A Malaysia Airlines Boeing 777-200 carrying 239 people lost contact over the South China Sea early Saturday morning on a flight from Kuala Lumpur to Beijing, and international aviation authorities still hadn't located the jetliner several hours later.
Malaysia Airlines CEO Ahmad Jauhari Yahya said at a news conference that Flight MH370 lost contact with Malaysian air traffic control at 2:40 a.m. (18:40 GMT Friday), about two hours after it had taken off from Kuala Lumpur. It had been expected to land in Beijing at 6:30 a.m. Saturday (22:30 GMT Friday).
Pham Hien, a Vietnamese search and rescue official, said the last signal from the plane detected by the aviation authority was 120 nautical miles (140 miles; 225 kilometers) southwest of Vietnam's southernmost Ca Mau province. Lai Xuan Thanh, director of Vietnam's civil aviation authority, said the plane was over the sea and bound for Vietnamese airspace but air traffic officials in the country were never able to make contact.
The plane "lost all contact and radar signal one minute before it entered Vietnam's air traffic control," Lt. Gen. Vo Van Tuan, deputy chief of staff of the Vietnamese army, said in a statement issued by the government.
More than 10 hours after last contact, officials from several countries were struggling to locate the plane, which carried passengers from at least 14 countries, mostly from Asia but also from the U.S. and Europe.
All countries in the possible flight path of the missing aircraft were performing a "communications and radio search," said John Andrews, deputy chief of the Philippines' civil aviation agency. Xinhua said China has dispatched two maritime rescue ships to the South China Sea to help in the search and rescue efforts.
"It couldn't possibly be in the air because it would have run out of oil by now," said Shukor Yusof, an aviation analyst at S&P Capital IQ. "It's either on the ground somewhere, intact, or possibly it has gone down in the water."
At Beijing's airport, authorities posted a notice asking relatives and friends of passengers to gather to a hotel about 15 kilometers (nine miles) from the airport to wait for further information, and provided a shuttle bus service. A woman wept aboard the shuttle bus while saying on a mobile phone, "They want us to go to the hotel. It cannot be good!"
"Our team is currently calling the next-of-kin of passengers and crew. Focus of the airline is to work with the emergency responders and authorities and mobilize its full support," Yahya said in a statement. "Our thoughts and prayers are with all affected passengers and crew and their family members."
Fuad Sharuji, Malaysian Airlines' vice president of operations control, told CNN that the plane was flying at an altitude of 35,000 feet (10,670 meters) and that the pilots had reported no problem with the aircraft.
Finding planes that disappear over the ocean can be very difficult. Airliner "black boxes" -- the flight data and cockpit voice recorders -- are equipped with "pingers" that emit ultrasonic signals that can be detected underwater.
Under good conditions, the signals can be detected from several hundred miles away, said John Goglia, a former member of the U.S. National Transportation Safety Board. If the boxes are trapped inside the wreckage, the sound may not travel as far, he said. If the boxes are at the bottom of a deep in an underwater trench, that also hinders how far the sound can travel. The signals also weaken over time.
Air France Flight 447, with 228 people on board, disappeared over the Atlantic Ocean en route from Rio de Janiero to Paris on June 1, 2009. Some wreckage and bodies were recovered over the next two weeks, but it took nearly two years for the main wreckage of the Airbus 330 and its black boxes to be located and recovered.
The Malaysian Airlines plane was carrying 227 passengers, including two infants, and 12 crew members, the airline said. It said there were 153 passengers from China, 38 from Malaysia, 12 from Indonesia, seven from Australia, four from the U.S., three from France, two each from New Zealand, Canada and Ukraine, and one each from Russia, Italy, Taiwan, the Netherlands and Austria.
Yahya, the airline CEO, said the 53-year-old pilot, Zaharie Ahmad Shah, has more than 18,000 flying hours and has been flying for Malaysia Airlines since 1981. The first officer, 27-year-old Fariq Hamid, has about 2,800 hours of experience and has flown for the airline since 2007.
The tip of the wing of the same Malaysian Airlines Boeing broke off Aug. 9, 2012, as it was taxiing at Pudong International Airport outside Shanghai. The wingtip collided with the tail of a China Eastern Airlines A340 plane. No one was injured.
Malaysia Airlines' last fatal incident was in 1995, when one its
planes crashed near the Malaysian city of Tawau, killing 34 people.
Malaysia Airlines has 15 Boeing 777-200 jets in its fleet of about 100 planes. The state-owned carrier last month reported its fourth straight quarterly loss.
The 777 had not had a fatal crash in its 19-year history until an Asiana Airlines plane crashed in San Francisco in July 2013. All 16 crew members survived, but three of the 291 passengers, all teenage girls from China, were killed.