According to FlightRadar 24, Sriwijaya Air flight SJ182 from Jakarta to Pontianak on the island of Borneo departed from the Indonesian capital’s airport at 2.37pm local time (7.37am GMT).
The 452-mile flight is scheduled to take 95 minutes.
The Boeing 737-500 flew a short distance north of the airport and above the Java Sea before contact was lost.
Adita Irawati, the Indonesian Transport Ministry spokesperson, told the South China Morning Post: “At this point, we are investigating and coordinating the matter with Basarnas (the search and rescue agency) and KNKT (the transport safety body). We will release more information as soon as there are developments.”
Airfleets.net show the plane as being delivered to Continental Airlines in the US in May 1994. It joined the Sriwijaya Air fleet in 2012.
Sriwijaya Air is a small carrier with a 737-only fleet. According to Airfleets.net it is operating only nine aircraft at present: three -500 series planes, five -800s and one -900.
These are all earlier versions of the 737 than the latest Max variant.
In October 2018, a Lion Air Boeing 737 Max crashed in the Java Sea, just north of Jakarta, shortly after take off from the capital.
All 189 passengers and crew on board died. It was the first of two tragedies that led to the 20-month grounding of the Max.
The Boeing 737 Max re-entered service in December 2020 after comprehensive changes to an anti-stall system that, when activated by a faulty sensor, triggered both crashes.