In the third air incident connected to Malaysia this year, an AirAsia plane with 162 people on board disappeared Sunday while flying over the Java Sea after taking off from Indonesia's second-largest city for Singapore at 5:31 am local time (4:01am IST).
The two countries immediately launched a search and rescue operation for Flight 8501. Rescue efforts for the day were halted in the evening, even as there was no trace of the plane more than 10 hours after it went missing.
AirAsia, a regional low-cost carrier founded in 2001 by Malaysian businessman Tony Fernandes, said in a statement that the missing Airbus A320-200 was on the submitted flight plan route. However, it had requested deviation due to weather before communication with the aircraft was lost while it was still under the control of Indonesian Air Traffic Control.
AirAsia, which has a presence in most of Southeast Asia and recently in India, has never lost a plane before and has a good safety track record.
"We don't dare to presume what has happened except that it has lost contact," Djoko Murjatmodjo, Indonesia's acting director general of transportation, told reporters. He said the last communication between the pilot and air traffic control was at 6:13am (4:43 am IST) when the pilot "asked to avoid clouds by turning left and going higher to 34,000 feet (10,360 meters)."
He said there was no distress signal from the cockpit.
The contact was lost about 42 minutes after the single-aisle, twin-engine jetliner took off from Surabaya airport, Hadi Mustofa, an official of the transportation ministry, told Indonesia's MetroTV. It was about an hour before it was scheduled to land in Singapore at 8:30am (6am IST).
The plane had an Indonesian captain and a French co-pilot, five cabin crew and 155 passengers, including 16 children and one infant, AirAsia Indonesia said in a statement. Among the passengers were three South Koreans and one each from Singapore, Malaysia. The rest were Indonesians.
It said the captain had a total of 6,100 flying hours, a substantial number, and the first officer a total of 2,275 flying hours.
At Surabaya airport, dozens of relatives sat in a room, many of them talking on mobile phones and crying. Some looked dazed. As word spread, more and more family members were arriving at the crisis center to await word.
Murjatmodjo, the Indonesian official, said the plane is believed to have gone missing somewhere over the Java Sea between Tanjung Pandan on Belitung island and Pontianak, on Indonesia's part of Borneo island.
Transport minister Ignasius Jonan told reporters in Surabaya that the position was believed to be near the coast line. He said search and rescue efforts now involved the Indonesian army, the national Search and Rescue Agency as well as Singapore and Malaysia. But that effort will focus on the area around Belitung island.
Air Force spokesperson Hadi Tjahjanto said three aircraft, including a surveillance plane, had been dispatched to the area. The Singapore air force and the navy had pressed into action two C-130 planes.
Flightradar24, a flight tracking website, said the plane was delivered in September 2008, which would make it six years old. It is not clear if it has any satellite tracking devices on board. AirAsia said the aircraft had last undergone scheduled maintenance on November 16.
Malaysia-based AirAsia, which has dominated cheap travel in the region for years, flies short routes of just a few hours, connecting large cities of Southeast Asia. However, recently it has tried to expand into long-distance flying through its sister airline AirAsia X. AirAsia Malaysia owns 49 percent of its subsidiary, AirAsia Indonesia.
Fernandes, who is the face of AirAsia and an active Twitter user, sent out a tweet saying: "Thank you for all your thoughts and prays. We must stay strong." He tweeted later that he was heading to Surabaya.
Fernandes stirred controversy earlier this year after incorrectly tweeting that Malaysia Airlines flight 370, now synonymous with one of aviation's enduring mysteries, had landed safely. The wide-bodied Boeing 777 went missing soon after taking off from Kuala Lumpur for Beijing on March 8. It remains missing until this day with 239 people.
Another Malaysia Airlines flight, also a Boeing 777, was shot down over rebel-controlled eastern Ukraine while on a flight from Amsterdam to Kuala Lumpur on July 17. A total of 298 people on board were killed.
William Waldock, an expert on air crash search and rescue with Embry-Riddle Aeronautical University in Prescott, Arizona, cautioned against drawing comparisons to the disappearance of Malaysia flight 370.
"I think we have to let this play out," he said. "Hopefully, the airplane will get found, and if that happens, it will probably be in the next few hours. Until then, we have to reserve judgment."
The circumstances bode well for finding the plane since the intended flight time was less than two hours and there is a known position at which the plane disappeared, he said.
Malaysian Prime Minister Najib Razak, expressed solidarity with AirAsia. In a tweet he said: "Very sad to hear that AirAsia Indonesia QZ8501 is missing. My thoughts are with the families. Malaysia stands ready to help."
President Barack Obama, who was vacationing in Hawaii, was briefed Sunday evening on the plane's disappearance, and officials were tracking the situation, the White House said.
The Airbus A320 is a workhorse of modern aviation. Similar to the Boeing 737, it is used to connect cities anywhere from one to five hours apart. There are currently 3,606 A320s in operation worldwide, according to Airbus. The A320 family of jets, which includes A319 and A321, has a very good safety record, with just 0.14 fatal accidents per million takeoffs, according to a safety study published by Boeing in August.
It's too early to say what might have caused a crash, but the safest part of a trip is when a plane is flying at its cruising elevation. Just 10% of fatal crashes from 2004 through 2013 occurred while a plane was in that stage of flight, according to the August Boeing safety report.
However, in 2007, an Indonesia-owned Adam Air flight carrying 102 people vanished during a domestic flight. Debris was found a few days later, but much of the fuselage remains on the ocean floor. In 1995, another Indonesian plane, Merpati Nusantara Airlines, also disappeared over open water while flying between islands in the archipelago nation. The 14 crew and passengers were never found.
Passing through bad weather, such as severe thunderstorms, could have been a factor. Airbus jets are very sophisticated and are able to automatically adjust to wind shears or other weather disruptions. However, weather has played a role in past air disasters that occurred at cruise elevation, including the 2009 Air France Flight 447 crash over the Atlantic Ocean.
Another possibility is some type of catastrophic metal fatigue caused by the cycle of pressurization and depressurization associated with each takeoff and landing cycle - something that flight 8501 would have done a lot. Still, metal fatigue is unlikely because this plane is only six years old.
Watch: Relatives anxiously await news at Singapore airport