Lessons re-learned

According to an Indonesian National Transport Safety Committee (INTSC) report issued in November, the airline had encountered 23 faults with the rudder travel limiter.

The fault was caused by cracked solder that resulted in a loss of electrical continuity.

Indonesia AirAsia flight QZ8501 was en route from Surabaya-Juanda Airport, Indonesia to Singapore’s Changi Airport when it crashed into the Java Sea on December 28.

The INTSC report highlights missed opportunities for maintenance technicians to fix the problem, and pilots not following instructions and not being trained in stall recovery, despite the lessons and recommendations flowing from the Air France 447 crash in 2009 highlighting the problem of high-altitude upset.

“Loss of the aircraft to a high-altitude aerodynamic stall is not the most dispiriting aspect of the crash,” industry publication Flight Global editorialised. “More bewildering is that it occurred just five years after Air France AF447 – an accident which had left the airline community stunned that highly-trained and experienced pilots could have failed to recognise one of the most rudimentary upset conditions in aeronautics. ” On the day of the Indonesia AirAsia tragedy there were four cautions in-flight that the rudder travel limiter had failed.

Three faults were handled by the pilots in accordance with the set ECAM procedures, but the fourth led to the crash after the circuit-breakers were reset – a solution that had been used on the ground.

Indonesian Captain Iriyanto, a 20,537-hour veteran who was assisting French copilot Remi Emmanuel Plesel who was the pilot flying, disconnected the autopilot and auto-thrust and removed the flight protections.

“Subsequent flightcrew action resulted in inability to control the aircraft in alternate law, causing the aircraft [to depart] from the normal flight envelope and entering [a] prolonged stall condition that was beyond the capability of the flightcrew to recover,” says the INTSC.

Critically, the captain’s actions also caused a deflection in the rudder to the left resulting in the plane rolling.

While trying to correct the roll, the copilot pulled back on the control stick and the aircraft climbed before experiencing an aerodynamic stall. There also appears to have been confusion over language, with Capt Iriyanto calling for the first officer Plesel to “pull down” instead of “push down” on the side stick control.

Indonesia AirAsia chief executive Sunu Widyatmoko said the airline had engaged former US airline regulators to make further recommendations on improving safety.

“We have also introduced several safety initiatives prior to the release of the report including the inclusion of upset recovery training to the recurrent training syllabus and additional simulator training sessions,” he said.

He also said “there are many lessons to be learned for the entire aviation industry and we will continue to be dedicated on ensuring that AirAsia Indonesia’s safety standards remain at the highest level in the industry. ” The issue of Indonesian air safety is contentious – the country failed its most recent ICAO safety audit.

But there are lessons for all in the crash of QZ8501. As Flight Global wrote: “Handling an aircraft at rarefied cruise altitudes requires care and finesse, and stable flight is a delicate balancing act normally entrusted to the flight-management system and autopilot. Yet this environment in which pilots need a separate array of handling abilities is also the one in which they are least likely to gain hands-on experience. ” Indonesia AirAsia is introducing 51 safety measures as a result of the crash, recognition perhaps, as Flight observed that: “Critical moments after the discovery of an unexpected problem are no time for a lesson in aerodynamics. To operate a complex machine safely and effectively requires a prior understanding . . . of the laws by which it lives. ”

Subsequent flightcrew action resulted in inability to control the aircraft in alternate law.