Indonesian investigators say a chronically faulty component and the crew’s attempts to fix the problem contributed to the crash of an AirAsia passenger aircraft last year, killing all 162 aboard. The A320 aircraft crashed into the Java Sea less than halfway into a two-hour flight from the Indonesian city of Surabaya to Singapore in December 2014.
The report noted that the aircraft’s flight control computer had a cracked solder joint that malfunctioned repeatedly, including four times during the flight, and 23 times the previous year. “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,” Indonesia’s national transport safety committee said in a statement today.
After the autopilot disengaged and the flight controls switched from the highly protective “normal law” to “alternate law”, the aircraft rolled to the left by 54 degrees – beyond the 45 degree angle considered to exceed normal parameters, deeming it an “upset”.
While attempting corrective action, the first officer pitched up to the point where stall warnings were triggered and the aircraft climbed to 38,000 feet at a low speed. As the aircraft stalled, the Indonesian-born captain told the French-born first officer him to “pull down” – a confusing instruction say aviation experts citing the standard, “pull up” and “push down”. Neither the captain nor first officer were native English speakers.
The flight data recorder recorded no evidence that the first officer had tried to recover from the stall by lowering the nose as stated in the quick reference handbook. The scenario is similar to the crash of Air France 447 in 2009 which was also due to an unrecovered stall following a mechanical malfunction – leading to an industry-wide focus on preventing such an incident from occurring again.
In the wake of the Air France crash, many civil aviation authorities required that pilots receive upset recovery training, although the AirAsia Indonesia crash report said Indonesia’s director general of Civil Aviation has no such requirement and neither of the pilots were trained in upset recovery on an A320.