PARIS, France (CNN) -- The jet carrying 228 people from Rio de Janeiro, Brazil, that disappeared overnight as it entered an area of strong turbulence probably crashed into the Atlantic Ocean, the CEO of Air France said Monday.
The first three hours of what was to have been an 11-hour flight appear to have been uneventful, CEO Pierre-Henri Gourgeon said.
But about 4:15 a.m. Paris time, Flight 447's automatic system began a four-minute exchange of messages to the company's maintenance computers, indicating that "several pieces of aircraft equipment were at fault or had broken down," he said.
"This succession of messages signals a totally unforeseeable, great difficulty," he said. "Something quite new within the plane."
During that time, there was no contact with the crew, Gourgeon said.
"It was probable that it was a little bit after those messages that the impact of the plane took place in the Atlantic," he added.
He said the Airbus A330 was probably closer to Brazil than to Africa when it crashed.
He noted that turbulence made flying "difficult" in the area but that it is "too early to say" exactly what happened.
The chances of finding any survivors from were "very low," French President Nicolas Sarkozy admitted Monday.
"This is a catastrophe the likes of which Air France has never seen before," he said at Charles de Gaulle International Airport, where he met with relatives of the missing.
"I said the truth to them: The prospects of finding survivors are very low," he said.
Asked the nationalities of those aboard, he said most of them were Brazilians but added, "that changes nothing, of course. They're victims. It doesn't matter about their nationality."
The airline company identified the nationalities of the victims as two Americans, an Argentinean, an Austrian, a Belgian, 58 Brazilians, five British, a Canadian, nine Chinese, a Croatian, a Dane, a Dutch, an Estonian, a Filipino, 61 French, a Gambian, 26 Germans, four Hungarians, three Irish, one Icelandic, nine Italians, five Lebanese, two Moroccans, three Norwegians, two Polish, one Romanian, one Russian, three Slovakian, two Spanish, one Swedish, six Swiss and one Turk.
Sarkozy said French authorities had sent ships and planes to the area about 400 kilometers from Brazil. "Our Spanish friends are helping us; Brazilians are helping us a lot as well."
He added that authorities were seeking the help of satellites that might be able to pick up signs of what happened to the 4-year-old Airbus 330.
No possibility was being excluded: Turbulence in the area was strong, but other planes were able to pass through it without incident, he said.
The plane had reported a problem with the electrical system, "but the specialists refuse for the moment to express themselves about any possibility," Sarkozy said.
The jet had also sent out a warning that it had lost pressure, the Brazilian air force said.
It lost contact with air traffic control between Galeao International Airport in Rio de Janeiro and Charles de Gaulle International Airport in Paris, the airline said Monday.
The Airbus A330 sent out an automatic signal warning of the electrical problems just after 2 a.m. GMT Monday as it flew "far from the coast," said an Air France spokeswoman who declined to be identified. It had just entered a stormy area with strong turbulence, she said.
The jet was flying at an altitude of 35,000 feet and a speed of 521 mph, the air force said.
Among the passengers were 126 men, 82 women, seven children and a baby, in addition to the 12 crew members, Air France officials in Brazil said.
Much of the route is out of radar contact, Brazilian air force Col. Henry Munhoz told TV Globo.
Brazil's air force launched a search near the archipelago of Fernando de Noronha in the Atlantic Ocean, 365 km (226 miles) from Brazil's coast, a spokesman for the air force said.
Two Brazilian squadrons are searching for the plane, although it disappeared after it left the country's radar space, said the officer, who declined to be identified.
The flight, AF 447, took off from Galeao International Airport at 11:30 p.m. Sunday GMT. It was scheduled to land in Paris at 9:10 a.m. GMT.
Its last known contact occurred at 2:33 a.m. GMT, the Brazilian air force spokesman said.
It was expected to check in with air traffic controllers at 3:20 a.m. GMT but did not do so, the Brazilian air force said in a statement.
Brazilian authorities asked the air force to launch a search mission just over three hours later, at 6:30 a.m. GMT, the statement said.
The plane reported no problems before takeoff, Joao Assuncao, Air France's manager in Brazil, told the country's Record TV.
The French ambassador to Senegal told BFMTV that French military aircraft had been dispatched to search around Cape Vert, or Green Cape, off the coast of the west African country.
The airline set up a crisis center at the Paris airport. It listed numbers for families to call: 0 800 800 812 for people in France and 00 33 1 57 02 10 55 for families outside France.
At a crisis center at the airport in Rio, relatives of the missing complained of a dearth of information from Air France, the Brazilian state news agency reported.
One man, who identified himself as Bernardo, said his brother, Romeo Amorim Souza, and his wife were on the missing flight.
"I came to the airport because I wasn't finding information, and my parents are very nervous," he told Agencia Brasil.
The missing A 330 last underwent a maintenance check on April 16, the airline said.
CNN air travel expert Richard Quest said the twin-engine plane, a stalwart of transatlantic routes, had an impeccable safety record, with only one fatal incident involving a training flight in 1994.
"It has very good range and is extremely popular with airlines because of its versatility," he said.
Its crew was composed of three pilots and nine cabin crew members, including a captain who has logged 11,000 hours in flight. About 1,700 of those hours were on the A330 and A340. Of the two co-pilots, one has 3,000 hours of flying experience and the other 6,600 hours. The aircraft has flown 18,870 hours.
The model is "capable of communicating in several different ways over quite long distances even if they are out of radar coverage," said Kieran Daly of the online aviation news service Air Transport Intelligence.
The French Accident Investigation Bureau for civil aviation is investigating, the company said in a statement.
