KUALA LUMPUR, Malaysia — Two large oil slicks spotted yesterday by the Vietnamese air force offered the first sign that a jetliner carrying 239 people had crashed into the ocean after vanishing from radar without sending a single distress call.
An international fleet of planes and ships scouted the waters between Malaysia and Vietnam for any clues to the fate of the Malaysian Airlines Boeing 777, which disappeared less than an hour after taking off from Kuala Lumpur bound for Beijing.
The oil slicks sighted off the southern tip of Vietnam were each between 10 kilometers (6 miles) and 15 kilometers (9 miles) long, the Vietnamese government said in a statement.
There was no immediate confirmation that the slicks were related to Flight MH370, but the government said they were consistent with the kind of slick that would be produced by the jet’s two fuel tanks.
After the oil was spotted, authorities suspended the air search for the night. It was to resume today. A sea search continued in the darkness, the airline said.
The jet’s disappearance was especially mysterious because it apparently happened when the plane was at cruising altitude, not during the more dangerous phases of takeoff or landing.
Just 9 percent of fatal accidents happen when a plane is at cruising altitude, according to a statistical summary of commercial jet accidents done by Boeing.
Malaysia Airlines CEO Ahmad Jauhari Yahya said there was no indication the pilots had sent a distress signal. That might mean that whatever trouble befell the plane happened so fast the crew did not have time to broadcast even a quick mayday.
The lack of a radio call “suggests something very sudden and very violent happened,” said William Waldock, who teaches accident investigation at Embry-Riddle Aeronautical University in Prescott, Ariz.
The plane was last inspected 10 days ago and found to be “in proper condition,” Ignatius Ong, CEO of Malaysia Airlines subsidiary Firefly airlines, said at a news conference.