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AF447

Old 16th Jun 2009, 13:13
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BOAC :
1) Do we have ANY evidence to rule out some sort of mechanical disruptive event or fire around the cockpit/electronics bays?
No trace of fire in the debris , so far... and we're arguing about inflight break up or ocean surface impact. We don't know enough.
On this subject, there is the Crew Rest Container : two of its parts have been found on separate occasions ; one with the labelling, the other with that arrow pointing FWD. I personally have tried to find out whether they were part of the same debris trail or on very far apart locations. Guess we will eventually be told.
Another mystery is the left #1 spoiler, found by a tanker. Was it surrounded by other debris or was it all by itself away from everything else ?

2) Is it established that we have no ACARS message recording LOSS of cabin pressure AND is it confirmed that the ACARS message we have refers to excessive cabin DESCENT rate?
Yes, apparently. There is an advisory linked to a "cabin vertical speed", related to the ECAM presentation... It indicates a cabin vertcal speed in excess of 1800 ft/min up or down, translated on the ECAM screen as a very small green-pulsing bar.
A depressurisation would have been indicated by an "EXCESS CABIN ALT" warning, telling of a cabin above 9500 ft....That warning is not part of the received ACARS messages.

3) There have been several (I think unanswered) requests here for positions of the groups of bodies found. Do we have any, and has anyone back-plotted the position of the second recovery vis a vis ocean currents to see where they would have been in relation to the first, and likewise for the first to the POSSIBLE crash site?
I, for one, would be interested in that kind of info... See above.

4) All the ACARS messages COULD have related to software interpretations of events. Amongst them, is there any hard evidence of ACTUAL failures?
In this case it's at a very low level of interpretation. The messages are akin to two kinds of reporting :
1/-Hi ! I'm system X. I've diagnosed that I'm too sick to keep on working. Something is wrong with me and I've informed the crew through a warning or an advisory message on their ECAM.
2/-Hello ! This is X and Y. We've determined that Z is going nuts and we don't trust him anymore and we've put him in a straight jacket. We'd like the crew to look into the matter...
We seem to have here a convergence of related failures, detected by the computers which need air data inputs to function properly. In all fairness, that's about the extent of our knowledge.
On the other hand, we've already seen similar events, with very similar messages, in similar orders pointing a finger at the ADRs total pressure channels...
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Old 16th Jun 2009, 13:18
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From what I read here, way back when, the pitot problem is one of poor quality control of the bleed hole. I have not read why they could not be reworked. Does anybody know the price of the new tubes? AF had them sheduled for the next C check, when a full pitot/static check would be performed anyhow.

I also read somewhere in all this that AF was not convinced the new pitot tubes were really an improvement.

GB
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Old 16th Jun 2009, 13:44
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Af Sop

On AF SOP
Was the Captain in the cockpit at the time or was he taking his rest? Who was in his seat - the guy with 800h or the guy with 2600? Not that it matters so much, but in an extremely stressful sit, it will won't it?(post #383 - Air France A330-200 missing thread from Tech Log)


Pardon me for repeating myself, but I would like to put this question again, after 2 weeks to our grieving AF colleagues - what are the AF In-flight Relief procedures - this can give us a lot of easy food for thought...
Merci BCP
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Old 16th Jun 2009, 13:56
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Originally Posted by BOAC
Deep breath time again. Can I request a summary from 'the knowledgeable'?

2) Is it established that we have no ACARS message recording LOSS of cabin pressure AND is it confirmed that the ACARS message we have refers to excessive cabin DESCENT rate?
I don't think it has been established that it was a DESCENT rate. I believe this is simply an advisory of a rate of change either up or down that exceeds a set parameter. It has been said that this parameter is 1800 fpm.

Some are suggesting that due to de-pressurization the cabin vertical rate showed an excessive rate of climb, and others are suggesting a possible excessive rate of descent as the aircraft descended to the sea. Either scenario is possible.

It appears that some people are confused by the fact that the cabin pressure PSI will decrease as the cabin climbs or that the cabin pressure will increase as the cabin descends.

In reality the message is only about a simple rate of change in cabin altitude (vertical rate) and at this point it tells us very little.

The cabin altitude could be changing due pressurization at altitude (resulting in a climbing cabin) or it could also mean the cabin was descending below the normal cabin altitude of about 8000' when at cruise. (If the aircraft was in any sort of a dive, the cabin would at some point have to descend below 8,000 feet)
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Old 16th Jun 2009, 13:57
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Seeing the motion available in the joystick video and knowing that;

- fighter joysticks have limited forward travel due to inadvertant correction under negative g.

- Civil transport manufacturers wouldn't test to the neg 1 g limit outside of the simulator and that wouldn't simulate the pilots arm coming off the rest.

- sitting in your chair with arm on armrest, if you pivot your forearm upward, raise the elbow but keep the hand in place, the hand, (handle), pivots forward.

Then perhaps introducting even more negative g. Who knows. Depends on the ergonomics.

Anybody have access to a full motion A330 sym that wants to check this out. Set moderate/severe turbulence at high alt cruise. Grip sidestick controller in manner an experienced pilot would under such conditions with the autopilot off and in alternate law. Lift yourself up against the lap belt, raising the elbow an inch or two. Anything happen. In the interest of safety, worth a quick check at least.

Or does nomal everday flight in turbulence rule out this concern, i.e., already been demonstrated in the real world.
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Old 16th Jun 2009, 14:05
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"I also read somewhere in all this that AF was not convinced the new pitot tubes were really an improvement."

Other way round, according to what I've read, Graybeard. Airbus said that there was no proven need to replace the pitot tubes, Air France (an airline for which I personally have enormous respect) reckoned different and replaced them anyway.

A bit of what I personally consider to be 'good news.' My daughter is a prosperous international lawyer living in Hong Kong. She often makes short visits home and I've quite often 'advised' her to choose Boeings, rather than A330s/A340s, whenever possible. Without going into too much technical detail.

She just emailed me this arvo to say, "Thanks, Dad. Reading about the Air France thing, guess I'll try to follow your advice from now on........."

Anyone on here think that a basically-thick, but luckily 'cunning,' guy like me was over-reacting? Or that my (highly-intelligent, 'to a fault', honours-law-degree and Masters' ticket) daughter, who knows nothing at ALL about aviation, is over-reacting too?
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Old 16th Jun 2009, 14:35
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No it doesn't - it needs some answers!

Who was in the the flight deck?

Why did they did get into the weather?

With all the ACARs messages, why hasn't a replay of the the last few minutes of flight been reproduced?

Why has there been a deafening silence from Airbus?
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Old 16th Jun 2009, 14:46
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This isnt an "Armchair crash vulture and enthusiasts" Forum. When BEA decide to release those details, then maybe it is worth further discussion but until then this thread has run its course especially by such purile posters as BigFootDriver and Barbies boyfriend.

Why has there been a deafening silence from Airbus?
Probably because they are awaiting details and facts from the investigation team. They are not going to respond to flightsim wonder kids, spotters and conspiracy theorists who masquerade on this website like some sort of experts.
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Old 16th Jun 2009, 14:59
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Originally Posted by Lemurian
Originally Posted by me
2) Is it established that we have no ACARS message recording LOSS of cabin pressure AND is it confirmed that the ACARS message we have refers to excessive cabin DESCENT rate?
Yes, apparently. There is an advisory linked to a "cabin vertical speed", related to the ECAM presentation... It indicates a cabin vertical speed in excess of 1800 ft/min up or down, translated on the ECAM screen as a very small green-pulsing bar.
A depressurisation would have been indicated by an "EXCESS CABIN ALT" warning, telling of a cabin above 9500 ft....That warning is not part of the received ACARS messages.
- picking up on just this one part of your reply - if only we could be sure we have ALL the ACARS messages in sight, then there is a very good chance we can rule out a high-level break-up in view of the lack of an "EXCESS CABIN ALT" warning as you say. Without such a signalled disruption to the cabin pressure, the only subsequent ACARS message must surely refer to a descent? Dare we surmise? PJ? Bsieker?
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Old 16th Jun 2009, 14:59
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Originally Posted by Five Livers
No it doesn't - it needs some answers!

1) Who was in the the flight deck?

2) Why did they did get into the weather?

3) With all the ACARs messages, why hasn't a replay of the the last few minutes of flight been reproduced?

4) Why has there been a deafening silence from Airbus?
Your questions are answerable. I think they border on being ridiculous.

1) How do you propose to find out who was in the flight deck with the limited information now available?

2) There is no proof they went "into the weather". Only speculation. They may have diverted many miles around the nasty weather.

3) The ACARS messages can not replay anything. They are only very simple automated notices designed to give a "heads up" to maintenance.

4) Considering the lack of any concrete information at this point, what do you want them to say?
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Old 16th Jun 2009, 15:07
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tomorrow

tomorrow at 1000-1100 bea have a press conference.........
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Old 16th Jun 2009, 15:10
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Originally Posted by ttse
1)You've heard of sublimation but at your low elevations probably haven't witnessed it. It's a common process in Colorado and I would expect melting ice on the exterior of pitot's to sublimate. An unknown question becomes whether heated ice crystals within the pitot system sublimates or melts into water.
I have actually been looking into this after reading of a number of pitot icing issues where I thought supercooled liquid water could be ruled out. Meteorological survey reports were a major source of information in that research.

I have concluded that there must be a secondary process by which ice forms in pitot tubes at high altitudes where there is a very low temperature and a high density of ice crystals. My guess is that sublimation is involved in this process, but I can't be sure. I can see two hypotheses for this icing:

The first is that the ice crystals deposit but don't form a hard solid mass. Since the ice will have greater mass than the air it displaces, it will also have more inertia, and thus a partial obstruction of the pitot tube with loose ice crystals would dampen pressure changes (venturi effect). The problem with this hypothesis in my view is that the small ice crystals are small enough to be dispersed more evenly and even occasionaly ejected by pressure changes which occur in turbulance. Thus I have trouble imagining this process causing problems over ten or twenty minutes.

The second hypothesis is that the ice crystals, once deposited, may sublimate and condence, fusing them together into a hard mass (similar to the way wind-crust develops on ski slopes). An obstruction of this sort would also reduce pressure via the venturi effect, but would be less prone to being ejected from the tube by changes in pressure.

There have been enough reports of pitot tube icing in met. surveys of MCS's outside of strong convection (in one of the main cases I came across, in a DC-8 ;-) ) that I think we can understand that there is a process that the pitot tubes can ice up in the absence of liquid water. What that process is exactly may be harder to verify.

The absence of supercooled liquid water does not mean that pitot tubes were unlikely to be iced up in AF447. The parallels I have been able to find suggest that the pitot tubes would have almost certainly iced up.
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Old 16th Jun 2009, 15:22
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Pitot Icing

I have a question:

When you get pitot icing, how quickly does it occur? i.e. is the state of the pitot from reliable to unreliable a binary one? or does it show some degradation of service which allows you to consider icing as an issue?

Also, does pitot heating always work or is it sometimes overwhelmed by the icing conditions?
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Old 16th Jun 2009, 15:28
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BOAC,
if only we could be sure we have ALL the ACARS messages in sight,
There is absolutely NO way of confirming that, apart from the declarations from the BEA and AF.
Secondly, these messages concern ONLY the ACARS sent to the maintenance department.
Missing are all those transmitted to OPS /CDG station / GIG plus all the routine queries for en-route alternate weather, routine messages to base, the automated initiation message, flight plan, loadsheet, the OUT and OFF....
then there is a very good chance we can rule out a high-level break-up in view of the lack of an "EXCESS CABIN ALT" warning as you say.
I don't think so. Look, these messages are just the picture until 0214Z. What happened next is pure speculation. Is the last message the very last transmitted ? Was there a power failure after the last transmission.?...Conjectures...
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Old 16th Jun 2009, 15:40
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Originally Posted by Lemurian
Look, these messages are just the picture until 0214Z. What happened next is pure speculation.
- maybe I'm not expressing myself clearly. I'm looking UP TO 0214Z, not 'next'. The point I am making is that there MAY be a case for saying the cabin was INTACT until the descent warning, which would cast doubt on the "the fin fell off and tore open the fuselage" line. In fact, how long would it take for the cabin to achieve 1800fpm? Could they even have been descending before the 0210Z message stream we have?
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Old 16th Jun 2009, 15:41
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No it doesn't - it needs some answers!

Who was in the the flight deck?

Why did they did get into the weather?
No one knows !! but if the captain was in his seat, then another F/O would have been in the right hand one.
If the captain was on his break, then, the most experienced F/O would have been in the right hand seat. That's AF SOP for long haul crew relief so that the one in charge of let's say an emergency descent does it from the seat he is used to.
To tell you the truth, given the catastrophic system meltdowns, I can't see myself being able to fly the aircraft in a such a weather and no attitude indicator.

Why ???? When you answer that one give me a call.

Last edited by Me Myself; 16th Jun 2009 at 15:59.
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Old 16th Jun 2009, 16:13
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Dysag -

Curious; are you saying Mr. Larson's Report is false? Seems fairly credible to me. Afterall, this a/c was in service for how long, and how many cycles?
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Old 16th Jun 2009, 16:16
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supercooling and sublimation

sublimation is the direct passage between the solid state to the gaseous state, without spending time in the liquid state. This is the normal method by which dry ice dissipates, and is common in many situations involving water.

A much earlier message from someone stated that energy input is needed to convert water to ice. In fact, the opposite is true - you remove energy to convert water to ice. In the reverse case, there is a parameter called the energy of fusion, easily demonstrated by applying heat to a mixture of water and ice. The temp remains right at the freezing point, no matter how much heat you apply,, until the ice is all melted, at which point the temp begins to rise.

wikipedia should have more appropriate definitions...
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Old 16th Jun 2009, 16:21
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Jetdoc;
I think what you have got there is the AMM references for the maintenance of those components, not fault codes.
Thanks - its very possible - the document is ancient and very difficult to navigate within - finding fault-failure codes is difficult - also I'm unaccustomed to using the document. The point of course is to convey complexity - these may not be the fault codes so that argument appears compromised somewhat until one understands that this applies to all systems including fault/failure analysis; I strongly suspect there are "more numbers" which may or may not be available and which will further determine which sensors were providing "bad" data. I appreciate the comment, and hope others pick it up as well.
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Old 16th Jun 2009, 16:43
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Origin of the known ACARS messages

Being curious about the source of the two pages of ACARS messages, which are labelled 28/256 and 29/256, I looked around to see where they originated. Amazingly, this seems to be it:
AF447 accident - icing, pitot tubes and radar in the frame - Unusual Attitude
So the crucial text on which everyone is basing analysis, was hand copied from a screen visible during a TV interview! Furthermore I gather from other comments here, that this is just one ACARS stream (maintenance messages?) of several. Also that it isn't publicly known for certain that these two pages are even all the relevent messages from that stream.

I'm new to this forum, and have no aviation-related expertise whatsoever. (I'm an electronics and computer engineer.) I greatly respect the professional experience present on this forum and others. But... I'm astonished that there doesn't seem to be any indignation that Air France and the French aviation authorities have not seen fit to release *all* the ACARS messages from AF447. Are there legal reasons why they wouldn't? Liability? Insurance? Given that what appear to be at least a large proportion of the critical ACARS messages are now public, why not either officially release them all, or at least make some effective demonstration that there were no more?

If this topic has already been dealt with, my apology. 87 pages...

For reference, here are some other links to the ACARS messages and commentary:
http://www.pprune.org/4975386-post45.html single post - ACARS msgs
http://img197.imageshack.us/img197/3410/acarsaf447e.png ACARS msgs

Engineer decodes Air France Flight 447 emergency messages
20090608 Engineer decodes Air France Flight 447 emergency messages

http://www.iag-inc.com/premium/acars2.pdf
Line by line commenting on the ACARS msgs.

http://www.nytimes.com/2009/06/13/wo...lane.html?_r=1
Error Messages From Air France Jet Offer Details but Little Insight

The New York Times > World > Image > The Last Minutes of Flight 447
http://graphics8.nytimes.com/images/...ane-graf01.jpg

http://www.eurocockpit.com/images/acars447.png
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