The search has resumed for AirAsia Indonesia flight QZ8501, which has gone missing with 162 people on board, an Indonesian official has said.
The Airbus A320-200 disappeared over the Java Sea early on Sunday en route to Singapore from Surabaya, Indonesia.
The pilots had requested a course change due to bad weather but did not send any distress call before the plane disappeared from radar screens.
AirAsia boss Tony Fernandes said this was his "worst nightmare".
The search began as soon as possible on Sunday but was largely suspended as night fell.
Although some ships continued the hunt overnight, the main search planes and vessels, from several nations, resumed at first light.
Indonesian transport ministry official Tatang Kurniadi said: "Our primary task is to find the plane. We are co-operating with every possible department, and relevant countries.
"This includes the department responsible for aircraft design, the aircraft manufacturer from France, and relevant operational teams from AirAsia and Malaysia."
Bambang Soelistyo, the head of the Indonesian search-and-rescue team, said his nation was providing 12 ships, three helicopters and five military aircraft.
Malaysia was to deploy a C-130 plane, along with three ships, with Singapore lending a C-130 and Australia also providing help.
AirAsia Chief Executive Tony Fernandes addresses the media and relatives
The search area is near Belitung island.
Flight QZ8501 had left Surabaya in eastern Java at 05:35 local time on Sunday (22:35 GMT Saturday) and was due to arrive in Singapore at 08:30 (00:30 GMT).
Last contact was at 06:24 local time.
Dense storm clouds were reported in the area at the time the plane lost contact.
Co-pilot Remi Emmanuel Plesel (left) and Captain Iriyanto 
The Airbus, pictured here on an earlier flight, disappeared about an hour after takeoff The pilot had asked permission to climb to 38,000ft (11,000m) to avoid the clouds.
Indonesian officials said the request could not be immediately approved due to traffic, but the plane disappeared from the radar screens before the pilots gave any further response.
Mr Fernandes flew to Surabaya and later said: "We are very devastated by what's happened, it's unbelievable.
"Our concern right now is for the relatives and for the next of kin - there is nothing more important to us, for our crew's family, and for the passengers' families."
A woman leaves the cordoned off area in Changi airport in Singapore 
Rescuers check search coordinates in Surabaya Oceanographer Simon Boxall told the BBC the plane should not be too difficult to find if it went into the water.
The sea floor is within diver depth, he says, and it would be "likely that they'll get answers within a few days".
Difficult yearThe AirAsia Indonesia plane in question was delivered in 2008, has flown 13,600 times, completing 23,000 hours, and underwent its last maintenance on 16 November.
William Kai waits in Surabaya: "We still have hope. We cannot lose hope"
The captain, Iriyanto, had more than 20,500 flight hours, almost 7,000 of them with AirAsia, Mr Fernandes said. The co-pilot is French national Remi Emmanuel Plesel.
The AirAsia group has previously had no fatal accidents involving its aircraft.
AirAsia has set up an emergency line for family or friends of those who may be on board. The number is +622 129 850 801.
Special centres were set up at both Singapore's Changi airport and Juanda international airport in Surabaya.
There were 155 passengers on board, the company said in a statement:
- 137 adults, 17 children and one infant
- Most were Indonesian but several were from other countries: one UK national, a Malaysian, a Singaporean and three South Koreans
- The BBC understands that the British national is Chi-Man Choi
- Two pilots and five crew were also on board - one French, the others Indonesian
This has been a difficult year for aviation in Asia: Malaysia's national carrier Malaysia Airlines has suffered two losses - flights MH370 and MH17.
Flight MH370 disappeared on a flight from Kuala Lumpur to Beijing in March with 239 passengers and crew. The wreckage, thought to be in southern Indian Ocean, has still not been located.
MH17 was shot down over Ukraine in July, killing all 298 on board.
- Low-cost airline group with main hub in Kuala Lumpur, Malaysia. Founded in 2001
- AirAsia Group services now comprises eight affiliates, including AirAsia Indonesia
- Group employs more than 15,000 staff
- Operates fleet of more than 150 Airbus A320 aircraft with 200 more on order
- Flies to about 100 destinations in some 15 countries. Carried almost 8 million passengers in 2013
- Tony Fernandes has been the group's CEO since December 2001
Tony Fernandes: Flying and football
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Search resumes for AirAsia plane
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