The co-pilot of the crashed AirAsia jet was in control of the plane when he struggled to recover the aircraft as stall warnings sounded, Indonesian investigators have said.
The Airbus A320-200 crashed into the Java Sea on December 28, halfway from the Indonesian city of Surabaya to Singapore. All 162 people on board were killed.
The National Transportation Safety Commission’s chief investigator, Marjono Siswosuwarno, said that the cockpit voice recording indicated that the co-pilot, French national Remi Emmanuel Plesel, was flying the plane while the captain was monitoring.
The captain was a former fighter pilot with more than 20,500 flying hours, while less experienced Mr Plesel had about 6,000 hours.
Mr Siswosuwarno said the plane was struggling to recover as stall warnings sounded until the end of the recording.
Mr Siswosuwarno said the black boxes retrieved from the seabed provided a clear picture of what went wrong in the last moments of AirAsia Flight 8501.
“However, we are still examining many other things on the issues,” he told a news conference.
Another investigator, Ertata Lananggalih, said that based on the voice recorder, Indonesian captain Iriyanto was monitoring and communicating with air traffic control while Mr Plesel was flying the plane.
“But it is normal practices, both pilots can exchange their roles with each other,” said Mr Lananggalih.
Investigators concluded that the plane was in airworthy condition before the crash.
The flight and cockpit data recorders showed the jet was stabilised cruising at 32,000ft before the pilot contacted ground control saying they were turning left, and a minute later sought permission to climb to 38,000ft. Controllers at Jakarta’s Sukarno-Hatta airport asked them to stand by.
Mr Siswosuwarno said the weather satellite images at the time showed a formation of storm clouds reaching up to 44,000ft. He added that flight data showed the jet was in a dangerously fast climb and stalled before going down slowly into the last position of 24,000ft recorded on the radar.
He said investigators were still looking into whether turbulence or updrafts contributed to the plane’s drastic climb as repeated stall warnings were heard clearly on the cockpit recording from four minutes to the end of the recording.
Indonesia transportation minister Ignasius Jonan has said previously that radar data showed the Airbus A320 was climbing at an abnormally high rate, about 6,000ft a minute, before it disappeared.
“In many cases, the engine is not strong enough to fly in this high angle,” Mr Siswosuwarno said.
Indonesian rescuers have retrieved 72 bodies, with the last two found drifting off Sulawesi island yesterday. Unconfirmed reports said another body had been discovered today about 620 miles east of the crash scene.