Flight SJ-182 plunged into the Java Sea on 9 January 2021 minutes after take-off from Jakarta, killing all on board.
In their final report, investigators blamed several factors including a repeatedly faulty throttle system.
It was Indonesia’s third major air accident in the space of six years.
Investigators said the plane – which was 26 years old – had an automated throttle system that suffered a malfunction shortly after take-off.
That had caused the jet to tilt sharply off-course before it nosedived 3,000m (10,000 ft) into the sea, the National Transportation Safety Committee (KNKT) said.
Investigators also noted that those in the cockpit had not reacted to the plane’s deviation in time – perhaps due to complacency that resulted in “less monitoring” from the pilots.
The Sriwijaya Air crash underscored Indonesia’s dismal air safety record, with three major commercial flight crashes in recent years.
In 2014, an AirAsia A320 jet crashed during bad weather into the Java Sea, killing 162 people.
Four years later, in 2018, a Lion Air Boeing 737 Max plane crashed into the sea, killing 189 people.