank you all very much! >>

Fair enough. Let's start with this:

YOU've said that a ball lighting was the most likely cause.
Now YOU support that. I'll be here for the constructive discussion.

[Fear_of_Flying]

Originally Posted by Gabriel

What on Earth leads you to that? I think that even Evan has shown to be very aware that the unreliable speed is just a necessary, but not sufficient, link.

Reasonable to speculate? Perhaps it would turn out?
What are you talking about?

That's one of the most certain things here. Other A-360 have suffered an unreliable speed event and were not lost. That proves beyond any reasonable doubt that something else, in addition to the unreliable speed alone, was necessary to bring the plane down. Whether we will ever learn what it was is another story. And chances are that we will not. If the information from the black boxes is not retrieved, the best we'll ever have will be several speculative scenarios of how things could have been to end as they did.

In post 218, Evan says the following:

While pilot error could one day be determined to be a factor, I doubt this will be reconciled to a primary cause. More paramount is the issue of previously undocumented weather phenomena and the inability for certain air data probes to reliably operate within it. Another large factor is the cascade of vital system failures following an unreliable airspeed event, and the barrage of ECAM messages that ensue. Add darkness and turbulence to this confusion, loss of autoflight, alternate law, loss of instrumentation in IMC, and you have a recipe for disaster. What happened here is most certainly a recipe for pilot error rather than pilot error itself.

It seems to me the implication of this post is that the pilots found themselves without flight data in overwhelming circumstances, so it is unlikely that the primary responsibility would fall on them: they were simply unable to accomplish what might have been an extraordinarily challenging task.

My suggestion was more along the lines that it's possible an altogether redeemable situation was completely botched - a different nuance given the same set of information - that puts the focus of the cause back on pilot error.

So to your point that it is "proven beyond a reasonable doubt" (really? I thought we just got over our lack of certainty) that something else happened beyond the loss of speed data, the question is, was it simply that the pilots were helplessly falling in a dark turbulent abyss without much legitimate chance of success given the circumstances, or did they take inappropriate actions that contributed significantly to the aircraft's fate?

[TeeVee]

and what all the techies are forgetting or ignoring, is the the "unreliable speed event" may itself have been precipitated by an outside force. i haven't noticed anyone here waiving an electrical specialist flag around. whose to say an external electrical event struck the nose of the a/c took out the probes, and began what has now been termed a cascade of system failures. seems to me, with my almost non-existent knowledge of electricity, that this is feasible.

when i was 9 or so, lightning struck our house. the immediately recognizable effect was our chimney being shattered, and two holes in the side of the house through solid brick.

later, multiple electrical items in the house failed: fridge, toaster, thermostats, blah blah blah.

im just sayin...

[Fear_of_Flying]

Originally Posted by Evan

"a certain level of technical understanding"

Not an airmanship certificate. Not a technical degree.

Where does one get this understanding?

By carefully reading the reports and both threads in their entirety.

Beyond that, by taking initiative to find and research other technical publications and reports related to the incident.

Is that arrogance, or just a reasonable request for anyone interested in contributing anything valuable to this forum?

So in other words, you have decided, I guess on behalf of all members who meet your criteria, that your level of technical understanding and your level of familiarity with the accident are precisely what are required in order to make a meaningful contribution? How'd that work out so well? And you don't find that the slightest bit egocentric? What's to prevent a pilot or engineer from telling you your opinions are a "useless nuisance" since you have no field experience or formal training in any facet of aviation? I don't plan to protract this argument, but the comment was uncalled for. If you consider some posts to be beneath you, easy solution - don't respond to them.

[Evan]

Originally Posted by Fear_of_Flying

So in other words, you have decided, I guess on behalf of all members who meet your criteria, that your level of technical understanding and your level of familiarity with the accident are precisely what are required in order to make a meaningful contribution? How'd that work out so well? And you don't find that the slightest bit egocentric? What's to prevent a pilot or engineer from telling you your opinions are a "useless nuisance" since you have no field experience or formal training in any facet of aviation? I don't plan to protract this argument, but the comment was uncalled for. If you consider some posts to be beneath you, easy solution - don't respond to them.

I don't consider asking people to read the threads and the reports they are disparaging the slightest bit egocentric, no.

And if they did this, we wouldn't have to keep retreading the same trodden ground.

[VANGHELL]

To get a discussion on this going... even though it may not sound feasible to everyone, I consider it quite possible. Since we only know the effect of what happened. And we can only speculate about what caused it.

The first part of an airplane to encounter anything while flying is the nose cone. It is made out of glass fibre, and, thus a poor conductor of electricity. If flying through an area of intense electrical activity, such as a thunderstorm, the first thing anything electrical in nature would hit, is the pitot tubes, since they stick out and point forward, much like an antenna would be on a house, and they are made of stainless steel, and heated to an incredible ammount (arguably more than 200 degrees Celsius), as I have been told in my training (never ******* touch one cus it'll burn a hole through your hand!!!!). They are heated through electrical power, and since they would be hit first, shortcircuts, if not worse can happen. Since they have sensors to read pressure, which are also dependant on electrical power, which lightning can produce a lot of, it is safe to conclude that electrical overload can also be considered a culprit.

And let's not forget the angle of attack probe also sticking out, which is also key to the good operation of flight computers.

And furthermore, I was taught, in flight school, pitots can handle ridiculous ammounts of icing and work wonderfully. We have had the pleasure to learn from some A310 and A318 pilots some of the intricacies of flying an Airbus, and I specifically asked them if they thought such an event was possible. And you know what they said? It is highly unlikely that ice would build up on the pitot, which is heated, and has a very small surface, and not build up on the wings and stabilizers, leading to a stall!

[Evan]

Originally Posted by VANGHELL

And furthermore, I was taught, in flight school, pitots can handle ridiculous ammounts of icing and work wonderfully. We have had the pleasure to learn from some A310 and A318 pilots some of the intricacies of flying an Airbus, and I specifically asked them if they thought such an event was possible. And you know what they said? It is highly unlikely that ice would build up on the pitot, which is heated, and has a very small surface, and not build up on the wings and stabilizers, leading to a stall!

Here is the history, from post #2867 of the original thread 'Air France plane missing'. To fully understand this, you must also read the AD's listed below:

There are three standards of pitot probes currently in service on the A330/A340 family. 1) Thales (formerly Sextant) P/N C16195AA; 2) Thales P/N C16195BA; 3) Goodrich (formerly Rosemount, formerly BF Goodrich) P/N 0851HL.

The Thales (Sextant) P/N C16195AA has been faulted in Service Bulletins and is being phased out.
The Goodrich (Rosemount) P/N 0851GR has been faulted in an AD and is phased out.

Going through all the AD's that I've found, Goodrich probes have been cited in AD's as well as Thales according to the following history:

11/1994 - Airbus issues OIT: LOSS OF AUTOPILOT AND NORMAL LAW UPON AIR DATA DISAGREEMENT" It states the following:

SEVERAL OPERATORS HAVE REPORTED A FEW CASES OF AUTOPILOT (A/P) LOSS AND A REVERSION TO ALTERNATE LAW (ALTN) OF THE ELECTRICAL FLIGHT CONTROLS (EFCS) WHEN FLYING IN ICY, STORMY AND TURBULENT CONDITIONS. THE FOLLOWING MAIN ECAM WARNINGS WERE REPORTED:
- AUTO FLT AP OFF
- F/CTL ADR DISAGREE
- F/CTL ATL LAW

It also states:
IT HAS BEEN HIGHLIGHTED THAT IN SOME ICING ATMOSPHERES, THE AIR DATA PARAMETERS SUCH AS TOTAL PRESSURE MAY BE TEMPORARILY BUT SIGNIFICANTLY DEGRADED, DUE TO THE CONTAMINATION OF THE PITOT PROBE BY ICE CRYSTALS OR LIQUID WATER MIXED WITH ICE CRYSTALS. THIS PHENOMENA IS COVERED BY TFU 342000011.

It provides the following operational advice:

DO NOT ALLOW THE CREW TO RESET ANY FCPC IN FLIGHT. INDEED, IN THE CASE OF MISINFORMATION ORIGINATED FROM AT LEAST TWO ADR PARAMETERS, IN PARTICULAR THE ANGLE OF ATTACK (AOA), SUCH RESET COULD INDUCE AN UNEXPECTED ACTIVATION OF A FLIGHT ENVELOPE PROTECTION.

And finally:

AN INVESTIGATION IS BEING LAUNCHED TO DEVELOP A NEW PITOT TUBE FEATURING IMPROVED ANTI-ICING AND DRAINAGE CHARACTERISTICS. TARGETED SCHEDULE FOR CERTIFICATION IS JULY 1996.

The OIT does not specify any pitot manufacturer or P/N.

11/2001 - CASA issues AD/A320/128 for all A319/20/21, requiring replacement of Thales P/N 50620-10 with Thales P/N C16195AA. Compliance by 9/18/2003.

A/C with BFGoodrich P/N 0851HL are not included in the AD.

7/2002 - Airbus issues OIT "ATA34 AIRSPEED DISCREPANCY WITH THALES PITOT PROBES". It warns of unreliable airspeed indications and contains the following information:

INVESTIGATIONS CARRIED OUT SHOW THAT BURRS CAN REMAIN IN THE PITOT PROBE AFTER DRILLING OF THE DRAIN HOLES. AS A CONSEQUENCE THE BURRS COULD ASSIST THE ACCUMULATION OF EXTERNAL POLLUTION AND CONSEQUENTLY COULD BLOCK THE DRAIN HOLES. SUCH A DRAIN HOLES BLOCKAGE CAN EXPLAIN THE WATER FOUND IN THE PITOT TUBE. THIS ISSUE CAN AFFECT ALL AIRCRAFT FITTED WITH THE THALES PITOT PROBES.

The probes in question are the THALES P/N C16195AA

11/2002 - DGAC issues AD 2002-586(B) regarding Thales P/N C16195AA with a serial number (S/N) lower than 4760. The directive cites manufacturing defects that can lead to drainage problems. The requirement is to inspect and repair within 700 flight hours.

12/2002 - CASA issues AD A330/1 for all A330/340, requiring replacement of all Rosemount (now Goodrich) P/N 0851GR with either BFGoodrich P/N 0851HL or Sextant (now Thales) P/N C16195AA. Compliance by 12/31/2003.

5/2004 - FAA issues AD 2004-10-02, for all Airbus a/c, requiring inspections for damage and obstruction issues with Thales pitot probes. Goodrich probes are not affected by the AD.

7/2004 - FAA issues AD 2004-03-33, for all Airbus a/c, requiring replacement as follows:
- For Model A300 B2 and A300 B4 series airplanes; Model A300 B4-600, A300 B4-600R, and A300 F4-600R (collectively called A300-600) series airplanes; and Model A310 series airplanes: Replace the Thales (formerly Sextant) pitot probes with new Rosemount (formerly BF Goodrich) pitot probes per Airbus Service Bulletin A300-34-0166.
- For Model A300 B4-600R, A310-203, and A310-304 series airplanes: Replace the Thales (formerly Sextant) pitot probes with Thales or Sextant pitot probes per Airbus Service Bulletin A300-34-6141.
- For Model A319, A320, and A321 series airplanes: Replace the Thales (formerly Sextant) pitot probes] with new Thales pitot probes, per the Accomplishment Instructions of Airbus Service Bulletin A320-34-1127.
- For Model A330-301, -321, -322, -341, and -342 series airplanes: Replace the Rosemount pitot probes with new Rosemount (formerly BF Goodrich) pitot probes, per the Accomplishment Instructions of Airbus Service Bulletin A330-34-3038.
- For Model A330-301 series airplanes: Replace the Rosemount pitot probes with new Thales (formerly Sextant) pitot probes, per Airbus Service Bulletin A330-34-3071.
- For Model A340-211, -212, -213, -311, -312, and -313 series airplanes: Replace the Rosemount pitot probes with new Rosemount (formerly BF Goodrich) pitot probes, per the Accomplishment Instructions of Airbus Service Bulletin A340-34-4042.
- For Model A340-211, -212, and -311 series airplanes: Replace the Rosemount pitot probes with new Thales (formerly Sextant) pitot probes, per the Accomplishment Instructions of Airbus Service Bulletin A340-34-4079.

9/2007 - Airbus releases a Service Bulletin to A330/340 operators: "NAVIGATION - SENSORS POWER SUPPLY AND SWITCHING - INSTALL THALES PITOT PROBE C16195BA"

It describes the new probe as having "improved resistance to water ingress and icing under severe conditions resulting in improved airspeed behavior". It also cites improved resistance to corrosion.

6/1/2009 - Air France AF447 crashes into the Atlantic Ocean. ACARS messages indicate unreliable airspeed data.

6/8/2009 - Air France Pilot's Union advises pilots to refuse to fly unless Thales -AA probes are replaced with -BA models.

7/2009 - Airbus sends out a Request for Information Concerning In-Flight Unreliable Airspeed to all A330/A340 operators.

7/13/2009 - AF1905, an A320 flying Rome to Paris, experiences 'brutal' unreliable airspeed data. Probes installed were reported to be Thales C16195BA.

7/19/2009 - LOT FLT LO-2, a Boeing 767, experiences unreliable airspeed out of Chicago (overspeed warning, stick shaker, EEC warnings) and descends 5000ft, diverts to Toronto. Condition returns while holding at FL10, crew are unable to hold altitude, a/c eventually lands without incident after fuel dump. According to Airframer.com, the 767 relies exclusively on Goodrich sensor probes.

7/29/2009 - Air France pilots union demands all a/c be fitted with Goodrich probes and all Thales probes be phased out.

[VANGHELL]

Ok. Agreed to the above stated evidence...
However... since the pitot is heated it has a much better chance of withstanding severe icing conditions (not speaking here of the THALES malfunctioning model). But, then... going on the severe icing conditions theory... is it not prudent to say the aircraft as a whole will have been covered by a substantial layer of ice? Meaning the wings... or more precisely the leading edge of the wings. Of course, these are heated too, but not as much as the pitot, since they are not stainless steel, and in fact alluminum! Clear icing, as is the case when an aircraft encounters super cooled water in flight, is the most dangerous type, simply because, other than deforming the shape of the airfoil, thus increasing drag, and making airflow over the wing more tubulent, it also increases weight and is very hard to get rid of in flight. This, in turn, exposes the aircraft to stalling conditions.

Now, as far as I can remember, the interim reports, have not pointed out aircraft icing, nor a stall. Yet I can deduce from the phrase "the aircraft hit the surface of the water at a high rate of vertical speed", the fact that, in this case it could have been in a stall!...

[Gabriel]

Nobody said that the airplane wasn't affected by ice beyond the pitot tubes (let alone to know how severe that eventual ice would have been), or that it didn't stall.

In fact, there seems to be a clear indication that the plane wither crashed at a high AoA (high descent rate, about flat attitude). Whether it was stalled or not nobody knows yet, but it looks pretty plausible.

If it was stalled, nobody knows yet if it had been stalled for a while or if it was a last pull-up attempt to prevent the impact.

But bear this in mind. You've said:
"However... since the pitot is heated it has a much better chance of withstanding severe icing conditions (not speaking here of the THALES malfunctioning model)."

This airplane was fitted precisely with the THALES malfunctioning model. So it could be that the pitot was iced and the rest of the plane not.

Note that I've said COULD. This post is fully in the domain of speculations, not facts.

[Fear_of_Flying]

Originally Posted by Gabriel

Nobody said that the airplane wasn't affected by ice beyond the pitot tubes (let alone to know how severe that eventual ice would have been), or that it didn't stall.

In fact, there seems to be a clear indication that the plane wither crashed at a high AoA (high descent rate, about flat attitude). Whether it was stalled or not nobody knows yet, but it looks pretty plausible.

If it was stalled, nobody knows yet if it had been stalled for a while or if it was a last pull-up attempt to prevent the impact.

But bear this in mind. You've said:
"However... since the pitot is heated it has a much better chance of withstanding severe icing conditions (not speaking here of the THALES malfunctioning model)."

This airplane was fitted precisely with the THALES malfunctioning model. So it could be that the pitot was iced and the rest of the plane not.

Note that I've said COULD. This post is fully in the domain of speculations, not facts.

I agree that this scenario is in the domain of speculation. However, it does make a certain amount of sense given the few pieces of evidence that we have - namely, weather conditions at the time, the fact that the pitot tubes apparently iced up, and the possibility that the plane had entered a stall. This would also provide that additional factor that would have made recovery more problematic than in similar occurrences of blocked pitot tubes. I don't recall this theory getting much attention on the previous thread, but it's been awhile. Also, I don't know how much more can be said about it other than, 'It's possible."

[Evan]

Originally Posted by VANGHELL

Ok. Agreed to the above stated evidence...
However... since the pitot is heated it has a much better chance of withstanding severe icing conditions (not speaking here of the THALES malfunctioning model). But, then... going on the severe icing conditions theory... is it not prudent to say the aircraft as a whole will have been covered by a substantial layer of ice? Meaning the wings... or more precisely the leading edge of the wings. Of course, these are heated too, but not as much as the pitot, since they are not stainless steel, and in fact alluminum! Clear icing, as is the case when an aircraft encounters super cooled water in flight, is the most dangerous type, simply because, other than deforming the shape of the airfoil, thus increasing drag, and making airflow over the wing more tubulent, it also increases weight and is very hard to get rid of in flight. This, in turn, exposes the aircraft to stalling conditions.

Now, as far as I can remember, the interim reports, have not pointed out aircraft icing, nor a stall. Yet I can deduce from the phrase "the aircraft hit the surface of the water at a high rate of vertical speed", the fact that, in this case it could have been in a stall!...

The suspected problem with the pitots was not insufficient deicing capability (probe heat). The replacement probes use the same (115DC?) current. The suspected problem was insufficient water egress due to insufficient drainage performance and/or ice contamination due to probe form factor and manufacturing defects (drilling burs). AFAIK, the A330 bleed air system can deal with leading edge icing in those conditions. I would have to go back into the report to get more detail, but wing surface icing was not cited as a probable cause here. Also, reported incidents previous to the crash did not indicate wing surface icing issues, only indicated airspeed fluctuations.

[Evan]

Originally Posted by Gabriel

I don't think so. I don't remember it exactly, but within the first steps of the unreliable sped procedure were the memory items "thrust: climb, pitch: 5 deg ANU", or something similar. That's pretty straightforward.

According to the 2nd interim report, investigation into 13 other reported UAS events revealed that in none of the cases was application of the memory items indicated. Specifically, the thrust levers were not moved (and therefore still in 'thrust lock' mode, which kicks in when the AT fails or disconnects) and no actions to apply 5° of pitch were observed.

Originally Posted by BEA Second Interim Report

For the cases studied, the recording of the flight parameters and the crew testimony do not suggest application of the memory items(13) in the unreliable airspeed procedure:
 The reappearance of the flight directors suggests that there were no disconnection actions on the FCU;
 The duration of the engagement of the Thrust Lock function indicates that there was no rapid autothrust disconnection actions then manual adjustment on the thrust to the recommended thrust;
 There was no search for display of an attitude of 5°.

If the AT had recently retarded thrust to reduce airspeed while entering turbulence, the thrust lock feature would have kept the retarded thrust setting throughout the failure sequence. In theory, in Alternate Law, this could have led to a stall, particularly if this crew had also neglected the memory items and was distracted trying to diagnose a barrage of ECAM messages. Perhaps some light wing accretion or runback icing could have furthered narrowed the margin of stability. Once again, a recipe.