An AirAsia Indonesia airliner flying from Indonesia to Singapore with 162 people on board has lost contact with air traffic control.
The plane, an Airbus A320-200, disappeared midway into the flight of more than two hours and no distress call was issued.
Indonesian military planes and aircraft from Singapore are searching an area of the Java Sea.
The flight left the Indonesian city of Surabaya in eastern Java at 05:20 local time (22:20 GMT) and was due to arrive in Singapore at 08:30 (00:30 GMT).
The missing jet had requested a "deviation" from the flight path due to bad weather, AirAsia said.
Indonesia's transport ministry said the pilot had asked permission to climb to 38,000 ft (11,000m) to avoid thick cloud.
The latest incident caps a tragic year for Malaysian aviation with the disappearance of one Malaysia Airlines plane and the downing of another.
Flight MH370 disappeared on a flight from Kuala Lumpur to Beijing in March with 239 passengers and crew.
MH17 was shot down over Ukraine in July, killing all 298 on board.
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