Aviation experts said the risk the plane was brought down by lightning was slim.

A woman looking for information about the Airfrance flight 447 that has been reported missed on its way between Rio de Janeiro and Paris, is surrounded by Brazilian journalists in Rio de Janeiro, Monday, June 01, 2009.[Agencies]

"Lightning issues have been considered since the beginning of aviation. They were far more prevalent when aircraft operated at low altitudes. They are less common now since it's easier to avoid thunderstorms," said Bill Voss, president and CEO of Flight Safety Foundation, Alexandria, Va.

He said planes have specific measures built in to help dissipate electricity along the aircraft's skin.

"I cannot recall in recent history any examples of aircraft being brought down by lightning," he told The Associated Press.

Experts said the absence of a mayday call meant something happened very quickly.

"The conclusion to be drawn is that something catastrophic happened on board that has caused this airplane to ditch in a controlled or an uncontrolled fashion," Jane's Aviation analyst Chris Yates told The Associated Press.

"I would suggest that potentially it went down very quickly and so quickly that the pilot on board didn't have a chance to make that emergency call," Yates said, adding that the possibilities ranged from mechanical failure to terrorism.

Families who arrived to meet passengers on board were cordoned off, away from reporters, at a special Air France information center at the Charles de Gaulle airport. That center said 60 French citizens were on the plane. Italy said at least three passengers were Italian.

"Air France shares the emotion and worry of the families concerned," Barrand said.

The flight was supposed to arrive in Paris at 0915 GMT (5:15 a.m. EDT), according to the airport.

Air France said it alerted planemaker Airbus and France's civil aviation investigation office, known by its French acronym BEA.

If all 228 people were killed, it would be the deadliest commercial airline disaster since Nov. 12, 2001, when an American Airlines jetliner crashed in the New York City borough of Queens during a flight to the Dominican Republic, killing 265 people.

On Feb. 19, 2003, 275 people were killed in the crash of an Iranian military plane carrying members of the Revolutionary Guards as it prepared to land at Kerman airport in Iran.

Airbus said it was cooperating with transport authorities and Air France, but would not further comment until more details emerged.

"Our thoughts are with the passengers and with the families of the passengers," said Airbus spokeswoman Maggie Bergsma.

The Airbus A330-200 is a twin-engine, long-haul, medium-capacity passenger jet that is 58.8 meters (190 feet) long. It is a shortened version of the standard A330, and can hold up to 253 passengers. It first went into service in 1998 and there are 341 in use worldwide today. It can fly up to 7,760 miles (12,500 kilometers).

Rick Kennedy, a spokesman for GE Aviation, expressed doubt that the engine was at fault. He said the CF6-80E engine that powered the Air France plane "is the most popular and reliable engine that we have for big airplanes in the world."

He said there are more than 15,000 airplanes flying in the world with that engine design and GE Aviation officials were on standby to help.

French President Nicolas Sarkozy expressed his "extreme worry" and planned to visit the Charles de Gaulle airport later Monday.