Indonesian investigators announced Tuesday that the crash of an AirAsia plane last year was the result of a faulty rudder control system on the jet, which had shown problems with the system almost two dozen times in the year prior to the deadly crash.
The National Transportation Safety Committee announced in Jakarta that an analysis of the passenger jet’s data recorder showed that the pilots’ response to the rudder problems led to the plane stalling and crashing into the Java Sea. All 162 people on board the flight were killed.
The AirbusA320 crashed less than halfway into a two-hour flight from Indonesia’s second-largest city of Surabaya to Singapore on Dec. 28 last year.
Indonesian investigators did not single out one reason as to why flight QZ8501 disappeared from controllers’ radars, but rather set out the sequence of events that preceded the fatal crash. It marked the first public report on the air disaster.
Investigators said a system controlling rudder movement had cracked soldering that malfunctioned repeatedly, including four times during the flight alone, and 23 times the previous year, the Reuters news agency reported from the Indonesian capital.
“Subsequent flight crew action resulted in inability to control the aircraft...causing the aircraft (to) depart from the normal flight envelope and entering a prolonged stall condition that was beyond the ability of the flight crew to recover,” The National Transportation Safety Committee said in a statement, Reuters reported.
Officials said there were indications from the black box data recorder that the plane’s pilots had tried to shut off power to the computer that controls the rudder system by resetting a circuit breaker.
“The indication was that it (the circuit breaker) was pulled according to (the flight data recording),” one of the investigators, Nurcahyo Utomo, said, Reuters reported. But, he added there was no concrete proof that such an event occurred, the agency reported.
The investigators ruled out bad weather as a cause of the crash.
The malfunction with the rudder system led to four warnings, the report showed. On the fourth warning, the plane disengaged from autopilot, causing the crew to lose control of the aircraft. No distress signal was received, though.
Investigators examined aircraft maintenance records and found that the intervals with the rudder system problems had become shorter in the three months before the crash.
Investigators called the airline’s maintenance system “not optimal,” but added that the airline had carried out 51 safety measures to improve conditions since the crash, Reuters reported.
“There is much to be learned here for AirAsia, the manufacturer and the aviation industry,” AirAsia parent group founder Tony Fernandes said on Twitter.
Airbus declined immediate comment.
“Airbus has just received the final accident report. We are now carefully studying its content,” a spokesman said by email, according to Reuters.