AF 447 Search to resume [Archive] - Page 15

auraflyer

15th Apr 2011, 01:28

Chris Scott wrote:
Is there a possibility that Turbine D is right, and that it is the tail section (by which I think he is referring to the aft fuselage)?

Would the debris field alignment (approximately 070/250) necessarily be roughly indicative of the heading at sea-level impact, despite currents on the way down? If the curved piece in the north-east was the aft fuselage, would that suggest the Hdg 250 rather than the 070?

I think auv-ee addressed this recently - he suggests it's probably more indicative of the underwater currents. I think it also depends on the degree of fragmentation. We also don't know if this is the entire field (though it looks to be).

My understanding is that if parts are relatively intact, you get a sort of ballistic trajectory that depends on the resistance offered by the falling parts. You can see an indication of this in the HMAS Sydney report -- see the final page of:

http://www.defence.gov.au/sydneyii/finalreport/Report/Chapter%2016.pdf

and again on p 218 of

http://www.defence.gov.au/sydneyii/finalreport/Report/Chapter%2012.pdf

"As she continued her plunge she would have tended to level off, and she probably adopted a trim by the stern because the shape of the forward part of the ship offered more resistance to the passing water."

The relative distribution of the parts in turn will be affected by underwater currents pushing on them during the time of descent, but unless they further fragment (eg implosion) what you see in the sonar tends to reflect their original shape.

The question of the relation between resting orientation and orientation at impact is something you'd need expert comment on. My lay impression is that a relatively intact airframe would tend to fall through water nose first, as I presume that would offer least resistance.

However, if the wreckage is heavily fragmented, my understanding is that the final debris field is often spread much further, because each individual fragment behaves differently. The pieces which are both densest and offer least resistance, descend fastest and move least with current. Pieces that are lightest and with the most resistance take the longest to fall and are pushed furthest by the current. Other things fall in between.

The sidescan suggests large parts could be contiguous, but the few photos do show a lot of fragmentation of parts - see at Oprations de recherche en mer : images du site (http://www.bea.aero/fr/enquetes/vol.af.447/images.du.site.php) , especially the one titled "Partie de fuselage".

It's hard to tell without seeing more of the cabin, but I assume it hasn't been shown because human remains were visible. From mm43's post (http://www.pprune.org/tech-log/395105-af-447-search-resume-176.html#post6371001), it does however look like the main part of the debris field is about 400m long out of the 600m shown, whereas the intact A332 aircraft is about 59m long? Given the amount of internal parts (eg galley parts) found on the surface, from both galleys, I assume there were either multiple breaks in the fuselage, and/or rupturing, to allow them to escape.

nb Several people here have already shown that they have much more knowledge than I on this and I would defer to them if the above is wrong.

Also, compare the tidiness of the HMAS Sydney image with the AF 447 one. I don't know enough to know if this means anything.

Shadoko

15th Apr 2011, 02:46

@auv-ee: thank you for your documented answer #3504.

About bodies injuries vs a/c attitude: it seems (imho) that there is kind of circular arguments (tautology) about them:The compression fractures of the spinal column associated with the fractures of the pelvis(2), observed on passengers seated throughout the cabin, are compatible with the effect, on a seated person, of high acceleration whose component in the axis of the spinal column is oriented upwards through the pelvis.So, it is fully compatible with the a/c attitude supposed by BEA.
BUT. Bodies recovered are probably those from passengers who were not attached. And they could have been in every position and place in the cabin at impact, depending of what happened before.

In fact, I can't imagine this aircraft falling from 35000' to 0 keeping a "normal" attitude all along (and not attached passengers remaining in their seats*). Adding a storm, is this "flat" fall truly possible ?

*If that was which happened, thanks for it: passengers kept sleeping all the way. It had to be more rude for the crew.

Mr Optimistic

15th Apr 2011, 06:35

Forgive the noob question on sonar, but is the image produced on a single pass, eg from the rov above the eastern edge of the lane, or is it the addition of two half pictures, one from the east and one from the western pass ? Also what would the effective lateral beam width be, ie the length of image producted by a point object (are the N/S 'smearings' a reflection of pulse width and not debris dimension ?). Noting its a jpeg, any need to be careful about compression artefacts ?

Grity: never heard of Lilienthal: impressively ahead of his time !

The image of fuselage section looks like it supports a limited front/aft impact load, and if people/seats and attachments are intact, that would also indicate realtively limited impact loadings.

Is the linear debris trace trending roughly north from the centre taken to be the remains of a late breaking stb wing ?

BOAC

15th Apr 2011, 08:13

It would appear to me to be completely fruitless to attempt ANY 'analysis' of heading at impact from the lie of any wreckage. The remains of the aircraft will 'fly' just as well in water as in air, and since most seem to be postulating some sort of rotating motion at impact there is no reason why this should not continue during the 4000m drop resulting in ANY sort of orientation. Until FDR data is recovered, all the wreckage tells us at the moment is roughly where it hit the surface.

Mr Optimistic

15th Apr 2011, 08:34

Fair comment, stb was perhaps pushing it. First thought was it was a debris trail as if both engines have been pictured, where is the other wing.

With respect to other recent musings, re-reading the BEA report reminded me that a concurrent flight had to carefully adjust the weather radar to get the full picture and that no big issue is made of the difference between ACARS 'WRN' and 'WRG' : it doesn't reference interconnection failure for the latter, just a mistrust.

Chris Scott

15th Apr 2011, 09:18

'Morning BOAC,

Quote:
"It would appear to me to be completely fruitless to attempt ANY 'analysis' of heading at impact from the lie of any wreckage."
I'm not sure you or I know enough to make that assumption. Let's keep on interrogating the experts, just in case. As auraflyer (while admitting to be a layperson) says: "The pieces which are both densest and offer least resistance, descend fastest and move least with current. Pieces that are lightest and with the most resistance take the longest to fall and are pushed furthest by the current. Other things fall in between."

Comparing the pattern of returns in the east and west, I have a hunch that swordfish41 and others may resolve the 250/070 dilemma at a glance. However, as I asked earlier, is the orientation of this debris field necessarily indicative of the heading ar sea-level impact?

Quote:
"The remains of the aircraft will 'fly' just as well in water as in air, and since most seem to be postulating some sort of rotating motion at impact there is no reason why this should not continue during the 4000m drop resulting in ANY sort of orientation."
Cannot agree with any of that.

Quote:
"...all the wreckage tells us at the moment is roughly where it hit the surface."
It depends what you mean by roughly. For a start, the engines - presumably both detached at sea-level - would have gone pretty-much straight to the bottom. As mm43 commented some time ago, their position relative to this debris field is of the essence.

Maybe the BEA will divulge the Lat/Long of this debris field eventually. But I, for one, am not holding my breath. Pity: I can't see any third party being able and inclined to interfere.

swordfish41

15th Apr 2011, 09:31

Sorry to get back a bit late into this. I did say "hazard a guess," and it could be the object is the tail section, although I assumed that the swathe width was 700m, and that the altitude of the AUV was therefore much higher than 60m, suggesting that the object was also higher above the seafloor than auv-ee suggests. If it is the tail I expected to see an equaly large object at the western end of the debris trail, and I was influenced in this by mm43's graphic of the likely break up of the fuselage at impact.I disagreed with mm43's view that the the debris would be fairly well confined, and I was wrong about that too. However the two Remus vehicles will have completed the photo mosaic now and BEA will know just where everything is. I've followed all the threads from this incident from day one, and incredibly fascinating its been. Throughout I have had at the back of my mind a story told me by the Chief Lab Technician on Odin Finder. He was engaged to search for an RAF Jaguar that crashed in the Adriatic. The pilot had ejected quite late, and confidence was high that the position of the aircraft on the sea floor was known. After no trace was found he fielded the usual questions, "Is your equipment working properly?" "Have your technicians missed anything?" with his own, "where do you want the ship to go now, north, south, east or west?" My granny told me when I lost something that it would be in the last place that I looked.

Mr Optimistic

15th Apr 2011, 09:45

With respect to orientation, on reflection agree with BOAC's chastisement. However, the assymetry N/S, with apparent distribution linearly to the north not reflected to the south may reflect something. But perhaps if you stare long enough into the darkness you will eventually see a ghost. Hoped for a clear debris trail.

swordfish41

15th Apr 2011, 10:04

Mr Optimistic has hit the nail on the head. The great danger is to see what you want to see.

Chris Scott

15th Apr 2011, 10:06

swordfish41,

Further to previous posts by me and others, is it possible to say if the 070/250 orientation of the debris field has been created purely by the prevailing currents during the descent, or is it in any way indicative of the aircraft's heading at sea-level impact?

BOAC

15th Apr 2011, 10:42

Not 'heading' in my book. By the way, I'm puzzled why do you not view water as a liquid? "Cannot agree with any of that."

Debris orientation/position at 4000m will be governed only by the currents and the 'flying'/break off motion of individual separate parts and there will be a ZERO effect of any motion vector at impact. All bits will come to a pretty abrupt halt at immersion. Water is hard at that speed. As said, separated engines will go pretty much straight down. The fin/seat cushions etc float. Plot all points between?

Chris Scott

15th Apr 2011, 11:00

BOAC,

I cannot DISagree with any of that! But it is completely at odds with the sentence I criticised in your previous post:
"The remains of the aircraft will 'fly' just as well in water as in air, and since most seem to be postulating some sort of rotating motion at impact there is no reason why this should not continue during the 4000m drop resulting in ANY sort of orientation."

Re your latest: would you prefer "track"? Not sure the difference is significant in this case.

BOAC

15th Apr 2011, 11:20

Heading/track no matter. Neither apply. 'Track' becomes meaningless with no overall forward speed. Break off part of a wing and see what happens to 'heading' as the wreckage sinks. You can, in my opinion, deduce nothing.

My post is actually COMPLETELY in agreement with my previous. Hydrodynamics work pretty much as aerodynamics at low speeds. A wing will produce a force of some sort. An attached tailplane will produce a pitching motion as the wreckage sinks.

Next time you fill a deep bath, generate a gentle 'current' by moving your hand around in the water. Then throw in a small strip of metal and see if you can deduce from where and how it sits on the bottom which way it was travelling when it hit the water - or how fast, for that matter. Now imagine that bath thousands of times deeper.

JD-EE

15th Apr 2011, 11:28

Shadoko, you may be right that the bodies recovered were those not seated. However, on the old thread a fellow involved in recoveries from water suggest that dead bodies seem to work their way out even from tight seat belts when you have water to work with. They even work their way out of their clothes much of the time.

Given how small the pattern is I suspect those recovered may have been in seats such as those recovered. But they did not float to the surface from a seat still attached to a large piece of fuselage.

I find it interesting so many were not sitting and not strapped in. Were they holding a dance in the aisles for entertainment? It's another of the surprises associated with this accident.

JD-EE

15th Apr 2011, 11:41

Chris Scott, color me blabbymouthed broad but I'm going to riff a little. The superposition of the actual aircraft size images on the debris field was eye opening.

What we see, I suspect, is a very broken up, shredded airplane. We have pieces of different shape, weight, and buoyancy. The debris field has probably a shape more related to the currents and shapes of pieces as they fell. Engines and possibly landing gear will be least affected by currents or "flutter" effects. Small relatively light pieces will flutter more on their way down and be more subject to the current moving them slightly.

I'd bet the overall orientation reflects some prevailing current involved. And the width would be related to how much the pieces fluttered as much as it's a function of the current.

If that's accurate then one end has the heavy stuff. And the rest is graded by how much "flutter" and current moved them away from falling straight down. So I'd expect some "astonishing" juxtapositions of pieces.

We're not seeing an airplane there. We're seeing thousands of pieces of airplane all different sizes, shapes, and weights all dropped at nearly the same place into an impressively deep bathtub.

Edit: (Grin - I see BOAC got there before I did. I didn't think he'd make it after saying the plane would sort of fly equally well underwater.)

cuddieheadrigg

15th Apr 2011, 11:49

Shadoko:
In fact, I can't imagine this aircraft falling from 35000' to 0 keeping a "normal" attitude all along (and not attached passengers remaining in their seats*). Adding a storm, is this "flat" fall truly possible ?

Well, I may as well chime in (again).

Airspeed discrepancy in turb. Icing. Pilots quickly realise a stall is in progress and 'Alt law' in force. They pitch down to maintain airspeed, and manually control the throttles. Descending through the weather, they in theory may have levelled off a few times, but any pitch down would prodice a high-ish rate of decent. If the wings were iced then is that not akin to popping the lift dumpers?

So whatever the 'downward' speed, the aircraft still has forward motion, but despite recovering to 'level' flight a few times, the iced wings overcome available thrust and the drop cannot be reduced much.

Could it actually be described as a very hard ditching, with forward velocity possibly only about 250-300% of downward velocity IE still 'realtively fast in direction' but not to maintain flight.??

swordfish41

15th Apr 2011, 12:25

Chris Scott,
I'm beginning to regret saying anything. As you can see from the dispute about the object I thought might be the cockpit remains, its dangerous to make any assumptions from just one, third or fourth hand sonar picture. The point of my story about the technician on Odin Finder (a survey ship I first used for the Ark Royal) is that there is a big change in behaviour once objects make the transition from air to water, and I have to agree with the essence of BOAC's point.This was one of the reasons why I disagreed with mm43's view that the debris field would be realtively compact. Given the depth of water I think I said that I expected it to be spread over a kilometre. As I also said I was wrong.

What we have, publicly at least is a very rough indication of the location of the debris field, and an accurate last known position. I gather that a lot of people thought that the aircraft would have travelled farther from the last known position than it appears to have done. This obviously was the planning assumption behind the first searches. So there is a huge unknown here. What is also unknown is whether the aircraft remained substantialy intact after its impact with the surface,( I know the fin and parts of the galley and crew quarters were recovered, I'm not sure what else was) how long the wreckage remained on the surface before starting to sink and how it's break up was affected by the various currents it encountered in its descent, as well as what attitude it had adopted before its impact with the seabed, which would have cause further damage. Even the recovery of the flight data recorder and the cockpit voice recorder won't tell us much about that part of the aircraft's journey. mm43 made the point that the location of the engines in relation to the rest of the debris would be important in providing answers to some of these questions. Can I ask if it is safe to assume that they would have seperated on impact in all circumstances?

auv-ee

15th Apr 2011, 12:25

Forgive the noob question on sonar, but is the image produced on a single pass, eg from the rov above the eastern edge of the lane, or is it the addition of two half pictures, one from the east and one from the western pass ? Also what would the effective lateral beam width be, ie the length of image producted by a point object (are the N/S 'smearings' a reflection of pulse width and not debris dimension ?). Noting its a jpeg, any need to be careful about compression artefacts ?

See post 3169 http://www.pprune.org/6357167-post3169.html for most of this info. The published image appears to be mosaic of two images, one looking east (from the west side of image) and one looking west. The AUV travelled in the center of the dark bands (one to the west and one to the east). I do not expect that image compression has affected the image significantly. The north/south smearing is a function of beam width and vehicle motion.

Mr Optimistic

15th Apr 2011, 12:33

Autonomous Undewater Vehicle-Electronics Engineer ? Thanks. Wondered how it was done. Apologies for not having read your posting first time around. Any chance of a deconvolution algorithm ?

Lonewolf_50

15th Apr 2011, 12:37

In a jocular vein ...
Were they holding a dance in the aisles for entertainment?
Well, they were fresh out of Rio ... :)

But regarding things falling in water for about two and a half miles.

IF (big if) the wings maintain their general shape at impact (even if shearing off from fuselage at impact) then during a two and a half mile excursion down (after a brief dwell time at the surface as the internal cavities fill with water and buoyancy is eventually overcome) I'd expect that eventually, with tumbling action, the wing would take on a generally "tip down root up" alignment as the entire cavity fills with water. (Yes, there is probably fuel trapped within fuel tanks that would render the general buoyancy of the wing greater than other pieces as they tumble downward).

I'd expect the wings, were they separated from the fuselage, to be more, not less, subject to currents under the surface than most of the rest of the aircraft.

As I have not been able to view quite a number of the images posted (filter issues on my browser, I suspect), do they depict the wings still attached to, or separated from, the fuselage? Or, am I gettting ahead of it all, and resolution not sufficient to determine same?

EDIT: I had a look at the A330-200 fuel system (outline) from a 1999 era document here (http://www.smartcockpit.com/data/pdfs/plane/airbus/A330/misc/A330_Flight_Deck_and_Systems_Briefing_For_Pilots.pdf).

As I understand the flow, engines are fed from wing tanks (inner) and wing tanks replenished by the, outer, trim, and center tanks as fuel depletes over time. (Do I understand that correctly? It is a sketchy summary of the fuel system.)

(*Scratches head.* If not, then perhaps the flow is out to the engines from the center tank (via plumbing and pumps) and center tank replenished from all other tanks ...) Not all that important, but of interest to consider which cavities / tanks were emptied or low on fuel at that point in the flight, and how that would influence downward trajectory toward the sea bed.

Mr Optimistic

15th Apr 2011, 12:44

Given the rough ride surely the signs were on and every one seated ? Don't know what proportion of CC identified but can't trust the 'it all happened so fast theory'. Some pretty big stuff escaped the wreckage. Surprising that objects with such different 'ballistic coefficients' arrived in more or less the same place after a 4000m descent and that the field has such symmetry. However, there must be a reason..........

lomapaseo

15th Apr 2011, 13:24

As I note a lot of discussion here about aircraft parts sinking thousands of feet to the seabed I thought taht I would offer some ancedotal evidence I came across years back.

Apparently the US Navy was doing a recovery years ago of an F14 that was sitting about 10000 ft down at the bottom. Their submersibles at the time were manned and even after locating the scattered wreckage they would have a difficult time going from one end of the field to the other, since they really didn't know precisely (enough for vision) which way they were heading and where the ends of the field were.

The mother ship with its gear did know where it was on the surface but not where the submersible was. I'm sure today the technology is a lot different. What they did back then was to take a whole bunch of 55 gallon drums, paint numbers on them, then cut holes in the drums then align the mother ship in a line somewhere (they hoped) over the expected debris field and then put the drums over the side of the ship at time intervals while underway.

The drums sank to the bottom (10000 ft down) and presto even with the various currents they were found later by the submersible strewn out roughly in a line that transversed the debris field (in a random drection).

Now I'll leave it to the reader to draw any inferences they care from that experiment ;)

JD-EE

15th Apr 2011, 14:06

Ah. Lone, the pictures show a 200 meter high by 600 meter wide major field of debris with a few outriders. The field is vaguely whale shaped with about 300 meters by 150 meters of dense debris and a lump out maybe 300 meters to the fat end of the whale shape and a little knife shape sticking out from the middle of the whale and another short bright line of something maybe 400 to 500 meters away on the same side as the "knife". Compare that with the size of the plane itself and you can easily see this isn't well related to the size of the plane. It fits within the debris field with a lot of spare no matter which way you turn the plane. (The whale points roughly to the East for its "head" end. I bet that's where the engine is with the rest being where the smaller pieces fell. So the currents seen were predominantly east to west. That's a surmise, though. I'm no expert in this.)

grity

15th Apr 2011, 14:46

BOAC: Hydrodynamics work pretty much as aerodynamics at low speeds. A wing will produce a force of some sort. BOAC I agree with you, the main difference between falling in air and in water is the specific whight of the medium, and it goes into the speed formula with his square root.....
water is 1000 times heavier than air, sqrt 1000= 31.6

so if it was fallen through the air with 75 m/s it will sink under water with a dimension of 75/31,6=2,4 m/s
and so it will need around 4000/2,4=1666 sec (half an hour!) to reach the sea bottom

a very long time to turtle around

grity

p.s. again my question: what else did wie see on the underwater picture with the wing??
http://www.pprune.org/6352263-post3037.html

sensor_validation

15th Apr 2011, 17:26

The original pictures are available on Sea search ops : wreckage images (http://www.bea.aero/en/enquetes/flight.af.447/images.du.site.php) - I guess the highest quality?

Are the 2 images both the same engine?

Mr Optimistic

15th Apr 2011, 17:52

For the Titanic, estimates of terminal speeds between 20 and 60 mph are talked about. Judging by the photo's of the engines which look chewed up but are not buried in the sediment wasn't too high a speed. 20 mph would give less than 9 minutes.

valvanuz

15th Apr 2011, 18:47

:* 60mph is awfully fast. Fastest nuke sub (Russian) barely reached 45kn. Average is in the 25 to 30kn range with big powerfull propellers and hydrodynamic shape...

Chris Scott

15th Apr 2011, 18:52

Thank you swordfish41,

Apologies if my series of questions have the tone of a precocious boy in class... Think you've answered all them, except:
"Could the laterally-lying pieces extending northwards include a wing box?"

Last night (APR14/2120z), with his excellent enlarged image, mm43 posted (http://www.pprune.org/tech-log/395105-af-447-search-resume-176.html):
"....If this is the case, then the heading at impact was around 070°T."
In the wee-small hours here in Blighty, I interpreted "impact" as being what I call the "sea-level impact" (end of flight). I now realise he was probably referring to the sea-BED impact...

Does everyone agree that the answer to my question
"Would the debris field alignment (approximately 070/250) necessarily be roughly indicative of the heading at sea-level impact...?"
is something like: "No, Scott, think again – (stupid boy)." ?

Chris Scott

15th Apr 2011, 19:03

Lonewolf50,

As you still seem to be waiting for an answer to your fuel-tank management question, and with A330-drivers PJ2 and CONF_iture apparently AWOL, I'll try and shed some non-definitive, tentative light (thanks for that link).

Fuel is fed to the engines from the inner wing-tanks. For efficiency, in the cruise the CG is normally adjusted aft of the ideal for take-off and landing. On all A330s, the tailplane trim-tank helps, but I'll ignore that for the moment. This A330-200 also has a centre tank. This is, broadly speaking, forward of the wings, so is generally only used if the crew needs more than full-wings (71.7T) for the flight. In flight, it is emptied first, into the inners, which may also help with wing-bending relief. (Fuel will never be transferred from wings to centre tank.) In this case, the take-off fuel was only 70.4T, so the centre tank would have been empty throughout. In the climb, some fuel is normally transferred to the tailplane trim-tank, unless it's already full, pushing the CG aft by a suitable amount.

Wing-bending relief is also achieved by retaining full outer wing-tanks until the fuel in the inners is fairly low. When there's about 7T (tonnes) between the 2 inners, the 2 outers transfer their combined 5.7T into them. This does not happen until the trim tank has been emptied (via the inners). So at this point there is about 12.7T fuel remaining (< 3 hrs).
Normally, all this is controlled automatically (no grizzled flight-engineer...).

At the LKP, with nearly 7 hrs still to go to CDG, the fuel distribution should have been roughly as follows:
Tailplane full (4.9T) or part-full; *
Centre empty;
Inners part-full; **
Outers full (each 2.8T);
Vent Tanks empty (outboard of the Outers).

* According to the zero-fuel CG, and the current fuel distribution elsewhere, to optimise CG (relative to MAC).
** They were nearly full (all but ~0.6T each) at take-off, and would have been depleted to the extent of the total fuel burned (in 3:41 of flight) PLUS whatever was in the Trim tank at the time. (I think it would have been empty on departure.)

Hope this helps,
Chris

valvanuz

15th Apr 2011, 19:03

Given that all studies show weak and rather random sea currents, I would agree. Nevertheless, I would not bet on east to west vs. west to east direction... That bird was obviously way out of control!

PJ2

15th Apr 2011, 19:10

Lonewolf, JD-EE, in searching for some idea of the wreckage condition and layout, the China Airlines A300 stall accident at Nagoya in April of 1994 may be of interest.

The aircraft stalled on short final, (to keep this short, the reasons for the accident are in the report, here (http://www.mlit.go.jp/jtsb/eng-air_report/B1816.pdf)), and impacted in essentially the same attitudes as the BEA has described.

From the report (translated from the Japanese):
"3.1.4.1 From the DFDR records, it is estimated that the aircraft stalled, then descended steeply with wildly changing roll angle, and impacted the ground.

The spot where the aircraft hit the ground was an unpaved, flat landing area. There were marks left on the ground surface that clearly identified those portions of the aircraft which had hit the ground. From the shapes of the marks and these positional relationships as well as the condition of destroyed landing gears, it is inferred that on impact, the aircraft was in a somewhat left-wing down, nose-up attitude, and was in an almost level attitude." - p67,
The impact would be essentially the same, but the hard land surface in the Nagoya accident permitted a longer/wider distribution of wreckage with perhaps far more secondary damage as parts collided with each other and ground objects before coming to rest.

A water impact, as has been pointed out, would be as hard, but once the initial impact had shattered the aircraft, the high inertial energy vertical and horizontal components of the resulting wreckage would quickly be absorbed by the water, remaining largely together in a collected mass, their individual weight and buoyancy then acting as a distribution filter, slowly separating heavier from lighter parts as they descended and were affected by whatever currents there were, creating the pattern observed in the AUV image, (as observed by others, JD-EE in particular has described quite well above). I think a general conclusion may be made as to direction of flight. All parts descending through the same "water column" (roughly), would be affected in the same general manner.

And it doesn't seem as though some of the larger parts have, due to their shape, etc, "flown/glided" down (as some have observed I know), but rather may have "glided locally" and largely together, settling as described, by weight and buoyancy as a group.

Regardless of surface, the Nagoya accident shows quite clearly what happens to the fuselage in a high-vertical-speed impact - it collapses and, we may surmize, the substantial volume of air thus instantly compressed would escape through the breaks which would likely be at the mid-line of the fuselage as viewed on-end, with fractures at those fuselage sections we have seen before...behind the cockpit, just in front of and just behind the wing-box, and just ahead of the vertical/horizontal stabilizers and pressure bulkhead, (the section shown being manufactured in Machaca's superb photographs at post #3170 (http://www.pprune.org/tech-log/395105-af-447-search-resume-159.html#post6357179)), all permitting large sections of the cabin to be ejected relatively cleanly, without more than glancing collisions with other parts, leaving them in the condition we see in the collected wreckage.

Chris, just spotted your note to Lonewolf...in my recollection of the system, that was a nice description of how it works. Bit different than the DC8...

Lonewolf_50

15th Apr 2011, 19:30

At the time of the accident, with nearly 7 hrs still to go to CDG, the fuel distribution should have been as follows: Tailplane full (4.9T) or part-full; * Centre empty; Inners part-full; ** Outers full (each 2.8T); Vent Tanks empty (outboard of the Outers).

Chris
Thanks very much, I had it a bit arse backwards there.
The thought I had of the wing tanks having a lot of fuel (in combination) seems roughly right. I'll guess that the fuel tanks suffered trauma, and fuel escaped both as parts first floated just after impact, and then eventually began to sink. I have an idea beginning to form that any fuel slick might not have been very large ...

PJ2:
Thanks as well for the explanation, and the link to the Nagoya crash.
A water impact, as has been pointed out, would be as hard, but once the initial impact had shattered the aircraft, the high inertial energy vertical and horizontal components of the resulting wreckage would quickly be absorbed by the water, remaining largely together in a collected mass, their individual weight and buoyancy then acting as a distribution filter, slowly separating heavier from lighter parts as they descended and were affected by whatever currents there were, creating the pattern observed in the AUV image, (as observed by others, JD-EE in particular has described quite well above). I think a general conclusion may be made as to direction of flight. All parts descending through the same "water column" (roughly), would be affected in the same general manner.

grity

15th Apr 2011, 19:40

@mm43; pickyPerkin; Chris Scott

if we press the sidescan picture in the hight to 14% it lock much more as a view to a debrisfield....... smal parts to the left bigger one to the right
sortet by the different falling time and a slow deeper water current?
grity
http://s7.directupload.net/images/110415/cdy98q4c.jpg (http://www.directupload.net)

Turbine D

15th Apr 2011, 19:51

sensor validation
Are the 2 images both the same engine?

My guess would be that we are looking at one engine with a slightly different camera orientation (height, distance and lighting) in the two photos. The clue to me is the piping that extends outward and downward to the seabed. The chances of that being the same for both engines would be very great odds indeed.

PJ2

15th Apr 2011, 20:02

Lonewolf;
I'll guess that the fuel tanks suffered trauma
I think it is reasonable to posit that the wing surfaces would have separated as a result of a "hydrodynamic pressure surge" from the [incompressible] fuel, (discussed in the BEA Report on the Concorde accident, Appendix 9, in French here (http://www.bea.aero/docspa/2000/f-sc000725a/pdf/appendix9p.pdf), and on pg. 111 of English version of the entire report here (http://www.bea.aero/docspa/2000/f-sc000725a/pdf/f-sc000725a.pdf)), and relatively little air-space in the outer and inner tanks, and the horizontal stabilizers would likely behave the same way as they would have been full.

grity...very imaginative work - I was also examining it using various color filters to see what showed in terms of patterns, etc...

One thing about stretching...we have the vertical and horizontal scale so we have a ratio...does stretching the image maintain the ratio, I wonder? It's essentially 1:3...

mm43

15th Apr 2011, 20:15

Originally posted by grity ...
the main difference between falling in air and in water is the specific weight of the medium, and it goes into the speed formula with his square root.....
water is 1000 times heavier than air, sqrt 1000= 31.6

so if it was fallen through the air with 75 m/s it will sink under water with a dimension of 75/31,6=2,4 m/s and so it will need around 4000/2,4=1666 sec (half an hour!) to reach the sea bottomTechnically true, but Archimedes' principle gets involved at the air/water interface. As I have pointed out in previous posts there are reciprocal buoyancy moments that interact at the time of impact, and even during the course of a break-up, there will be items that are compressible and others that aren't. For instance, the moment the originally intact hull is breached, the total buoyancy moment is lost, but within the hull there are numerous items that retain buoyancy - not to forget the fuel.

This aircraft has broken up at the surface after a high AoA and high rate of descent impact. Some items, e.g. engines will part company with the pylon mounts immediately due to the obvious disparity in their mass and volume when compared to the intact area of the wing to which they were attached. The engines actual impact velocity will be further reduced by the difference between the acceleration force that stops the wing and the force that shears their mountings.

All that means is that it is not a simple matter to determine at what rate an object will sink, as it will depend on many factors that make up a homogenous mass. Some items with profiles that present "slippery" surfaces in a fluid dynamics sense may take trajectories that their shape permits, while other stuff will just "sink".

As has previously been said, there will be no rush to the bottom, as increasing pressure equals increasing surface friction.

There will be a relationship to where items are located on the bottom and the time that it took them to get there. A small subsurface current heading west will be responsible for some of the east/west distribution.

In the case of the HMS "Ark Royal", it would appear that it broke in two on the surface, and the two separate halves then had differently distributed centers of gravity and fluid dynamics allowed them to head to the bottom on differing trajectories. Remember that a ship that no longer floats will still have intact water-tight compartments that will impact on its center of buoyancy and cause its attitude to change during the sinking process. Hence a possible reason the two halves were found so far apart.

HazelNuts39

15th Apr 2011, 20:20

Lonewolf;
I'll guess that the fuel tanks suffered traumaLook also at what appears to be wing lower skin attached to MLG, with tank access holes.

HazelNuts39

15th Apr 2011, 20:42

the main difference between falling in air and in water is the specific weight of the mediumJust to keep it simple, in water as in air, three forces and their moments are at play on a free-falling body: Weight, buoyancy and fluid dynamic force. Buoyancy is equal to the weight of the displaced volume of the medium, usually negligible in air but not in water. The fluid dynamic force is equal to fluid density times velocity-squared times a factor that depends on the geometry of the moving body: dimensions, shape and orientation relative to the direction of movement.

auv-ee

15th Apr 2011, 20:48

As has previously been said, there will be no rush to the bottom, as increasing pressure equals increasing surface friction.

Generally agreed with your post, except this statement. Perhaps you meant something else. The density of water changes very little (some, but not much) with increasing pressure. The form-drag (in the applicable regime) is proportional to the density of the media, and no other property of it. Thus drag is not a significant function of depth.

Edit: mm43 did mention skin drag in his post, and I believe that involves the viscosity of the media. I found a reference (Water Viscosity at High Pressure and Temperature (http://adsabs.harvard.edu/abs/2006AGUFMMR43C1094G)) that shows the viscosity to double at 1Gpa, roughly equivalent to 4000m depth. However, I think the drag of these A/C parts is dominated by form drag. I'm definitely getting out of my area here, but I've never heard the MEs I've worked with factor depth into drag calculations.

--

I might point out that objects that tend to "kite" off the vertical during descent will also be likely to turn. Thus most objects will still end up near each other after either a straight or spiral descent. The example of the Ark Royal differs in that symmetry and mass will make the turn rate very slow, and thus a hull section could wind up a long way away. It is the rare object that will drift away on a constant heading.

Shadoko

15th Apr 2011, 21:50

Hi,

About the meanings of the wreckage sonar picture : "The most notable discovery the team made was that the ship had split apart, the stern section lying 1,970 feet (600 m) from the bow section and facing opposite directions." (RMS Titanic - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/RMS_Titanic)). Titanic. A ship, standing (not enough...) at the surface. No speed. No big "splash". Sea like a mirror, as it is known. About the same depth. So ...

HazelNuts39

15th Apr 2011, 22:07

what can be the struktur right forward of the wing? part of the wing or part of the fuselage?Just a guess: I think we are looking at the upper skin of the left wing tip, with aileron hinge brackets. The structure in the background could be a slat.

mm43

15th Apr 2011, 23:01

Originally posted by auv-ee ...
Perhaps you meant something else.Perhaps I did!

An object sinking under the influence of gravity is subject to a resistance/drag force which increases with velocity. A maximum velocity is reached when the drag force equals the propelling force. This constant velocity is the "terminal velocity". There is also a case where objects are moving at low speeds and where turbulence is a minor factor, that viscous drag determines the "terminal velocity".

So in a sense, you can "have your cake and eat it to". In the original rather crass statement, I should really have said that objects will reach a terminal velocity rather implying that pressure and viscous drag were directly related.:ouch:

auv-ee

16th Apr 2011, 00:33

...the stern section lying 1,970 feet (600 m) from the bow section and facing opposite directions." (RMS Titanic - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/RMS_Titanic)). Titanic. A ship, standing (not enough...) at the surface. No speed. No big "splash". Sea like a mirror, as it is known. About the same depth. So ...

This phenomenon was just discussed in posts 3550 and 3553, above, and is, I believe, applicable to the Titanic.

Machinbird

16th Apr 2011, 03:58

AUV-EE comment
I might point out that objects that tend to "kite" off the vertical during descent will also be likely to turn. Thus most objects will still end up near each other after either a straight or spiral descent.
Good comment! The MLG strut probably came down like a helicopter after the surface breakup due to the attached skin panel. Any angle of attack of that 'vane' would cause a rotation. Probably accounts for the relative angle of the panel and gear (appearance of being extended).

Are we agreed that the subsurface current dispersing the wreckage was in a East to West direction?

The dispersion of this wreckage reminds me of an accident where the fuel washed components of the fractured forward fuselage out of the crater and they were dispersed with port side components further from the crater than starboard side components but spread out along a narrow angle corresponding to the distance off axis in the aircraft. In that case, it was easy to find components by observing what was in the vicinity.

With AF447 components being sorted by starting position, and fall rate, it is a much more difficult problem to figure out where to find things. But if the recorders are as dense as others have indicated and if they have torn loose, at least they should be close to other items of similar density (as modified by their starting position).

I expect that the recovery team will go for the tail section first to attempt to locate the recorders there. If they are no longer there however, they had best be careful because once they disturb the 'indian signs' on the bottom, they will have to locate the recorders by means other than visual.

AF447 is a bit more broken up than I was hoping for. I expect one of the reasons that the pingers were not located is that they are buried and the bottom muck attenuated the signal.
I expect people at BEA and the recovery team are going over the wreckage pictures trying to develop an initial orientation for the aircraft so they can make some educated guesses where things can be found.

auv-ee

16th Apr 2011, 04:33

Are we agreed that the subsurface current dispersing the wreckage was in a East to West direction?

That is the way the image looks to me. I don' t know if that interpretation is supported by any other current data. At this point, the debris dispersion may be the only evidence of the actual current at that time and place. It may be that no one really knows the current by any other means, because the measured data are so sparse and the current is so variable.

mm43

16th Apr 2011, 04:51

Originally posted by Machinbird ...

Are we agreed that the subsurface current dispersing the wreckage was in a East to West direction?In the Shom (http://www.bea.aero/fr/enquetes/vol.af.447/shom.050609.pdf) PDF document on page 5, there is a current chart showing that at 1,000m the current is west at about 8cm/sec. I suspect possibly a little slower at 4,000m. Photographs of debris show no sign of any sand scouring and it looks very still on the bottom.

grity

16th Apr 2011, 06:48

I think we are looking at the upper skin of the left wing tip, with aileron hinge brackets. The structure in the background could be a slat. HazelNuts39, it is not only the tip, it is the middle part of the left wing "...NOT WALKE OUTSIDE THIS ARE...." in this area are spoiler not ailerons
but which slat has such a complex struktur? grity
http://www.bea.aero/fr/enquetes/vol.af.447/images/wing.jpg

JD-EE

16th Apr 2011, 12:11

Chris Scott, please leave the "stupid boy" off. I try to respect people more than that. (As one slightly your senior I can't even pat you on the head and utter words about "silly boy".)

(I might note you did get me to use my modest amount of gray mush to look again at the debris field size and figure out what it probably amounts to, which is not the plane's heading.)

Shadoko

16th Apr 2011, 12:40

Hi,

According to the relative sizes of the "DO NOT WALK OUTSIDE THIS AREA" writings and the wing width, it seems that quite half the front part of the wing is missing. Or bent downward? Is this compatible with a belly strike, nose up? In other way, all mobile surfaces seem ripped out. What attitudes at impact could be compatible with both? Very high speed, anyway, no?

Machinbird

16th Apr 2011, 19:08

There are several elements that are outliers in the scan image. By outliers, I mean wreckage lying at a greater distance from the mean wreckage centerline than can be explained by their starting location on the aircraft. I am reposting MM43's image below:

http://i53.tinypic.com/2ceix60.jpg

Possible explanations for these outliers are:

Thrown away from the aircraft during the initial crash and flew through the air for some distance.
Floated on the surface for some time before sinking.
Glided in a very slow turning stable configuration on its way to the bottom.
Identification of these outliers and their configuration should answer which influence applied. The elements that could have been thrown have particular interest in that part of the aircraft's velocity vector can be imputed from their location (but not directly from its final position). It is still necessary to estimate its time of flight in the water column.

Probably the best way to impute the aircraft's final heading is by drawing a line normal to the locations of the two engines. It won't be perfectly accurate, but probably within 20 degrees of actual due to dispersion probabilities. The heading/reciprocal heading should be inferred by relative position of various wreckage elements or by actually ID of a particular engine.

CONF iture

16th Apr 2011, 19:13

Transportation Safety Board of Canada - AVIATION REPORTS - 2008 - A08W0007 (http://www.tsb.gc.ca/eng/rapports-reports/aviation/2008/a08w0007/a08w0007.asp)

Very informative report by the canadian TSB.
A good reminder how inputs on flight controls at cruising flight levels must be moderate.

Also of interest :
The automatic reversion to alternate law due to differences in computed angle of attack values was also a product of pilot control inputs.

Mr Optimistic

16th Apr 2011, 20:38

There are a number of 'objects' which are doubled up, ie have a parallel twin just to one side (including the northern most outlier). Presume these are in fact images one of another where the two scans didn't quite align when the composite was constructed ?

HarryMann

16th Apr 2011, 22:25

Generally agreed with your post, except this statement. Perhaps you meant something else. The density of water changes very little (some, but not much) with increasing pressure. The form-drag (in the applicable regime) is proportional to the density of the media, and no other property of it. Thus drag is not a significant function of depth.

Well, you might think that, but I couldn't possibly comment...

But will, anyway.

If the viscosity changes significantly with depth (x 2), then Reynolds number does too (for a given free-fall speed).
Form (profile) drag definitely changes with Re, as Re determines the flow regime* (hint: dimples in golf ball make large difference, they simulate a much higher Re)

Thus, I'd say, even profile drag is depth dependent, although one would have to iterate to get the terminal speed (Re not invariant with speed), which may go up or down with >> Viscosity. Not going to predict that here.. :rolleyes:

Agree that profile drag (form drag) is an order of magnitude more than skin friction, but this would still change somewhat

* e.g. Laminar separation bubble; vortex wake; fully attached (inviscid); fully separated flow, etc

NB. This effect is either negligible, small or if Re near a critical flow regime change (Re crit) > then could make quite a big difference to drag.
Streamlined shapes (auvs en vol de ligne!) at a particular (low) speed range could well, as you say, have effectively depth independent drag.
But certainly not every object at any speed...

Chris Scott

16th Apr 2011, 23:49

Salut Conf iture,

I think that sensor_validation and you raise a very relevant point about this serious incident or accident in 2008, which was exacerbated by the PF’s over-control in roll and yaw. The TSB of Canada’s report (http://www.tsb.gc.ca/eng/rapports-reports/aviation/2008/a08w0007/a08w0007.asp) makes very interesting reading. I’m going to repeat the sentence you quoted:

“The automatic reversion to alternate law due to differences in computed angle of attack values was also a product of pilot control inputs.”

Here are some passages from the report’s description of the way the aircraft was handled after the PF disconnected the AP in unexpected wake turbulence, which he apparently mistook for AP misfunction.(Any highlighting is mine.)

Quote:
"During the 18-second duration of the event, heading varied from 065ºM to 086ºM. The captain reacted to the rolls with a total of nine sidestick roll inputs, accompanied by coordinated rudder pedal deflections. Five sidestick inputs were to full travel of 20º."

Quote:
"From 06:48:07 to 06:48:25, pilot sidestick roll inputs were 90º out of phase with aircraft motion. From 06:48:07 to 06:48:15, lateral accelerations and heading deviations were approximately 90º out of phase with the rudder pedals. This indicated that after the autopilot was disconnected, most of the aircraft motion in the roll axis resulted from pilot inputs and that lateral accelerations were due mostly to pilot rudder control inputs."

Quote:
“Abnormal accelerations in the normal or vertical axis were correlated with changes in angle of attack, and sidestick pitch control inputs opposed these aircraft angle of attack excursions.”

I think the expression “sidestick pitch control inputs” may have been unintended, because it goes on to say:
“...the accelerations in the vertical were a result of external influences on angle of attack associated with wake turbulence,”
　
In March 2008 – long before the issue of the TSB of Canada’s report – PPRuNe (as CONF iture, PJ2 and others will remember) was discussing at length a rough landing by an A320 in a limiting crosswind at Hamburg. The subject of SIDESTICK technique came up when someone gave a link to this video of a pilot using the sidestick during a crosswind landing. (N.B. This was NOT a video of the Hamburg incident!) One poster described it as coffee stirring. Having seen it before from the jump seat during 12 years’ line-checking, I called it “sidestick abuse” in this post:
http://www.pprune.org/tech-log/316096-lh-a320-rough-landing-hamburg-24.html#post3979423

[SIZE=2][FONT=Verdana]As for the use of "co-ordinated" RUDDER at cruise speeds, I would argue that it was nothing of the kind: the report suggests that, notwithstanding the rudder-travel limiter, A320-family pedal loads need to be increased. (No comment re the A330.) Should rudder ever be used in cruise-flight, apart from the asymmetry case? I remember being disturbed by one copilot, who moved a pedal significantly when stretching a leg that had "gone to sleep".

In view of the possibility that AF447 encountered sudden, severe turbulence, perhaps we should be adding another scenario to the list of possible causes of LOC and Control-Law degradation. Could it be compatible with the analysis of ACARS messages? I think it might be.

JD-EE

17th Apr 2011, 01:17

JD-EE

17th Apr 2011, 01:31

HarryMann, auv-ee is exactly what his moniker implies. He is involved in the AUV industry as an EE. We've conversed a bit. He's anything but dumb or ignorant of the underseas environment.

Something of note on my personal experience is that I've watched activities at levels a little below the surface and thanks to BP's many streaming videos under very deep water. I could see no salient differences in the way materials moved or the vehicles moved. Water does not get thicker or denser as you go down except by very small amounts. It's viscosity/pressure profile shows very little change until you hit the phase change that turns it into some form of ice. Water is NOT thick air. So you cannot infer much of anything from your experience with air.

MG23

17th Apr 2011, 03:00

This phenomenon was just discussed in posts 3550 and 3553, above, and is, I believe, applicable to the Titanic.

From what I remember the belief as of a few years ago was that the Titanic's bow broke off at the surface, and the stern then turned around before sinking. New evidence might have changed that since.

auv-ee

17th Apr 2011, 04:04

HarryMann:

I am generally aware of the effect of Reynold's Number on drag regimes, but as this is not my area (I am an EE, as JD says), I can only say that it is my understanding, from having "watched hydrodynamics done" :) , that form drag dominates for the conditions of interest here. If anyone still cares at the end of the week, when I return from travel, I will ask an ME who does this sort of work for a more definitive answer.

Outliers:

The target to the north might, as others have suggested, be a piece that drifted on the surface before filling with water and sinking, or it might be something that is not related to AF447.

Machinbird

17th Apr 2011, 04:42

Machinbird, what would it take to throw something four football fields? Answer that and I'll entertain your notion.

I'd rather expect they were large more or less flat surfaces that could have flown a little as well as fluttered on their way down. That might be pieces of one of the wings. Then, again, it might not. But, THROWN more than four football fields? About the only thing that had a prayer of being thrown that far would be the VS. And we know where it was found.

JD-EE, the one fair sized piece up to the North almost certainly had to be a float-sink event.
The large parts significantly away from the centerline are more what I'm interested in. They are located roughly in the center of the field E-W and are in a rough N-S alignment and located over a greater distance than their original location on the aircraft would account for.
AUV-EE's comment about items circling or spiraling in their descent applies. There is nothing to stabilize them except their own rotational inertia. Only when you begin to consider ship size objects do these inertial stabilization effects become really significant (really big circles).

grity

17th Apr 2011, 05:12

@JD-EE the viscosity of water changes a little bit with the amaunt of salt in it.....

but if air is part of the bouyancy, this air will be compressed under the waterpressure, so in that case the bouyancy decrease with deph, and this objekt then sinks faster

To the wing: now I think it is the right wing, (not the left) seen from the front
the text "do not walke outside this area" is written two times on each wing

auraflyer

17th Apr 2011, 06:46

grity wrote:

the text "do not walke outside this area" is written two times on each wing

This sort of shows it:

Photos: Airbus A330-203 Aircraft Pictures | Airliners.net (http://www.airliners.net/photo/Air-France/Airbus-A330-203/0596825/L/)

edit:

see also

Photos: Airbus A330-203 Aircraft Pictures | Airliners.net (http://www.airliners.net/photo/Air-France/Airbus-A330-203/1365991/L/)

and

Photos: Airbus A330-203 Aircraft Pictures | Airliners.net (http://www.airliners.net/photo/Air-France/Airbus-A330-203/1516944/L/)

2nd edit:

Really going out on a limb here ... the block of French text is longer than the block of English text.

It looks like the French text block appears inboard on the trailing edge labelling of each wing, and outboard on the leading edge labelling.

On the left wing, it therefore looks like the block of English text is on the left, with the block of French on the right, in both places.

But on the right wing, it looks like the English text is on the right for each.

If that's correct, since the image you posted has the English block on the left, this suggests it is the left wing.

Anyone have better eyes or access to the full size picture, which would assist?

PJ2

17th Apr 2011, 08:42

auraflyer;

I've worked with the images a bit to bring out greater detail. Unfortunately the highlights have no detail at all and just "gray down" so I've left them as is.

http://i277.photobucket.com/albums/kk76/batcave777/AF447/wingdetailfinished.jpg

As suggested I think we're looking at the left wing aileron mounts in the above photo.

In the same image, but on the right in the dark background may be the slat tracks and perhaps some of the anti-ice plumbing:

http://i277.photobucket.com/albums/kk76/batcave777/AF447/wingdetailcopy2.jpg

In the following image of the right wing, looking forward, I now wonder if the flap track to the right of the photograph is the #2 track on the right wing, and where the engine pylon was is just to the left where the horizontal "V" is in the skin-join, and the where the #1 flap track was is just to the right of the gear.

I believe this after examining a number of drawings and suitable photographs; - the distance from the MLG to the still-visible flap track is too long for that track to be the #1. If true, it means the pylon is completely missing along with the main wing box forward of the rear spar to which the rear trunnion of the gear is fastened. The rivet and fastener detail is over-exposed in this area and the detail is difficult to bring out.

In fact it is apparent that all the lighter structure forward and aft of the wing box is separated...all flight controls etc and their support structures are all that remain.

http://i277.photobucket.com/albums/kk76/batcave777/AF447/landing-gear-aenlarged.jpg

In the following image, (which I have rotated 90deg CCW), of the left MLG, if we look at the retract cylinder, it can be seen that it, and the side brace have sheared from their fittings on the MLG strut. Also, the small uplock pin near the bottom of the strut (two small 'ears') is missing, lending some support to the notion that the gear broke away and began its extension at impact, as discussed.

http://i277.photobucket.com/albums/kk76/batcave777/AF447/lftlanding-gear-enlargedburn-dodge.jpg

Two re-worked images of the engine to bring out greater detail:

http://i277.photobucket.com/albums/kk76/batcave777/AF447/engine-bfinished.jpg

http://i277.photobucket.com/albums/kk76/batcave777/AF447/engine-afinished.jpg

mm43

17th Apr 2011, 09:09

PJ2;

I was looking at the last photograph of the engine and realized that it had probably arrived at the bottom rear end first. The reason for saying that is the small crater visible there, but no signs of a heavy landing on the forward end.

Likewise, the MLG has a a pair of wheels that have dug in, but everything else is pristine, with no signs of current scour round any of the photographed items.

Its very obvious that the impact trauma was extreme.

chrisN

17th Apr 2011, 09:37

MM3 - just clariifying - you mean the impact trauma at the sea surface/ditching, not at the sea bed when these things hit bottom?

(By the way, many thanks to you and the other well-informed people on here who contribute so much really helpful technical data and research, and have put up, with far more patience than I would have, the ill-informed queries and theories of people who know notthing and think they know a lot!)

grity

17th Apr 2011, 11:28

On the left wing, it therefore looks like the block of English text is on the left, with the block of French on the right, in both places.
@ auraflyer, brilliant analysed ! the french text can be a little bit like "ne pas marche.......(à l'extérieur de cette région???)"

if airfrance never changed the side of the text, it must be the LEFTwing!, but possible the break line along the middle of the wing deludes us, and we even look from the front to the wing..... the fuselage then was to the left side of the picture and not to the right??? grity

BOAC

17th Apr 2011, 11:34

chrisN -"you mean the impact trauma at the sea surface/ditching" - absolutely, in my book. I cannot see any way that a wing section could hit the seabed hard enough to cause that damage. I might surmise that a wing section, if tumbled along the sea bed by strong currents, could be extensivley damaged, but since it appears to lie near the other debris I think that scenario is unlikley.

As BEA proposed, some impact.

Mr Optimistic

17th Apr 2011, 12:43

Well, no expert but...

If the separation into parts occured at impact with the sea the dispersion during the fall to the sea bed was relatively limited (what is the main debris field 400m by 50m ?) and unchaotic (linear). The l:d ratio of the debris is about 8:1 excluding outliers, that of the pristine fuselage about 12:1 as I understand ( 60m x 5m).

Is it a coincidence that in its basic form it reflects the geometry of the original structure ?

There is no 'fanning' at either end visible as you might expect if parts were being sorted by density and slowly separated.

Presumably at least some of the linear stretch would be due to the motion as the aircraft slewed across the surface after impact and isn't it at that phase, were there is reasonable speed compared to any subsequent current, that any sorting by form factor/density etc would have occured.

Is everyone so sure that the orientation of the debris doesn't give more information ? If the fwd and aft ends of the a/c are subsequently found at either end of the debris trail, it would be a clincher wouldn't it ie (ie that the debris reflects heading at impact)?

If the main structure stayed together, then perhaps not, but then would you expect the separated parts to so neatly fall in line ?

As the ratio of structure dimension to debris trail doesn't depart much from the original, about 10:1 each way (and there is plenty of rough calc here), perhaps consistent with a limited fwd speed relative to vertical at impact.

auraflyer

17th Apr 2011, 12:44

Thanks Grity. I think the French might read "Ne pas marcher a l'exterieur de l'encadrement", which would make sense, but I'm not certain.

Best image I can find is Photos: Airbus A330-203 Aircraft Pictures | Airliners.net (http://www.airliners.net/photo/Air-France/Airbus-A330-203/1365991/L/&sid=e8187eb5e28035eaeef2a3ad653f3f4d)

PJ2, great work on the pics. I don't know enough to comment on your identification re the flap track, but looking at p13 of the BEA 2nd report, I think none of the lighter structures forward were recovered (in fact from either wing).

Chris Scott

17th Apr 2011, 13:27

Quote from mm43:
the MLG has a a pair of wheels that have dug in, but everything else is pristine,

Quote from PJ2, re Left MLG assembly:
Also, the small uplock pin near the bottom of the strut (two small 'ears') is missing, lending some support to the notion that the gear broke away and began its extension at impact, as discussed.

(Thanks for the enhanced images!) Yes, what a noteworthy difference between both MLGs and the rest of the debris...

Chris Scott

17th Apr 2011, 14:10

Quotes from Mr Optimistic:
Is it a coincidence that in its basic form it reflects the geometry of the original structure ?
...Is everyone so sure that the orientation of the debris doesn't give more information ? If the fwd and aft ends of the a/c are subsequently found at either end of the debris trail, it would be a clincher wouldn't it... ...?

At risk of looking foolish all over again (my back is broad), I shall merely say that I notice a degree of hesitance (wouldn't go quite as far as to say inconsistency) in some of the analyses on this subject.

Sometimes, what is staring you in the face can be dismissed as just too simple to be true. I still wonder.

Shadoko

17th Apr 2011, 14:17

Hi,

By looking at auraflyer wing picture link and the BEA picture, it seems that many "details" are suggesting a rear view of the left wing:
http://i24.servimg.com/u/f24/14/14/01/64/wing_c10.jpg

(The images were distorted to compensate for different viewing angles. Without clear picture of the A330 wing leading edge structure, a small doubt subsists).

Chris Scott

17th Apr 2011, 14:34

Shadoko,

Bien-fait, Monsieur. Can you say which spoilers they are? 2 & 3?

Shadoko

17th Apr 2011, 15:19

Hi,

Can you say which spoilers they are? 2 & 3?

IF the BEA picture shows the left wing, and IF the writings are in the same place as on the picture http://cdn-www.airliners.net/aviation-photos/photos/1/9/9/1365991.jpg of the auraflyer post, they are n°2 and 3 according to this post : http://www.pprune.org/tech-log/395105-af-447-search-resume-64.html#post5722863
So, the wreckage in the upper right corner of the BEA picture could be part of the leading edge structure? With the 3 parallel "ribs" (?) from the wing intrados?
But ... make no mistake:I am just a curious with no knowledge in aeronautics nor a/c!

JD-EE

17th Apr 2011, 15:29

Chris and others....

Here is a fairly simple experiment to carry out. Get a tall pail or bucket. Fill it with water. Let it sit awhile so that it's stopped all motion.

While it is stopping raid, a sewing kit for some needles, buttons of various sizes, thimbles, and so forth. (Don't mess up any of the bobbins or things like that. Be kind to the owner of the sewing kit.) Create an arrangement to have them fall straight into the water. See if you notice any patterns that appear when the debris hits the bottom and settles.

A taller the bucket and the wider the array of objects will probably give clearer results.

The results I am looking for are similar to the arcade type gadgets which have you drop a coin through water to get it into a specific slot. These gadgets make a lot of money. The coins all flutter and slip aside.

Draw conclusions as you will. I contend that the array on the bottom is fairly surprisingly compact. Currents must have been really slow compared to the rate of fall through them.

Machinbird

17th Apr 2011, 17:21

Mr. Optimistic
Is everyone so sure that the orientation of the debris doesn't give more information ? If the fwd and aft ends of the a/c are subsequently found at either end of the debris trail, it would be a clincher wouldn't it ie (ie that the debris reflects heading at impact)?

I suspect you are being a bit 'optimistic' sir.:) The bits on the bottom probably do reflect the orientation of the aircraft at impact, but not in the way you suggest.
For example, if the aircraft impacted in a N-S attitude and the wing tip navigation lights broke off neatly from the structure in comparable size lumps, you would find the green light fixture approximately one wing span to the east of the red light fixture and located roughly along the centerline of the wreckage pattern.
If the aircraft impacted in a E-W direction, you would find the two light fixtures north and south of the wreckage centerline, separated by approximately one wing span, and the line between the two fixtures would be approximately N-S. The displacement from the right edge of the wreckage field would be dependent on fall rate through the water column and initial position on the aircraft in both of the above examples
There is a dispersion factor as aluded to by JD-EE. The dispersion factor is essentially a bell shaped curve around the calculated bottom impact position (based on the integral of local current velocity over fall time) and the span of the dispersion is proportional to radius of curvature that an object describes in its hydrodynamic trip to the bottom. You also have to consider possibility of collisions between particle elements deflecting them away from their original trajectories through the water.
All and all, it is a bit daunting problem in locating components of interest, but not impossible. If you find an element of comparable mass and hydrodynamic drag to a component you wish to find, and if you have an idea of initial aircraft orientation, you can significantly reduce the area to search for a target item, but you need to have an idea if the item immediately began to sink or might have traveled before sinking.

Mr Optimistic

17th Apr 2011, 18:03

Machinbird, thank you for the considered answer. One point though, the bell curve (by which I guess you mean 2-D gaussian distribution) clearly had very different dispersions in x and y to give the narrow CEP.

mm43

17th Apr 2011, 18:33

Originally posted by chrisN ...

... just clarifying - you mean the impact trauma at the sea surfaceMy references to "impact" are of the aircraft with terra-oceania, and contact of debris with the seabed can more readily be called a "landing".:hmm:

mike-wsm

17th Apr 2011, 18:59

Dunno why you all bother. The whole lot has been photographed in great detail. When we see the pics all will be revealed. I rather suspect all this argument about dropping thimbles into buckets of water is being wasted because some vital fact has been misunderstood. For example, how do we know the sonar scan has the same horizontal and vertical scales? It's not a map, is it?

PJ2

17th Apr 2011, 19:12

mike-wsm, understand what you're saying, but for some here, it's just what we do... ;-)

Mr Optimistic

17th Apr 2011, 19:13

The Bea slide had the scales. The 'why bother' observation could be applied across the piece. Perhaps it's just in the nature of people to want to know. Is there any harm in it ? It could be a long 2 year wait for an inconclusive answer and an unsatisfactory response.

Machaca

17th Apr 2011, 19:21

No harm in a bit of component identification and moderately informed speculation while we wait for better official information. None here expects to discern a full explanation from the keyhole view afforded us so far.

The contributions by those who are expert in various related fields have greatly expanded our understanding on a multitude of fascinating topics.

We all eagerly await greater understanding of the actual contributors and causes of this tragic event.

Here's some wing images for the sea floor tin-kickers:

http://i337.photobucket.com/albums/n385/motidog/A330wingassem1.jpg

http://i337.photobucket.com/albums/n385/motidog/A330wingfull1.jpg

http://i337.photobucket.com/albums/n385/motidog/A330wingunder1.jpg

Machinbird

17th Apr 2011, 19:38

Mike-WSM
Why bother? It relates to the factors involved in trying to find particular objects on the bottom. A photomosaic map of the bottom is but a starting point. Until an item in question is recovered, it is still in Neptune's grasp.
Even after they find the recorders, prudence would say to continue recovering items that tell about critical events on the aircraft as it fell.
Suppose the recorders are destroyed by corrosion. Wouldn't you think it prudent to learn the position of the slats and THS trim actuator? Wouldn't you want to look for witness marks on a whole range of components? Wouldn't you want to see how the cockpit switches were set up? Wouldn't you like a look at the engines to determine power setting at impact?
Mr Optimisitic
One point though, the bell curve (by which I guess you mean 2-D gaussian distribution) clearly had very different dispersions in x and y to give the narrow CEP.
Actually I weasel worded my earlier statement to indicate two wingtip lights with equal geometry and mass. The ballistic CEP has equivalent scale in all directions, but there is another probability at work as well. Supposing one wing tip light retained a tab of metal that influenced its sink rate compared to the other. The uncertainty in configuration causes a second dispersion (or uncertainty) in the underwater current direction only.

henra

17th Apr 2011, 19:47

I suspect you are being a bit 'optimistic' sir.:) The bits on the bottom probably do reflect the orientation of the aircraft at impact, but not in the way you suggest.

When looking at the N-S extension of the main Debris Trail, I have to admit I'm somewhat in the boat of Mr. Optimistic here.

The N-S extension of the trail is mostly below 100m.
Considering a length of the 'bus of almost 60m this is really not much. It would suggest that nothing broke lose on impact and stopped immediately or no parts continued in forward direction after impact at leat for a couple of dozen meters.

IMHO if any significant forward speed (>50kts) was present I would consider a N-S heading rather unlikely. In that case I would not expect only single pieces outside the main trail basically forming something like
-+- but rather a more rectangular wider area with random debris.
So if I had to put money on the general heading I would put it on something more West to East.
But as always: Happy to stand corrected after FDR Data has been examined and published.

However, I agree the length of the trail and the distribution of the bits and pieces along the trail would be basically purely drift due to currents.

Machinbird

17th Apr 2011, 20:27

http://home.comcast.net/~shademaker/bigchunks.jpgHi Henra,
The N-S extension of the trail is mostly below 100m.
Please check your scale. I see large components of the wreckage spanning 180-200 meters in the N-S direction. They are located both south and north of the centerline, part of the 'outliers.'
I've added arrows to some apparent large chunks of wreckage using PickyPerkins' original graphic. You can see that they appear to relate to the original size of the aircraft fuselage, but sonar returns can be tricky to interpret.

henra

17th Apr 2011, 20:42

Hi Henra,
Please check your scale. I see large components of the wreckage spanning 180-200 meters in the N-S direction. They are located both south and north of the centerline, part of the 'outliers.'

Hi Machinbird,

The 100m was referring to the main trail w/o the outliers.

That's what I meant with the -+-. The width of the outliers is wider but they are on a single axis vertical to the main trail. with very little drift spread along this orthogonal axis.

In case of N-S impact with some remaining forward velocity I would expect the 200m not only in one line but more or less over the full length of the trail.
I.e. something like IIIIII or maybe IIII+-- instead of ---I--

Why would only the mid- part drift differently due to currents ?
And even more mysterious : Why would the bits lost at the beginning of the sequence drift equally far to the bits at the end of the impact sequence, i.e. have similar flotation /drag characteristics and everything in between have a very wide spread of drift / flotation characteristics.

Mr Optimistic

17th Apr 2011, 21:04

Machinbird, thanks once again. My experience in this subject is limited and I hope I don't sound presumptious.

grity

17th Apr 2011, 21:13

@PJ2 in this picture of F-GZCP I see the text"do not walke..." only two times written on each wing

http://images3.jetphotos.net/img/1/7/9/9/28761_1238106997.jpg

Currents must have been really slow compared to the rate of fall through them. @JD-EE, if a light peace will fall with mayby 0,6 m/s and if the currend moves with the 0,1 m/s, than it will move horizontaly around 600m after the falling time over 4000 m.....

and compared to a heavy part, falling mayby between 4-10 m/s the same currend will be very slow, it moves <50m horizontal

a slow deapwater currend with 0,1 m/s will flow very laminar, and after a longer time there is no reason that the speed will be much different in different levels, the deapwater currend is part of a big stream with amount the same water volume like the golf stream, until it is the backroute of the same water... grity

Turbine D

17th Apr 2011, 21:24

PJ2 & mm43

PJ2, thanks for the enlarged enhanced photos, prior to these, I was cautious about saying much about the engine that was photographed. So now, here is my observations about the engine:

1. The first photo depicts the central conical hub just aft of what would have been the fan blade rotor, in fact, the fan disk drive arm to attaches to this hub, but is gone. Also, the "A" roller thrust bearing is at this same location but is also gone.

2. With the exception of two visible by-pass guide vanes (one at 6 o'clock - the other at 1 o'clock), everything is generally missing forward of the one piece titanium fan frame. That includes fan booster blades and vanes (3 stages) forward of the fan frame.

3. It is possible that a portion of the fan frame (7 o'clock to 12 o'clock) is missing.

4. In the second engine photo, I think the white (shiny) tube that curves around the top, just aft of the conical hub is the "A" oil feed line to the "A" bearing.

5. In the second engine photo, all of the active clearance control tubing is stripped from the LPT module casing, at least on the visible side.

6. The engine orientation sitting on the sea bed appears to be resting on its side as I think that part accessory gear box is visible behind the fan frame.

7. I fully agree with mm43's assessment that the engine hit the sea bed LPT module end first. With all of the fan, fan casing, kevlar fan containment, booster vanes & blades missing, the rear of the engine would be much heavier than the remaining front end.

According to the BEA interim report, the aircraft hit the water with a high vertical rate of speed, a lesser forward motion in a slight bank orientation with a pitch upward. Depending on what is meant by "slight bank," the engine on the low wing would be first to hit the water. My thoughts for discussion would be that the engine was torn from the left wing pylon (engine sits ahead of the wing). Could the structure being seen in front of the wing be the most forward part of the pylon bent around to the left and twisted rather than the internals of the slats?

Machaca & Shadoko, thanks for all the great photos and diagrams:ok:

deSitter

17th Apr 2011, 21:29

Pretty clear that the airplane shattered on impact. Like the one in Libya a while back, that belly flopped on final. So why was the fin spared? Could be the part some distance away is the empennage?

PJ2

17th Apr 2011, 21:37

grity;
@PJ2 in this picture of F-GZCP I see the text"do not walke..." only two times written on each wing grity

One thing consistent about airplanes is a "variations on a theme" of entities which are under constant modification and updating.

We have 3 such variations here, (and this is only one small item), ...the diagram, the wreckage and now the photo of the subject aircraft.

For those driven by knowing and positing, ...how the airplane ended up like this, how the wreckage rests and the what the relations are between the location of parts are important because sense can be made of seeming chaos and seemingly unimportant small details. But the tiny flashlight we are forced in total darkness to use means the details can be argued until someone inevitably sees a different pattern and changes our view or knowledge becomes unimportant and superceded in the light of later developments. The best description about all this is, it's "tea leaves" even as some remain driven in the face of it.

lomapaseo

17th Apr 2011, 21:53

For those driven by knowing and positing, ...how the airplane ended up like this, how the wreckage rests and the what the relations are between the location of parts are important because sense can be made of seeming chaos and seemingly unimportant small details. But the tiny flashlight we are forced in total darkness to use means the details can be argued until someone inevitably sees a different pattern and changes our view or knowledge becomes unimportant and superceded in the light of later developments. The best description about all this is, it's "tea leaves" even as some remain driven in the face of it.

PJ2

I'm not sure that I see what detail of the latest pics is necessary to understand vs what is fun to explore on a discussion board.

So far what I see is confirmation of what the BEA said initially about how the aircraft hit. Of course even before they released that info some of us had deduced that from the recovered wrechage photos :)

The clock positions of the damage to the major case behind the fan (with the struts) viewing both engines would both confirm if the engines were both attached (same wreckage area) and what roll angle the wings were in. Views of the inlet cowls on the bottom would also both confirm this as well as the pitch.

So far an awful lot of what we see fits nicely into Occams razor of a flat impact per the BEA. If there is some other theory I haven't seen anything in the latest pics that points to this.

Machinbird

17th Apr 2011, 22:10

Machinbird, thanks once again. My experience in this subject is limited and I hope I don't sound presumptious.

At the moment, I have a mental vision of how the aircraft reached the bottom scattered as it is. All I can do is explain the concept as best I can until someone with a better understanding comes along and blows my mental construct out of the water.:} Like some of the others on this forum, I've kicked the tin remaining from an accident and tried to interpret the meaning of the damage patterns. There are always surprises to be found. But one consistent fact is that the impact energy is passed through the structure in interesting ways and almost nothing escapes some form of damage.
So if I have presumed too much myself, please be kind as you explain the error of my ways.:)

mm43

17th Apr 2011, 22:19

For what it is worth (IMHO), I wouldn't go getting too "excited" by the bottom spread. There are four important factors that have helped each independent part of the debris to arrive where it has. They are:-

Current profile, i.e. vector and velocity at different depths.
Object profile and terminal velocity.
Distance, i.e. depth of water.
Time.

Generally, those items with low density and poor hydrodynamic profiles will have taken the longest time to reach the bottom, and those with the highest density and best hydrodynamic profiles will be the fastest. The observed debris pattern would suggest that the overall current vector was about 270°T, and as the aircraft has impacted with a high AoA and high rate of descent, its residual horizontal momentum was arrested in less than 10 meters. It could further be deduced from the sidescan sonar image that those objects located to the east (right) of center arrived on the bottom first, probably with the exception of the eastern most outlier. The remaining objects heading west now fit into a low density/poor profile category and are the stragglers.

As for the outliers, their positions will ultimately come down to what happened as the aircraft broke up, and whether their profiles gave them the opportunity to "kite" off rather than "spiraling/spinning" to the bottom.

We all think we know what air is, and likewise water. As simple as water may seem, its structure has properties that are anomalous when compared with other liquids.

London South Bank University - Structure of Water (http://www.lsbu.ac.uk/water/anmlies.html)

PJ2

17th Apr 2011, 22:37

lomapaseo;

Of course, you're right...I just didn't want to use the term 'fun' but for those who take to puzzle-solving and examining "the trace", even ones with serious and tragic origins, it is, (as I observed), "what we do", so to speak. The other aspect of this is the discussion itself, in public, which is often helpful for those who may be affected or who are seriously curious about the how and why, even if the general facts within Occam's famous notion are known but who may not ordinarily see or even take part in such a discussion. The thread is among the best in a number of excellent threads on PPrUne and for me, is the singular, fundamental value of such a place. And then there are those who live in JB-land...aiyaiyai...

Gerard13

17th Apr 2011, 23:18

Auraflyer:

Not that it's important, but your version of the French text on the wing is absolutely correct, as evidenced by the more readable picture on post #3573.

Shadoko

18th Apr 2011, 00:07

Hi,

Thanks to PJ2 (post #3577) for the drawings and to Machaca for the pictures, especially the second one...

This diagram may help...as may be expected, the "Do Not Walk.." labelling would be in a number of locations along the leading and trailing edges of the wing..
Perhaps my first sights were misleading : looking at the structural line between the two red lines, I can't find anything compatible with rear view of the left wing : on the trailing edge near spoilers 2 and 3, stuctural wing lines aren't parallel to the area line. So, it may be front view of right wing, whose shape could be the one bertween the green lines...

http://i24.servimg.com/u/f24/14/14/01/64/wing6010.jpg

With a bet changing every half day, may be I will find the truth some day: perhaps better to leave this to informed ones!

BarbiesBoyfriend

18th Apr 2011, 00:17

Total speculation warning.:uhoh:

Fins have come off airbus before.
This airbus's fin was found intacto and seperate. It didn't finish up where the wreckage of the a/c was found.

If rough rudder action can snap an airbus fin off, surely a MF Cb could too.

I'll betcha that fin came off and precip'd the accident sequence.

Turbine D

18th Apr 2011, 00:54

Shadoko

"More often than not your first inclinations are correct" and I think in this case this is a true statement. If you refer back to your #3573 post, the attachment points of the spoilers in your picture match very well with what is seen in the crash photo. The leading edge of the wing in the crash photo isn't there. IMHO, the wing tore from root to tip, maybe as a result of the forces of the engine and pylon tearing away. The bend you see (outlined in green) may have more to do with the location and angulation of the interior structural spar in the wing. The painting of the words in English & French "Do not walk beyond this point" may vary slightly in location from aircraft to aircraft over time, but the spoiler attachment points do not.

Machinbird

18th Apr 2011, 01:17

I'll betcha that fin came off and precip'd the accident sequence.
That is a bold bet BB. There are a lot of people at BEA who would stake their professional reputations on you being wrong. Can I get a piece of the bet too:E.

Have you been reading that A319 wake turbulence incident that SensorValidation mentioned recently? That aircraft overstressed its VS attach points but without causing permanent damage.

I found the trace of that aircraft's flight control inputs vs surface positions pretty clearly showed some control rate limiting occuring.http://www.tsb.gc.ca/eng/rapports-reports/aviation/2008/a08w0007/images/a08w0007_figure_3.jpg

Unfortunately the graphic is a bit fuzzy, but if you print it out full size you can then easily read the legends along the margins.
A wake turbulence encounter is probably a good comparison with what happens inside a developed Cb, only perhaps a bit gentler.
If you look at the elevator trace, you will notice one side of the elevator lagging the other side. This is probably the result of its active hydraulic system not keeping up with the demand in that time frame. Later (after the vertical green line) you can see the rudder doing something quite different than what the pedals are commanding. Probably a good thing that the wake encounter only lasted a few seconds.

CONF iture

18th Apr 2011, 01:34

In view of the possibility that AF447 encountered sudden, severe turbulence, perhaps we should be adding another scenario to the list of possible causes of LOC and Control-Law degradation. Could it be compatible with the analysis of ACARS messages? I think it might be.
Except maybe for the message related to the pitot tubes which, in my opinion, is absolutely central in the AF447 ending.

But unreliable airspeed + turbulence + no natural horizon + AP disconnect + alternate law ... could be the perfect recipe for overcontrol.
We know how easy it is to over control especially with the sidestick.
The indicated airspeed may be little, but the real true airspeed would not cope well with anything more than tiny sidestick solicitations ...

I remember being disturbed by one copilot, who moved a pedal significantly when stretching a leg that had "gone to sleep".

Reminds me how smart it can be to put some distance with the rudder pedals before taking a nap. Never know if you gonna play it like Ronaldo in your half sleep ...

JD-EE

18th Apr 2011, 03:16

Mike-wsm, do you remember the old TV game show (in the US) called "Name That Tune?" The premise was to tell the contestants something about the tune to be played. Then the contestants would hit their buzzers and suggest they could guess the tune in some number of notes. (The record is zero notes. They asked, "This is the theme from a 1940s musical that forever changed musical theater." There is only one such, "Oklahoma.")

The group of us are essentially playing "Name That Crash" with the little bits of information BEA vouchsafes us. This "tune" er Crash is strange enough I am not sure we'll all agree that a solution has been found even with CVR, FDR, and CMC (?) all recovered and readable and essentially the entire plane recovered from the bottom of the ocean.

I've learned that FDRs really do not store an exhaustive array of data that could tell us what the radar was showing, whether somebody dozed off at a critical instant, weather every outside the plane sensor froze up at about the same time, or any of dozens of other potential phenomena. So I am betting with myself that when this is all over we'll still be a few dollars short of a full set of clues. I for one am just suspicious enough of BEA's motives etc that I'd like to see their report audited by a second panel of experts. We certainly seem to have a plethora of really sharp experts here. I suspect that if this group and BEA arrive, ultimately, at different causes "I'd demand a recount" as it were bu a team of airplane accident investigators from all around the world.

This group will, ultimately, let me know of my native cynicism and paranoia should express itself.

For example, The fact that they built a 40 nm search radius for an event that went down in a violent storm in 4 minutes is just a small indictment of BEA's motives and expertise. Figure the plane's ground speed in 4 minutes. Figure it was PROBABLY (only probably) below a few thousand feet at the time of one of the last messages and guess how far the plane could be from the LKP. I am figuring 8 to 12nm. I am guessing more or less North. If they REALLY had claimed finding it 30nm South in a compact debris field I'd have raised holy heck about that.

I figure this group is providing a rather nice forum for this "reality check."

(I also love learning when not ordered to by somebody else. And I've had tremendous fun learning here. And I bet if the BEA takes good enough notes about recovery locations for specific objects some very interesting data for undersea currents in that area could be derived from the BEA data. I hope they do not waste THAT opportunity.)

JD-EE

18th Apr 2011, 03:21

Machinbird

18th Apr 2011, 03:53

Machinbird, with your tab on a wing tip light example I'd suggest "imagine a maple seed." They do NOT fall straight down or deflect in breezes the same. The tab makes them "fly" more rather than sink like an avocado. And their spiral is non-trivial.

JD-EE, That was one of the mental examples I used, but I was having trouble rembering what kind of tree produced those seeds.
Guess my forgetter is working very well.:O But in water, the rotation rate of a maple seed type airfoil would be severely slowed.

auraflyer

18th Apr 2011, 04:20

shadoko wrote:

Perhaps my first sights were misleading : looking at the structural line between the two red lines, I can't find anything compatible with rear view of the left wing : on the trailing edge near spoilers 2 and 3, stuctural wing lines aren't parallel to the area line. So, it may be front view of right wing, whose shape could be the one bertween the green lines...

I have to say, looking closely at the shape, it really resembles a fracture line or even a tear to me. Look how it "curves" going towards the BEA logo - down, then up then down again.

Is this part of the wing skin a composite material?

Could the damage here be due to the engine being forced up against the wing on impact with the water?

henra

18th Apr 2011, 08:08

Hi,

Perhaps my first sights were misleading : looking at the structural line between the two red lines, I can't find anything compatible with rear view of the left wing : on the trailing edge near spoilers 2 and 3, stuctural wing lines aren't parallel to the area line. So, it may be front view of right wing, whose shape could be the one bertween the green lines...

Hi Shadoko,

I'm with Turbine D on this one: Looking at the position of the supports of the plates in front of the spoilers in relation to the 'Do not step...' at the trailing edge they match perfectly. In your own post #3573 the images show it nicely.

That said it would mean everything behind the main wingbox (behind the aft spar) including the area in front of the spoilers were torn off on impact. However, as these arejust panels bolted/glued on the supports that doesn't seem too unlikely.

So I'm pretty sure you hit the nail on the head with your first assumption.

cuddieheadrigg

18th Apr 2011, 08:35

Random question time.

In what must be one of the best ditichings ever, even conditions-wise unless the plane had floats, US1549 suffered substantial damage. What would we have seen if it had ditched +30 or 40 kts?

Anyway - since (presumably) there's some forward momentum here (??)

How does the size of the aircraft reflect damage? By that - are design loadings directly proportionate to size - in that - does a 1 tonne wing need twice the strength of a half tonne wing? (if that makes sense!)

Similarly, if a wing is longer, it has longer control surfaces - which is more area to contact water - mor drag - more 'distorting force' - a similar thing could be said for engine housings - if they are larger then they will scoop up a greater volume of water and if so - would this give 'more' damage - say it had been an A330 ditched in the Hudson at the same velocitys would there be more damage (even if only by the aircraft weight?)

Ignoring he seabed position, can much be deduced from the images beeing seen about the aircraft's dispostion at impact?

henra

18th Apr 2011, 09:02

Total speculation warning.:uhoh:

Fins have come off airbus before.

Yes. But in all cases except one this happened during the impact sequence

This airbus's fin was found intacto and seperate.

As is the case in almost all instances where an Airbus crashes. Even the Afriqiah Fin looked pristine compared to the rest of the plane.
The fins are simply extremely strong compared to their weight. So their own inertia is low compared to their strength.

It didn't finish up where the wreckage of the a/c was found.

[How do you know that, while even the investigation experts don't know it / don't agree ?

If rough rudder action can snap an airbus fin off, surely a MF Cb could too.

If a Cb shears something off it would rather be the HS.
That is in most cases the first control surface which fails in a dynamic overload. In the remaining cases it is the wing that fails.
Loss of VS is extremeliest rare.

Besides that I do not see giant lateral forces in a Cb, mostly vertical forces.

I'll betcha that fin came off and precip'd the accident sequence.

Where can I place my money for this bet ?

henra

18th Apr 2011, 09:53

While we are at speculating:
(Attention: This is all really speculation and I'm impatiently awaiting the results of the FDR /CVR analysis after they will be hopefully found soon). Will be interesting to see in hindsight where the brain farts were.

So for what it's worth:
Here comes my scenario which I have in mind based on what we know atm :

2:09:30
Being in Cb with supercooled droplets. Pitots starting to freeze over.
2:10:00 - 2:10:15
Pitot fail, unreliable airspeed.
AP A/THR disconnect.
Possibly showing overspeed causing the Pilots to reduce Thrust, leading to slow decelleration
ADR disagree, Alternate Law 2
Edit: Following comment by @Sensor_validation I agree AP /A/THR deactivation and switch to Alt2 probably occured more or less simultaneously, time delay in ACRAS only due to ACARS transmission
/Edit
2:10:15 - ~2:11:00
Pilots manually trying to keep the plane straight and level, significant turbulence being countered by significant control inputs, not being covered by protections.
Meanwhile:
2:10:34 Last position report transmitted, already in Alt 2 3nm left off course possibly indicating pilots already fighting the situation.
Probably shortly after reporting of LKP:
Manual overcontrol in pitch combined with reduced speed and strong vertical gusts leading to accelerated stall causing massive wing drop. Causing loss of spatial orientation due to severly moving Attitude indication.
2:11:30 - 2:14:30 Aircraft progressively stalled.
Heavy loss of forward velocity, decellerating from ~250kts CAS to <100 kts. Potential course reversal after initial wing drop. Pilots regaining horizontal attitude.
Heavy loss of altitude, RoD ~ 20000 ft/min. 'Falling Leaf attitude'. possiibly combined with slow rotation or erroneous heading change while dropping. In between partly recovery possible. Re-activation of AP possible while Airspeed still unreliable but consistent. Potentially followed by subsequent stall(s).
In denser atmosphere RoD decreasing to 15000 ft/min. Forward speed reduced to < 100kts.
2:14:30 - 2:15:15.
Edit:
Following Comment by @Sensor_validation I tend to agree time of crash seems more likely towards 2:14:30
/Edit
Impact on the surface: Vertical speed : 150kts, horizontal speed: 50 - 100 kts. Pitch angle: 20 - 30° Nose up, perhaps slightly less. Engines at high N1/EPR. (Does that match the pictures of the engine ?)
Heading at impact: between 090 and 180.

Is there any obvious thing which I oversaw which contradicts this sequence? Are there any obvious brain farts identifiable already now ?
Any comments ?
Please feel free to challenge/dissect it part by part.

sensor_validation

18th Apr 2011, 10:18

For example, The fact that they built a 40 nm search radius for an event that went down in a violent storm in 4 minutes is just a small indictment of BEA's motives and expertise. Figure the plane's ground speed in 4 minutes. Figure it was PROBABLY (only probably) below a few thousand feet at the time of one of the last messages and guess how far the plane could be from the LKP. I am figuring 8 to 12nm. I am guessing more or less North. If they REALLY had claimed finding it 30nm South in a compact debris field I'd have raised holy heck about that.

To be fair they, and the Brazilian Navy, were originally trying to guess where the last message came from - based on 4 mins at 10 NM/min from the last position report, which was 3NM 'left of track'. As repeated recently had it just been dual engine failure the aircraft could have glided much further and possibly back towards Brazil, but it appears that never taken seriously.

...If a Cb shears something off it would rather be the HS...

Which bit of F-GZCP knocked the tail off F-GTAM on 17.08.2006 ?

The attachment points of the A330 do look like the are specially reinforced compared to similar early designs?

http://www.airliners.net/photo/Untitled-%28Air-France%29/Airbus-A330-203/0786517/L/Photos: Airbus A330-203 Aircraft Pictures | Airliners.net (http://www.airliners.net/photo/Untitled-%28Air-France%29/Airbus-A330-203/0786517/L/)

The natural feature was then incorporated into AF's paint job.

Perhaps they should start to search for the remains of half of it "UNDER THE FOOT OF THE BEAR" (Nevil Shute)

deSitter

18th Apr 2011, 10:26

henra said "As is the case in almost all instances where an Airbus crashes. Even the Afriqiah Fin looked pristine compared to the rest of the plane. The fins are simply extremely strong compared to their weight. So their own inertia is low compared to their strength."

On the contrary, the fin was quite thoroughly damaged, and was mixed up with the remainder of the empennage and HS in a tangled mess.

Libya crash's boy survivor doing well | World | News | Toronto Sun (http://www.torontosun.com/news/world/2010/05/12/13918136.html)

henra

18th Apr 2011, 10:40

On the contrary, the fin was quite thoroughly damaged, and was mixed up with the remainder of the empennage and HS in a tangled mess.

Apart from the TE obviously having contacted the hard surface and taken a little beating, the fins looks relatively fine to me !?

Where do you see damage to the rest of the fin structure (apart from the TE as said) ?
Have you looked at the remainder of the aircraft and what has been left of it compared to the fin ? It is a 10 million item 3d puzzle.

Can't you see a pattern there ?

deSitter

18th Apr 2011, 11:27

What I see is that a belly flop on the hard desert pan of sufficient violence to completely destroy the aircraft, did not separate the fin from the empennage or from the HS, but that the rudder was torn all to hell.

Rescue workers examine debris from Afriqiyah Airways flight 8U771 at Tripoli airport May 12. (http://www.globaltoronto.com/entertainment/story.html?id=3019586)

Chris Scott

18th Apr 2011, 11:45

I wrote (currently post (http://www.pprune.org/tech-log/395105-af-447-search-resume-178.html#post6396085) #3556), in the light of the TSB of Canada’s report (http://www.tsb.gc.ca/eng/rapports-reports/aviation/2008/a08w0007/a08w0007.asp)[SIZE=2] of an A319 wake-turbulence encounter:
"In view of the possibility that AF447 encountered sudden, severe turbulence, perhaps we should be adding another scenario to the list of possible causes of LOC and Control-Law degradation. Could it be compatible with the analysis of ACARS messages? I think it might be."

Was the original fault that led to the degradation from Normal Law to Alternate-2 (ALTN2) Law either:
(a) AoA-probe anomalies caused by pilot-induced yaw;
or
(b) pitot-probe anomalies caused (perhaps) by icing?

[FONT=Verdana]CONF iture points out (http://www.pprune.org/tech-log/395105-af-447-search-resume-181.html#post6397809):
"...the message related to the pitot tubes which, in my opinion, is absolutely central in the AF447 ending."

So (a) looks less likely than (b).

However, CONF iture continues:
"We know how easy it is to over control especially with the sidestick.
The indicated airspeed may be little, but the real true airspeed would not cope well with anything more than tiny sidestick solicitations ..."

During the minute from 0210z, for whatever reason, the PF undoubtedly found himself in Alternate Law (probably ALTN 2), sans-AP, trying to keep the wings level (or fly a safe turn) and control the pitch. ALTN 2 does not apply in the case of the A320 family, but the DFDR trace (reproduced above by Machinbird) shows an experienced PF trying to cope with the transition from AP to sidestick and Alternate Law in moderate-severe turbulence on an A319.

Again in the light of the TSB of Canada’s report, I also wrote:
Should rudder ever be used in cruise-flight, apart from the asymmetry case?

If the answer to that is in the negative, there is now more than anecdotal evidence that some pilots do use rudder at any speed, and that undesired yaw-cycling can be the result. This may compromise aerodynamics and/or structure; and even the quality of sensor-data in the ADRs.

Turbine D

18th Apr 2011, 13:37

henra

Impact on the surface: Vertical speed : 150kts, horizontal speed: 50 - 100 kts. Pitch angle: 20 - 30°. Engines at high N1/EPR. (Does that match the pictures of the engine ?)

Given only the photos of the engine remains, it is impossible to tell if the engines were operating at high N1, there is nothing to go by at the moment. Usually one can tell this by visually observing the fan blades or compressor blades which would be bent in the opposite direction of rotation.

I am thinking the upward pitch angle would be less, more like 5°

AVLNative

18th Apr 2011, 13:45

Did anyone see this article? BabelFish translates the heading "Zu hohe psychische Belastung" to "Too high psychological load"

Absturz von AF 447: Kieler Forscher steigen bei Wrack-Bergung aus - SPIEGEL ONLINE - Nachrichten - Wissenschaft (http://www.spiegel.de/wissenschaft/technik/0,1518,757492,00.html)

lomapaseo

18th Apr 2011, 14:02

The engines would probably not tolerate a flat impact without stalling and spooling down ala the A300 at Nagoya

sensor_validation

18th Apr 2011, 14:29

While we are at speculating:
...
Any comments ?
Please feel free to challenge/dissect it part by part.

I'm sure you are right that it is significant what happened just before 02:10z - did the auto controls take action on 'bad-data' before disconnecting, was a turn or step-climb in progress etc.

I think you need to revise your timings a bit though to fit in with the detailed ACARS timings - presented in colour here

AF447 ACARS MESSAGES - Color Coded & Interactive Version (http://countjustonce.com/a330/acars.html)

Couldn't all the 02:10 messages have been generated early in 02:10, just output in priority order over the next 2 minutes - interrupted only by high priority position report?

The aircraft was clearly in stable enough orientation to stream the messages in with only the occasional missed 6 or 7 second slot until 2:12:16. The BEA identified one missing ACARS that should have been transmitted before 2:15:15, but impact could have been at 2:14:30. A shorter time of fall seems to fit in better with a single stall/ fall rate. Much discussion earlier that true 'flat spins' a feature of T-tail, and 'falling-leaf' delta-wing, still lots of unknowns.

3holelover

18th Apr 2011, 14:42

Wouldn't the simplest explanation (keeping Mr Occam and his razor in mind) for both engines having lost their entire forward fan sections, including all traces of fan, be that they were singing pretty fast when they hit the water? Also, from the looks of them, near half of both of their remaining fan case sections have been crushed on impact, so I don't think there was much "spooling down" going on... More like sudden stoppage, no?

I've examined the photos and would like to offer my observations...

The wing with the text decals still visible is undoubtedly the left wing.
The wing with gear still attached is definitely the right wing. The pointed bit of structure just inboard of the visible flap track shows some of the plumbing that would indicate where the pylon would have been.
On the left gear, there is a hunk of 'stuff' between the #3 and 4 wheels... It looks like it might be some of the I/B flap track and carriage assembly... which it sort of lives near when the gear is up and locked... Perhaps impact forces allowed for the gear to have ripped this from it's roots on it's way down? Anyway, whatever it is, I'm sure it also has a story to tell...

I too enjoy reading and learning from all of this. Thanks to all of you for the opportunity!

henra

18th Apr 2011, 14:54

I think you need to revise your timings a bit though to fit in with the detailed ACARS timings - presented in colour here

Yes, the exact timings of the real events related to the ACARS messages that's where I was a bit unsure indeed.
The only thing which seemed reasonable to me was the sequence
Icing -> A/THR /AP lost -> Alt2.
The exact timing may well have been closer together.
so that close to 2:10:05 they were already in Alt2.

Couldn't all the 02:10 messages have been generated early in 02:10, just output in priority order over the next 2 minutes - interrupted only by high priority position report?

Yes, agreed, see above.

The BEA identified one missing ACARS that should have been transmitted before 2:15:15, but impact could have been at 2:14:30. A shorter time of fall seems to fit in better with a single stall/ fall rate.

Agreed that is the second area of uncertainty: It could reasonably have crashed between 2:14:30 and 2:15:15.
I was just on the conservative side, admitting that an earlier impact fits better with the RoD's that can be expected in such a scenario.

I will include the updated timings based on your remarks in my original post.

Lonewolf_50

18th Apr 2011, 15:46

henra:

Here comes my scenario which I have in mind based on what we know atm :
2:09:30 Cb with supercooled droplets. Pitots starting to freeze over. 2:10:00 - 2:10:15 Pitot fail, unreliable airspeed. 2:10:15 - 2:10:30 AP A/THR disconnect. (Ovspd induces thrust redux, decel) 2:10:30 - 2:10:45 ADR disagree, Alternate Law 2 2:10:45 - 2:11:30 (significant control inputs not covered by protections => overcontrol => accel stall => wingdrop=> loss of spatial orientation and forced to Unusual Attitude Recovery on instrument scan after stall/upset
2:11:30 - 2:15:00 Aircraft progressively stalled.

henra, my only comment is your supposition of the nose low attitude (20-30 deg nose low) ... which I think you intend to be attitude at impact? (If not, then I misread your post).

I see the crew confronted with three different challenges all at once
1. The stall/upset (agree with your posited wing drop)
2. Stall recovery (3-D) using an IFR scan
3. Unusual attitude recovery on an IFR scan directly related to the stall recovery

I'll add to numbers 2 and 3 (caveat, it may be a load of rubbish if the gyros in the A330 are not prone to tumbling ...)

"these recoveries to be accomplished on instruments with an attitude gyro that has tumbled." (As I was speculating about some posts back.) In other words, a spin (or at least a rotating sort of stall) followed by an unusual attitude recovery, all with a partial panel scan.

There would be an unknown interval of time before the crew recognized that their primary attitude reference is buggered (possibly shown by the PFD reset attempts?) and they are called upon to recover from a 3-D upset using a partial panel scan. Is this trained for? (From my own experience, that particular taks is hard, even when you are ready for it, and in a training environment).

Added to this degree of difficulty is a reasoned belief that for a good portion of the descent, airspeed indications, (primary ref on partial panel scans) are unreliable.

If all I had to rely on to recover from an under the bag spin recovery was turn needle, balance ball, and Vertical speed, I might or might not manage it on the first go. I was trained to use airspeed as a primary reference for partial panel scan.

The aircraft gets to a high RoD ... then airspeed indication finally come back (at lower alt) and the pilots begin to catch up ... maybe unstall again, and then get stuck in a problem of accelerated stall at the end of it all as they 'pull up' (altitude keeps getting smaller in large chunks, one has to break the descent ...). Given "in the goo" scan and possibly disoriented pilots, the plane is in the process of a major pull up (nose at or above horizon) when it restalls yet again, accelerated, and falls ... this time, with no altitude left. (Hence not quite hitting in the nose low attitude you suggest ... )

I base this amplified version of your scenario on a mishap that killed a colleague of mine. He was in a spin or a spiral, went into clouds, and as he came out (finally not in the clouds anymore) was making a major correction to his high rate of descent when he got into an accelerated stall "close to the ground." The eye-witness saw the vapor trails coming off the wings (similar to what you see the Thunderbirds or Blue Angels create in their high G turns at airshows) and reported that he saw the aircraft abruptly controlled flight with little to no altitude left for one last recovery ...

That was a lot of text to suggest why the BEA nose attitude assessment might be spot on, within the general scenario you presented.

henra

18th Apr 2011, 15:48

henra:

henra, my only comment is your supposition of the nose low attitude (20-30 deg nose low) ... which I think you intend to be attitude at impact? (If not, then I misread your post).

Hmm, probably my fault.
My assumption was 20-30° Nose up during impact (damage to the lower TE of the fin)
Should have made it more clear, will amend my original post.

Lonewolf_50

18th Apr 2011, 15:55

Aha, thanks, then your proposed scenario (high AoA in the end game) seems to match what was in my minds eye pretty closely. (If I read your post incorrectly, apologies).

(By 3-D stall, I meant "a 3-axis upset:" Pitch, roll, yaw)

BJ-ENG

18th Apr 2011, 15:57

@Turbine D

Given only the photos of the engine remains, it is impossible to tell if the engines were operating at high N1, there is nothing to go by at the moment.

Attached is an interesting comparison showing turbine damage on two identical engines, one where most of the blades are broken off about half way between root and tip, operating with some power applied, and another on the same aircraft which, at the time of impact, was stationary or windmilling with little or no power on. Compare this with the two photos of the same engine from AF447, where the rotating blades are missing, apparently torn away at the roots. Another example of a stationary or mild windmilling fan section, is that shown in my previous post where we see just the bottom section of one of TWA800 engines with fan blades bent in both directions away from the point of impact.

PICTURES: BA Boeing 777 Heathrow crash evidence (http://www.flightglobal.com/articles/2008/01/18/220935/pictures-ba-boeing-777-heathrow-crash-evidence.html)

TWA800 example:

ImageShack® - Online Photo and Video Hosting (http://img851.imageshack.us/i/no2twa800.jpg/)

grity

18th Apr 2011, 16:12

@ shadoko, aurafleyer

the wing picture just shows a unexpected smal part of the wing, the holder are not between the spoilers they are just between the smaler flaps in front of the spoilers

if I scale the outline of the wing-picture with the holders onto this cutaway, than your red lines follow direkt along the inner part of the middle stringer !!!

the cutaway is on flightglobal.com
http://s7.directupload.net/images/110418/w4v3dv93.jpg

Lemurian

18th Apr 2011, 18:09

Given "in the goo" scan and possibly disoriented pilots, the plane is in the process of a major pull up (nose at or above horizon) when it restalls yet again, accelerated, and falls ... this time, with no altitude left. (Hence not quite hitting in the nose low attitude you suggest ... )
There's another possibility and probably the only one that fits with all the BEA text about vertical acceleration and an attitude comparable to a level flight :
At low altitudes, they recovered all the instruments, checked the descent and were starting to pull out of the descent (dive ? )... they hit the sea surface at the bottom of that recovery curve.
Then you have it all ; centrifugal G forces plus still a downward vertical acceleration, interrupted by the collision with the water, with a lesser longitudinal deceleration which still left important traces.
All the scenarios that involve a stall fail short of the observed attitude published by the BEA.
What I don't know is what law they were in hence whether they could have had a dynamic stall or they just ran out of skyspace.

alph2z

18th Apr 2011, 18:18

Since people are talking quite a bit about a high altitude stall here is a video from the ASB (Australian Safety Board) of a 777 stalling at high altitude due to the computers and AP wrongly using erroneous data from the faulty accelerometers.

YouTube - REAL Pitch Up Boeing 777 Incident
.

mm43

18th Apr 2011, 19:52

Machinbird back at post #3601 (http://www.pprune.org/tech-log/395105-af-447-search-resume-181.html#post6397803) made reference to the DFDR flight control inputs trace from an A319 wake turbulence incident investigated by the TSB of Canada.

A enlarged image of the DFDR trace is here (http://i51.tinypic.com/omzqh.jpg)

Svarin

18th Apr 2011, 19:53

To alph2z :

Now that is chillingly close to the kind of problem I have in mind regarding our thread subject matter, keeping in mind vast differences in design philosophy between the 777 and the 330. Could you please provide a link or reference to the official report ?

Turbine D

18th Apr 2011, 23:04

3holelover

I think the problem with the simple solution (Occam's razor) has to do with what lomapaseo pointed out. When there isn't much forward speed, but significant vertical drop speed, inlet distortion comes into play on commercial high by-pass fan engines. The engines become starved of air, stall and flameout during the rapid descent resulting in the spool down situation. Whatever rotational speed is left, it ends at impact. Quite honestly, the vertical speed in this incident, resulted in one of the most significant destruction of a high by-pass engine I have ever seen. Even the TWA 800 engine appeared to suffer less destruction.

JD-EE

18th Apr 2011, 23:41

sensor validation, If I am reading Wikipoodle correctly the speed of sound at commercial aircraft altitudes is around 660 MPH or 573 kn. That gives a speed of 7.8 nm/s for .82 Mach. If the plane flew on the entire time the radius would be 31 nm.

Just from ACARS it is pretty clear the plane was not at altitude by the last minute when the cabin pressure indication appeared. Unless the plane was intentionally driven into the ocean at the fastest speed possible without breakup it could not be outside the 31 nm radius. If it was falling, that would indicate, to me at least, that it had stalled. Perhaps some stall recovery could have taken place. However, in a stall my understanding is that the plane is making very little headway with a serious amount of altitude loss.

Admittedly this is in retrospect, basically because I am not a pilot, it seems fairly obvious the plane is not going to be immediately at LKP. And it's probably not going to be much past 4 minutes of flight minus the time it takes for it to fall the full 35000'. You might define an annulus about 5 nm to 15nm. Then erase the part "behind" the LKP. That's a more limited area to search and has the advantage of being the most likely region for the plane to crash. Instead they ass-u-me-d that the plane continued on for a good minute after the last message before deciding to plant itself forcefully into the ocean with small headway compared to vertical speed.

I repeat, what in heck were they doing out there so far from where the plane could possibly get to? (And how-in-'ell could it get 40 nm BEHIND LKP, which they were supposedly ready to search?)

I can buy it that this was ineptitude caused by the intense political pressure, just barely. I am suppressing comments from accident investigators about the reliability of reports. If the accident happens in a third world area, the report quality is poor because of the untrained and inexperienced investigators. If the accident is not politically charged and is in a "first world" nation the reports tend to be pretty good. If politics enters the picture the reports are what the politicians wanted them to say. That's from their experience. I suspect that is what this investigation started out to be. This latest search probably fell out of the unrelenting public oversight and demands. It would not go away. So the plane had to be found. At least that's what I get if I let my cynicism and "too many decades of real world experience" get out of hand. I still expect a political report. But I expect it's going to be as honest as the politicians permit. (And Wikileaks exists as a means of forcing honesty on politicians.)

(As a pair of side notes it has been reported here that the Russians, with (heh) more experience than others with crashes, have found that you start at or near the LKP when searching for crash locations. And I further note that mm43's current backtraces also placed the accident location fairly close to LKP but, if I recall, a bit South of where BEA hinted it actually fell.)

JD-EE

18th Apr 2011, 23:49

deSitter, hard desert pan is not ocean water. Reexamine mm43's drawings of how he imagined the plane hit. Note the tail. Think of the tail surfaces. Where is the tail assembly going to go when the tail surfaces hit the water with the rest if the plane trying to force it deeper?

The tail assembly is going to be pushed upwards, distorting it heavily and pretty much pivoting it around a point a little rear of the nose of the tail fin. That fits the damage seen to the leading edge. Pushing it up that way places tremendous strain on the attachment clevises. They break. Tail fin pops off, probably to one side or the other. Back where it lives the only stuff to hit amounts to the elevators and tail cone. Being thrown free of that debris by the combination of the popped clevises releasing hold down pressure on the fin and wind is not nearly a stretch of my imagination.

If it did come off before the plane hit, where is the ACARS message about a massive hydraulics failure? It could NOT have been the precipitating cause of the accident.

lomapaseo

19th Apr 2011, 00:19

Turbine D

I think the problem with the simple solution (Occam's razor) has to do with what lomapaseo pointed out. When there isn't much forward speed, but significant vertical drop speed, inlet distortion comes into play on commercial high by-pass fan engines. The engines become starved of air, stall and flameout during the rapid descent resulting in the spool down situation. Whatever rotational speed is left, it ends at impact. Quite honestly, the vertical speed in this incident, resulted in one of the most significant destruction of a high by-pass engine I have ever seen. Even the TWA 800 engine appeared to suffer less destruction.

The TWA800 engines and PA103, and etc. etc. all hit the ground/water in free fall terminal velocity relatively flat, shearing the LPT turbine case and last stage turbines away from the rest of the engine. However, that while their fan cases were also sheared away the fan rotosr stayed with the engines and thus the blades were easily visible for examination.

The only thing that seems to be different here is the completely missing (to us) fan disk and blades. No doubt there are lots of other photos that the investigators have to work with so I'm not going to try guessing at their hand :hmm:

777fly

19th Apr 2011, 00:56

Might it possible that this was a high speed upset? I think it doubtful that a fully stalled A330 would descend at a much greater rate than 6,000 ft per minute. There is, after all, still some lift being generated even at quite low IAS. The speculated rates of descent in the order of 20,000 fpm are only achievable in steep descent attitudes at high subsonic Mach numbers. The photographs of the left wing section show that a large section of the outboard upper wing surface is missing and broken wing spars can be clearly seen. This kind of damage is often seen when a wing is overstressed in a high speed dive recovery. Of course, such damage might have occured at impact, but it would be interesting to know if those missing outboard wing sections are found with the main wreckage, elsewhere, or not at all.

TWT

19th Apr 2011, 01:09

Could you please provide a link or reference to the official report ?

http://www.atsb.gov.au/media/24550/aair200503722_001.pdf

Machinbird

19th Apr 2011, 01:47

A enlarged image of the DFDR trace is here (http://i51.tinypic.com/omzqh.jpg)MM43, thank you for that beautiful readable DFDR trace. Much better than the fuzzy one in the online accident report!!

The A319 is the baby brother of the A330. Much smaller but with a strong family resemblance. As such, many of the design concepts that went into the A320 family are reflected in the A330, but executed or packaged in slightly different ways. If the A319 is showing signs of control rate limiting, then it is likely that the A330 can do the same.

With this in mind, I would like to call attention to some anomalous indications in the DFDR trace.

First, look at the position of the R & L elevators. Wouldn't you expect both elevators to be moving synchronously? But just before 14:48:10, the L elevator (brown trace) follows a stick pulse, but the R elevator (blue trace) does not. Then at 14:48:12, the R elevator responds to a stick input, but the L elevator does not. This split behavior continues until 14:48:17 at which point the aircraft has apparently flown out of the turbulence and is in a recovery phase.

Now look at the blue and magenta traces in the middle of the graphic. This is rudder position(magenta) and rudder pedal position(blue). Wouldn't you expect the two to be nearly synchronized with a slight lag for the hydraulics to catch up with the pedals? But at 14:48:06, before the autopilot is switched off, we are beginning to see the rudder lagging the pedals. (I don't wish to get into a discussion about whether he should have been on the pedals in the first place, just how well the aircraft followed the pilots commands.) By 14:48:15, the rudder acts as if it has a mind of its own and is doing other than what the pedals commanded. Finally by 14:48:23, the rudder starts to follow the rudder pedals (coincident with the aileron trace quieting down).

There are other indications in the aileron traces themselves. Yes the right and left ailerons mirror each other fairly well, but they are lagging the control input by almost a second and the position traces are becoming triangular in shape.

To me, these events in the trace may be the results of hydraulic supply rate limiting, but I realize that yaw damper inputs can superimpose on the pilots rudder inputs. Others on this forum have no doubt seen such DFDR traces before and may have better insight as to the cause, but I am concerned that the hydraulic demand from continually moving ailerons and spoilers could cause a control problem in very turbulent conditions on Airbus aircraft.:suspect:

And if I am definitely barking up the wrong tree, please set me straight.

jcjeant

19th Apr 2011, 02:04

Hi,

I can buy it that this was ineptitude caused by the intense political pressure, just barely. I am suppressing comments from accident investigators about the reliability of reports. If the accident happens in a third world area, the report quality is poor because of the untrained and inexperienced investigators. If the accident is not politically charged and is in a "first world" nation the reports tend to be pretty good. If politics enters the picture the reports are what the politicians wanted them to say. That's from their experience. I suspect that is what this investigation started out to be. This latest search probably fell out of the unrelenting public oversight and demands. It would not go away. So the plane had to be found. At least that's what I get if I let my cynicism and "too many decades of real world experience" get out of hand. I still expect a political report. But I expect it's going to be as honest as the politicians permit. (And Wikileaks exists as a means of forcing honesty on politicians.)

(As a pair of side notes it has been reported here that the Russians, with (heh) more experience than others with crashes, have found that you start at or near the LKP when searching for crash locations. And I further note that mm43's current backtraces also placed the accident location fairly close to LKP but, if I recall, a bit South of where BEA hinted it actually fell.)Family associations with the help of some aviation professionals suggested to search first around LKP
I agree with that... but it's make of me a conspiracy accomplice :)
Like those conspirators from one of the family association :

MARNET-CORNUS Henri
MECIFI Amine
TERRACHER Jacques
ARNOUX Gérard

Liste des membres du Conseil d (http://www.asso-af447.fr/liste-des-membres-du-conseil-dadministration-du-bureau-et-des-commissions.html)

Methink AF447 go in a irrecuperable stall by all means even if Svetlana Kapanina was in command.
http://www.youtube.com/watch?v=GNjzHkMZinE&NR=1
http://www.youtube.com/watch?v=BkKZnXAiTQQ

mm43

19th Apr 2011, 03:20

Originally posted by 777fly ...

The photographs of the left wing section show that a large section of the outboard upper wing surface is missing and broken wing spars can be clearly seen. This kind of damage is often seen when a wing is overstressed in a high speed dive recovery. Of course, such damage might have occured at impact, but it would be interesting to know if those missing outboard wing sections are found with the main wreckage, elsewhere, or not at all.The control surfaces have been smashed off due to the high AoA and high Rate of Descent. Note that attachment spars etc. are all that remains, and the composite components have gone. Early signs that confirmed the BEA's "en ligne de vol" with a high vertical component, were the top of the RADOME was recovered, and an Outer Spoiler showed signs of being punched vertically from its stowed position.

If any hydraulic control system had suffered damage, that would have certainly generated an ECAM and subsequent ACARS message. With the information we have, none of that happened. That doesn't preclude the Outer Spoiler mentioned above from having left in the air, but the visual evidence of its found condition has all the hallmarks of a upward punch by the sea surface, and I suspect the lack of symmetry would have created another warning - before the Cabin Vertical Speed advisory.

PJ2

19th Apr 2011, 04:54

Machinbird;
I would like to call attention to some anomalous indications in the DFDR trace.

. . . .

First, look at the position of the R & L elevators. Wouldn't you expect both elevators to be moving synchronously? But just before 14:48:10, the L elevator (brown trace) follows a stick pulse, but the R elevator (blue trace) does not. Then at 14:48:12, the R elevator responds to a stick input, but the L elevator does not. This split behavior continues until 14:48:17 at which point the aircraft has apparently flown out of the turbulence and is in a recovery phase.
There is an alternate explanation which might help. It comes from the way flight data recording works.

Remember how popular strobe lights were? Let's put two such strobes in a dark room where a lot of people are dancing to disco music...(yes, I remember). Let's point one strobe one way and the other in the opposite direction, (left and right); let's pretend they're shielded so they dont' light up the whole room but just where they're pointed.

Let's then fire one strobe a bit later than the other and film the position of the dancers lit as the first strobe fires, and compare their positions with the dancers lit by the second, later-firing strobe and ask, Are the dancers lit by the second strobe in the same position they were in when the first strobe was fired?

We know by now that they're not. Dancers are always moving!

Are the second group of dancers "lagging" behind the first? Again, no, we just see them slightly later because of the "snapshot" way the data was taken and recorded.

The same happens with digital flight data recorders. The process is sequential, not all at once.

So we know each parameter has it's place and time of recording and it is different than all the others.

All aircraft parameters are also generated and recorded at different rates per second.

Fuel quantity is recorded every four seconds because a faster rate isn't needed to notice change. Heading is recorded once per second, roll is recorded at twice a second, pitch at 4x/sec, while vertical 'g', which changes rapidly, is recorded up to 16x per second and sometimes higher.

These "frame rates" are a matter of design and software programming. QARs, (Quick Access Recorders used in FOQA/FDA programs) often record
many more parameters and at far faster frames per second than DFDRs or SSFDRs.

The key point is, parameters can't be recorded all at once. If there are 1800 parameters (in binary form) coming into the system, the system must have a way of "listening, parsing and recording". The data frame software is how that process is handled.

As the second begins at '0' and proceeds to '1', the data frame runs through all parameters, sometimes "flashing the strobe" 16x a second, sometimes less, sometimes not, and then places the binary data received in the data frame cells (much like a spreadsheet...simple data frames are 4 columns, 64 rows, filled each second), at the programmed recording rate.

Without getting more complicated, (because it has to if we go any further and everyone will be asleep), the nature of recording can give the appearance of a 'lag', when there "may, or may not" have been one.

I say "may or may not", because there is one more thing to know.

As with the strobe light, when the lights are "off", no one knows what position the dancers are in, until the next strobe fires. This is equivalent to the position of the aileron or sidestick, etc, not being recorded, even when these devices will always have a certain position.

Further, one can make absolutely no assumptions whatsoever, about the positions of the dancers, while the lights are off. Similarly, in the time between the snapshots of the left aileron position and the right, one can make no assumptions about what these controls were doing while not being recorded, even as they logically had a position at all times.

If the sidestick (recorded on the A319/A320/A321 at 8x second in most frames) is moved so rapidly that the frame rate can't catch every important position, then what we see in the data may be misleading. A rapid sidestick movement full forward then full aft in about a second will not look like a smooth fore and aft movement and, depending when in the entire recording sequence such motion was made, the data may not show full aft or full forward because "the strobe was off at full deflection"...

So it is with all aircraft parameters.

To introduce what will be a reasonable complexity, there may actually exist some lead or lag in the flight controls. But there is no way to tell as slower frame rates and ground testing is the only process that can answer the question.

I haven't studied the Air Canada traces so can't comment in detail but this kind of explanation is the way recording works.

This isn't to say that the recordings aren't still extremely useful, obviously. But it takes experience and training, and in cases as fine-tuned as these it would be up to the maintenance people and the aeronautical engineers to say whether the positions of the flight controls, as they relate to the side-stick and rudder pedals even with the lag, affected control of the aircraft in a certain way vice another way.

This is why I think, even when the recorders are found and read, (which I am confident they will be), that the real discussion will just be starting.

grizzled

19th Apr 2011, 05:09

PJ2...

A superb explanation -- as usual.
(However I was a tad worried at one point that you were going to introduce Schroedinger's cat onto the dance floor...) ;)

gums

19th Apr 2011, 05:18

Salute!

PJ has some great points about digital recording on a serial bus.

Working with flight test recorders in my previous life, we had several "channels" of data streams, all synched with time stamps. Even the analog data. The biggest difference between test profile recording and day-to-day maintenance and such recording for the big jets is the update rate. If we sample at 100hz or faster, we can build very accurate relationships between all the inputs. But then we need a huge storage capacity.

Looks to me that the stuff we see from the "maintenance" recorders and transmissions from the AF jet was only "blips" of all the data that still resides in the flight data recorders.

There are several independent "channels" on the flight recorders, and just look at some of the traces for various accidents/mishaps. We can see all kindsa things that happened at the same time.

and now back to the experts and regular program.

Machinbird

19th Apr 2011, 06:57

Thank you PJ2 for the excellent reminder about the vagaries of data collection and an interesting presentation of the concept.:ok: Just because a point is plotted on a DFDR chart does not mean it is not an interpolated or smoothed point seems to be a key element of your message.

There is one more factor to be considered in analyzing flight control data. The maximum uncertainty of position for those items that are moving (such as control surfaces and actual controls). Real objects move at characteristic rates. A control stick will not move from full left to full right in a millisecond. Even if it could, and then immediately returned to its original position, could a hydraulically driven control surface follow such a short signal?
Suppose a rudder surface takes a full second to go from neutral to full right at maximum control input. If sampled 4 times a second, you may not know exactly when it reaches maximum deflection or exactly when it reversed its direction of motion, but you can still know it moved at close to its maximum rate and achieved approximately full travel. Estimates can be made for the uncertainty and approximate behavior determined.

The AA587 investigation had real problems with the DFDR data because the low sampling rates masked the dynamic nature of the oscillations. Lets hope that more rapid sampling rate recorders were mandated as a consequence.
If data is recovered from AF447's recorders, will the sampling rates be high enough to definitively show dynamic behavior of the aircraft and its controls? Let us hope so.

Meanwhile, does anyone have knowledge of the sampling rates on the Air Canada A319 aircraft we were just discussing?

PJ2

19th Apr 2011, 06:59

grizz;

That's why it's called a PFM box... you never know for sure.

gums;
Looks to me that the stuff we see from the "maintenance" recorders and transmissions from the AF jet was only "blips" of all the data that still resides in the flight data recorders.
The mistake some made in the early discussion was treating the 24 ACARS messages as the same kind of information as flight data recorder information - most on the thread now know that inferences from the messages is a mug's game.

There are data recording solutions which come close to resolving the timing issues, but "granularity" becomes an issue if important parameters, (especially in older equipment) are not recorded at sufficient rates-per-second, (and can't be precisely coordinated with others which aren't recorded at the same rate. If the sidestick is recorded at 16x/sec and the elevator rate, for example, is recorded at 4x/sec, how does one match each side-stick data point with the 4 existing elevator points? And this is quite different than the problem of "filtering", which the FAA has addressed, (and towards which I do not wish to divert the thread).

Not sure what you mean by "sampling at 100hz" or how such a parallel system would work, but there is a lot of variations on a theme.

PJ2

19th Apr 2011, 07:14

Machinbird;
Just because a point is plotted on a DFDR chart does not mean it is not an interpolated or smoothed point seems to be a key element of your message.
No, I would specifically wish to avoid this interpretation of my note. "Filtering" can be used to smooth data as we know, but I don't see how it can be so smoothed when "the strobe is off", so to speak. Notwithstanding your very reasonable statement regarding logical assumptions (which I do not necessarily disagree with), the issue is decideability...by what means and by what justifications in data work is smoothing decided and for what parameters, some, all, none? I have seen both the raw, (very lumpy) data and smoothed data and both work for various purposes, but the only way to resolve the issues raised by AA587 are, as the FAA has indicated, finer granularity, (higher sample rates, larger storage capacity). A variation on the issue trivially arises when using lossy JPG formats in digital photography, which is why so many who know what they're doing prefer a form of RAW; - the information in the spaces in between is real, not derived.

Meanwhile, does anyone have knowledge of the sampling rates on the Air Canada A319 aircraft we were just discussing?

I believe the places where the symbols are placed on each parameter's line represents each sample point for that parameter.

I don't think there is anything in the A319 event that relates to the AF447 event. The AC event was wake turbulence...quite different than TCu's.

BJ-ENG

19th Apr 2011, 08:28

FDR and filtering etc:

Filtered Crash Data on AA587 Surprising and Disappointing to NTSB (http://www.iasa.com.au/folders/Safety_Issues/dfdr-cvr/TheFDR%20story.html)

sensor_validation

19th Apr 2011, 08:33

sensor validation, If I am reading Wikipoodle correctly the speed of sound at commercial aircraft altitudes is around 660 MPH or 573 kn. That gives a speed of 7.8 nm/s for .82 Mach. If the plane flew on the entire time the radius would be 31 nm.

Indeed - you also have to allow for wind speed, and if you calculate distances between the history of 10 minute locations you get about 80nm per 10minutes - so the initial +40nm position was 5 minutes of forward flight, or 4min + dive slope. There was some confusion about the pedigree of this report in initial days after crash see Air France 447 - AFR447 - A detailed meteorological analysis - Satellite and weather data (http://www.weathergraphics.com/tim/af447/) for example. Much discussion here about possible location - including turn back and south of LKP, and expectation of 10nm radius - but rather than change it seems BEA stuck with the initial determination 'most likely within 40nm'.

Bahrd

19th Apr 2011, 09:50

Any chance of a deconvolution algorithm ?
Looks like a blind one...
In order to estimate the impact location (in case when the recorders are destroyed) one can consider an INS equipped bathyscaphe starting from the position of the plane's remains and compensating on-line ocean currents when climbing up.
Such a procedure is - to some extent - a reverse of the Monte Carlo approach described by lomapaseo in http://www.pprune.org/tech-log/395105-af-447-search-resume-89.html#post6393355.
A variation on the issue trivially arises when using lossy JPG formats in digital photography, which is why so many who know what they're doing prefer a form of RAW; - the information in the spaces in between is real, not derived.
For the sake of precision: the information in color RAW files is real but not complete anyway due to the presence of the Bayer color filter preceding a sensor.
All images - when retrieved from a RAW data - need to be transformed by a so called demosaicing (http://books.google.com/books?id=ynKEs6Zg0k8C&lpg=PA33&dq=demosaicing&hl=pl&pg=PA33#v=onepage&q=demosaicing&f=false) procedure (which is a kind of interpolation algorithm).

syseng68k

19th Apr 2011, 09:57

BOAC

19th Apr 2011, 10:01

mm43

19th Apr 2011, 10:24

Irrespective of data interpolation points versus timing interval, be it at 8Hz, 16Hz, 32Hz or as PJ2 queried 100Hz, a smoothing curve can ultimately be provided to cover the slower data rates. As PJ2 has pointed out, the side stick may be moved at a very high rate and not be recorded, however the reaction time of the hydraulics will normally reveal something that has been missed and show it as a potential overshoot/undershoot.

The feedback loop in the hydraulics system will have a gain that makes it track the inputs fairly accurately, but inevitably it will have some lag, as anticipation is not built into it by design. Rather, in the case of the rudder, a damping action to avoid excessive yaw is provided, and it is evident when looking at the TSB of Canada's A319 trace. The lateral 'g' records provide a guide as to how that correction is being applied.

The disparity on the left/right elevator positioning is rather disconcerting, but I am sure there is a valid reason for it - part of which could be PJ2's reasoning.

Back to reality.... Does the A319 have a PTLU (Pedal Travel Limiter Unit) in the system, and is there an acceptable rate of change built in that further limits the commands to the rudder? From what I have seen in these traces, I suspect not.

As has already been suggested, the A319 example will not be valid with what is recorded by AF447 - it certainly wasn't wake turbulence that brought it down.

henra

19th Apr 2011, 10:49

Way back in post #3262, Lonewolf wrote "caveat, it may be a load of rubbish if the gyros in the A330 are not prone to tumbling ..."

This has been rumbling around since day 1 and I'm not sure I've noticed an answer. I was under the impression that the notified failures were all ADC related?

Do we have any indication that the IRS attitude was faulty?

Not that I'm aware of.
I think the tumbling referred to tumbling due to excessive maneuvering of the aircraft.
However, I have serious doubts that the IR part of the ADIRUS are prone to tumbling like a classic gyro although I don't know for sure.

And the standby AI in this case was a Laser Ring Gyro if I remember correctly which should also not be prone to tumbling.

That said, I could well imagine that recovering a tumbling airliner in turbulence and complete darkness only by the instruments after having been taken by surprise and with a plethora of ECAM message popping up might not be quite as easy as in an aerobatic aircraft in good visibility during a planned and well trained maneuver....

grity

19th Apr 2011, 11:11

#3531 Fuel Distribution ......some fuel is normally transferred to the tailplane trim-tank, unless it's already full, pushing the CG aft by a suitable amount.....@ Chris Scott, if one reduce the speed in view of turbulences, is it feasible (or generally used) to transferre the CG again to the front somewhat, or did one trust into the steering system, and deside the risk of stall vs reduce of energy, even in this case, in the same way as in normal cruise flight and let the CG aft as before ?

hetfield

19th Apr 2011, 11:19

if one reduce the speed in view of turbulences, is it feasible (or generally used) to transferre the CG again to the front somewhat, or did one trust into the steering system, and deside the risk of stall vs reduce of energy, even in this case, in the same way as in normal cruise flight and let the CG aft as before ?

In the company I was working for it's SOP to shift CG fwd in turbulence.

Chris Scott

19th Apr 2011, 11:24

grity,

I see what you mean, but am afraid I can't answer that one. Never flew the 330/340. Perhaps PJ2 will when he gets up (GMT -7), or CONF_iture (if he's not flying).

Lonewolf_50

19th Apr 2011, 12:05

Thank you, to henra and BOAC in re attitude reference systems. Not familiar enough with what is used in big metal to have any intuitive feel for how they respond during upset. Your point on "no system fault" transmitted may have been the answer to my question in the first place.

Also a big thank you to PJ2 for the analogy in re data sampling, although I did cringe at the memory of strobe lights and the disco era. (At least you didn't meantion leisure suits and polyester shirts! :eek: )

For syseng68:
Although messages may not be written in real time, or perhaps even in strict sequence of arrival is irrelevant, since each message will have it's own timestamp.
Good point.

Lazerdog

19th Apr 2011, 12:30

Anyone have any links to the schedule of the recovery effort? The vessel named in the prior news articles appears moored at Las Palmas.

HazelNuts39

19th Apr 2011, 13:32

Since people are talking quite a bit about a high altitude stall here is a video from the ASB (Australian Safety Board) of a 777 stalling at high altitude ...According to the ATSB incident report: Stall protection activated, stall warning and stickshaker activated, and indicated AoA reached 10.5 degrees.

The report doesn't say that the airplane actually stalled, but maybe we can take the AoA as an indication that it did, or came very close?

PS:: The airplane was pitching down at the time (17:03:52 - 17:03:59) the AoA was recorded. Therefore the vane AoA may have been greater than the airplane AoA.

gums

19th Apr 2011, 14:03

Salute!

BJ and mm43 have cracked the code.

The info I can find on the DFDR's reveals very slow sampling rates, and I am not sure if the data is time-stamped at the sensor or by the "black box" when it receives the data.

My background was in military testing, and we sampled the digital data at 50 hz or better. Our analog data from accelerometers and pots were recorded on old-fashioned tape! However, the digital stuff was parallel on the tape (7 channels), so we had a mechanical means of synchronizing the data.

As the referenced report by BJ states, the sampling rate was too slow to get an accurate replay of the rudder reversals by the 587 jet.

For my business we needed to see very good parallel data streams of control position, force inputs, and aircraft/missile attitude, gee, etc.

The serial data recorder using a single memory device has to use various update rates depending upon the parameters of interest. And I agree with the observation that filtering the data as it is being recorded is not a good thing. Our data reduction facility could filter as necessary, but we captured the "spikes" and such as raw data.

Chris Scott

19th Apr 2011, 14:15

Quote from JD-EE (posted (http://www.pprune.org/tech-log/395105-af-447-search-resume-182.html#post6399225) Apr18/2341z):
"...If the accident happens in a third world area, the report quality is poor because of the untrained and inexperienced investigators. If the accident is not politically charged and is in a "first world" nation the reports tend to be pretty good..."

Apologies for slight thread-drift. As a BBC Radio4 addict, I recommend this fairly balanced programme (http://www.bbc.co.uk/iplayer/console/b010025s) on the problems of accident investigation in third-world countries – strictly only for those who can manage without pictures...

valvanuz

19th Apr 2011, 14:34

Lazerdog

Ile de Sein is due to leave las Palmas april 21st to start the search. Apparently, the ship has been doing sea trials yesterday off the coast. (Testing new equipment?)

bearfoil

19th Apr 2011, 14:52

mm43

With most respect, I tend to disagree re: your studious conclusion about the found spoiler, and by inference other composite panels. The spoiler was found on the surface beaten up badly, and fractured, but retaining its full size and shape. Given the scope of the destruction to metallic forgings and extrusions evident in the seabed photos, I have to say the spoiler without doubt was removed by air loads, extreme airloads. The actuator attach was badly fractured, but the damage was tight to its location, and gave way to a retention of integrity just inches into the panel's skin surrounding the fasteners. In my experience, FRP has a signature failure in high energy impacts that is unmistakable. It explodes. I believe that if the spoiler panel (#4??) had been on the wing at water impact, there would be virtually nothing left to find. This has also to do with my admittedly stubborn conviction that the Vertical Stabilizer and Rudder were not on the fuselage at impact. The Radome is even money, I think it is likely to have left the airframe prior as well, perhaps in overspeed, or due to hail damage.

I am thrilled at the location of the aircraft's site, and my optimism is high. I think that here on PPRuNe, this thread is as incisive and academically brilliant as any accident report I've seen. You and the others are absolutely brilliant in your knowledge, logic, and utmost respect for one another.

kudos, and back to read....

MurphyWasRight

19th Apr 2011, 16:45

lonewolf :
Also a big thank you to PJ2 for the analogy in re data sampling, although I did cringe at the memory of strobe lights and the disco era. (At least you didn't meantion leisure suits and polyester shirts! :eek: )

For syseng68:

Quote:
Although messages may not be written in real time, or perhaps even in strict sequence of arrival is irrelevant, since each message will have it's own timestamp.

Good point.

I strongly suspect (but don't have doc's to qoute) that the data arrives at the black box at a much higher rate than it is recorded and that the recorded sampling rate is set by the black box.

What could be done to help with correlation is to snap-shot all the data at relevant frame boundries, to use PJ2's analogy synchronize the strobes. The data could then be saved over the frame time.

This would avoid artifacts such as phantom splits in control surfaces due to "sampling lag"

On the other hand there may actually be more value in sampling the data as it is recorded, helping to fill in gaps using semi-related parameters.

To put it in engineering terms "no matter how hard you try Nyquist wins". (And wagon wheels will continue to go backwards in movies)

PJ2

19th Apr 2011, 16:57

Sorry to disagree, but the recorders would not affect the time relationship between messages. A much more likely scenario would be for each message to be timestamped as it arrives at the recorder, then queued for writing. The queue would be of a length to ensure that no messages are lost.

Although messages may not be written in real time, or perhaps even in strict sequence of arrival is irrelevant, since each message will have it's own timestamp...
You're talking about two completely separate systems. Flight data recorders have nothing to do with the ACARS messages - that's been the point all along. The recorders don't see these messages, don't/can't record these kinds of messages, don't "timestamp" data and don't hold them in memory. That's not how flight data recording works.

grity;

Fuel transfer and the CG is managed by the FCMC [Fuel Control and Monitoring Computers]. There are no procedures established to move the CG forward to "guard against stall" - in fact, no airplane which would require such an intervention should be flying as a commercial transport. The aircraft is certified to be loaded and fueled in certain ways and CG limits are established as part of the design and certification process.

Procedures are in place to handle the abnormalities.

If for any reason the CG ends up too far aft, an ECAM message comes on requiring the forward transfer of the fuel. This is different than "deciding that the CG is 'too far aft' " all on the crew's own. You can get into an equal pile of trouble with too forward a CG, so even though the method is available, (by transferring the trim tank fuel forward, (requires a 3-deg ND pitch to do so)), you wouldn't do it without the ECAM message, just because you thought it would be a good idea.

Thanks gums, understand now. For clarification, flight data is not "timestamped". It is recorded, using synchro words for each parameter when recorded in the data frame. This enables each parameter to be synchronized in time.

The process you're describing would be great for event and accident investigation, but many here, perhaps even yourself, have seen how slow the FAA (and TC in Canada) are in keeping up with available recording technology. "Mandating" the recording of 88 parameters is actually embarrassing.

Back to the subject at hand.

The BEA Report indicates that AF447 had an SSFDR that records about 1300 parameters. AF also runs a FOQA Program and as I have mentioned before, at least a search for the QAR, (in the EE Bay underneath the cockpit) should rule-in/rule-out it's availability and use, although the way the forward section is understood to have impacted, the survival of the electronic gear (and their memory cards) may be questionable.

MurphyWasRight;

Re "arriving at the 'black box' at a higher rate than is recorded" there is no mystery or magic to this stuff - it is in its essence, bread-and-butter digital data transmission and recording, (which, aside from what I've commented on, I know unbelievably little about), so no, there is neither "higher rate" or "more" data, not, at least without the original equipment such as the sensors, the DFDAU [Digital Flight Data Aquisition Unit] software and data buses [ARINC 537, 429 standards etc) to support the designed and intended installation.

I really don't want to divert the thread into the minutae of recording. My comments were intended as a caution about too loose an interpretation on what is seen in the traces regardless of airplane, recorder sophistication and so on.

For those who would really like to understand this further, (and frankly, without some understanding of how data is generated, interpreted and recorded one cannot make comments that are relevant to the very simplified way I've outlined a couple of characteristics), I recommend the two sites below - they're great for a good understanding of the process; the third site is on FOQA in general, by the FAA.

Please see Appendix B of http://www.caa.co.uk/docs/33/CAP731.PDF , and pages 9-13 of the BEA document at http://www.bea.aero/etudes/use.of.fdr/use.of.fdr.pdf , and perhaps the following FAA document which is excellent on FOQA Programs in general,
http://www.ihst.org/portals/54/Attachment%20D_AC120-82.pdf

ChristiaanJ;

You're right in the sense that it would be the FDIMUs or DFDAUs, (which receive the incoming data from sensors all over the airplane, and change either the analog or digital/binary information into engineering units such as rates, discretes, positions, degrees, etc etc. It would be here that the DFDAU software could "filter" any and all data depending upon programming. It's these boxes that do the heavy lifting...the SSFDR and QAR where installed, are just the recording mediums.

The notion of "filtering" is perhaps another way of saying "manipulated". I would characterize it this way, because where there is no information, ie, no digital signal because the process is "in-between" signals, one has no information to say anything with, and so if one says something, (ie, the DFDAU "fills in the places in-between), one has manipulated the data; that is an entirely legitimate process providing one knows the basis upon which the data is thus manipulated, and providing the holes in the data aren't too large and that rates of change are not incommensurate with the rate of data capture. In standard flight data animation products, such smoothing is necessary, otherwise a series of images based solely upon the data rates with no smoothing, would be very jerky and difficult to interpret. This comes down to "why videos?" in the first place. They are a contextual tool, not a diagnostic tool and as such have great use, but, (for those who have read these cautions before), those who create such videos very often do not have an understanding of how the animation is possible and can draw some seriously incorrect conclusions from just watching the video. That is why this stuff does not belong in non-trained hands...it can badly mislead and the consequences can be serious. But in trained and experienced hands and eyes, it can tell a very accurate story, because the warts are seen and understood.

One can, as has been suggested, make some reasonable inferences from other systems, (mm43's hydraulic example is a good one). But I don't think this is merely a philosophical point: Where there is no data, "smoothing the data points to manufacture datapoints in the in-between, regardless of the mathematical methods used, is not "data" - it is inference, however conceived.

Such inference can be quite reasonable to the point of appearing to be accurate in, for example, a video or film, where our mind "knows" what the changing motions on the screen are "about" and we intuitively make those connections without difficulty, and with a high degree of accuracy.

However, in reading data points which are far enough apart for other things to occur that are beyond the capacity to measure, (like using a yard-stick to measure a foot...it can't be done "accurately" even though it could be inferred, if for example the object being measured is four feet long, which is "a yard and a bit"!),, those events will not have occurred so far as interpreting the data is concerned. They may be so-recorded in other parameters, which is mm43's excellent point, but in the end, one cannot make up data where it doesn't exist even though smoothing in some cases is a legitimate process.

ChristiaanJ

19th Apr 2011, 17:28

I'll take the risk of confusing the story....
Isn't most of the 'filtering', etc. done in the FDIU or FDAU (Flight Data interface or Acquistion Unit)?
Been there, done that, but too long ago to really be able to contribute anything useful. And no doc to hand....
Not even sure how and when the tme-stamping was done.

Machaca

19th Apr 2011, 17:59

bearfoil:
...if the spoiler panel (#4??) had been on the wing at water impact, there would be virtually nothing left to find.

The spoiler's condition is consistent with it being pushed up and off the wing from below by the much larger flaps.

FRP has a signature failure in high energy impacts that is unmistakable

In my experience (aerospace and motorsports) one signature does not fit all! Depends largely on which Fiber(s), the amount and direction of Reinforcing, and the type of Plastic.

stubborn conviction that the Vertical Stabilizer and Rudder were not on the fuselage at impact
Please make an argument as to how the VS and four of its entire forged lugs were together ripped up and forward from the tail section by loads achievable while in the air.

sensor_validation

19th Apr 2011, 18:02

I don't think there is anything in the A319 event that relates to the AF447 event. The AC event was wake turbulence...quite different than TCu's.

Sorry for diversion - having seen Ewa Ewa sucked into storm and lives to tell - National - smh.com.au (http://www.smh.com.au/news/national/dead-luck-ewas-flight-of-fury/2007/02/16/1171405421626.html) interviewed in the documentary 'CloudSpotting' again recently, and heard an explanation on how such big heavy clouds stay up - they don't they are continuously falling in their terminal velocity against the updraft - I believe vertical wind more likely to have been an issue. And then we are back to the effect of speed calculated from frozen pitot tubes and real altitude rise with working static ports...

Rob21

19th Apr 2011, 18:07

According to reporter Nadia Guerlanda Cabral (Folha.com), the Commander of CENIPA (Center for Investigation and Prevention of Aviation Accidents) assured today (19th) that Colonel Luiz Claudio Lupoli will be on board the ship Ile de Sein representing the FAB (Brazilian Air Force) on the rescue mission.

Colonel Lupoli said that it is difficult to estimate how long the rescue will last, since this depends on how many trips the "equipment" will have to make.
This equipment needs three hours to reach the bottom (@3.900 meters).

It seems to me BEA kwows exactly where to go with this "special mechanism" and bring up only the "essential"...

PJ2

19th Apr 2011, 18:50

I believe vertical wind more likely to have been an issue. And then we are back to the effect of speed calculated from frozen pitot tubes and real altitude rise with working static ports...Not sure what you mean by "real altitude rise with working static ports" - I'm aware of the effects of blocked pitots and statics on airspeed and/or altitude information - just trying to see your point.

That said, loss of airspeed information does not automatically result in loss of control as, (say) loss of attitude information would. So something else happened, and these points have been made throughout the thread. But my point remains, it has no relationship with the A319 event which was "local" and mostly roll not pitch related as someone has already keenly observed. BTW, they changed the VS on the aircraft.

mm43

19th Apr 2011, 18:56

"Ile de Sein" departed Las Palmas 2011-04-19 1540z and ETA Dakar is 2011-04-22 0700z.

grity

19th Apr 2011, 19:00

There are no procedures established to move the CG forward to "guard against stall" - in fact, no airplane which would require such an intervention should be flying as a commercial transport.@PJ2 thank for your detailed explanation!

shurely no commercial airplane should fly into a CB....

I did not mean a "guard against stall" just the few percent less risk, if one lift the aerodynamic stability on a truly higher level in case of expected turbulences, using existing technics......

I wonder, but it shows again the trust into the control system

JD-EE

19th Apr 2011, 20:02

sensor validation, I'd say "most likely within 40nm" is something a little less conservative than saying "most likely the Sun will not have gone out when it should rise in the morning." I'd use most likely for that annulus I described rather than for the entire region. The rest of the 40nm region is less likely but not utterly unlikely - erm, with the exception of the area +/- 30 degrees of the reverse course. To the rear the region would be punched in. That's why I always sorta head scratched over their nice perfect circles.

sensor_validation

19th Apr 2011, 20:13

Not sure what you mean by "real altitude rise with working static ports" - I'm aware of the effects of blocked pitots and statics on airspeed and/or altitude information - just trying to see your point

Nothing new, just referring back to much discussed effect of locked in pressure (ram and drain hole blocked *) - the 'apparent indicated airspeed' rises with altitude. Obviously most dangerous under take-off climb, which will likely be the design case for pitot tube heating/draining and procedures. Possibilities to climb under 'pitch and power' at cruise height include updrafts and that discussion that the Airbus/AF recommended pitch too high? Higher altitude, lower real air-speeds = lower margins?

* Note linked to your other discussions on sampling/filtering - it is possible to detect this by 'listening to the noise' and there are patented and commercial pressure instruments in the process industries that do "impulse line blockage detection".

sd666

19th Apr 2011, 20:24

Hi Bearfoil...

In my experience, FRP has a signature failure in high energy impacts that is unmistakable. It explodes.

Just humour me here, please.

What's your experience?... and can you point me to a Youtube video of this stuff exploding please. I'd love to see it.

I drove a Reliant Robin into a wall once, but that just cracked.

promani

19th Apr 2011, 21:07

SD666 drove a Reliant Robin into a wall once, but that just cracked

The speed they went, I am surprised it didn't just bounce off the wall with a scratch or two.:D

Chris Scott

19th Apr 2011, 21:46

Quote from PJ2 (Apr19/0714z, currently post (http://www.pprune.org/tech-log/395105-af-447-search-resume-183.html) #3646):"I don't think there is anything in the A319 event that relates to the AF447 event. The AC event was wake turbulence...quite different than TCu's."

PJ2 is absolutely right to remind us that wake turbulence is a very different phenomenon from turbulence in towering cumulus (or Cb storm-cells). I reckon he has experienced both, as I have.

For whatever reason, posts have been coming thick and fast over the last two or three days, and it's possible that even PJ2 may have missed something here. There are arguably at least four points of similarity between ACA190 (the Air Canada A319 wake-turbulence encounter that sensor validation kindly reminded us about) and AF447:
1) both involved Airbus FBW aircraft, whose artificial handling qualities are deliberately similar;
2) both occurred at medium subsonic-cruise altitudes;
3) both involved the PF suddenly and unexpectedly having to "hand-fly" the aeroplane, using the sidestick (the use of rudder pedals in ACA190 is another matter);
4) in both cases, for one reason or another, control laws were degraded.

Few line pilots dispense with the autopilot for regular handling practice at cruise altitudes, even in smooth conditions. Passenger comfort is our main priority. As for deliberate degradation of control laws (by selecting one or two of the 5 flight-control computers off, as someone once wanted to do on a flight with me in the early months of A320 operations), that is definitely taboo on the line.

chris weston

19th Apr 2011, 21:56

Reliant Robin V max is > 100 mph

Allegedly .....

CW

BBC News | BUSINESS | End of the road for Reliant Robin (http://news.bbc.co.uk/1/hi/business/945083.stm)

worlds fastest reliant robin - Wirral - wikiwirral.co.uk (http://www.wikiwirral.co.uk/forums/ubbthreads.php/topics/257400/Re_worlds_fastest_reliant_robi.html)

jcjeant

19th Apr 2011, 22:20

Hi,

In the press (BEA)
Communiqu de presse, 12/02/2010 (http://www.bea.aero/fr/enquetes/vol.af.447/com19avril2011.php)

The ship must recover the wreckage of the Air France plane crashed into the sea off Brazil in 2009, will join the port of Dakar on the night of Thursday to Friday and should be in the area of the accident during the Easter weekend.

"A few hours stopover in Dakar is scheduled to ship before the investigation team to visit the area of the accident," said a statement from the Bureau of Investigation and Analysis (BEA).

The director of technical investigation, Alain Bouillard, will be assisted by three investigators from the BEA, a safety investigator from the AAIB (UK counterpart of BEA), an investigator security CENIP (Brazilian counterpart) of three experts from European manufacturer Airbus, an expert Air France, an American specialist imaging sonar that participated in Phase 4 research at sea and a psychologist.

In addition, four police officers (OPJ) and three specialists from the Institute of Criminal Research of the National Gendarmerie will be on board for the judicial side.

"Phase 5 will begin with the detailed observation of the accident site and search for flight recorders," said BEA. "Once located, they will be reassembled (...) and immediately placed under seal. They will then be escorted by a Navy ship to a French port, and then airlifted to BEA under the responsibility of an OPJ" , said the French agency.

Khashoggi

19th Apr 2011, 22:39

Sounds like a reasonable complement of personnel to ensure transparency. The psychologist is a curious addition.

mm43

19th Apr 2011, 23:16

Remora 6000 - ROV Specifications (http://www.phnx-international.com/Equipment/Remora6000_lr.pdf)

http://www.phnx-international.com/Pictures/Photogallery%20-%20Company%20Profile/Remora%20&%20Winch%20%20ARES%20Deck%20View3.jpg

promani

19th Apr 2011, 23:24

cjeant, that BEA communique was last December, I wonder if that is the team that is onboard now, and if Plan 5 remains the same?

mm43

19th Apr 2011, 23:29

promani

The link text as posted is incorrect. The media release in French is dated 2011-04-19 and represents the current situation with regard to the Phase 5 - Recovery operation.

AVLNative

19th Apr 2011, 23:36

The psychologist is a curious addition.

I suspect that is due to the report in Der Spiegel that the Alucia left due to "Too high psychological load" on the workers.

wozzo

19th Apr 2011, 23:37

The psychologist is a curious addition.

According to German news reports, the IFM-GEOMAR institute (Kiel/Germany), which participated in the last mission with their REMUS 6000 (AUV ABYSS) declined to participate in the upcoming mission (with their ROV Kiel 6000) because the "level of psychological stress would be too high". So maybe there's a hint why a psychologist is part of the team.

In German:
SPIEGEL report
Absturz von AF 447: Kieler Forscher steigen bei Wrack-Bergung aus - SPIEGEL ONLINE - Nachrichten - Wissenschaft (http://www.spiegel.de/wissenschaft/technik/0,1518,757492,00.html)
Press Release IFM GEOMAR
IFM-GEOMAR: Aktuelles aus dem IFM-GEOMAR (http://www.ifm-geomar.de/index.php?id=537&tx_ttnews[tt_news]=721&tx_ttnews[backPid]=1&cHash=fb05a18b54)

bearfoil

19th Apr 2011, 23:53

machaca

howdy. I see two planar considerations for Fin performance, lateral (side to side), and longitudinal (fore and aft). Each of these planes is addressed separately. The pins and brackets snub each stress in differing responses relative to strength. The side to side is captured by a narrow breadth of lug to lug span, the longitudinal by the distance of the saddles fore to aft. The longitudinal consideration addresses drag, the lateral, Rudder deflection and or fin divergence from airstream (Fin/AoA). The stronger structure reacts to drag (it has greater length, or 'pivot'), and the lateral relies on a shorter throw to control what I see as a potentially larger stress, that of side to side sweep, the action that destroyed 587.

Each of these planes is of course rectilinear, though the stresses are not always so in flight. The Fin and Rudder are constantly changing their respective 'attitude' depending on the slipstream, and control inputs. The failure of 587's VS started at the aftermost right lug and rotated forward capturing each of the other lugs in sequence, in a circular motion due to torsional, side to side, and longitudinal stresses. The alteration of stress puts right angle joints at a disadvantage, for the designed consideration weakens as the stress partner acts in the other plane.

An airload that could be responsible for the removal of 447's fin could be drag alone, in overspeed, with an overswept Rudder. Such drag would put a great load on the aft bracket downward into the fuselage, perhaps scrubbing the Rudders corner as it pressed down into the tail cone. If there were other stresses in 'concert' with drag, eg lateral and longitudinal, it would not surprise that the Fin may have failed sequentially, losing its joins 'gradually'. Remember that 587's engines were scraped clean in an aft and sideways manner at less than 210 knots.

Further, looking at 447's powerplant, with no vestige of pylon or wing structure attached, one's breath is taken, and to consider that somehow a rather fragile structure as the fin survived 'unscathed' simply defies logic.

Nothing of what I propose is meant to dissuade or foreclose other explanations, at all. I am astonished at the complete disintegration in the debris field here. Absolutely nothing seems to have remained attached to anything.

Chris Scott

20th Apr 2011, 00:00

Not sure where you sourced that press communiqué in English, jcjeant (is it your own translation?), but it can't be dated 12/2/2010...

The Anglophone edition of the BEA website is understandably lagging a bit behind the Francophone, but – for the record – here is the French text at this hour:

"Communiqué de presse diffusé le 19 avril 2011

"Le navire câblier Ile de Sein d'Alcatel-Lucent et Louis Dreyfus Armateurs quitte le port de Las Palmas (Iles Canaries) aujourd'hui, avec à son bord un robot Remora 6000 et l'équipe d'opérateurs de Phoenix International Inc. Il doit rejoindre le port de Dakar dans la nuit du jeudi 21 au vendredi 22 avril. Une escale de quelques heures est prévue à Dakar pour embarquer l'équipe d'enquête avant de se rendre sur la zone de l'accident.

"Cette équipe, dirigée par le directeur de l'enquête, Alain Bouillard, assisté de trois enquêteurs du BEA, sera composée :
- d'un enquêteur de sécurité de l'AAIB (homologue britannique du BEA) ;
- d'un enquêteur de sécurité du CENIPA (homologue brésilien du BEA) ;
- de trois experts d'Airbus ;
- d'un expert d'Air France ;
- d'un spécialiste américain d'imagerie sonar ayant participé à la phase 4 des recherches en mer ;
- d'un psychologue.

"Seront également à bord du navire : quatre Officiers de la Police Judiciaire (OPJ) assistés de trois spécialistes de l'Institut de Recherches Criminelles de la Gendarmerie Nationale (IRCGN)

"La phase 5 débutera par l'observation détaillée du site de l'accident et la recherche des enregistreurs de vol. Une fois localisés, ils seront remontés à bord de l'Ile de Sein et placés immédiatement sous scellés ; ils seront ensuite convoyés par un navire de la Marine nationale vers un port français, puis acheminés par voie aérienne au BEA sous la responsabilité d'un OPJ.

"Dans l'intervalle, les pièces de l'avion utiles à l'enquête seront relevées.
Le BEA rappelle que la remontée des corps et des effets personnels est placée sous la responsabilité des représentants de la justice."

I'm delighted that they have decided to entertain both Brazilian and British air-accident investigators, not to mention one of the Woods Hole sonar-imagery experts, who seem to have done such a great job in Phase 4. wozzo's theory on the reason for the presence of a psychiatrist/psychologist makes sense in the particularly difficult circumstances of this recovery.

RatherBeFlying

20th Apr 2011, 00:37

The cable laying ship Ile de Sein of Alcatel-Lucent and Louis Dreyfus Shipowner is leaving the port of Las Palmas (Canary Islands) today, with a robot Remora 6000 and operating team of Phoenix International Inc onboard. It should stop at the port of Dakar the night of Thursday 21 to Friday 22 April. A stop of a few hours is foreseen at Dakar to board the search team before heading to the accident zone.

"This team, directed by by the Director of the investigation, Alain Bouillard, with the assistance of three investigators of BEA, will be composed of:
- an investigator from AAIB (British equivalent of BEA) ;
- an investigator from CENIPA (Brazilian equivalent of BEA) ;
- three experts from Airbus ;
- one expert from Air France ;
- an American sonar imaging spécialist who has participated in phase 4 of the sea search ;
- a psychologist.

"Will equally be on on the ship: four Officers of the Judiciary Police (OPJ) assisted by three spécialists of the Institute of Criminal Research of the National Poliice (IRCGN)

"Phase 5 will begin with detailed observation of the accident site and the search for the flight recorders. Once found, they will be raised on board the Ile de Sein and immediately placéd under seal; they will then be taken by a national Navy ship to a French port, then flown to BEA under the responsibility of an OPJ officer.

"In the meantime, pieces of the aircraft useful for the investigation will be raised.
BEA reaffirms that raising bodies and personal effects remains under the responsibility of the judicial representatives."

Bonus: Louis Dreyfus Armateurs (http://www.lda.fr/press_release-78.html)

broadreach

20th Apr 2011, 01:46

Psychologist on the ship?

Come on. The limited view of the wreckage in the BEA photos should be indicative. The Alucia crew will all have seen much more gruesome detail and the Ile de Sein crew will see more. Not all can be expected to have the thick skins of accident investigators. Also, it is one thing is seeing remains of a land crash and being able to spew your guts out off-site, but another altogether seeing real, and apparently intact, people in their seats as you trawl over them photographing and looking for evidence, recognizing real people from a few frames before, even using them as reference points. And then being stuck on a ship day after day with all the people who've seen the same images or heard about them. Remember, the Ile de Sein is a cable laying vessel. Regardless of how segregated the teams are, the images or reports of same will get around. BEA may later think two psychologists might have been better.

Astrax

20th Apr 2011, 01:46

Live Ships Map - AIS - Vessel Traffic and Positions (http://www.marinetraffic.com) :

Ile de Sain
Call Sign: FOUD
IMO: 9247039, MMSI: 226235000
Lat / Lon: 26.72469˚ / -15.76169˚ (http://www.marinetraffic.com/ais/default.aspx?oldmmsi=226235000&zoom=10&olddate=4/19/2011%2011:04:26%20PM)
Last Known Port: LAS PALMAS (http://www.marinetraffic.com/ais/default.aspx?centerx=-15.41635&centery=28.141&zoom=13)
Info Received: 23:05 UTC
Destination: DAKAR
ETA: 2011-04-22 07:00

Machaca

20th Apr 2011, 01:48

Hello bearfoil:

The failure of 587's VS started at the aftermost right lug and rotated forward capturing each of the other lugs in sequence

Yes, the lugs failed. Only the lugs. The six clevis remained intact as did the entire hoop/frame/skin assembly of AA587's section 19.

An airload that could be responsible for the removal of 447's fin could be drag alone, in overspeed, with an overswept Rudder. Such drag would put a great load on the aft bracket downward into the fuselage, perhaps scrubbing the Rudders corner as it pressed down into the tail cone. If there were other stresses in 'concert' with drag, eg lateral and longitudinal, it would not surprise that the Fin may have failed sequentially, losing its joins 'gradually'.

So you are suggesting AA587's VS pulled up and off due to excessive side loads, but similar excessive side loads on AF447's VS pushed it down with enough force to work the clevis lugs apart from the frame hoops?

somehow a rather fragile structure as the fin survived 'unscathed' simply defies logic.

That's just silly -- the VS is far from a fragile structure!!!

deSitter

20th Apr 2011, 02:11

broadreach - well said. The very eeriness of once living and loving persons, on the forlorn and barren ocean floor, effectively a billion miles from anything human, is almost too horrible to imagine, much less witness. At such times, prayers are the only recourse.

Machinbird

20th Apr 2011, 02:53

Not wishing to be gruesome, but aren't they going to recover portions of the fuselage from off the bottom. If so, it isn't going to be just images that the Ile de Sein crew encounters.
A psychologist is a good idea, I just hope he/she is a bit more effective than the one who used to greet us coming back from combat missions with a small satchel of government rotgut whiskey miniatures. :mad:

grizzled

20th Apr 2011, 04:33

For the reasons already mentioned, a psychologist (if properly trained and experienced in such things) is an essential ingredient in efforts to reduce stress levels on such tasks. And I'm referring to both acute reactions to the work and the possibility of long term residual effects.

The inevitably nasty ("gruesome") nature of some of what will occur is of course one (very significant) component of that need. Additionally, if you have ever lived and worked at sea, or worked with a diverse group who may be less than comfortable with each other's roles (especially when you know the world is watching), or worked long long hours both day and night for a few months at a time, then think of the cumulative effect of all those stressors on this group of people.

In this case, I just hope one psychologist is enough... ;)

Khashoggi

20th Apr 2011, 05:02

Is a psychologist part of every accident investigation team?

Or is the nature of AF447 unique enough to warrant it... Were they used on the TWA800 recovery vessels?

I don't downplay the potentially gruesome nature of the accident scene, but am sure most large accidents are gruesome, by nature, to the untrained.

The ship may have several crew members untrained in dealing with mass trauma scenes, so a psychologist may be useful and appropriate.

SLFguy

20th Apr 2011, 05:33

Khashoggi,
You are correct - very useful.

I have been involved in ROV/Dive Team recovery of sunken vessels, (the O'Bahia trawler being one), on which the bodies of crew memebers were expected to be found.

Although we had them on the POB as 'Counsellors' rather than trick cyclists.

As an aside, hairy arsed divers being what they are, most of the counsellors time was spent with the ROV pilots not the divers!!

grizzled

20th Apr 2011, 05:57

Is a psychologist part of every accident investigation team?

Well, in most "first world" (and I certainly use that term loosely) investigations the answer is that access to a psychologist is a planned part of the "on scene" portions of an investigation. And also for some of the subsequent activities. For example, as you might imagine, actual voice recordings can be most traumatic to listen to.

Clearly, in this case access to a psychologist means that the person must be onboard the ship.

PJ2

20th Apr 2011, 06:18

bearfoil;

It was observed and stated somewhere shortly after the crash in 2009 that there wouldn't be sufficient dynamic pressure above FL200 or so, to cause the VS to fail as it did and that upset would be the only event which could produce sufficient forces which means loss of control could only precede any loss of the VS before impact.

Another way to examine it is, (and this too, has been said before, by myself and others in the thread), if the fin broke off due to upset, entry into a thunderstorm etc, then almost certainly loss of control at high altitude followed by a high-speed impact would have been the result and the available evidence does not lead us to such a conclusion. If the loss of the VS occurred lower, then such loss was not the precipitating event.

The wreckage in the photographs is "relatively" intact, even "pristine" when compared to that of Swissair 111 after an impact of 300kts. The recovered wreckage, mostly from the cabin, is similarly absent of any evidence of high-speed collision with water or other parts during the breakup sequence. Ejected overhead bin parts, the defibrilator (red box) and doctor's medical kit (yellow box), are all in pristine condition, relatively speaking, again, evidence against a high-speed impact.

In fact, the larger parts such as galleys, FA seats, washroom doors etc came from those areas which are major joins in the barrels of the fuselage - just behind the cockpit, just in front of and behind the wing box and just ahead of the tail section aft of the pressure dome.

We can't say any more about it other than that's where the larger pieces came from but it is reasonable to believe that this is how the wreckage will be distributed.

It's been mentioned many times...the track that AF447 took in comparison with others on the same two tracks, especially the number of diversions left and right of track taken by the aircraft behind AF447. I wonder if 123.45 was as busy that night as it usually is on the Pacific and Atlantic?...

grizzled

20th Apr 2011, 06:55

PJ2...

Your question re "123.45" is interesting. Many of us have postulated that a lack of comms from AF447 to "fellow travellers through the ITCZ" that night is indicative of something. Quite what, we aren't sure of course.

What we can say -- as you have alluded to -- is that exchanges of some sort on 123.45, in that area at that time of day, are the rule rather than the exception. For there to have been no participation by AF447 is, to me at least, a possible hint that things weren't quite "normal ops" up front. I'm choosing my words carefully as I have no idea what the apparent failure to use that resource specifically means. There are so many possible reasons for it: one or more radios inop (we have an indication pre-takeoff of a possible problem in this area); something else on the flight deck taking priority (for a longer time than we may have been supposing); and on and on...

At this point this tragedy must be accepted as a puzzle with too many pieces missing to solve it. All we can hope is that the DFDR and the CVR, along with the aircraft remains of course, will provide the investigators enough pieces to solve this puzzle. I, for one, am optimistic.

deSitter

20th Apr 2011, 07:38

PJ2,

Your vast experience and knowledge is compelling, but so is the lack of any flotsam around the fin and spoiler panel when they were found. How do you explain that? Surface tension tends to keep such debris islands intact.

HazelNuts39

20th Apr 2011, 08:29

An airload that could be responsible for the removal of 447's fin could be drag alone, in overspeed, with an overswept Rudder. Such drag would put a great load on the aft bracket downward into the fuselageThe aerodynamics of the vertical tailplane are similar to those of a wing: the drag force is of the order of one-twentieth of the sideforce (lift). And, as you say:

The side to side is captured by a narrow breadth of lug to lug span, the longitudinal by the distance of the saddles fore to aft.
EDIT:: I.e. 0.8 m laterally vs 2.5 m longitudinally. Therefore the lug force due to aerodynamic side force is 50 - 60 times greater than that due to aerodynamic drag.

milsabords

20th Apr 2011, 08:50

The on board psy may also help smoothing potential conflicts between the involved groups of people.

infrequentflyer789

20th Apr 2011, 12:01

In my experience, FRP has a signature failure in high energy impacts that is unmistakable. It explodes.

Curious as to what you regard as "high energy" impact.

From the wreckage photos and descriptions, Air-NZ Perpignan crash looks to me to be much higher engery that AF447 - but still the VS didn't "explode".

How would you compare these two crashes (with what info we have) as regards impact energy (and condition of other wreckage), departure of VS before impact or not, and condition of VS after impact ?

sd666

20th Apr 2011, 12:55

desitter:

Surface tension tends to keep such debris islands intact.

Water drag and wind are more important. Since the tail was largely submerged it's going to act like a sea-anchor, while lighter debris (such as lifejackets) are going to be exposed to wind.

Therefore, you wouldn't expect them to stay together.

On another note. Bearfoil:

Originally Posted by bearfoil http://www.pprune.org/images/buttons/viewpost.gif (http://www.pprune.org/tech-log/395105-af-447-search-resume-post6400435.html#post6400435)
In my experience, FRP has a signature failure in high energy impacts that is unmistakable. It explodes.

I'm still looking for evidence of exploding composites. Erm... nope. Still not found any. (Lucky for me or that Reliant Robin could have gone up like a Ford Pinto.)

Bearfoil, you can't have it both ways. The VS shows that the composites were stronger than the metal lugs and yet you theorise that the spoilers would be atomised on impact and leave no trace.

SaturnV

20th Apr 2011, 13:19

If the VS departed during flight, then, and I'm theorizing, it presumably would have been nearer the LKP, and immediately buoyant on the ocean surface. The French overflew the LKP and areas west and east of the LKP (perhaps as much as 10 NM west) at about 1530 hours on June 1, and saw nothing. The Brazilian AF also overflew the LKP on June 1, although their search box was not as far to the west as that done by the French Dassault Atlantique 2. (Have not found times for the Brazilian search.) Brazil saw nothing either.

The question to be answered is why nothing was seen on June 1, but perhaps part of the answer involves the law of buoyancy, and whether objects detached from a relatively intact airplane as it was sinking, and gradually made their way to the surface.

jcjeant

20th Apr 2011, 13:27

Hi,

If the VS departed during flight, then, and I'm theorizing, it presumably would have been nearer the LKP, and immediately buoyant on the ocean surface. The French overflew the LKP and areas west and east of the LKP (perhaps as much as 10 NM west) at about 1530 hours on June 1, and saw nothing. The Brazilian AF also overflew the LKP on June 1, although their search box was not as far to the west as that done by the French Dassault Atlantique 2. (Have not found times for the Brazilian search.) Brazil saw nothing either.

The question to be answered is why nothing was seen on June 1, but perhaps part of the answer involves the law of buoyancy, and whether objects detached from a relatively intact airplane as it was sinking, and gradually made their way to the surface. Good question indeed.
BTW .. the VS even if released from the plane from under the surface (any depth) will no take days for emerge .......

RatherBeFlying

20th Apr 2011, 13:45

The last underwater recoveries, Swissair 111 and TWA 800, were done from land; so, the shrinks could be seen on shore the same day if the need was felt.

It's quite bad enough dealing with a recently dead intact body; in this case the bodies have been on the bottom for a considerable time and I expect the bodies are already colonised by a number of creatures:(

promani

20th Apr 2011, 14:21

Maybe they should have medically qualified personnel onboard, as I think there were seven children and a baby on that flight. I get choked up just thinking about it, eventhough I have seen dead children in the past. I do not envy those on their way to recover the remains and wreckage. Brave people.

syseng68k

20th Apr 2011, 14:30

PJ2 Wrote:

You're talking about two completely separate
systems. Flight data recorders have nothing to do with the ACARS
messages - that's been the point all along. The recorders don't see
these messages, don't/can't record these kinds of messages, don't
"timestamp" data and don't hold them in memory. That's not how flight data recording works.

I don't know where acars comes into this, because I understood from your
post that the context was flight data recording ?.

From your original post 3640:

The key point is, parameters can't be recorded all at once. If there are
1800 parameters (in binary form) coming into the system, the system must have a way of "listening, parsing and recording". The data frame software is how that process is handled.

And then:

Without getting more complicated, (because it has to if we go any
further and everyone will be asleep), the nature of recording can give
the appearance of a 'lag', when there "may, or may not" have been one.

Which is what I was disagreeing about. A few general data logging and
comms system basics may help here, but apologies if preaching to the
choir :-).

To start, there may be many sources of data/parameters to log, in different
formats (ie: "language") and at different sample rates, (ie: how often a
parameter is examined). The data format, sample rate and accuracy of
measurement depend, of course, on the requirements of each parameter to
be measured.

Sampled data is typically sent across high speed data buses (ie: highways),
at microsecond rates, encapsulated in frames, or "packets". A fair data bus
analogy is a road full of houses, each with a unique address, containing
people with different names. A fair analogy for a frame is a posted letter,
which will have a destination address, the sender's address, perhaps time
and date, with the measured "data" on the page inside the envelope. For
frame based data comms, all the above information would normally be
included in one form or another, as well as checksum data to allow
detection of errors in transmission. (ie: a torn envelope) Where letters can
take an indefinate amount of time to deliver, avionics buses are designed to
provide guaranteed delivery within very strict time limits.

Between the data source and recorder there may be, depending on the
application, a "data aquisition unit". The function of this is to provide a
central "clearing house" for the various sources and to measure and / or
translate to a common format, or language, to send to the recorder. It may
also timestamp the incoming data, and filter or manipulate it in other ways.
In some systems, acquisition and logging are combined into a single
physical unit, but the functionality remains the same. Such systems often
use queueing techniques to avoid date loss at peak rates, but the data
would be timestamped *before* insertion into any queue. This avoids time
displacement errors where the actual data is stored some time later. By
“some time”, I mean milliseconds, not seconds or minutes.

The key thing i'm, trying to get across here is that accurate timestamping
is fundamental to any data logging application such as this. It is always
designed to have sufficient accuracy in terms of measured value and timing
to meet the needs of the application...

MurphyWasRight

20th Apr 2011, 15:15

syseng68k to PJ2:From your original post 3640:

The key point is, parameters can't be recorded all at once. If there are
1800 parameters (in binary form) coming into the system, the system must have a way of "listening, parsing and recording". The data frame software is how that process is handled.

And then:

Without getting more complicated, (because it has to if we go any
further and everyone will be asleep), the nature of recording can give
the appearance of a 'lag', when there "may, or may not" have been one.

Which is what I was disagreeing about. A few general data logging and
comms system basics may help here, but apologies if preaching to the
choir :-).

There may be confusion here between time stamps,synchronous sampling and lower than nyquist sample rate artifacts

Even with accurate time stamps there can be artifacts such as phantom split control surfaces if the data is not sampled (and time stamped) at the same instant or at a high enough rate to allow full fidelity.

Phantom split control surfaces can be caused by the time (up to 1/2 the sampling interval) difference between A and B samples.

If a short "jog" (less or near sample interval) is sent to A and B only A might show movement with B appearing stationary.

If the data for 2 surfaces are sampled at the same instant the artifact will not happen.
Eihter both will be captured moving or the "jog" will be missed entirely.

Note though that no more "real" data will be available, if anything slightly less since sampling related data with a time offset may help in filling in the time gaps.

PJ2

20th Apr 2011, 15:44

syseng68k, now I understand - my thanks for the explanation on timestamping - it makes sense to me now...the "ACARS" item turned up because of previous discussions on timestamping of messages and I had incorrectly assumed your reference.

MurphyWasRight, thanks - much clearer; - that's what my rudimentary "strobe" example was trying to convey. I know about flight data analysis but much less about data transmission protocols so I appreciate all explanations.

I considered the notion of "lag", (which it isn't, really...), to be important for the very reasons cited and in response to Machinbird's concern about "elevator split"...that what is in the minutae of the data may not re-present exactly what occurred - I've seen such disparities lots of times and the context (did other systems, or the aircraft, exhibit behaviour commensurate with the split?), often supports the notion that (for example) the flight controls weren't out of sync. It is offered as a caution to be mindful of the process of recording and interpreting...that reading recorders is not at all straightforward.

gums

20th Apr 2011, 15:45

Salute!

Will keep beating the horse, 'cause when the FDR's are decoded we will be able to see what actually happened with much higher resolution than the "maintenance" messages sent via ACARS. Could and probably will reflect the whole story.

I go with Chris, another systems engineer re: data recording.

Wrote the spec for a data reduction facility, managed it during test missions and had to provide the "system experts/designers", as well as managers, with good representations of what happened and when for a recce system. Unlike space vehicles, UAV's and manned aircraft experience turbulence that lasts for fractions of a second. This poses problems primarily for video sensors versus RF sensors, as you can imagine.

I look at the VS separation accident ten years ago and realize that many parameters were captured/recorded at rates too slow for the stuff I had worked on, but still good enough to determine the cause of the crash. So comparing the FDR data with the ACARS messages will help all figure out what happened.

I am saddened to see some of the frame rates BEA references, as I cannot rule out a similar scenario where pilot inputs may have aggravated the situation, especially in severe turbulence. And BTW, I have flown thru CB's and it isn't fun, tho I wasn't concerned about structural integrity for the Viper and Sluf. Was more concerned with not getting the jet into a stall or spin or inverted, heh heh.

Bottomline for our discussion, way I see it, is to square away the ACARS transmission protocol/timing, etc. with what we shall see with the decoded FDR data.

Data acquisition units are damned cheap - some even tens of $$$ for precision in terms of tenths of a gee, or fractions of a degree of surface movement, or tenths of feet per second at 100 hz for velocities. It's the final "mother" recorder that has to store it all for later analysis. And much data can be acquired and transmitted with tiny messages, like 8 bits to get 256 th's resolution of a parameter. Only thing I ever had to work with requiring ultra-high resolution and timing was vibration data to characterize optical sensor performance.

Great thread here, and I am tickled we are not getting into conspiracy theories and simplistic suppositions concerning the aerodynamic and structural aspects of the event.

bearfoil

20th Apr 2011, 16:32

infrequentflyer789

Hey. Perpignan was a nose plant at flying speed: 14 degrees ND??

We are told 447 was a buttdrag at nominal speed, certainly not flying.

So the impact aspects were totally different. The 320 assumedly lost its VS fully forward, clear of the impact debris, while 447 is said to have landed on its tail, then belly. This is the upshot of my disagreement: 447 drove her VS into the tail cone, then clear?. No evidence is apparent that the skin of the fin spent any time whatsoever in a decelerating trajectory into the mass of structure that is the tail: APU, HS, Elevators, Pressure cap, tankage, etc. Nor is there evidence on the inner perimeter of the torn out fuselage frames of rupture that would have occurred as the energy of the Fin was dissipated into the axis of the fuselage.

machaca

At twenty nine feet tall and three feet thick, The Vertical Stabiliser has perhaps the best strength to weight ratio of any structure on any swept area of the aircraft. Of course it is silly to call it fragile, it is not. However, it has diminished survival futures in a debris field because of its light 'weight' relative to other structures, due to its strength from 'spread' rather than 'mass'. It is susceptible to puncture and asymmetric torsional stress, something it likely would not have seen had it been lost prior to impact. It is reasonable I think to posit that it would survive a flat impact with the water at some terminal velocity in free fall, but would show immediately any puncture or insult from thousands of pieces of structure with which it would have shared the impact site.

Of course FRP does not 'explode', that was a poor term choice. Better "Shatter, or Disintegrates".

chrs

jcjeant

20th Apr 2011, 17:04

Hi,

Despite all show the contrary (so far in official interim reports .. VS separated from plane at impact) a VS separation in flight is very seducing .. as a consequence of the loss of VS in flight is that you get a plane that is no more controllable ... what appears to have been the case for AF447

deSitter

20th Apr 2011, 17:14

jcjeant - that's right - the great unknown in all of this is the behavior of composite structures under atypical stresses - there are many competing models, often mutually wildly divergent, all highly non-linear, of composite failure under stress.

sd666 - not quite sure what you mean about anchoring, but the water moves as a body, any flotsam would be well inside the boundary layer of air at the water interface, and any islands of debris, large and small, would tend to remain together until dispersed by divergent currents of water, not air. The Perpignan fin was just the largest piece in a huge swarm of debris, and I would have expected something similar here.

BJ-ENG

20th Apr 2011, 17:23

@bearfoil

...my strong conviction that the Vertical Stabilizer and Rudder were not on the fuselage at impact...

To add to the many suggestions attempting to answer your question regarding how the VS became detached, it is worth considering just how water impacts vary from those on hard terrain. During impacts with rigid ground the undercarriage, if deployed, absorbs a significant portion of the impact energy, with the remainder being transferred to the stiffest structural members such as the energy absorbing subfloor beams. These are generally designed to progressively collapse in order to limit to G load on the occupants. For a water impact, the loading mechanisms differ significantly. The landing gear is unable to absorb the impact energy and instead the impact loads are distributed as a transient dynamic pressure load over the fuselage skin. This initial absorption by the skin momentarily slows the rate that force is applied to the structural members, and has the effect of inhibiting the buckling process to the extent that energy absorbing subfloor components become ineffective. This is why in recent years Navy helicopters have been designed with additional features to improve their crashworthy response over both hard terrain and water.

If the skin is compromised, and the fluid is uncontained, as is the case with a high velocity impact, constant interactions occur between fluid and structure, inducing continuous changes in the loads applied throughout the crash event. In addition to the previous mechanism, the structure now experiences considerable hydraulic shock allowing large pressure forces to act directly upon the cabin floor and interior and as a consequence, increases the vertical accelerations experienced by the occupants.

Drop tests on passenger sized airframes at NASA Langley Research Center have shown how the cabin section experiences quite a pronounced deformation even for a 10m/s drop. For the impact suffered by AF447, which likely descended at a rate in the region (60 to 80m/s), the deformation would have looked more like that for the Trident accident (Papa India in 1972), where the appearance of the main cabin sections are very much more flattened . Given the likely fuselage distortion under AF447's VS, even with the rear bulkhead support, the tendency will be for the fixings under the VS to suffer serious deformation and fracture. Now, some milliseconds later, add hydraulic shock imparted by HP water meeting the underside of the cabin roof, and one can easily imagine how the downward movement of the upper cabin shell is arrested, while at the same time, the inertia of the VS imposes itself on the support fixings with the resulting failure and separation. The evidence for significant hydraulic damage is apparent in the photo of the fuselage/door section where the inner lining has been scoured away.

What happened next to the VS is open to some conjecture. It has been suggested that the VS flipped forward over the airframe and splashed down in front of the aircraft. I find this scenario less than convincing since that pathology report gives no indication of any forward injuries, which would suggest minimal forward motion. If the VS had just fallen over onto the airframe, then surely there should have been some noticeable damage to the leading edge. Mechanical structures tend to break at the weakest points, which in aircraft impacting horizontally, is for cabin failure forward and aft of the wings, and near door openings. One possible visualisation is for the rear section, around 73/74, to become detached at impact (rotate to the rear), to rapidly submerge, followed by the buoyant VS in turn becoming disentangled and returning to the surface.

With regard to whether or not impact was horizontal or vertical; aside from the relatively intact galleys etc, and the deformation evidence in the recovered wreckage, the pathology tells its own story. In studies on the analysis of the pattern of injuries (Nato study - Cullen et el 1980), it was demonstrated that the pattern of injuries in water impacts strongly correlated with aircraft attitude at the time. In one example, those in the rear of an aircraft incident suffering a tail down impact were likely to be more severely injured than those in the front - the implication here being that a typical passenger carrying aircraft crash is likely to result in either a pattern of uniform injuries or a steady logical gradation in severity (TWA800 being the exception). Given that the 43 recovered bodies were distributed between rows 1 to 42, the forensic pathology would have provided similar clues as to the nature of AF447's attitude at the time of impact - and as the BEA have concluded, was probably horizontal. The fact that 43 appear to have suffered pelvic fractures strongly suggest that they were seated at the time and in their designated positions.

http://rpmedia.ask.com/ts?u=/wikipedia/en/thumb/c/c6/G-ARPY_Felthorpe.jpg/250px-G-ARPY_Felthorpe.jpg

PJ2

20th Apr 2011, 17:47

gums;
I am saddened to see some of the frame rates BEA references,

. . . .

Data acquisition units are damned cheap -
And compact - memory and processing power is cheap.

The expensive parts as you likely know, are the STCs, the cooperation from Boeing and Airbus as the case may be, to obtain dataframe information on older aircraft to be able to verify/update/change DFLs to capture more parameters.

It isnt very often that it is a physical sensor and/or wiring problem, but a lot of this information is proprietary and therefore cannot be legally shared even just to help someone out with a dataframe issue such as conversion factors or knowing where the words are put for a certain parameter. THAT is where the time, money and even political problems lie because the airlines lobby against any legislation which can increase costs without a "direct, demonstrable" benefit.

Refitting DFDAUs/FDIMUs (not even recorders), is an extremely expensive proposition...new DFDAUs in older airplanes can run, all in, over US$60,000 per airframe even though the equipment itself is comparatively inexpensive. Why should we take that route when "88 parameters at the legal sampling rates is legally good enough"? I have heard that a number of times, along with "we'll just take the 'statistical approach' and equip a few airplanes in the fleet." The joke was, at the end of the day we all had the "GE" trademark from the FOQA lab fridge embossed backwards on our foreheads.

Obtaining certification for changes to DFDAU software, which is essentially a licensing matter and not an engineering/certification matter, puts such changes out of reach in terms of making the business case for most airlines. While some know the value of data and support the work wholeheartedly, you wouldn't believe the gyrations some airline managements go through to avoid such "unnecessary" changes. One can't expect a blank cheque, but one can expect the understanding that not all departments can be "profit centers". I'll leave that particular item at that.
... some even tens of $$$ for precision in terms of tenths of a gee, or fractions of a degree of surface movement, or tenths of feet per second at 100 hz for velocities. It's the final "mother" recorder that has to store it all for later analysis. And much data can be acquired and transmitted with tiny messages, like 8 bits to get 256 th's resolution of a parameter.
Precisely.

The International Working Group on Flight Data Recovery, (link on the BEA AF447 website (http://www.bea.aero/en/enquetes/flight.af.447/flight.af.447.php)) submitted their final report on "lessons learned", called "Triggered Transmission of Flight Data Working group (http://www.bea.aero/en/enquetes/flight.af.447/triggered.transmission.of.flight.data.pdf)". The need was stated quite succinctly in the working group's first report: "The difficulties encountered have raised questions about the adequacy of existing flight data recovery technology, when considering accidents over oceanic or remote areas."

I don't want to discuss AA587 nor the larger issues now outlined here by many contributors, but here is another problem highlighted by yet another accident: - locating the recorders in hostile, essentially inaccessible environments.

If the industry wants high data granularity of the very kind you're describing for SMS and accident investigations, it is from the regulator, not private enterprise under a de-regulated economic environment, that the mandates to do so must come.

SaturnV

20th Apr 2011, 17:47

jcjeant, the analysis by the Russian Interstate Aviation Group and BEA concluded there was about a 55 percent probability that the impact would be within 6 NM from the "start of the emergency", and nearly 70 percent probability it would be within 8 NM. It seems the Metron analysis used the LNP as the "start of the emergency" for purposes of its calculations. But the LNP is rather late in the sequence,

Perhaps a reason the BEA is not releasing the exact coordinates is that it may be closer to the LNP then many of us assume, and if so, both Brazil and France would have overflown the impact point on both June 1 and June 3. (France clearly overflew it on June 1 (wherever it turns out to be) given the search graphic in the Metron analysis for June 1.)

If visual conditions for the search on June 1 were poor, one would think that search would be repeated when conditions were improved. That seems not to be the case.

I am certain that an impact quite close to the LNP would raise all manner of questions about the adequacy of the initial searches, and that would be a subject that the BEA and the French and Brazilian military would rather not be distracted by at this point. There was also a ship, the Douce France, that searched in the area of the LNP on June 1, but its track has not been publicly released.

bearfoil

20th Apr 2011, 18:09

BJ-ENG

I think it more likely that if at impact, the VS separated and was thrown back.

The Pressure vessel terminates at the Aft Bulkhead, and the a/c essentially flies (and crashes) in close formation with the Tail. If tail first, the dynamics of Hydraulic action would emanate differently than at the Fuselage, not to mention the likelihood that the Tail may have completely separated from the body at impact. If there was a separation at impact, the angle of attachment would grow progressively more acute, suffering the remaining structure to progessively separate from its closest neighbors still connected to the hull. The fuselage, having acted in essence as a giant airbag, would accelerate the loss of velocity of the fuselage as the tail continued. If the body 'rebounded' (that certainly would need explanation), the tail may have been 'rejected' (rather emphatically) by the Fuse and the VS pulled itself loose from the forward lug/bracket and flew backwards to escape corruption by a presence in the chaotic debris of the main impact area. This would basically (sic) explain the damage to the VS' LE via contact with the dorsal area of the fuselage at initial deceleration, (the tail having 'folded over' this area) and the corrupted corner of the Rudder as the Fin/Rudder rolled over the tail cone in aft fashion with the violent pull on the empennage by the fuselage remaining essentially near the surface after initial contact.

jcjeant

What is seductive to me is some verbiage expressed by the BEA that may lead to false assumptions.

It seems completely apparent that 447 departed controlled flight. The late portion of the fall by BEA's description is of a free fall with some horizontal component, and a slight lateral rotation of the airframe, with the a/c essentially intact.

There was no aerodynamic flight.

447's trajectory was down, and her hull had no heading, by their own explanation. Intact, this aircraft's nose would have a heading only after all its rotation had ceased. It's nose was unwinding the compass' rose in a left rotation, laterally.

There was no heading.

No Flight, No Heading. No "En Ligne de Vol". I wager 98 per cent of the reading public think the aircraft was in controlled flight on her way to Paris when by misfortune she hit the water.

Words have meaning.

Tailspin Turtle

20th Apr 2011, 19:14

Instead of not having enough altitude for a square loop, imagine a transition from a wings-level high-speed pullout during a spiral dive recovery to a relatively low-forward speed, nose-up, high-sink rate impact with the water:

Aviation Video: FA-18 MCAS El Toro Crash | Patrick's Aviation (http://www.patricksaviation.com/videos/Starfighter/951/)

A loss of control eventually resulting in a spiral dive also keeps them in the vicinity of the LKP.

mm43

20th Apr 2011, 19:17

Originally posted by bearfoil ...

There was no aerodynamic flight.

447's trajectory was down, and her hull had no heading, by their own explanation. Intact, this aircraft's nose would have a heading only after all its rotation had ceased. It's nose was unwinding the compass' rose in a left rotation, laterally.Technically, your "no aerodynamic flight" is true, but you need to consider that the attitude the aircraft attained was an aerodynamic compromise. Rightly, or wrongly my interpretation of the BEA's description, backed by their photographic evidence of impact damage, was that the aircraft had entered an unrecoverable stall regime whereby the attitude and bank angle had become stabilized in the lost lift vortex in which it was slowly rotating. Its trajectory was certainly down with a high angle of attack and high rate of descent, though in your terminology, "winding the compass' rose in a right-hand rotation, laterally."

That resulted in the tail swinging to port (left) on impact and following the culmination of the forces acting on its clevis joints in all planes and vectors, not forgetting the reciprocal buoyancy forces, the Vertical Stabilizer finished up in the water on its port-side with its rudder hard to starboard.

At the time of the impact, the wind was from the north at 25~30 knots, and the rudder aspect was such that the V/S was quite capable of "sailing" away from the scene.

jcjeant

20th Apr 2011, 21:26

Hi,

At the time of the impact, the wind was from the north at 25~30 knots, and the rudder aspect was such that the V/S was quite capable of "sailing" away from the scene.

But certainly not in a order of 10 Km or more :)
So I stay with ONE of my wonder: (provided the VS separated on impact)
Why this VS was not discovered during the first aerial researches in the vicinity of the LKP.... ?
This VS is not the size of a little plastic bag or a lifevest and have not the abilities of a submarine (dive and surface at his will)

mm43

20th Apr 2011, 22:32

Originally posted by jcjeant ...

Why this VS was not discovered during the first aerial researches in the vicinity of the LKP.... ?I am sure there were issues with the initial searches, be they from the air or sea surface. As you are well aware, search grids have been posted in this forum, but whether the published grids were actually flown is another matter. Basically, the SAR phase was the responsibility of the Brazilian military, and showed a lack of precise direction and purpose, e.g. chasing rainbows.:}

bearfoil

20th Apr 2011, 23:22

mm43

bonjour. The VS was semi submerged when spotted, its colors probably difficult to discern. The structure gave me the impression of never being 'proud' of the surface, and I assumed it acted as its own sea anchor from loss to discovery. BEA stated that the Rudder was flapping, and had no resistance to pressure in its axis of sweep. I do not think it "sailed" at all. I can not remember its position when found, but was it not WNW of LKP a fair bit? Does this not conflict with your winds from 000 at ~25-30 ??

I also conclude the VS did not sink with other structure, to break free and surface on its own. It would have had to retain some air in pockets, and at 50 meters, it would have experienced permanent rib collapse, no?

Permit me a display of ignorance or inattention, (both?) but the LKP at 02:10, is that actual, timed transmission stamp, or receipt by ACARS??

My feeling is twofold, and I cannot blame BEA and/or ABI/AF. No one involved who had a stake in this accident wanted to believe that this sota a/c fell out of the sky, steeply, especially having lost some bits. I think their bias to 40 nm away or further reflects some wishful thinking on their part. Understandable.

SaturnV

21st Apr 2011, 00:14

bear,

LNP @
2.58.8'N
30.35.4'W

VS sighted June 6 @ 13h38 @
3.61 N
30.62 W

VS recovered June 7 @ 18h35 @
3.47N
30.68W

On June 1, north of the LKP, surface winds were blowing from the NNE to NE direction, with much convection.

On June 2 and days following, winds became more easterly, and decreased. Convection was less as well.

On June 1, the drift group's optimal interpolation of the current near the LNP is that it was from the N/NNE toward the S/SSW, South of 3N, the current quickly turns SE and then east.

Khashoggi

21st Apr 2011, 00:21

If AF447 lost its VS in flight, it would have resulted in a CG shift forward. I don't know the mass of the VS, but would it have been enough of a shift to prevent a level attitude, if not the presumed slight nose high, at impact?

ACLS65

21st Apr 2011, 00:32

If the VS separated when the tail was submerged, especially the closer the wreckage got to the bottom, I suspect to some degree it would glide to the surface. Depending on which area has the most buoyancy it might make a series of gliding loops, or swirl like Sycamore seed. In most pictures the rudder was also positioned to the starboard side, if firmly enough in that position it would also affect the ascent.

My guess would be that the deeper the VS separated the more likely it is to be found farther from the impact site. Even if it were to rise perfectly vertical the subsurface currents would have a longer time to act upon it.

A piece of wreckage like a cabin section might tumble upon ascent, but seems less likely to glide or sail than something aerodynamic.

Once upon the surface it will all depend on wind and currents, and whether there is more submerged or exposed area to be acted upon by each. Wreckage with a similar profile might stay together, but again over time one would expect those items more driven by wind or currents to separate.

rh200

21st Apr 2011, 02:13

I'm obviously missing something, I would have thought that if the VS separated at any sought of real depth it would still be down there?:confused:

grizzled

21st Apr 2011, 02:46

BJ-ENG...

Superb post.

PJ2

21st Apr 2011, 06:40

Grizz, I completely agree. BJ-ENG's post is in my view required reading. Understanding the difference between aircraft structures impacting solid ground and water is, I think, important to understanding what the photographs have shown us in terms of the "stopping" capacity of water vs level ground, (ie, Tripoli vs what we see here thus far). I think how BJ-ENG's post describes this difference has added a great deal to the thread's knowledge.

HazelNuts39

21st Apr 2011, 07:06

Khashoggi:

The VS weighed about 1800 kg and had an area of 53 m^2.

PS: Just a flimsy illustration (https://docs.google.com/leaf?id=0B0CqniOzW0rjMTU0MDQyNzYtN2M2Yy00MzVkLWFhZWYtZmI1NGU 4MjdjMTY5&hl=en_GB&authkey=COmi6eIM) to BJ-ENG's post.

henra

21st Apr 2011, 08:55

deSitter,

jcjeant - that's right - the great unknown in all of this is the behavior of composite structures under atypical stresses - there are many competing models, often mutually wildly divergent, all highly non-linear, of composite failure under stress.

Did you care to have a look at the wreckage photos of BEA's second report?
If you had done so you would have noticed that it was primarily the METAL support structure that broke not the composites. In contrary the composites survived the loads much better than the 'tin' (as is often the case btw.).
That makes any philosophying about the strength of composites obsolete.
Sorry if I sound a bit rude but it starts to get annoying having unfounded generalisation (which oviously does not apply in this case) repeated over and over again.

jcjeant,

.. as a consequence of the loss of VS in flight is that you get a plane that is no more controllable ... what appears to have been the case for AF447

If an airliner loses its 'feathers', the result will very likely not be a 'pancake' impact at 150kts vertically and 50kts forward but a high speed forward impact.
AA587 impacted in a spiral dive, not flat btw.

sensor_validation

21st Apr 2011, 09:11

Permit me a display of ignorance or inattention, (both?) but the LKP at 02:10, is that actual, timed transmission stamp, or receipt by ACARS??

Time-stamped 2:10, received 2:10:34, so presumably the actual position at 2:10:30? slotting in as high priority message in the initial bunch of errors, re-presented here

AF447 ACARS MESSAGES - Color Coded & Interactive Version (http://countjustonce.com/a330/acars.html)

BEA use these receipt times to report

end of the flight between 2 h 14 min 26 and 2 h 15 min 14There was an analysis a long time back of 10 minutes sector times, distance travelled and speeds, which made it clear the actual position time within the minute must shift. Assumed, but never confirmed as far as I know, that AF systems must adjust this timeslot to avoid aircraft using same satellite at same time.

If you want to repeat this the numbers used by the BEA in the flight path graphic time in seconds 'rounded to nearest minute', decimal location to ACARS 2 decimal place precision given in

http://www.bea.aero/en/enquetes/flight.af.447/trajectoires/data/AF447.txt

Chris Scott

21st Apr 2011, 10:09

Quote (http://www.pprune.org/tech-log/395105-af-447-search-resume-187.html#post6403381)[SIZE=2] from SaturnV:
LNP @ 2.58.8'N 30.35.4'W
VS sighted June 6 @ 13h38 @ 3.61N 30.62W
VS recovered June 7 @ 18h35 @ 3.47N 30.68W

Just to point out that the quoted positions appear to be defined as follows:
LNP (LKP) position is in degrees/minutes/decimals-of-minutes.
However, VS positions are in degrees/decimals-of-degrees.

VS (fin) posn June06/1338: N03.61/W030.62 [FONT=Symbol]º N03°36.6'/W030°37.2'
VS (fin) posn June07/1835: N03.47/W030.68 º N03°28.2'/W030°40.8'

I don't know how accurate the "sighted" position would have been, but here goes the number-crunching. (Not sure if the VS position-timings are GMT, but that doesn't affect the issue.)

In roughly [U]29 hrs, 6 days after the accident, the VS apparently moved
9.1 nm (16.9 km) on mean TRK 203°T

Taken on face value, this may support mm43's suggestion (http://www.pprune.org/tech-log/395105-af-447-search-resume-186.html#post6402917) that:
"the rudder aspect was such that the V/S was quite capable of "sailing" away..."
Others may comment on wind and current.

In case it's of interest:
VS (fin) recovery position, relative to LKP (N02°58.8'/W030°35.4), is
29.9 nm (55.4 km) BRG 350°T

Chris

SaturnV

21st Apr 2011, 11:41

Chris, thanks for correcting my non-use of the silent K in the acronym.

The positions are from Table 1 of the Drift Analysis report. The only position observation in that table which is qualified is that for "Galley G2" sighting on June 6. (The qualification probably stems from the sighting and recovery coordinates being identical, even though the two events are four hours apart.)

In re-looking at the Drift Analysis report, the only model of the eight used that came close to an impact near the LKP was the U.S. Navy's HYCOM model, and regarding its results:

This [HYCOM] model gives a crash point near 3°15’N 30°30’W, and has been discarded from our analysis, on the basis that the velocity field is not realistic enough and the backtracked debris were scattered over 93 km (Figure 37). However the Ursulla sighting is backtracked not far from our 95% confidence area.

The 95% confidence area had a lower bound roughly at 3°20’N at 30°30’W

The Ursulla object sighting was one of six objects for which trajectories were calculated backwards in time in each of the models. Interesting that the VS was not one of the six reference objects.

wes_wall

21st Apr 2011, 13:39

It assumes all have accepted the discovered site as close to the LKP, but what are we considering "close?" Given the BEA's close to the vest attitude, the "close" could mean about anything. The bones thrown by BEA really do not provide enough information to formulate any true picture, only continued speculation. However, I expect a lot of our speculation to be right on point.

lomapaseo

21st Apr 2011, 14:31

An update to a lot of what's being talked about on this forum

Aviation, Defense and Space News, Jobs, Conferences by AVIATION WEEK (http://www.aviationweek.com/)

....
(Bloomberg) - Investigators seeking to explain why Air France flight 447 plunged into the night ocean two years ago will rely on gear pioneered by telecommunications and oil companies as well as a Hollywood director to unlock the mystery.

The wreckage of the Airbus SAS A330 jet was discovered this month 3,900 meters (12,800 feet) deep in the Atlantic Ocean off the coast of Brazil after multiple searches. Few aircraft salvage missions have probed the same depth, where the sea is perfectly black, temperatures approach freezing and water pressure is equal to the weight of a car on a postage stamp.

Diving deeper than the Titanic's final resting place, a robot tethered to a surface ship will sift through the aircraft debris in search of the two flight recorders bolted inside the tail of the fuselage. Their data promises the best chance yet to explain the crash, the deadliest in Air France's history. Complicating the mission is the presence of numerous bodies, some still strapped into their seats and preserved by the cold water and lack of oxygen or light.

"At that depth, it is pitch black, and the difficulty is knowing where you are while keeping track of things," said Dave Gallo, director of special projects at the Woods Hole Oceanographic Research Institute in Falmouth, Massachusetts, whose robots helped locate and map the wreckage. "It's a question of operational skill."
No Survivors

The Airbus disappeared en route to Paris from Rio De Janeiro on June 1, 2009, leaving no survivors among the 228 aboard. While some fragments and bodies were recovered from the surface of the sea, most of the jet remained missing until this month. The data recorders are built to withstand submersion and extreme impact, though until retrieved there is no certainty the data they stored will be readable.

The expedition will gather at the port in Dakar in Senegal tomorrow, before traversing the Atlantic on the Ile de Sein vessel to the location of the aircraft, about 435 nautical miles off the coast of Brazil.

French phone-equipment maker Alcatel-Lucent SA is providing the 140-meter ship, which normally lays deep-sea cables. Aboard will be 70 people, including members of the French BEA air accident authority, investigators from the U.K. and Brazil, experts from Airbus and Air France, as well as one psychologist. Family members of the victims were not permitted aboard.
Robot Submarines

Underwater engineering company Phoenix International Holdings Inc. is sending one of its two "Remora" robotic submarines, or ROVs, equipped with high-resolution cameras and two manipulator arms. The basket on the ROV can recover as much as 200 kilograms (440 pounds) of debris in a single mission.
"There are about six to eight ROVs in the world capable of descending as deep" as the Remora, said Tim Janaitis, business development manager at Phoenix, who spoke from Largo, Maryland. Typically, the robot's missions include work on deep-sea oil drilling, and a recent descent took the vehicle to the Titanic wreck in the northern Atlantic, Janaitis said.

The search for the remains of the doomed ocean liner in the mid 1980s, and the 1997 blockbuster movie directed by James Cameron helped advance deep-sea technology, spawning high- resolution cameras and robots that can scour through wrecks.
Nazi Battleship

Following the success of the Titanic movie, which won 11 Academy Awards and cost about $200 million to make, Cameron embarked on an underwater expedition to Nazi battleship Bismarck, which sank in the Atlantic in 1941.
"Stuff like that is enough at times to help keep research going," said Robert Jensen, chief executive officer of Kenyon International Emergency Services, a Houston-based company that helps airlines handle disasters. "Look at what they spent on the Cameron movies. He went down on several submersibles to look at ships, to recreate as realistically as possible what happened."

The Remora robot can work as far down as 6,000 meters. To ensure steady operation, a team of nine Phoenix experts will operate the 900-kilogram sub from the ship using large video monitors to track its progress. Every movement of the vessel at the surface is translated to the Remora's umbilical cable with a delay, said Brennan Phillips, manager of ROV operations at the University of Rhode Island in the U.S.
Delayed Reaction

"If the ship moves, it takes half an hour for the vehicle to feel it," he said. "You need an extremely stable ship."

Of the almost 100,000 photos taken of the wreck and surrounding area, BEA publicized several black-and-white images of the landing gear, an engine, a wing and parts of the fuselage. While the black boxes have not been spotted, the robot has located the part of the tail that normally houses the recorders. Investigators withheld images of bodies and made them available only to researchers involved in the mission. For some, the sight was too much to bear.

"There were many bodies, and our people initially said they would not like to participate in any such recovery operation," said Peter Herzig, director of the Leibnitz Institute of Marine Sciences in Kiel, northern Germany, whose Remus 6000 robot sub was one of three that located the wreck.

Team members later changed their minds, though in the end, Herzig's group wasn't asked to participate, he said.

Should the recorders be found, they will be pried from the wreck, lifted aboard the Ile de Sein and immediately placed under seal, before being transported by a French Navy vessel to a French port. From there, they will be sent by air to the BEA under the responsibility of a judicial police officer.
Recovering Bodies

Recovering the victims is a more complex and contentious task. Only 51 bodies, including the pilot, were recovered from the ocean surface in the weeks after the crash.

Nelson Marinho, who leads a group of victims' relatives, said not all families want to see corpses brought up, though they recognize the obligation to present forensic evidence for a criminal probe. A French prosecutor is pursuing allegations of manslaughter against both Airbus and Air France, and autopsies may help answer questions such as whether passengers were still alive when the plane sank. BEA said all decisions concerning human remains will be made by France's Justice Department.
"The worst feeling, for us, is the risk of even more damage to these corpses," Marinho said. "French officials want to transport them to France, but we want to bring them directly to Brazil." Among the victims were 58 passengers from Brazil, 61 from France, 26 from Germany, and other nationalities including travelers from China and South Korea.
TWA Crash

Past aircraft salvage missions have managed to recover the bodies of victims. The U.S. National Transportation Safety Board brought up all the bodies from TWA flight 800, which crashed off Long Island in 1996, and EgyptAir 990, which went down 60 miles from Nantucket in 1999, former director Jim Hall said.
"I think as human beings, it's the humane practice, and it would be a disservice to family members by the airline and regulators not to recover them," he said.
The greatest technical challenge will remain operating at an extreme depth. Only one past air crash has forced salvage teams to dive deeper. The wreckage and black boxes of a South African Airways Boeing 747 that disappeared near Mauritius in 1987 were located 14 months later under 14,000 feet of water.
"It's only relatively recent that we even have the technology to consider these kind of recoveries," said Paul Hayes, director of safety at London-based aviation consultant Ascend Worldwide Ltd. "And it sounds simplistic, but I think we tend to forget how vast the oceans are."

Razoray

21st Apr 2011, 15:18

Of the almost 100,000 photos taken of the wreck and surrounding area, BEA publicized several black-and-white images of the landing gear, an engine, a wing and parts of the fuselage. While the black boxes have not been spotted, the robot has located the part of the tail that normally houses the recorders. Investigators withheld images of bodies and made them available only to researchers involved in the mission. For some, the sight was too much to bear.

This makes things a lot clearer. 100,000 pictures! I do believe this puzzle is about to be solved. And now we know the full extent as to why a psychologist is involved.

Chris Scott

21st Apr 2011, 15:40

wes wall and SaturnV (have you seen the Haynes Manual in the UK?),
Don't have to tell you that this topic has been discussed at length on this or the old thread. With that sense of déjà-vu, I've been trawling through the pages from this time last year, so far without success. (No doubt the antipodal mm43 will remind us later where to find it.)

SaturnV,

Regret I've no expertise in this area. Is "HYCOM" the same as the "NCOM" referred to in BEA Interim Report 2, page 79?

Looking at BEA Interims 1 & 2, I've noticed a discrepancy on the recovery position of the fin. This makes a complete nonsense of the 29-hour "voyage" (for want of a better expression) in my post above, in terms of both track and distance. Can you confirm the source of the recovery position you quoted:
"VS recovered June 7 @ 18h35 @ 3.47N 30.68W" ?

Unless I've missed it, neither report specifies the Lat/Long, but the map in Interim 1 (enlarged slightly in the Appendix, page 107) has the June7-"recovery" diamond position-symbol at about:
N03° 36'/W030° 37', i.e., in the language of your quote, 3.60N 30.62W.

That looks almost identical to the "sighted" June 6 position you quoted. Can you shed any light?

[EDITED ADDITION]: See my subsequent post (http://www.pprune.org/tech-log/395105-af-447-search-resume-188.html#post6404678) (#3743 next page).

wes wall, (quote):
It assumes all have accepted the discovered site as close to the LKP, but what are we considering "close?" Given the BEA's close to the vest attitude, the "close" could mean about anything.

You say that if you like; I couldn't possibly comment...

Chris

bearfoil

21st Apr 2011, 15:42

henra

Without VS/Rudder, both JAL 747 and Sioux City DC10 'landed' flat. Pilots were active and had some control, but we haven't determined that P1P2 on the deck of 447 didn't have same. So loss of directional control structure does not mean nose first dive necessarily?? 587 had lost all controls due to loss of both engine structures. 587 also had presumably alive alert pilots after VS/R loss. rgds.

Chris Scott

I still await mm43's response. He mentioned the winds at surface LKP as 000@25-30, does not this conflict with a Northerly drift of the VS. Of course that doesn't take into account the actual crash site.

Razoray

I am always hopeful of strong and important changes to the industry to emanate from the finality of such a heartbreaking tragedy. These changes are entirely dependent on BEA and their report, for they have the tools and the evidence to make this fateful flight an eternal memory of people who perished for good of others. My hope is that a new level of disclosure and openness will evolve in the results of this. Flying is uncommonly safe, and we are all human, so things go wrong sometimes. It must be made safer.

SaturnV

21st Apr 2011, 15:46

Reading between the lines of the Bloomberg articles, it would seem that Alucia and two Remus subs will rejoin the effort. I would think Woods Hole has produced a detailed mosaic map of everything, given the quantity of pictures. The question becomes, how intact is the tail, and how much cutting will be needed to access where the recorders presumably are?

SaturnV

21st Apr 2011, 16:12

Chris Scott,

My pdf version on the BEA Second Interim report only goes to p. 72, so I can't speak to the reference you cite.

The latitude and longitude coordinates for the sightings and recoveries are from Table 1 of the

"BUREAU D’ENQUETES ET D’ANALYSES POUR LA SECURITE DE L’AVIATION CIVILE
Scientific Report from the Drift Group"

Published on June 30 2010

This is Table 1 in non-tabular format
Ursulla sighting U June 5 2009 at 16h10 3.63N 30.45W
Brazilian sighting 1 S1 June 5 2009 at 21h02 3.56N 30.44W
3m part sighting 2 S2 June 6 2009 at 10h59 3.47N 30.47W
Galley G213 (sighted)G2 June 6 2009 at 11h06 3.47N 30.66W
First two bodies BB June 6 2009 at 11h55 3.57N 30.46W
Galley G2 (recover.) June 6 2009 at 15h00 3.47N 30.66W
Case June 6 2009 at 16h10 3.46N 30.63W
Body E1 (sighted) E1 June 7 2009 at 9h11 3.65N 30.51W
Vertical fin(sighted) VTP June 7 2009 at 13h38 3.61N 30.62W
Body 2Z (recover.) June 7 2009 at 16h39 3.70N 30.50W
Body 3Z (recover.) 3Z June 7 2009 at 17h17 3.73N 30.48W
Body 6Z (recover.) June 7 2009 at 17h29 3.74N 30.48W
Body 4Z (recover.) June 7 2009 at 17h41 3.75N 30.47W
Vertical fin(recover.) June 7 2009 at 18h35 3.47N 30.68W
Body 5Z (recover.) June 7 2009 at 18h55 3.73N 30.47W
Body 7Z (recover.) June 7 2009 at 20h35 3.75N 30.47W
Body 8Z (recover.) June 8 2009 at 16h58 4.04N 30.46W
Body 9Z (recover.) June 8 2009 at 17h25 4.03N 30.45W
Body 10Z (recover.) June 8 2009 at 17h50 4.06N 30.44W
Body (recover.) June 8 2009 at 18h34 4.06N 30.43W
Body (recover.) June 8 2009 at 19h25 4.08N 30.43W
Body (recover.) June 8 2009 at 19h56 4.09N 30.43W
Body 11Z (recover.) June 9 2009 at 9h45 4.25N 30.44W
Body 12Z (recover.) June 9 2009 at 10h16 4.25N 30.43W
Body 13Z (recover.) June 9 2009 at 11h02 4.25N 30.41W
Body 14Z (recover.) June 9 2009 at 12h29 4.27N 30.42W
Body 15Z (recover.) June 9 2009 at 12h56 4.27N 30.43W
Body 16Z (recover.) June 9 2009 at 13h29 4.31N 30.45W
Body 17Z (recover.) June 9 2009 at 14h21 4.31N 30.51W
Body 18Z (recover.) June 9 2009 at 15h45 4.35N 30.52W
Body 19Z (recover.) June 9 2009 at 15h45 4.35N 30.52W
Body 20Z (recover.) June 9 2009 at 16h24 4.41N 30.52

13 Not fully confirmed

Of the seven models the drift group used, here is the estimated crash position for each model:

Table 2 Mean crash positions and estimated standard deviations for
the seven models selected.

Lat Long Standard deviation Model
3.579 -30.869 48 ZOOM2
3.673 -30.675 48 ZOOM2+ Stokes
3.364 -30.911 35 FVCOM
3.372 -30.856 35 FVCOMW
3.554 -30.756 20 OI50
3.590 -30.537 20 OI85
3.393 -30.983 40 PSY2AVG data fitted

This is the detail on HYCOM.
This global 1/12° ocean forecasting system is run at NRL Stennis Space Center. It uses 32 vertical hybrid layers. Surface mixing is parameterized with Large et al.’s (1997) K Profile Parameterization (KPP) surface ocean boundary layer model. The surface is forced by 3-hourly wind stress, wind speed, heat flux (using bulk formula) and precipitation from the Navy Operational Global Atmospheric Prediction System (NOGAPS). Runoff from 986 rivers is included as a virtual salinity flux with no mass exchange.

The system assimilates (i) SSH from Envisat, Jason-1 and Jason-2 (ii) SST from all available satellite and in situ sources, (iii) all available in situ temperature and salinity profiles (e.g., Argo, CTDs, moor- ings), and (iv) Special Sensor Microwave/ Imager (SSMI) sea ice concentration. Assimilation is performed using the three-dimensional MultiVariate Optimum Interpolation (MVOI) Navy Coupled Ocean Data Assimilation (NCODA) system (Cummings, 2005). In this scheme, corrections to the model state are obtained by linear combinations of model-observation differences. The MVOI analysis is carried out on 42 z-levels extending from the surface down to 2500 m. The model forecast is interpolated to z-levels before the analysis and the analyzed increments are added to the forecast and interpolated back to the model's hybrid vertical coordinate.

NRL is Naval Research Lab @ Stennis. Its responsibilities are to function as the major center for in-house Navy research and development in oceanography, marine geology, geophysics, geoacoustics, and geotechnology. It is also the Navy’s lead activity for mapping, charting, and geodesy research and development.