Actually, it is > 3,900 meters (13,000 ft).

More importantly, the pressure is 378 Atmospheres, or 378 times pressure at the sea surface. Some may find that 5,562 psi is more meaningful, but remember a lot of the composites that have been carried to the bottom will have had any residual softness compacted, and the same goes for anything else. Tyres (tires) on the landing gear will have deflated at the rims once the pressure exceeded that to which they had been inflated. Water will be occupying that space.

mm43, thanks for that information. I think the tires are inflated to about 220 psi but was unsure what the water pressure would be at 13,000 ft. Yes, the tires would obviously be deflated.

Hi,

In France-Soir (French newspaper) :
Google Vertaling
Original link:
Crash Rio-Paris : Fiasco du bureau d'enquête français | France Soir

Usual buzz for nothing.
People tend to forget now that this zone was already searched from the start by both SAR aircraft and the two French/US crews onboard the TPL trailers (Fairmount Glacier and Expedition). The main problem was that the recorders pingers could have malfunctioned.

Here is the map from Metron Inc. report for the BEA showing those TPL searches around LKP:
http://takata1940.free.fr/TPL_search.jpg

BEA says the detection range of the Underwater Locator Beacon (ULB) also called as Emergency Locator Pingers (ELP) is up to 2,000 m.

The manufacturer's technical brochure does give a detection range, but says the emission covers 80% of a sphere.

That would mean the microphone would have to be lowered by over 2,000 m to have had a chance at locating the pinger.

http://www.benthos.com/pdf/elp362D_001815_revK.pdf

Have you ever tried to find anything underwater in a reasonably challenging environment? I mean even in a spot where the parameters would seem to have it down to a fairly limited area ("it must be around here somewhere...", kind of thing).

Having failed after an initial, frantic, emergency search the group brain kicks in and tells you "it's not here, let's spread out guys". The theories get wilder from there on out.

I've been there, and also (totally coincidentally) personally involved in the final discovery and subsequent recovery 6 months later, which was (somewhat predictably and very much like this case) very, very close to the LKP

Nothing like the AF447 depths though, my experience involved puddle depth, a mere 200 fsw. I consider it fairly amazing they found any further trace mid Atlantic.

I believe the pinger(s) must have been down. There is no other logical explanation for not picking up signals during the first searches, unless I'm missing something totally obvious, generic conspiracy theories notwithstanding.

Whatever, this and the TechLogs original thread have been tremendous, thanks y'all.

Side scan sonar type
 

The REMUS 6000 has an Edgetech 4200 side scan as standard. That sonar image is not from an Edgetech 4200, it looks more like a SAS image (synthetic aperture sonar). It is a remarkably good image for such a long (600m) range.

But I repeat - that is a very flat seabed.

AF 447
 

My mother always used to advise me, "never put down to malice what is best explained by incompetence."

Given that this search has been overseen by the French....

:ouch:

It is easy to see those who don't understand the ocean and the sheer difficulty trying to find anything once you get under the surface which is a totally different environment. Hindsight is a wonderful thing, gentlemen but we should remember that the BEA has found the aircraft and done a very fine piece of work. Parading a lack of knowledge is also not the best way to go about things. My training - start at the furthest point that an item could have reached and then work in.

AF 447
 

Points taken,guys but two years is a long time....how long did the search to find the SAA Combi off of Mauritius take?
I think,now that the wreckage has finally been found,that the shut-door attitude is quite frustrating for all of the folks on both this and the technical forum.And I am sure that those on the tech forum have input a huge amount of work and research.
Area to search?Given that money is involved I would have started at the last known location and worked outwards,not the other way around! :hmm:

Loerie, if you have been reading the tech forum, the answer to your criticism of the search will be found there.

Very simply, search aircraft overflew the location of the crash on the day of the crash (June 1) and saw nothing. Why they saw nothing is a matter that needs to be examined.

But the logical thinking would be if you don't find evidence of the crash on the day of the crash when you overfly the crash location, then the plane didn't crash there. The result of them not seeing evidence on June 1 led them to searching elsewhere in the days, months, and years that followed.

AF 447
 

Hi,
Did they not see the Vertical Stabiliser at that point from the air and some passengers and crew from sea level or was that later and well away from the LKP and what of the kerosene trace---that must surely have been from aloft?
I will go back and check,thanks.
Not really complaining or anything,just curious as to why the Woods guys were not called in right away.After all,it has taken them under a week to find the Aircraft very close to where it came down.Would just have thought,and bearing in mind all the difficulties facing deep-water exploration,that possibly more effort and money immediately spent would have worked better.
Thanks for the courteous post and reply.I have been more immersed in the tech side of the forum but do not have that kind of tech to comment----just putting down my frustration at the apparent lack of co-operation apparently from so many,including,from what I read,the Brazilians who seem to have been slow in supplying information to the French investigative body.
On a happier note----nice day in the BVI`s today....!:oh:
Cheers.

They didn't know they had heard them until about the middle of last year. Thales only made the discovery after writing new software to reprocess the data recorded during the first search. If I've understoof correctly this discovery caused them to extend the search plan by a month before the equipment was needed for a military project.

Search strategy
 

If you are looking for something on the surface that is moving, that is a good strategy. You trap the item between its last known position and the furthest possible point and the search area should shrink over time as you clear sectors.

For an item on the bottom that is not moving, it may not be a good strategy.
The furthest possible position is a guess. The search area should not vary over time (except as new information comes to light) and the LKP is a good starting point (assuming it is reliably known).

Of course, the retrospective analysis approach can always find the flaw in the grand plan that should have been recognized at the beginning.:rolleyes:

They did find AF447's resting place though and that fact should be respected.

Hi guys,
May be one day you'll understand french politics'.
Up to know, nothing, absolutely nothing has been done by chance or coïncidence.
Ref to my previous post to Know about the future (i'm not Ms Irma) ;-)))

This thread is a classic example of why I love visiting these forums. I am always looking for ultra-talented people who can be head-hunted for international organisations who currently employ specialists and experts in their fields, who unfortunately don't have a clue.

Despite what the so-called experts will tell you, it seems that locating a downed airliner at 13,000' of Atlantic Ocean is childs play if you know what you're doing. All the finest minds in the various fields were simply incompetent. Our finest PPRuNe contributors should have been called up. All they needed to do was look at the various scopes and detection devices, locate the ping, from there send a scuba diver down to guide the robot submarine towards the wreckage, and while down there, before the SCUBA tank ran out, comprehensively document the cause of the crash, and issue recommendations for all future trans-Atlantic flights to prevent any possible mishap ever again.

nojwod,

Don't forget that while sorting out all of the above, they would also find time to spot spelling and grammar mistakes, moan about pay and allowances, and express disbelief that non pilots have the audacity to express an opinion on the mighty Pprune!
It does give us engineers a chuckle though.

Whilst reserving the right to tell all other professionals how to do their jobs.

Sea floor apparently . . .

Based on what figure of merit, what receiver, and what water conditions? :confused:

Given that the pinger is apparently under 3900m of water, and it was detected by a submarine sonar (with post mission FOM enhanced) at more than 2000m slant range, their range estimates appear to be "rough" and not "fine" in resolution. Not sure what sort of range resolution the sub might have been able to discern, even in post mission analysis, with

1) a signal that weak, at a comparatively high frequency (for sound in water)
2) angular direction being mostly "down" rather than lateral

Tricky sonar tracking and locating problem to resolve, for sure. Even more curious, I wonder if it was detected via a convergence zone sound ray path.

( I am about to draw blood from my scalp via head scratching on that one ... I can still only grok Direct Path from the geometry ... )

Tail section
 

I note the French Transport Minister being quoted yesterday as saying that the tail section has now been found.

One hopes the FDR and CVR will be either in that tail section, or nearby.

*crosses fingers*

The tail section of an Air France plane which crashed over the Atlantic in 2009 has been found on the ocean floor, relatives of those killed have said.
Investigators had told them the section was "relatively intact", they added.
The discovery has raised hopes that the "black boxes", which were located at the rear of the jet, may be recovered.
The voice and data recorders could yield crucial clues about the cause of the crash that killed 228 people on the flight from Rio de Janeiro to Paris.
There has been speculation that malfunctioning speed sensors were to blame, but officials say other factors must also have contributed.
'99% certain' Nelson Marinho of the Brazilian victims' family association said French Accident Investigation Bureau (BEA) officials had told them during a meeting in Paris on Monday that the "tail section had been found and that it was relatively intact so the black boxes are possibly still attached to it".
Continue reading the main story “Start Quote
Maarten Van Sluys Brazilian victims' family association
"I am 99% certain the black boxes will be recovered," he said.
BEA spokeswoman Martine Del Bono urged caution about the news.
"We are working intensely under a very short time span to have a maximum amount of information to able to find the black boxes," she said. "But we don't know where they are right now - we have to find them at the site."
Maarten Van Sluys, another member of the Brazilian victims' family association, said there was also concern about the condition of the black boxes after two years sitting in corrosive seawater under immense pressure, nearly 4km below the surface of the ocean.
"They made it clear that they could not guarantee that the content of the black boxes would be able to be retrieved," he told the Associated Press.
Flight 447 crashed into the Atlantic north-east of Brazil on 1 June 2009, after running into an intense high-altitude thunderstorm.
Automatic messages sent by the Airbus 330's computers showed it was receiving false air-speed readings from its sensors.
The French transport ministry has said that the ship Ile de Sein, which is equipped with a remotely-operated submarine, will leave Cape Verde on 21 April to being retrieving parts of the wreckage.

Hi,

Anyone know what will be at 3.900 meters dept the percentage of oxygen ?

At least the temperature should be low, this slows down chemical reactions. See the Titanic for example, almost 100 years in seawater without maintenance and still standing.

quote:
Anyone know what will be at 3.900 meters dept the percentage of oxygen ?

The oxygen content is irrelevant, with sea water the main cause of corrosion is electrochemical. Two dissimilar metals with a conducting path between them (and sea water is conductive) form a battery, and the least noble metal will just dissolve away. Since circuit boards contain copper tracks and tin/lead solder, the tracks disappear in a disappointingly short time if exposed to sea water. This isn't too big a deal if the chips are still intact, as they can be removed and re-soldered to a new circuit board.

However, the same thing happens if water gets into the chips themselves, typically along the interface between the package and the leads: the aluminium metallization on the chip just rots away. Putting chips in a pressure cooker is a standard quality-control test for hermiticity, you typically start getting failures after a few weeks, and that's at only 1 bar (although that's at 121 degrees C- I've no idea how this translates to a higher pressure and lower temperature).

There are techniques used in failure analysis where you can use the beam of an electron microscope to "read out" an unconnected circuit, but I don't know whether this will scale up to the megabits of data in the recorder chips.

Basically it's all down to how well the internal and external packaging has managed to keep the sea water out, after a year under water at umpteen bar and following a high-velocity impact. There is, unfortunately, a good chance the data will be unreadable.

Not that the conspiracy theorists will believe the BEA if that's what it ends up announcing.

Digital Memory Survival in Ocean
 

Don't know how deep this camera was submerged, but if a regular consumer memory card was able to survive a year on the seabed, there's hope the robustly packaged memory in the AF447 recorders will have survived as well :

Camera Returned After Year on Ocean Floor

looking at the pictures I'm a amazed at how intact the pieces are

given what can be figured out from a few shards scattered all over the countryside there must be a good chance of closure on this incident if they can get those pieces to the surface

The photos of the airplane and engine bits on the sea floor don't look bad.

SR111 didn't have a problem with the balck boxes or engine FADECs etc. etc.

Who will have legal jurisdiction (ownership) over the data recorders, if found?

I would have thought it would be the S. American authorities since they had initial jurisdication over the recovered bodies.

I think that is only because Brazilian ships picked them up (and possibly because they were, at least some, bodies of Brazilian nationals).

The French are the investigating authority, I believe that is as it is a French certified operator in international waters. The crash didn't happen anywhere near Brazil's jurisdiction.

Since the Brazilians initially refused to cooperate with the legitimate investigating authority over the autopsies, I doubt the French will be falling over themselves to give them access to whatever they can bring up from the bottom.

Hi,

Abnormal :

Seem's completely wrong for me.
Why the french taxpayer must paid for rescue operations of an airliner ?
All the costs must be for Air France .. the company who make benefits by exploiting this aircraft ....
If you take benefits .. you must also take the responsability and costs.

jcjeant

I suspect $5M is only a small portion of the total cost to retrieve the wreckage of AF447. I am sure a larger percentage will be paid by AF & Airbus. There is much at stake here to learn the true cause and prevent future occurrences. In the future, I am sure if the mission is successful, you as a PAX on an A-330 flight, will feel more at ease knowing the cause had been found and corrective action taken for only $5M, shared by many.

Hi,

I must emphasize that it's a very small percentage of french taxpayers who put their ass in the AF seats .... all types of aircrafts included.
Or are we speaking of "collectivism" when it's about AF ?
That "only $5M" can certainly be shared by the passengers of AF (air ticket price increase will compensate and give better safety) instead of Mr Toulemonde
As the old proverb say
You can not have your cake and eat it too

I would be very concerned if AF was to pay alone for the search.

jcjeant,

Every time you set foot on a passenger aircraft - no, make that any aircraft - you benefit from every incident investigation (and subsequent recommendation) that has gone before.

For example, floor-level lights were mandated after an incident where passengers could not find their way out due dense smoke and died as a result. The idea to use high-intensity wingtip strobes whilst on an active runway strip did not come about just whilst some bright spark was singing in the shower.

Airbus would also be itching to know why one of their products apparently fell from the sky. Frankly so am I, given I strapped into their products from time to time. If AF can't or won't pay, I'm glad someone is willing and able to.

Airbus "make benefit" by manufacturing this aircraft. Hence it is fair that Airbus "must also take the responsability and costs". And guess who has (at least in part) underwritten Airbus these last 40 years? Yep - the French / German / British / Spanish taxpayer.

Talking about investigation responsibility and costs is a diversion to this thread.

This properly resides in ICAO annex 13, but since those are recommendations and not law, some variations occur (mostly revolving around deep pockets vs holes in pockets)

Argiuments can exist for the manufacturer having the responsibility for correcting known airworthiness issues of aircraft in service. Since crashed aircraft don't belong to the manufacturer and are no longer in service ....

OK, the manufacturer has a need to respond to known deficencies as reported by the operator or investigating agency (BEA) to the satisfaction of the regulator (DGAC).

The manufacturer typically carries insurance for unexpected costs (deep ocean recovery is excluded)

ergo the responsibilty rests almost entirely with the investigating agency to make investigating decisions which can be economically supported by themselves.

No harm in anybody else offering support for the investigation (persons or money) but the buck stops there.