Sriwijaya Air Flight 182

Sriwijaya Air Flight 182 was a scheduled domestic passenger flight from Jakarta to Pontianak, Indonesia. Just four minutes after departing from Soekarno–Hatta International Airport on 9 January 2021, the Boeing 737-500 entered an upset and crashed into the Java Sea off the Thousand Islands, killing all 62 people on board. A search of the area recovered wreckage, human remains, and items of clothing. The flight data recorder was recovered on 12 January, and the data storage module of the cockpit voice recorder was recovered on 30 March. Flight 182 was the deadliest plane crash in 2021.

During the search, Indonesia's National Transportation Safety Committee (NTSC) used the available data from Flightradar24, and hypothesised that the plane's engines were still operating upon impact. It was known that the autothrottle on this aircraft had malfunctioned a few days earlier, and one line of investigation was whether this might have contributed to the accident.

A preliminary report released on 10 February 2021 suggested problems with the plane's autothrottle; the thrust lever for the left engine reduced thrust as the aircraft climbed, while the thrust lever for the right engine remained fixed. On 10 November 2022, the NTSC published the final report of the investigation, concluding that the crash had been caused by a combination of a faulty autothrottle, pilot error and inadequate training.

Flight timeline

Flight 182 was scheduled to depart from Soekarno–Hatta International Airport at 13:40 WIB (06:40 UTC), and to arrive at Supadio International Airport in Pontianak, West Kalimantan, at 15:00 WIB (08:00 UTC). Departure was delayed by monsoon rains, and Flight 182 took off from runway 25R at 14:36 local time (07:36 UTC). Due to the delay, it was expected to land in Pontianak at 15:50 WIB (08:50 UTC).

The aircraft departed on a standard instrument departure with a clearance to climb to 29000 ft. After being instructed by the ATC to pause their ascent at 11,000 ft, Captain Afwan entered the revised altitude into the autopilot. To level the aircraft off, the autothrottle attempted to move the levers back. While the left lever moved backwards, the right lever remained stuck at climb power due to excessive friction in the throttle control cable.

The aircraft was in a right turn, with the autopilot using the ailerons and spoilers to bank the aircraft to the right. But as the left lever kept decreasing while the right lever was still at climb power, thrust asymmetry caused the aircraft to start turning (yawing and rolling) to the left. The autopilot tried to keep the right bank going by deflecting the control surfaces to their maximum extent, but the thrust asymmetry continued to increase until it overpowered the autopilot. In the space of 68 seconds the aircraft rolled from a bank angle of 20 degrees right wing down to wings level, and after a further 15 seconds it was banked 37 degrees to the left. The pilots apparently did not notice the change of the aircraft's bank angle. The pilots had a few minor distractions at this point - a standard checklist to follow at 10,000', levelling off at 11,000' and almost immediately being cleared to 13,000' - but none of these activities should have taken their attention away from the task of monitoring the aircraft's flight path using the electronic attitude indicator ("artificial horizon").

When the bank angle reached 37 degrees, the Bank Angle warning sounded, startling the pilots. Because the autopilot was still holding the control wheel to the right, Captain Afwan probably assumed they were overbanked to the right, and instinctively yanked the wheel back to the left and disengaged the autopilot. In fact, the aircraft was actually overbanked to the left because of the asymmetric thrust - which the pilots were still unaware of - and the autopilot was resisting that tendency. The captain's hasty action ran counter to his training, which taught that pilots should first assess the situation by reference to their instruments before deciding how to recover the aircraft.

When the autopilot was disconnected, the crew lost any protection it had been giving them, and with Captain Afwan's left turn input, the aircraft banked through its maximum allowable bank angle and rolled through 90 degrees to the left. The nose

dropped and the aircraft descended, inverted, towards the Java Sea. First Officer Mamahit shouted to Captain Afwan regarding the bank angle, warning him that the aircraft had entered an upset condition. Realizing his mistake, Captain Afwan pulled the yoke back and attempted to recover from the dive. Due to being inverted, his action led to an increased rate of descent, and the aircraft dropped by 10000 ft in less than a minute.

Captain Afwan managed to almost level the wings and pull the nose up to a nearly 0-degree angle, but by then there was no more room for recovery as the altitude was too low and the aircraft was in overspeed condition. The aircraft crashed belly-first into the Java Sea near Laki Island and 19 km from Soekarno–Hatta International Airport, less than five minutes after takeoff. There were no survivors. During its climb, Flight 182 went off course to the northwest. Air traffic control (ATC) asked the crew about the deviation and got no response. A few seconds later, the aircraft dropped off radar. There was no distress call during the flight.