FERNANDO DE NORONHA, Brazil Military planes and ships struggled through high seas and heavy winds Wednesday as they searched for the bobbing wreckage of an Air France jet in the middle of the Atlantic Ocean, while an investigator said the plane's black boxes may never be found.
Rescue boats from several nations were sailing toward the site to start the recovery as aviation experts tried to determine why the plane carrying 228 people from Rio de Janeiro to Paris on Sunday night ended up in the sea.
An airplane seat, a fuel slick, an orange lifevest and pieces of white debris were spotted Tuesday in the ocean about 400 miles (640 kilometers) northeast of the Fernando de Noronha islands off Brazil's northern coast.
The floating debris is spread out in two areas about 35 miles (60 kilometers) apart, not far off the flight path of Flight 447. Brazilian Defense Minister Nelson Jobim said no bodies had been found and there was no signs of life.
Four boats and a tanker ship are en route to the scene but Brazil's lack of equipment to scour the ocean floor was a problem, a navy spokeswoman said Wednesday. Brazil was leading the search for wreckage, while France took charge of the crash investigation.
"The seas in the area are high, and that is slowing the arrival of our ships," she said, speaking on condition of anonymity. "We have four divers on the way, but the first of them will not get to the scene until midday Thursday."
The official said if the black boxes are at the bottom of the sea three miles deep in some nearby areas there was nothing the Brazil navy could do as they do not have the special remotely controlled subs needed to withstand the pressure at the ocean's bottom.
"We'll really only be able to carry out recovery efforts on the surface of the sea," the official said. "If the black boxes have sunk, we don't have the equipment to look for them."
The black boxes voice and data recorders are built to last 30 days underwater.
In Paris, the head of France's accident investigation agency, Paul-Louis Arslanian, said he was "not optimistic" that rescuers could even recover the plane's black boxes.
Arslanian said if rescuers don't find the black boxes, investigators should be prepared to continue the probe without them.
"I am not so optimistic. It is not only deep, it is also mountainous," he said. "We might find ourselves blocked at some point by the lack of material elements."
The reason for the crash remains unclear, with fierce thunderstorms, lightning or a catastrophic combination of causes as possible theories. France's defense minister and the Pentagon have said there were no signs that terrorism was involved.
The crew made no distress call before the crash, but the plane's system sent an automatic message just before it disappeared, reporting lost cabin pressure and electrical failure.
French military spokesman Christophe Prazuck said the naval recovery operation will start on the surface, then could turn to the use of submarines to help find the black boxes.
The effort is expected to be exceedingly challenging. Storm season is starting in the zone and low visibility hampered rescue efforts Tuesday. Water depths in the area sink down to 22,950 feet (7,000 meters).
Remotely controlled submersible crafts will have to be used to recover wreckage settling so far beneath the ocean's surface. France dispatched a research ship equipped with unmanned submarines that can explore as deeply as 19,600 feet (6,000 meters).
A U.S. Navy P-3C Orion surveillance plane which can fly low over the ocean for 12 hours at a time and has radar and sonar designed to track submarines underwater and a French AWACS radar plane were joining the operation Wednesday.
Arslanian told a news conference at Le Bourget airport north of Paris that in the absence of black box data right now, investigators were studying the plane's maintenance and other records.
"For the moment, there is no sign that would lead us to believe that the aircraft had a problem before it took off," he said.
He stressed the investigation was only beginning and was likely to last long. He said investigators didn't have enough information to determine whether the plane broke up in the air or upon impact with the sea.
"We don't even know the exact time of the accident," he said.
Asked whether the chief pilot was in the cockpit when the plane went down, Arslanian said, "We don't have for the time being the answer." Pilots on long-haul flights often take turns at the controls to remain alert.
Investigators are working with Air France, Airbus and meteorologists to determine what happened. A key possibility is some sort of collision with a brutal tropical storm in the area that sent winds of 100 mph (160 kph) straight into the airliner's path.
The man in charge of the investigation, Alain Bouillard, said Wednesday the accident investigation agency, known by its French acronym BEA, would submit its first preliminary report by the end of June.
Towering Atlantic storms are common this time of year near the equator an area known as the intertropical convergence zone. But veteran pilots said it was extremely unlikely that Flight 447's crew intended to punch through a killer storm.
"Nobody in their right mind would ever go through a thunderstorm," said Tim Meldahl, a pilot who has flown internationally for 26 years. "If they were trying to lace their way in and out of these things, they could have been caught by an updraft."
If no survivors are found, it would be the deadliest crash in Air France's history, and the world's worst civil aviation disaster since the November 2001 crash of an American Airlines jetliner in the New York City borough of Queens that killed 265 people.
On land, hundreds of relatives grieved deeply for those who were lost, a roster that included vacationers, business people, even an 11-year-old boy traveling alone back to school in England.
Brazil began three days of national mourning Tuesday and French President Nicolas Sarkozy and relatives of the victims were attending an ecumenical service at Notre Dame later Wednesday for the crash victims.
"We will miss your dancing feet," read a tribute from the Northern Ireland family of Eithne Walls, 29, a dancer-turned-doctor. "We will miss your silliness, your wit and your hugs. We will always hold you in our hearts and you are never truly gone."