AirAsia crash due to faulty component, actions of crew
Faulty equipment and the pilots' response to the malfunctions contributed to the crash of an Indonesian AirAsia jet last year, investigators said on Tuesday (Dec 1).
The Airbus A320 plunged into the Java Sea on Dec 28, less than halfway into its two-hour flight from Indonesia’s Surabaya city to Singapore, killing all 162 people on board.
In their report, Indonesia’s National Transportation Safety Committee revealed the sequence of events which led to flight QZ8501 disappearing from the radar.
Cracked soldering caused the system that helps control the rudder’s movement to malfunction and send repeated warning messages to the pilots, it said.
Investigators believe that when the pilots received the fourth warning, they tried to restart the system by resetting a circuit breaker.
But this also turned off the plane’s autopilot and removed automated protections meant to prevent upsets.
"Subsequent flight crew action resulted in inability to control the aircraft," said the report.
The plane went into a "prolonged stall condition that was beyond the capability of the crew to recover," it said.
Officials cautioned that while information from the black box data recorder indicated that the pilots had tried to reset the circuit breaker – something not usually done during flight – there was no proof of this.
The report said the faulty component had malfunctioned 23 times that year, not including the four times during the flight on Dec 28.
But maintenance records show the "repetitive defects" could not be identified and that their potential consequences were not analysed.
The airline’s maintenance system was "not optimal", investigators said, adding that the airline had implemented 51 safety measures to improve conditions since the crash.
Investigators said the stormy weather did not play a role in the accident.
The report is not intended to attribute blame but rather to make recommendations to avoid future accidents. Recommendations were addressed to the airline, Airbus and regulators.
Airbus declined immediate comment.
"Airbus has just received the final accident report. We are now carefully studying its content," a spokesman said by e-mail.
Sources: AFP, Reuters