Bart Jansen, and John Bacon

USA TODAY

Southeast Asia was mourning its third airline catastrophe of the year Sunday after an AirAsia jet with 162 people aboard vanished in violent weather and was believed to be at the bottom of an Indonesian sea.

The fate of Flight 8501 remained a mystery almost a full day after it vanished.

But at news conference today, Indonesian National Search and Rescue chief Henry Bambang Soelistyo said, "Based on the coordinates that we know, the evaluation would be that any estimated crash position is in the sea, and that the hypothesis is the plane is at the bottom of the sea."

The Airbus A320 was bound for Singapore from Surabaya, Indonesia, when it lost contact with air-traffic control Sunday at about 7:24a.m. Singapore time (6:24p.m. ET on Saturday), the airline said.

"We have no idea at the moment what went wrong," said Tony Fernandes, CEO of the regional, low-cost carrier. "Let's not speculate at the moment."

The search resumed after dawn Monday — early Sunday evening ET. First Admiral Sigit Setiayana, the Naval Aviation Center commander at the Surabaya air force base, said that 12 navy ships, five planes, three helicopters and a number of warships were talking part, along with ships and planes from Singapore and Malaysia. The Australian Air Force also sent a search plane.

Setiaya said visibility was good. "God willing, we can find it soon," he told the Associated Press.

The tragedy marks the third commercial air disaster involving airlines in the region this year. Mystery still shrouds Malaysia Airlines Flight 370, which disappeared without a trace en route to Beijing on March 8 with 239 people aboard. On July 17, another Malaysia Airlines flight was shot down over rebel-controlled eastern Ukraine while on a flight from Amsterdam to Kuala Lumpur, killing all 298 people on board.

Miami aviation lawyer Steve Marks said it's "inexcusable" that airlines, after the Flight 370 horror, don't use satellites to track every aircraft throughout every flight.

"The technology exists and has existed for years and for whatever reason, it has not been implemented," Marks said.

Djoko Murjatmodjo, Indonesia's acting director general of transportation, said that minutes before the AirAsia flight disappeared from radar, the pilot asked air traffic control for permission to avoid a cloud bank by turning left and going higher, to 34,000 feet. Flight 8501 gave no distress signal, he said.

Indonesia called off the daylong air search when darkness fell there Sunday. Achmad Toha, an official with the country's search and rescue agency, said some search ships remained in the area.

AccuWeather meteorologist Tyler Roys told USA TODAY the area along the flight path was blasted by a string of severe thunderstorms when the jet disappeared.

"It's hard to say if 34,000 feet would have been enough," Roys said. "We know the thunderstorms were very tall, very high up. They could have encountered severe turbulence, strong wind shear, lightning and even icing at that altitude."

Christopher Herbster, associate professor of applied meteorology at Embry-Riddle Aeronautical University in Daytona Beach, Fla., said vertical wind in a thunderstorm is profoundly turbulent and can reach hurricane force. Turbulence "can affect one side of an aircraft disproportionately more than the other side, and create that oscillating back-and-forth motion of the wings" that can terrify passengers, he said.

But even if the flight was affected by storms, the pilots should have been able to communicate the emergency, Herbster told USA TODAY.

"Something must have happened abruptly," Herbster said. "You would expect that unless something catastrophic occurred, they would have at least had time to declare an emergency."

AirAsia said in a statement that the jet has seven crewmembers and 155 passengers, including 16 children and one infant. Among the passengers are 149 Indonesians and three South Koreans, one Malaysian, a Briton and his 2-year-old Singaporean daughter.

Murjatmodjo said the jet 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. Contact was lost about 42 minutes after takeoff from Surabaya airport, authorities said.

At Surabaya's Juanda International Airport, dozens of relatives sat in a room, many talking on mobile phones, crying and looking dazed as the hours dragged on without additional news. As word spread, more arrived to await information.

Nias Adityas, a housewife from Surabaya, was overcome with grief when she found the name of her husband, Nanang Priowidodo, 43, on the passenger list. The tour guide had been taking a family of four on a trip.

"He just told me, 'Praise God, this new year brings a lot of good fortune,' " Adityas recalled, holding her grandson as she wept. "He apologized because he could not join us for the New Year celebration."

AirAsia, which has dominated cheap travel in the region for years, has never lost an aircraft. AirAsia Malaysia owns 49% of the Indonesian subsidiary. Flight 8501 was operated by AirAsia Indonesia. AirAsia officials changed the airline's Facebook and Twitter account logos from red to gray after the plane disappeared.

The plane's captain, identified in flight documents as Capt. Iriyanto, had a total of 20,000 flying hours, including 6,100 in the Airbus. The first officer had a total of 2,275 flying hours, said AirAsia, based in Sepang, Malaysia, near Kuala Lumpur.

Flightradar24, a flight-tracking website, said the Airbus A320-200 was delivered in September 2008. The jet, with registration number PK-AXC, had its last scheduled maintenance Nov. 16, airline officials said.

Worldwide, 3,606 A320s are in operation, according to Airbus. In a statement, the firm said the AirAsia aircraft had accumulated approximately 23,000 flight hours in 13,600 flights. It said it will provide full assistance to BEA, the French safety investigation authority, and to the authorities in charge of the investigation.

"The thoughts of the Airbus management and staff are with all those affected by Flight QZ8501," the statement added.

Finding the jet or its wreckage quickly has become more of an issue since the disappearance of Flight 370. Voice and data recorders, known as black boxes, will describe precisely what the pilots were saying and how the jet was behaving. The black boxes have locator beacons that signal if an aircraft sinks in water, but the batteries are only required to last 30 days.

That deadline has long since passed for Malaysia Airlines Flight 370. Now the clock is running for AirAsia Flight 8501.

"You really need to focus your efforts very quickly on the right search area to identify floating debris because it disappears over a period of weeks," Marks said.

Contributing: Jane Onyanga-Omara and Donna Leinwand Leger, USA TODAY; Associated Press