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AF 447 Search to resume

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AF 447 Search to resume

Old 21st Oct 2010, 17:49
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bearfoil;

Thanks for your reply. I hope I have not been lacking respect. It's not personal. I'm expressing my feelings with regard to a recent flurry of posts suggesting, without cause, that BEA is not sincere in its efforts to find the cause(s) of this accident, and to publish what they find. Of course you have every right to be sceptical, I'm too at times, but I protest when scepticism turns into plain distrust and insinuation.

CONF iture;

Agreed, but I think the discussion is primarily about BEA.

regards,
HN39
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Old 21st Oct 2010, 18:25
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Bearfoil,

I understand and respect your motivation of keeping the pressure up on BEA.
However, I'm not sure if this is really the right platform and the ideal way to achieve this.
What is written here will have very little effect in the grand scale of things....
Secondly, I'm not convinced that not finding the recorders is really in the interest of Airbus.
It leaves a doubt.
Which cannot be resolved without the recorders.
So they must be surely interested in finding it, to make clear that it can't happeb again to an Airbus (except if AF447 was really knocked out of the sky by the big one).
And if AI is interested in finding it, why should BEA be not.

Discussing all possibilities and their probabilities on the other hand is valuable and IMHO also appropriate here.
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Old 21st Oct 2010, 18:40
  #2263 (permalink)  
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henra

Thank you for your patience and insight, and also to HazelNuts 39.

This is Tech Log, after all, and I may seem to have lost the plot, perhaps I have. I too regret the appearance of unfounded criticism, and believe all comment should be backed up by experience and evidence; if I have missed the mark, I apologize. What I see as predictable, others see as acceptable, and the two are intertwined. That is the last I will refer to the lack of visibility and comment from the principals.

I think what got us relocated was an involved discussion of engineering, structures and their performance in flight, something I think is productive and adds to a community of understanding.

thank you both again.
bear
 
Old 21st Oct 2010, 18:46
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BOAC,

May be a bit too soon, still, to throw in your cards. Several promising areas of seabed have emerged from this thread's event analysis during the summer, where the lawn has not yet been mowed by the ROVs: near the LKP and southeastward towards the "slick." BEA, too, is revisiting their search assessments and calcs, and should present findings soon. Never having won the Lotto, for some reason I remain an optimist.

Being a recovering gadfly (but more of an iconoclast), I would join HN39 in welcoming Bearfoil's contributions. Masking out the anti-establishment invective, he has made some valid points. I myself often wonder how the Crew Rest with very little accompanying cargo hold luggage was ejected, not to mention PAX distributed from the very front to the very back of the A/C, in BEA's "flat" splash scenario.

GB
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Old 21st Oct 2010, 20:11
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The BEA's "mission statement" published on the home page of its website, proclaims the following:-
The sole objective of the technical investigation is to collect and analyze useful information, to determine the circumstances and the actual or possible causes of the accident or incident and, if necessary, to make safety recommendations in order to prevent future accidents and incidents.
I for one, believe that that is exactly what they have been doing regarding the AF447 accident. Surely, "Time is of the essence", I hear some say. That part is agreed, but based on the evidence they have acquired at various points into their investigation, the BEA has revealed its analysis of that data in a timely manner.

The current hiatus is nothing more than checking that the "deck chairs" are where they should be. As the construction of the DFDR/CVR packages were designed to withstand the known forces of the impact and the depths of the ocean, the data they contain will be available once they have been recovered. IMHO the right thing to do in these circumstances is to consolidate and investigate means of achieving a successful outcome of a further search.

To do so, a huge reanalysis of all data in their possession is reasonable, and in the case of the early air searches, a complete re-evaluation of their effectiveness is certainly in order. I am sure that when all that data has been considered in its entirety, that a case can be made for the spread and funds required to implement a Phase 4 search.

The only "bone of contention" I have in what has been achieved to date is, that if the MoD and MoT hadn't had their spat over the L'Emeraude pinger tapes during the Phase 3 search, and the search had continued as planned, we may not be currently having this discussion .

mm43

p.s. The "actual" underlined in the BEA statement is a word substitution not in the original. Makes for easier reading (imo).
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Old 22nd Oct 2010, 20:52
  #2266 (permalink)  
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Crew Rest

The unit was posed for its photo oriented base down, as evident by the signage and the assumed attempt by its holders to present evidence in a reasonable way. It thus appears to have experienced catastrophic loads in a way suggestive of a Cabin deck impact from above, against a resisting Hold deck below. For purposes of discussion, I use the nautical "deck" rather than floor, to include all structures as "decking" also.

The height as seen may be the end static dimension, or represent a "rebound" to the unit that returned some of its height post impact. It also appears to have failed almost completely in the vertical. If there was a horizontal component to the impact, it must have been minimal, or the unit may have slid forward to have then be collapsed in place. How did it escape the Hold to be discovered, where was its buoyancy to remain afloat? Trapped air most likely, even in a turbulent sea. As Great Bear asks, where are cargo containers? where are film wrapped pallets, materials that are buoyant on their own? For the Galley mod to have survived, the Cabin must have opened after the module was damaged. Or somehow it escaped a collapse of the fuselage upon it? Similar in fashion to the FA seat bulkhead, tray cabinet, etc.? Thence sent into the sea? The timing and descriptions (BEA) of the inferred impact explanations are not instructive, here.

The crew rest has the look of a laminated and boxed unit. From only the photograph it appears that the laminae failed and exposed their adhesive layer, an apparent phenolic film. In my experience when laminations part, it can be indicative of an explosive failure, such that the metallic layers vibrate beyond the film's strength due to extremely dense acoustic vibration.

Please know that here I describe a simple gas and pressure relief, not a chemical or man made device. The failures are not indicative of high outside pressure, but instead higher gas pressure within, perhaps showing a collapse while closed, and reasonably hermetic. This goes to the rapidity of the failure, nothing else. I do not see a photograph of the crew rest after it was opened. Of course it was opened. What was inside?

Has an a/c disintegrated at altitude before? Comet? Has a hull lost its integrity to survive? Aloha? (Except for Emily, who was ejected over the Pacific). Has an a/c fallen into the sea seeking the inverted, but run out of altitude? Alaska? Has an a/c impacted the surface and distributed all its pieces (Save the tail)? Afriqiyah?

Failing a logical introduction and chain of evidence for each of its descriptions, the reports infer alot. Possibilities are somewhat a different animal to inferences.

Last edited by bearfoil; 23rd Oct 2010 at 00:26.
 
Old 23rd Oct 2010, 15:24
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bearfoil,

I share your thoughts. I tend to come to the conclusion that such high-speed impact with water is a chaotic process. Trying to visualise it in 'slow motion' involves a lot of speculation. There must have been high levels of vertical and horizontal acceleration, water rushing in at a pressure of over 200 psi. Perhaps instead of saying what caused a particular damage pattern, it would be better to think in terms of what could have caused it. Can you conclude that it could not have happened as BEA describes it, or just that it could have happened differently?

regards,
HN39
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Old 23rd Oct 2010, 16:55
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I have continuously struggled to find some since of explanation as to why such a minimum of debris was recovered much less discovered. Other than precious little, historic accidents at sea have yield this limited amount of aftermath. When airplanes make contact with the water, or ships sink, the pattern of debris is normally very large in that most items surrender to the sea reluctantly. In this case, I guess most of you can recall, throwing a flat rock to skip across a pond, only having the air catch it, provide lift, and the rock rolls on it side and enters the water vertically with a kerchunk and barely a splash. Seems like this phonomia fits, only airplanes hardly contact anything with a kerchunk, and subsequently without a large reaction. However, ValuJet in 1969, left very little evidence on the surface where it impacted. Given the debris pattern, or lack thereof, simular thing in this case?
Contrary to BEA, other than high (load) vertical impact, and if wings level, would not lend itself to a rapid sinking.
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Old 23rd Oct 2010, 22:38
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Cool

Hi,

YouTube - Crash Landing - Ethiopian Airlines http://www.youtube.com/watch?v=tZyDrpeWoBw&NR=1B767
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Old 23rd Oct 2010, 23:56
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As HN39 said...
....such high-speed impact with water is a chaotic process.
I was already tempted to try and post the same link that jcjeant just put up.
It is really anybody's guess how much, and what, debris the uncontrolled impact of AF447 would have left on the surface.

CJ
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Old 24th Oct 2010, 03:59
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It is really anybody's guess how much, and what, debris the uncontrolled impact of AF447 would have left on the surface.
CJ, good point and a reminder that "uncontrolled impact" is the RESULT, not the CAUSE of this upset. Indeed, the recovered floating debris, while confirming the catastrophe, provides few clues about WHY the event happened.

All the more reason to continue the search for the CVR/FDR. Without hard data from before and during the upset, we are left with a string of ACARS messages, meteorology, and a great deal of guesswork -- not enough information or definition to reach the sort of conclusions expected from a BEA or a NTSB...

GB
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Old 24th Oct 2010, 05:32
  #2272 (permalink)  
 
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Here is some free speculation on the AF447 breakup sequence.

I've been studying the wreckage origination charts of the second interim BEA report. The large items found seem to be in close proximity to the doors. Not that I think the doors sprung open and the stuff floated out, it seems likely that the fuselage broke at or near the door openings.
See page 14 of the 2nd interim report and look at the blue and pink colored areas. These appear to be adjacent to entry doors.
Specifically, behind the cockpit, in front of the wing, behind the wing, and in front of the vertical stabilizer leading edge (4 locations).
It could be that the doors are near splice areas of the fuselage or that the door openings reduced the bending strength of the fuselage in that area.

The green marked overhead items probably all tore loose on impact throughout the aircraft except perhaps over the wing center section. Depending on the attitude of a section as it sank, pieces could be preferentially lost from one side of the aircraft.
If Bearfoil perceives overpressurization in the crew rest module, it wouldn't be surprising. Take a box that is sealed and crush it rapidly. The air trapped inside will cause any unsupported area to bulge before it blows out.

The Ethiopian 767 impact was a very different accident with significantly more horizontal velocity than this aircraft had. Only useful to show how rapidly things can turn chaotic. Didn't the wing tip hit a reef? It looked like the wing box was torn from the fuselage.
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Old 24th Oct 2010, 15:39
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Cool

Hi,

The Ethiopian 767 impact was a very different accident with significantly more horizontal velocity than this aircraft had
So far I have not accurate information about the horizontal velocity of the AF447 on impact .. do you have one ?
The BEA report about horizontal velocity is only assumptions .. nothing verified by datas or witnesses .. no movie on Youtube ....
Black boxes are holy grail and must be found.
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Old 24th Oct 2010, 17:28
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I think the ultimate informed theory will benefit from "unwinding" the evidentiary trail, in "backwards" fashion. Instead of the "body" of evidence informing the upset, it will be the upset directing the results. If the "upset" is based only on informed possibilities, it would not be the first time.

When confronted by an horrific event, it is in the nature of humankind to demand an explanation. Eventually the boxes will be found. My guess is that the data they contain will put a fine point on something offered before, perhaps even an initial PR release: "Fortes Turbulences".

"Fortes Turbulences" is by definition the cause, regardless of posits here and elsewhere, correct? The a/c stopped flying. From a general conclusion of upset (what else) every other surmise flows inevitably.

It is informative to nitpick at every informed piece of knowledge, but the fact remains most of the evidence and discussion is proprietary. To the extent that the authority can "embrace" data, the conclusion is of necessity closed.

No conflict should exist between the Public's demand for openness and the authority's command of the data. Yet there is one.

bear
 
Old 24th Oct 2010, 17:49
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jcjeant
So far I have not accurate information about the horizontal velocity of the AF447 on impact .. do you have one ?
Sorry, nothing I can easily pass on. Only a somewhat calibrated eyeball.
What I see in the AF447 wreckage that has been pictured is a strong vertical component of damage, a weaker horizontal component of damage, and a relatively short/low energy (less than 160 Knot total velocity) churn time (but my eye has been calibrated by just a few accidents involving smaller aircraft).
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Old 24th Oct 2010, 18:51
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jcjeant

In searching for a compelling composition of evidence to inform a "small horizontal component" of velocity, I look at the engineering involved in plain sheet design. It is not an accident of design that aircraft are built to resist longitudinal loads far more than "Horizontal ones". Tailstrikes, slips and skids, excessive Yaw are simply not primary considerations in commercial and utility a/c. It is assumed that flight aspect other than trimmed longitudinal is an aberration, forced upon a pilot(s) by artifacts of poor design, poor training, mechanical deficit or other "unusual" (and unexpected) circumstances. In flight, a "slippery" a/c is the goal, as evidenced by stowed (in flight) aero devices: Flaps, Slats, and Rats. Reconfig is an essential part of modern flight, where an a/c must be a truck and a bird, (hopefully not at the same time!). 447 experienced other than trimmed flight by definition (per ACARS: a/p drop). A water entry in vertical aspect is as far from designed for considerations as man can get. I wonder about BEA's "conclusion of low horizontal" velocity. An a/c is much more able to resist lengthwise loads than vertical. In flat vertical impact, evidence of this "design" is apparent, as in CAL Denver and Turkish Schiphol. Vertically, the a/c really is a "tube". Cylinders (fuselages) as structural concepts are meant to handle "bearing" load, not "rectilinear compression". Per Machinbird and his post, it is at "splices" (joins) where most of these failures accur. It is a consideration of "poly-geo" construction that we see this. Where once Vertical, horizontal, and spanwise elements were built as a unit, in one location, we now see fuse, tail, wing, and engine pylon/engine assemblies borne across Oceans on ther decks of freighters, or in the hold of high lift a/c.

An example would be the nose fail of the 737 at Schiphol and Denver, or the Tail assembly of AA587 La Guardia. Looking at bare brackets where an epoxy tab is missing is part of the "new" engineering. Do I disagree with this approach? Only when it causes the loss of an a/c and its people.

bear
 
Old 25th Oct 2010, 01:11
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Sorry if this is covered already recently in this massive thread but is there any kind of search continuing for this aircraft?
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Old 25th Oct 2010, 03:29
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Cool

Hi,

http://www.pprune.org/5976292-post2213.html
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Old 25th Oct 2010, 05:30
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Greatbear: Excellent post. So much of what we see here is sausage filling. Thank you.

bearfoil:
"Fortes Turbulences" is by definition the cause, regardless of posits here and elsewhere, correct? The a/c stopped flying. From a general conclusion of upset (what else) every other surmise flows inevitably.
Huh? Explanation or clarification please...
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Old 25th Oct 2010, 15:41
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In a direct way, an a/c can succumb to disrupted airflow either passively, as in a cell, or create its own airflow problems by upset. I should think that it is apparent 447 did either one or the other, or both.

cheers
bear
 

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