AirAsia Flight QZ8501: Icing did not cause plane to crash, says chief investigator

Flight QZ8501 climbed steeply very rapidly but its crash was not due to icing, said Mr Tatang Kurniadi, the chief of the agency investigating the accident, in debunking an earlier suggestion.

"No similarity with Air France 447. No indication (of icing)," Mr Tatang, who heads the National Transportation Safety Committee, said yesterday during a discussion on aviation safety with foreign journalists.

The loss of the Indonesia AirAsia plane en route from Surabaya to Singapore on Dec 28 has been compared to AF447's crash into the Atlantic Ocean in June 2009. In both cases, the planes stalled before crashing. 

The pilots of QZ8501 had asked permission to climb higher during bad weather but crashed soon after.

An unnamed investigator told Agence France-Presse that warning alarms in the aircraft were "screaming" as the pilots tried to stabilise the plane just before it plunged into the Java Sea.

"The warning alarms, we can say, were screaming, while in the background they (the pilot and co-pilot) were busy trying to recover," the investigator said, adding that the warnings were going off "for some time". The pilots' voices were drowned out by the sound of the alarms, he said.

On Tuesday, Transport Minister Ignasius Jonan told a parliamentary hearing that in the final minutes the plane had climbed at an abnormal speed. "The plane suddenly went up at a speed above the normal limit that it was able to climb to. Then it stalled," he said, citing radar data.

Former pilot Sardjono Jhony said it was not normal, though possible, to climb very rapidly at rates of 6,000 ft per minute or more. "It is possible to have a rate of climb of 6,000 ft per minute if you are in severe turbulence, and based on what (AirAsia pilots) are asking before they lost contact... that they want to change altitude, I believe at that level, they are experiencing severe turbulence and that's why they are not asking to go left or right to avoid it," he said.

Aviation analyst Gerry Soejatman cautioned against assuming that stalls result in crashes.

He also rejected speculation that passengers could have survived as the plane could have landed on water before sinking. "A stall was what happened, it is not what caused (the crash)... Does it make a difference to the survivability of this accident? If we look at the wreckage, we see the tail has been ripped off and you see extensive damage. It is not survivable in my opinion."

Mr Tatang, whose team is under pressure to issue a preliminary report within 30 days of the crash, has promised to do so on time or by next Wednesday, but not publicly - only to parties linked to the crash.

Under international aviation regulations, it is not mandatory for the preliminary report to be publicised but it has to be shared with the related parties, said Mr Gerry, adding that it is also up to those parties to release it.

A final report has to be released publicly within a year of the accident.