PARIS - Search teams scoured remote Atlantic waters Tuesday for an Air France plane that vanished with 228 people on board, with scant hope of finding survivors and few clues to explain the crash.
As investigators puzzled over a series of error messages sent by the Rio de Janeiro to Paris flight after it hit a fierce storm, Brazilian and French spotter planes battled foul weather to sweep a patch of ocean halfway between South America and Africa.
Officials have identified a zone around 1,100 kilometres (680 miles) off northeastern Brazil, based on the last signal from Air France flight AF 447 -- an automatic warning of multiple electric and pressurisation failures.
French President Nicolas Sarkozy and others warned there was very little hope of survivors from what appears to be the worst loss of life in Air France's history and the worst civilian air accident since 2001.
"The search will continue as long as necessary. All means are deployed in the area and we'll put as many assets at their disposal as necessary," French Defence Minister Herve Morin told Europe 1 radio.
A Brazilian pilot for TAM airlines reported seeing orange glimmers on the surface of the ocean under Senegalese airspace, but the French military's spokesman could not immediately confirm the sighting.
"We received this information at around 4.30am (0230 GMT) from a Brazilian pilot who said he'd seen faint glows on the surface, in an area consistent with the A330's last reported position," said Captain Christophe Prazuck.
Prazuck said that a French surveillance plane had flown from Cape Verde back along the missing jet's expected flight path to its last known position.
"We didn't find anything, but the weather was terrible, with what we call a tropical convergence front," he said, describing a phenomenon in which weather fronts from the northern and southern hemispheres clash violently.
Ecology Minister Jean-Louis Borloo, whose brief includes the transport portfolio, said that, if they so wished, relatives of the missing could be flown to the search zone to watch.
US President Barack Obama pledged his country's help in the search.
The Airbus A330 disappeared early Monday four hours into its 11-hour flight from Rio de Janeiro to Paris after flying into a storm.
Day and night searches by Brazilian air force aircraft found nothing.
While the cause of the disaster remained a mystery, Air France's chief executive said the aircraft had sent a series of error messages before it vanished.
"A succession of a dozen technical messages" sent by the aircraft around 0215 GMT showed that "several electrical systems had broken down" which caused a "totally unprecedented situation in the plane," said Pierre-Henry Gourgeon.
"It is probable that it was shortly after these messages that the impact in the Atlantic came," he told reporters at Charles de Gaulle airport, where the flight was to have landed on Monday morning.
Air France officials had earlier said the twin-engine airliner was probably hit by lightning, but Gourgeon declined to make a direct link between the horrendous weather conditions and the error messages.
"All possibilities must be examined. We cannot, by definition, exclude a terrorist attack, because terrorism is the main threat for all Western democracies," defence minister Morin said.
"But today we have no evidence whatsoever of the cause of the accident."
The 216 passengers included 126 men, 82 women, seven children and a baby. There were 11 French and one Brazilian crew while the passengers came from 32 countries, including 61 from France, 58 from Brazil and 26 from Germany.
"They were a very experienced crew with a well-maintained aircraft, who were extremely reliable," said Borloo.
The captain, whose named has yet to be released, was 58 and had been an Air France pilot since 1988, Air France said. He had 11,000 flying hours under his belt, including 1,700 on Airbus A330s or A340s.