A faulty component and the crew’s “inability to control the aircraft” led to the crash of an AirAsia jet last year, killing 162 people, Indonesian officials said Tuesday.
In their final report into the accident, Indonesia’s official National Transportation Safety Committee said the Airbus A320 aircraft’s flight control computer had a cracked solder joint that malfunctioned repeatedly, including four times during the flight.
Cracked soldering in the component that helps control rudder movement caused it to malfunction and send repeated warning messages to the pilots.
When they received the fourth warning, the pilots pulled circuit-breakers on one of the aircraft’s computers, removing power from the faulty system in a bid to reset it. But in doing so, they also turned off the plane’s autopilot.
“Subsequent flight crew action resulted in inability to control the aircraft ... causing the aircraft to depart from the normal flight envelope and enter a prolonged stall condition that was beyond the capability of the flight crew to recover,” the national transport safety committee said in a statement.
It added the flight data recorders did not indicate the weather had affected the aircraft.
The report said the faulty component, the Rudder Travel Limiter, had suffered 23 problems in the past 12 months, citing maintenance records.
Flight QZ8501 crashed less than halfway into a two-hour flight from the Indonesian city of Surabaya to Singapore on December 28 last year.
The crash triggered a huge international search, with ships and aircraft from several nations involved in a lengthy hunt that was hampered by strong currents and bad weather. The bodies of 56 victims were never recovered.
String of aviation disasters
A minister previously described how the plane climbed fast and then went into aerodynamic stall, losing lift, before it went down, while an investigator said the warning alarms were “screaming” as the pilots desperately tried to stabilise the aircraft.
Investigators had also revealed that the French co-pilot, Remi Plesel, was at the controls of the AirAsia plane in the moments before it crashed, rather than the more experienced pilot, Captain Iriyanto, who had around 20,000 hours of flying time.
Rescuers faced difficulties in the choppy waters of the Java Sea, but the main body of the plane was eventually located on the seabed by a Singapore navy ship and both black box data recorders were recovered.
Search efforts were finally called off in March after almost three months of hunting.
It was one of several aviation disasters in the sprawling archipelago in the past year, and the first major setback for Malaysia-based AirAsia group and its flamboyant boss Tony Fernandes after a spectacular run of success.
In August, a turbo-prop plane operated by Indonesian domestic carrier Trigana crashed in the remote, eastern region of Papua during a short flight in bad weather, killing all 54 people on board.
And in June an Indonesian military plane went down into a residential neighbourhood in the city of Medan, exploding in a fireball and killing 142 people.