An AirAsia flight travelling from the Indonesian city of Surabaya to Singapore has lost contact with air traffic control, the company has said.
Indonesian media say more than 160 people were on the Airbus A320-200.
Flight QZ8501 lost contact with air traffic control at 07:24 (23:24 GMT), Malaysia-based AirAsia tweeted.
Malaysia's national carrier Malaysia Airlines has suffered two disasters this year - flights MH370 and MH17 - but AirAsia has never lost a plane.
Flight MH370 disappeared on a flight from Jakarta to Beijing in March with 239 passengers and crew, and MH17 was shot down over Ukraine in July, killing all 298 on board.
AirAsia says that search and rescue operations are under way for the missing aircraft.
The flight had been due to arrive in Singapore at 08:30 (00:30GMT).
There were six foreigners on board the flight, reports say, three from South Korea and one each from the UK Malaysia and Singapore. The rest of the passengers were Indonesian.
An official with the transport ministry, Hadi Mustofa, told local media the plane lost contact over the Java Sea, between the islands of Kalimantan and Java.
He said the plane had asked for an unusual route before it lost contact and that the weather had been cloudy.
AirAsia have given few other details.
"At the present time we unfortunately have no further information regarding the status of the passengers and crew members on board, but we will keep all parties informed as more information becomes available," a company statement said.
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.