"The aircraft was on the submitted flight plan route and was requesting deviation due to enroute weather before communication with the aircraft was lost while it was still under the control of the Indonesian air traffic control," the airline said in a statement.
No distress signal had been sent, said Joko Muryo Atmodjo, air transportation director at the Indonesian Transport Ministry.
A search and rescue operation had been launched, the airline and the Indonesian air force said. Singapore said it had activated its air force and navy to help.
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