Thanks to all and specially 'mm43' for this very interesting thread. Here goes with a very small contribution.
Day before yesterday there was an interesting article in the Spanish press, namely the 'El Pais' newspaper. Just like many other newspapers they have also used the word 'located' in their headline, which raised my hopes that the 'black boxes' had been found but the article nonetheless offers other news that has not appeared in previous posts, so here goes with a translation:
Air France Rio-Paris airplane black boxes located
The black boxes of the Airbus flying from Rio de Janeiro with destination Paris belonging to the company Air France have been located nearly a year after the accident, when it crashed into the Atlantic on 1 June with 228 persons on board. They are to be found, according to the French Ministry of Defence, somewhere at a depth of 3,000 metres in an area of about 100 square kilometres at about 1,000 kilometres from the Brasilian coast. It will not be easy to find them. "It will be like looking for a shoe box in an area as big as Paris and with a mountainous area similar to the alps." said the French Navy Spokesman, Hurgues du Plessis. The find had been given up as lost, since the black boxes only had batteries that lasted two months to emit a signal in order to be located. The delimitation of the area has come about thanks to the investigators who have newly examined the recordings of a submarine that weeks after the accident combed the area blindly (blindly=randomly?)and at the time no signals were detected. Thanks to software developed by the industrial group THALES, it has been possible to isolate the toc-toc-toc signals from the boxes. But that sound no longer exists that would serve as a guide and finding the boxes will be a miracle.
The causes of the accident are still unknown. The official French organisation in charge of the investigation maintains that the aircraft crashed into the sea and that it did not disintigrate in the air, and that Pitot tubes, curiously also manufactured by the THALES group, that measured it's speed were giving contradictory inputs. This was one of the causes for the accident. But on its own would not explain the reasons for the accident.
First, it is difficult to imagine that a highly sofisticated and modern nuclear submarine would miss 'hearing' the signals from the black boxes but much more so to accept, that while they were recording sound, they did not record their position relative to the sound recording. Perhaps they did and for military reasons this information has been restricted. If then there is a record of the submarine's position that can be related to the sound recording, then finding the boxes becomes a real possibility in a fairly short space of time and perhaps the reason why the "Seabed Worker" is maintaining a position in a limited area, according to "mm43".
The other interesting bit of news is that the pitot tube manufacturers THALES are actively assisting in the search and developed the software to 'clean' the submarine's sound recordings and be able to identify the signals from the black boxes. Obviously THALES have an interest in finding the black boxes which might assist in establishing to what extent the pitot tubes were to blame for the accident and if there were other factors that contributed to the crash.