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.