Unveiled, This is the Cause of the Sriwijaya Air SJ-182 Plane with 62 People on Board Crashing in the Thousand Islands

Dream - The cause of the Sriwijaya Air SJ182 plane crash on the Jakarta-Pontianak route around the Laki Island, Thousand Islands. on Saturday, January 9, 2021, has finally been revealed.

According to the National Transportation Safety Committee (KNKT) team, based on the Flight Data Recorder (FDR) and Cockpit Voice Recorder (CVR) data, there was a disturbance in the mechanical system of the Boeing 737-500 aircraft with registration PK-CLC.

"During takeoff, there was a change in the autopilot mode which previously used the computer, switching to using the control panel mode," said Chairman of the KNKT Aircraft Accident Investigation Subcommittee, Nurcahyo Utomo, in a Hearing with the DPR Commission V in Jakarta, Thursday, November 3, 2022.

In normal operations, Nurcahyo said, the auto-throttle will move both thrust levers backward to reduce engine power. But in that flight, the auto-throttle could not move the right thrust lever.

After examining seven aircraft components, the KNKT confirmed that there was a mechanical disturbance in the aircraft, not in the computer system.

"Because of the density of flights that day and coincidentally there was an aircraft with the same destination, SJY182 flight was asked by the Air Traffic Controller (ATC) to stop at an altitude of 11,000 feet," he said.

As it approached an altitude of 11,000 feet, Nurcahyo added, the engine power decreased because the right thrust lever did not move, causing a greater difference in power between the left and right engines, known as asymmetry.

According to Nurcahyo, asymmetry causes a difference in engine power that generates a force that turns the aircraft to the left. The force to the left becomes greater than the force that turns to the right by the aileron and flight spoiler, causing the aircraft to turn to the left.

The delay of the Cruise Thrust Split Monitor (CTSM) in disconnecting the auto-throttle during asymmetry because the flight spoiler provides a lower value resulted in increasing asymmetry.

"The lack of monitoring on the instruments and the tilted position of the steering may have led to the assumption that the aircraft was tilted, so the recovery action was not appropriate. This recovery action could not be carried out effectively and in a timely manner," he said.

The aircraft carried 62 people, consisting of 12 crew members, 40 adult passengers, 7 children, and 3 infants.

Nurcahyo added that the investigation process is led by the KNKT and carried out in accordance with the International Civil Aviation Organization (ICAO) provisions, involving the aircraft manufacturer, Boeing from the United States, the Transport Safety Investigation Bureau of Singapore, the Air Accident Investigation Branch of the United Kingdom, and the General Electric engine factory. (Liputan6.com)