Indonesia's Sriwijaya Air lost contact with one of its Boeing 737 passenger planes shortly after take-off from the capital Jakarta, the transport ministry said Saturday.
"A Sriwijaya (Air) plane from Jakarta to Pontianak (on Borneo island) with call sign SJY182 has lost contact," said ministry spokesman Adita Irawati.
"It last made contact at 2:40 pm (0740 GMT)."
It was unclear how many passengers and crew were aboard the Boeing 737-500, which has a capacity of about 130, when it took off from Jakarta's Soekarno-Hatta international airport.
The usual flight time is about 90-minutes.
The budget airline said only it was investigating the incident.
Indonesia's search and rescue agency and the National Transportation Safety Commission were also investigating, Irawati said.
In October 2018, 189 people were killed when a Lion Air Boeing 737 MAX jet slammed into the Java Sea about 12 minutes after take-off from Jakarta on a routine one-hour flight.
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That crash -- and a subsequent fatal flight in Ethiopia -- saw Boeing hit with $2.5 billion in fines over claims it defrauded regulators overseeing the 737 MAX model, which was grounded worldwide following the two deadly crashes.