Indonesia says AirAsia plane crashed due to rudder control glitch, pilots' response

The rudder control system glitch had occurred 23 times in the 12 months prior to the December 28, 2014 tragedy.

Caskets containing the remains of AirAsia QZ8501 passengers recovered from the sea are carried to a military transport plane before being transported to Surabaya, where the flight originated, at the airport in Pangkalan Bun, Central Kalimantan in this January 2, 2015 file photo. Indonesian investigators say a faulty rudder control system and the pilots’ response led to the crash of the plane ion December 28, 2014 in which all 162 people on board were killed.

A rudder control system problem that occurred 23 times in the previous 12 months coupled with the pilots’ response led to last year’s crash of an AirAsia plane that killed all 162 people on board, Indonesian investigators said on Tuesday.

The National Transportation Safety Committee said an analysis of Flight 8501’s data recorder showed the rudder control system had sent repeated warnings to the pilots during the December 28, 2014 flight between the Indonesian city of Surabaya and Singapore.

Cracked soldering joint

Aircraft maintenance records for the Airbus A320 showed that problems with the rudder system had been reported 23 times during the year prior to the crash, with more frequent occurrences in the three months immediately before the accident. Investigators said the problem was caused by a cracked soldering joint on an electronic circuit board.

After the fourth warning during the flight, the pilots attempted to reset the control system while flying the plane manually, which caused it to enter a prolonged stall from which they were unable to recover, and the plane plowed into the Java Sea, the investigators said.

Pilot-co-pilot confusion

Investigator Nurcahyo Utomo said the plane’s voice recorder indicated possible confusion between the pilot and co-pilot. He said at one point the pilot said “pull down,” but in fact the plane was ascending.

“It seemed that there was a miscommunication between the pilot and co-pilot after the fourth fault,” he said.

Bad weather no factor

Bad weather conditions did not play a role, as initially believed, the investigators said.

The last contact between the pilots and air traffic control indicated they were entering stormy weather. They asked to climb from 32,000 feet (9,753 metres) to 38,000 feet (11,582 metres) to avoid threatening clouds, but were denied permission because of heavy air traffic. Four minutes later, the plane dropped off the radar. No distress signal was issued.

“There is much to be learned here for AirAsia, the manufacturer and the aviation industry,” AirAsia chief executive Tony Fernandes tweeted. “We will not leave any stone unturned to make sure the industry learns from this tragic incident.”