HONG KONG — Investigators trying to find out what happened to a Malaysia Airlines jet that disappeared somewhere over the Gulf of Thailand on Saturday were examining the usual causes of plane crashes: mechanical failure, pilot error, bad weather. But the discovery that two of the passengers were carrying stolen passports also raised the unsettling possibility of foul play.
As of Saturday night, there was little to go on: no wreckage of the jet, a Boeing 777-200 with 239 people aboard, and other than a 12-mile oil slick on the surface of the gulf, no clue that a crash had even taken place.
The airline said the plane had recently passed inspection, and Malaysia’s deputy minister of transport, Aziz bin Kaprawi, said the authorities had not received any distress signals from the aircraft. The plane was flying at 35,000 feet in an area of the world where it would not have been expected to encounter threatening weather.
After officials in Rome and Vienna confirmed that the names of an Italian and an Austrian listed on the manifest of the missing flight matched the names on two passports reported stolen in Thailand, officials emphasized that the investigation was in its earliest stages and that they were considering all possibilities.
“We are not ruling out anything,” the chief executive of Malaysia Airlines, Ahmad Jauhari Yahya, told reporters at Kuala Lumpur International Airport on Saturday night. “As far as we are concerned right now, it’s just a report.”
A senior US intelligence official said law enforcement and intelligence agencies were investigating the matter. But so far, they had no leads.
“At this time, we have not identified this as an act of terrorism,” said the official, who spoke on the condition of anonymity because of the continuing inquiry. “While the stolen passports are interesting, they don’t necessarily say to us that this was a terrorism act.”
Operating as Flight MH370, the plane left Kuala Lumpur, Malaysia, just after midnight Saturday, headed for Beijing. Air traffic control in Subang, a suburb of Kuala Lumpur, lost contact with the plane almost two hours later, at 2:40 a.m., the airline said.
That timetable seemed to suggest that the plane stayed in the air for two hours — long enough to fly not only across the Gulf of Thailand but also far north across Vietnam. But Fredrik Lindahl, the chief executive of Flightradar24, an online aircraft tracking service, said that the last radar contact had been at 1:19 a.m., less than 40 minutes after the flight began.
A Malaysia Airlines spokesman said Saturday evening that the last conversation between the flight crew and air traffic control in Malaysia had been around 1:30 a.m., but he reiterated that the plane had not disappeared from air traffic control systems in Subang until 2:40 a.m. China Central Television said that, according to Chinese air traffic control officials, the aircraft never entered Chinese airspace.
A European counterterrorism official said the Italian man, Luigi Maraldi, 37, had called his parents from Thailand, where he is vacationing, after discovering that someone by the same name was listed on the passenger manifest.
The official, who spoke on the condition of anonymity, said Maraldi’s passport was stolen last August, and he reported the theft to the Italian police. The counterterrorism official said the passport of the Austrian man, Christian Kozel, 30, was stolen about two years ago.
Malaysia, the United States and Vietnam dispatched ships and aircraft to the mouth of the Gulf of Thailand on Saturday to join an intensive search, and China said it had sent a coast guard ship that was due to arrive Sunday afternoon.
The Chinese Ministry of Transport said a team of scuba divers who specialize in emergency rescues and recovery had been assembled on Hainan, the southern island-province, to prepare to go Sunday to the area where the airliner may have gone down.
Boeing said in a statement that it was assembling a team of experts to advise the national authorities investigating the disappearance of the aircraft.
Lai Xuan Thanh, the director of the Civil Aviation Administration of Vietnam, said a Vietnamese navy AN26 aircraft had discovered the oil slick toward the Vietnam side of the mouth of the Gulf of Thailand. The oil slick is suspected to have come from the missing plane, he added.
Malaysia Airlines said the plane had 227 passengers aboard, including two infants, and an all-Malaysian crew of 12.