By Alonso Soto

RIO DE JANEIRO, June 3 (Reuters) - Brazilian navy divers rushed on Wednesday to reach the wreckage of an Air France jet and start the grim job of pulling debris from the Atlantic Ocean, where the plane with 228 people went down in the the airline's worst disaster in its 75-year history.

Four navy ships with recovery equipment and a tanker were headed to a 3-mile (5 km) strip of water strewn with airplane seats, an orange buoy, wiring, hunks of metal and jet fuel stains about 745 miles (1,200 km) northeast of the coastal city of Recife.

Rear Admiral Domingos Nogueira said the navy was battling tough weather as officials predicted the hardest task would be finding the flight data and voice recorders that hold clues to why the plane fell out of the sky during a severe storm in the middle of the night.

Distraught relatives who had prayed for a miracle gave up hope as experts were certain that all aboard died on the flight, which left Rio de Janeiro on Sunday night bound for Paris.

"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.

So far no bodies have been sighted on flyovers by the air force, which spotted evidence of the catastrophe on Tuesday, allowing the navy to mount a retrieval operation.

"The ships are equipped to arrive and pick up pieces of the Airbus," Nogueira said. "Each ship has two divers on board and smaller ships to throw into the ocean to try and get pieces."

Helicopters would then be used to take wreckage of the Airbus A330 from the ships to a base on the Brazilian archipelago of Fernando de Noronha, 430 miles (700 km) from the crash site.

MYSTERY

Officials said the recorders needed to identify the causes of the mysterious crash could be on the ocean floor at a depth of 6,600 to 9,800 feet (2,000 to 3,000 metres).

The recorders are designed to send homing signals for up to 30 days when they hit water but many do not float well.

One expert said it could be among the hardest recoveries since the decades-long search to find the Titanic.

Brazilian President Luiz Inacio Lula da Silva said he was confident that the black boxes would be located.

"I think a country that can find oil 6,000 metres (19,685 feet) under the ocean can find a plane 2,000 metres (6,500 feet) down," he told reporters on Tuesday in Guatemala, referring to recent oil finds by Brazil's state energy company in ultra-deep waters.

Authorities were at a loss to explain how a storm could have caused the plane, operated by three experienced pilots, to crash without sending a mayday call.

Officials from France have arrived in Brazil to lead the investigation with help from Brazilian teams.

Brazil's air force last had contact with Flight AF 447 at 0133 GMT on Monday when it was 350 miles (565 km) from its coast. The last automated signals, which reported an electrical failure, were received about 40 minutes later.

One theory is that a lightning strike or brutal weather set off a series of failures. But lightning routinely hits planes and could not alone explain the downing, aviation specialists said.

Two Lufthansa jets believed to have been in the same area half an hour before the Air France mishap could provide clues for investigators, the World Meteorological Organization said.

-Reuters