Despite intensive search, Brazil's Air Force and Navy have found no trace of the 228 people on board the Air France carrier that vanished in a mysterious plunge into a rough and dangerous section of the Atlantic Ocean three days ago.
The air force on Wednesday found new debris and a long oil trace in the crash region about 1,200 km north-east of Brazil's mainland.
"No bodies or survivors have been found," Brazil's Defence Minister Nelson Jobim said Wednesday evening at a press conference in Brasilia.
It is seen as next to impossible that any of the passengers or crew survived the crash, even as experts raised the possibility the Airbus A220-200 had disintegrated in mid-air.
Brazil, from where Air France flight 447 took off, was in the midst of three days of official mourning. French President Nicolas Sarkozy joined other dignitaries Wednesday at a multi-denominational service at Notre Dame Cathedral in Paris commemorating the victims.
Paris was the destination of the ill-fated flight.
The most urgent focus of the search was finding the two black boxes mandatory on every large plane: a flight data recorder and a cockpit voice recorder, which are essential in helping investigators in the painstaking search for the cause of a plane crash.
"We have to find the black boxes," said Paul-Louis Arslanian, director of France's Office of Accident Investigations and Analyses (BEA), in Paris. The BEA is leading the investigation.
US accident inspectors will also get involved since the engine was built by General Electric and some of the instruments were made by Honeywell, according to US media reports.
"This aviation catastrophe is the worst this country has ever suffered," Arslanian said in Paris. "We cannot allow ourselves to speculate. We must verify everything."
After the Brazilian Air Force searched Tuesday and Wednesday over tens of thousands of square kilometres of ocean, the Brazilian Navy was expected to concentrate Thursday on a 230 sq km defined zone near the Saint Peter and Saint Paul Islets, a small, uninhabited archipelago that is home to a Brazilian Navy scientific station.
"There is no doubt that the crash site is in this place," Jobim said.
Recovery workers face difficult challenges, with strong currents and uneven topography in the region, where the Atlantic plunges to a depth of 4,000 metres and has spiking underwater mountain peaks.
France has sent a vessel carrying diving equipment that can reach 6,000 metres down.
Jobim said the oil traces on the water would tend to exclude an on-board explosion as the cause of the accident. "When there are oil traces, that's because the oil was not burnt up," he said.
The air force found a piece of debris Wednesday that measured 7 metres in length, possibly a piece of the wing, officials said.
German aviation expert Heinrich Grossbongardt, analysing sparse details provided by Air France, gave an account suggesting several minutes of severe technical problems by the Airbus 330-200 before it crashed.
In an interview with DPA, Grossbongardt described a four-minute time span between 0210 and 0214 GMT Monday in which the A330 plane apparently experienced severe technical problems before all contact was lost.
At 0210, the plane's system reported that the crew had turned off the automatic pilot in order to fly the plane manually.
"Then, for a span of two to three minutes, there was a flood of malfunction messages: the navigation equipment had collapsed, the image on the onboard monitors was gone, and other things," Grossbongardt said.
The last information sent was at 0214 GMT: "The cabin pressure had dropped."
"That was the last report that was automatically transmitted from the airplane via satellite to company headquarters," he said.
Grossbongardt said the sequence of events also spoke against a mid-air bombing. Four minutes between the shut down of the auto pilot to the drop of cabin pressure "is a very long time. That means that the pilots were trying to get control of the problem".
He also ruled out a lightning strike, saying: "A lightning strike does not bring down any plane of this size from the sky."
The 228 people on board were from 32 countries, including 72 French, 60 Brazilians and 26 Germans.