PARIS - French officials said on Wednesday they might never discover why an Air France aircraft crashed into the Atlantic killing 228 people and that they might not even find the plane's black boxes on the ocean floor.
Brazilian and French navy vessels were rushing to an area about 745 miles northeast of Brazil's coastal city Recife, where debris from Monday's disaster was found, hoping to retrieve as much of the wreckage as possible.
France is also dispatching a mini submarine that can explore as far down as 6,000 meters (19,680 ft) and will try to locate the Airbus's flight data and voice recorders, which should shed light on the crash.
But Paul Louis Arslanian, the head of France's air accident investigation agency, said he was not sure that the black boxes would be recovered and said the probe might prove frustrating.
I am not totally optimistic. We cannot rule out that we will not find the flight recorders, Arslanian told reporters, warning that the inquiry could take a long time to wrap up.
I cannot rule out the possibility that we might end up with a finding that is relatively unsatisfactory in terms of certainty, he added.
A first report will be ready by the end of the month, with the investigation led by Alain Bouillard, who took charge of the probe into the crash of an Air France Concorde in 2000.
Arslanian revealed few new elements, confirming only that the crew had sent a radio message reporting turbulence as it headed toward the equator and that the plane had later sent a rapid series of automated messages reporting malfunctions.
For now, there is no indication to suggest that the plane had a problem before its take off, he said.
MOUNTAINOUS UNDERSEA LANDSCAPE
Brazil sent four navy ships and a tanker to a remote, 3-mile strip of water that was dotted with airplane seats, an orange buoy, wiring, hunks of metal and jet fuel stains.
The vessels have divers on board and smaller boats to lower into the ocean to try and retrieve the pieces.
France sent a vessel with the Nautile submarine aboard, but it was not expected to reach the zone until early next week.
Senior French government minister Jean-Louis Borloo said the recorders were believed to be at a depth of between 3,660 meters and 3,700 meters (12,010-12,140 ft), well within the reach of the submarine, but warned they would be hard to find.
We have never recovered black boxes that deep before and ... the sea currents are powerful that far down, he said.
Arslanian said the seabed in the area was very rugged.
It is practically in the middle of the Atlantic Ocean where the floor is very deep and varied. It is a mountainous seascape rather than a plain, he said.
The recorders are designed to send homing signals for up to 30 days when they hit water, but there is no guarantee they even survived the ferocious impact with the sea, Arslanian said.
Distraught relatives who had prayed for a miracle gave up hope as experts were certain that all aboard died on the flight.
I just want to find my son's body so that he can have a dignified burial, said Aldair Gomes, the father of Marcelo Parente, who was the head of the Rio mayor's cabinet.
France was due to hold an ecumenical religious ceremony for the relatives and friends of those on the plane at Notre Dame Cathedral in Paris later on Wednesday.
So far no bodies have been sighted on flyovers.
Authorities are baffled by how a modern plane operated by three experienced pilots could have suddenly plunged out of the sky, without even giving the pilots time to send a mayday call.
French investigators have divided into four teams to probe various aspects of the case, including a review of the plane's on board systems and maintenance record.
Paris magistrates said on Wednesday they would open a simultaneous inquiry, a routine procedure following such large loss of life.
(Additional reporting by Alonso Soto and Rodrigo Viga Gaier in Rio and Laure Bretton and Clement Guillou in Paris; Editing by Louise Ireland and Richard Balmforth)