Flight History
The aircraft departed Surabaya-Juanda Airport at 0535 local time and climbed to FL320. Nineteen minutes later, the crew requested clearance to climb to FL380 and divert to a heading of 310° due to adverse weather. Radio contact was lost at 0617, and the transponder ceased transmission one minute later as the aircraft disappeared from radar. At that time, the aircraft was at 36,300 feet with decreasing speed to 353 knots. The aircraft is believed to have crashed approximately 80 nautical miles southeast of Pulau Belitung Island, about 200 km from the Singapore Control Area. Onboard were 156 Indonesian citizens, three South Koreans, one Malaysian, one Singaporean, and one French copilot. Weather conditions were marginal with storm activity, rainfall, and turbulence between Belitung and Kalimantan.
Search and Recovery
The Indonesian Navy spotted the first debris approximately 48 hours after the accident, about 150 nautical miles east-south-east of Belitung. Around forty bodies were recovered through December 30. The tail section was retrieved on January 10, 2015, and the flight data recorder and cockpit voice recorder were located a day later. The DFDR and CVR were recovered from the water on January 12 and 13, respectively, and sent to Jakarta for analysis.
Probable Cause
The official investigation attributed the accident to a cracking of a solder joint in both channel A and B of the rudder travel limiter unit (RTLU), leading to loss of electrical continuity and RTLU failure. The aircraft had experienced repetitive unresolved faults with shorter intervals, and the same fault occurred four times during the flight. The flight crew responded to the first three faults in accordance with ECAM messages. After the fourth fault, the FDR recorded signatures similar to resetting of the FAC circuit breakers, causing electrical interruption to the flight augmentation computers. This resulted in autopilot disengagement and a change from Normal Law to Alternate Law, with the rudder deflecting 2° to the left, inducing a roll up to 54° angle of bank. The subsequent flight crew actions in Alternate Law led to an inability to control the aircraft, which departed from the normal flight envelope and entered a prolonged stall beyond the crew's recovery capability.