Media caption AirAsia Chief Executive Tony Fernandes addresses the media and relatives 
 
 AirAsia boss Tony Fernandes says he is "devastated" that a plane carrying 162 people from Indonesia to Singapore has gone missing. 
 
 AirAsia Indonesia flight QZ8501, an Airbus A320-200, disappeared over the Java Sea an hour into its flight at 06:24 local time (23:24 GMT Saturday). 
 
 Bad weather was reported in the area but no distress call was made and no wreckage has been sighted. 
 
 The search operation was halted for the night and resumes at about 23:00 GMT. 
 
 The plane had left Surabaya in eastern Java at 05:35 local time (22:35 GMT Saturday) and was due to arrive in Singapore at 08:30 (00:30 GMT). 
 
 Shocked relatives gathered at both airports, in Singapore and Surabaya, poring over the passenger manifests. 
 
 'My worst nightmare' 
 
 Mr Fernandes, AirAsia's chief executive, flew to Surabaya and later told a press briefing: "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. 
 
 "We hope that the aircraft is found quickly, and we can find out the cause of what has happened." 
 
 An air and sea search was immediately launched, with vessels and aircraft from Indonesia, Singapore and Malaysia scouring an area near Belitung island, but nothing was found before nightfall. 
 
 The Indonesian search and rescue force will resume at dawn with 12 ships, three helicopters and five aircraft. There will also be two C-130 planes - one each from Malaysia and Singapore - and three ships from those nations. 
 
 Dense storm clouds were reported in the area at the time the plane lost contact. 
 
 The pilot had asked permission to climb to 38,000ft (11,000m) to avoid the clouds. 
 
 Image caption The Airbus, pictured here on an earlier flight, disappeared about an hour after takeoff 
 
 Image caption Relatives await news in Surabaya, Indonesia 
 
 Image caption A couple head to a cordoned off area at Changi airport in Singapore 
 
 But Indonesian transport ministry official Djoko Murjatmodjo said the request "could not be approved at that time due to traffic, there was a flight above, and five minutes later [flight QZ8501] disappeared from radar". 
 
 Geoffrey Thomas, of airlineratings.com, told the BBC that radar plots had shown the plane was flying at 353 knots, 100 knots slower than it should have been. 
 
 Although he stressed it was only speculation, he said it was possible the pilots may have lost data on air speed because of an ice-up of pitot tube instrumentation. This was thought to have had happened in the loss of the Air France Airbus A330 over the Atlantic Ocean in 2009. 
 
 A recent safety study showed only 10% of fatal incidents occurred at cruising altitude. 
 
 The AirAsia group has previously had no fatal accidents involving its aircraft. 
 
 Mr Fernandes, who has owned AirAsia since 2001 and turned it into a highly successful operation, tweeted: "This is my worst nightmare." 
 
 Difficult year 
 
 The AirAsia Indonesia plane in question was delivered in 2008, has flown 13,600 times, covering 23,000 hours, and underwent its last maintenance on 16 November. 
 
 The captain, Iriyanto, has 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. 
 
 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. 
 
 Media caption William Kai waits in Surabaya: "We still have hope. We cannot lose hope" 
 
 Special centres were set up at both Singapore's Changi airport and the Juanda international airport in Surabaya. 
 
 AirAsia Indonesia CEO Sunu Widyatmoko said the company had "mobilised a support team to help take care of [relatives'] immediate needs, including accommodation and travel arrangements". 
 
 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. 
 
 What is the AirAsia Group? 
 
 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 
 
 Are you, or is someone you know, affected by this story? Do you know any of the passengers on the AirAsia flight? You can email haveyoursay@bbc.co.uk with any information. Please leave a telephone number if you are willing to be contacted by a BBC journalist. 
 
 Send your pictures and videos to yourpics@bbc.co.uk or text them to 61124 (UK) or +44 7624 800 100 (international). Or you can upload here. 
 
 Read the terms and conditions. ||||| SURABAYA, Indonesia/JAKARTA A missing AirAsia jet carrying 162 people could be at the bottom of the sea after it was presumed to have crashed off the Indonesian coast, an official said on Monday, as countries around Asia sent ships and planes to help in the search. 
 
 The Indonesia AirAsia plane, an Airbus A320-200, disappeared after its pilot failed to get permission to fly higher to avoid bad weather during a flight from the Indonesian city of Surabaya to Singapore on Sunday. 
 
 Flight QZ8501 did not issue a distress signal and disappeared over the Java Sea five minutes after requesting the change of course, which was refused because of heavy air traffic, officials said. 
 
 "Based on our coordinates, we expect it is in the sea, so for now (we think) it is on the sea floor," Soelistyo, head of Indonesia's search and rescue agency, told reporters when asked about the missing plane's likely location. 
 
 A senior Indonesian civil aviation source told Reuters that authorities had the flight's radar data and were waiting for search and rescue teams to find debris before they started their investigation into the cause. 
 
 Transport Minister Ignasius Jonan said the search was focused on an area of 70 square nautical miles between the island of Belitung, off Sumatra, and Borneo island. 
 
 He said the sea there was only 50 to 100 meters deep, which would be a help in finding the plane. Ships could hunt around the clock, but aircraft were expected to suspend operations at dusk. 
 
 Air force spokesman Hadi Tjahjanto said searchers were checking a report of an oil slick off Belitung. They had picked up an emergency locator signal off the south of Borneo but no subsequent signal was found, he said. 
 
 On board Flight QZ8501 were 155 Indonesians, three South Koreans, and one person each from Singapore, Malaysia and Britain. The co-pilot was French. 
 
 The disappearance caps a disastrous year for Malaysia-affiliated airlines. Indonesia AirAsia is 49 percent owned by Malaysia-based budget carrier AirAsia. 
 
 Malaysia Airlines Flight MH370 went missing on March 8 on a trip from Kuala Lumpur to Beijing with 239 passengers and crew and has not been found. On July 17, the same airline's Flight MH17 was shot down over Ukraine, killing all 298 people on board. 
 
 The AirAsia group, including affiliates in Thailand, the Philippines and India, had not suffered a crash since its Malaysian budget operations began in 2002. The group's shares in Kuala Lumpur closed 8.5 percent lower. 
 
 ANGER GROWING 
 
 Indonesian Vice President Jusuf Kalla, visiting relatives of people on the flight in Surabaya, told reporters the search by 30 ships and 15 aircraft, about halfway between Surabaya and Singapore, was being hampered by bad weather. 
 
 Anger grew among about 100 relatives at a crisis center at the airport in Indonesia's second-largest city. 
 
 "We only need clear information every hour on where they are going," said Franky Chandra, who has a sibling and three friends on the flight, referring to the search teams. 
 
 "We've been here for two days but the information is unclear. That's all we need." 
 
 Australia, Malaysia, Singapore and South Korea have sent ships and aircraft to join the search. 
 
 In a statement on its website, China's Defence Ministry said it had sent a warship to the South China Sea and planes "have begun preparatory work" for search operations. 
 
 Soelistyo said Indonesia might not have the best technology to search underwater and had accepted offers of help from the United States, Britain and France. 
 
 Flight QZ8501 was traveling at 32,000 feet (9,753 meters) and had asked to fly at 38,000 feet to avoid clouds. 
 
 Permission was not given at the time due to traffic in the area. Five minutes later, at 6.17 a.m. on Sunday (6.17 p.m ET on Saturday), the plane lost contact with air traffic control, transport officials said. 
 
 Data from Flightradar24.com, which tracks airline flights in real time, showed several nearby aircraft were at altitudes ranging from 34,000 to 36,000 feet at the time, levels not unusual for cruising aircraft. 
 
 Pilots and aviation experts said thunderstorms, and requests to gain altitude to avoid them, were not unusual in that area. 
 
 "The airplane's performance is directly related to the temperature outside and increasing altitude can lead to freezing of the static radar, giving pilots an erroneous radar reading," said a Qantas Airways pilot with 25 years' experience flying in the region. 
 
 The resulting danger is that pilots take incorrect action to control the aircraft, said the pilot, who requested anonymity. 
 
 PLANE CLIMBING TOO SLOWLY? 
 
 Online discussions among pilots centered on unconfirmed secondary radar data from Malaysia that suggested the missing plane was climbing at a speed of 353 knots, about 100 knots too slow in such weather conditions. 
 
 "At that altitude, that speed is exceedingly dangerous," Sydney-based aviation expert Geoff Thomas told Reuters. 
 
 "At that altitude, the thin air, the wings won't support the aircraft at that speed and you get an aerodynamic stall." 
 
 Safety authorities say accidents involving a loss of control, such as might occur in bad weather, are rare but almost always catastrophic. 
 
 The Indonesian pilot was experienced and the plane last underwent maintenance in mid-November, the airline said. The aircraft had accumulated about 23,000 flight hours in some 13,600 flights, according to Airbus. 
 
 Malaysia AirAsia chief Tony Fernandes flew to Surabaya and, along with Indonesian officials, updated relatives. 
 
 "My heart bleeds for all the relatives of my crew and our passengers. Nothing is more important to us," he said on Twitter. 
 
 (Additional reporting by Wilda Asmarini, Fransiska Nangoy, Cindy Silviana, Kanupriya Kapoor, Michael Taylor, Nilufar Rizki and Siva Govindasamy in JAKARTA, Al-Zaquan Amer Hamzah and Praveen Menon in KUALA LUMPUR, Saeed Azhar, Rujun Shen and Anshuman Daga in SINGAPORE, Jane Wardell in SYDNEY, Ben Blanchard in BEIJING, and Tim Hepher in PARIS; Writing by Dean Yates and Paul Tait; Editing by Robert Birsel and Mike Collett-White)
– An AirAsia plane with 162 people on board lost contact with ground control today while flying over the Java Sea after taking off from Indonesia for Singapore, initiating a massive search for the third possible aviation disaster to affect the region this year. AirAsia, a regional low-cost carrier based in Malaysia, said the missing Airbus A320 was on its submitted flight plan route. However, it had requested permission to deviate because of weather. "We don't dare to presume what has happened except that it has lost contact," said Indonesia's acting director general of transportation. He said the last contact between the pilot and air traffic control was at 6:13am local time when the pilot asked to go up to 34,000 feet, apparently to avoid stormy weather. It was last seen on radar at 6:16am, and a minute later was no longer there, he said. Darkness has fallen in the region, reports the BBC, and the search has been called off for the night. It will resume in the morning. He said there was no distress signal from Flight QZ8501. The contact was lost about 42 minutes after the single-aisle jetliner took off from Indonesia's Surabaya airport. It still had about an hour to go before arriving in Singapore. The plane had seven crew and 155 passengers, including 16 children and one infant, said the general manager of Surabaya's Juanda airport. There were six foreigners—three South Koreans, including the infant, and one each from Singapore, Britain, and Malaysia. The rest were Indonesians. The 6-year-old 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 Kalimantan island. The AP has a list of key developments in the plane's disappearance here.