Flight 8501 appears to have stalled after climbing steeply, an Indonesian government minister said, while its cockpit voice recorder provided no evidence of terrorism having brought down the plane.
The Airbus Group NV (AIR) A320 probably entered a stall, in which the flow of air under the wing is disrupted, causing a loss of lift, after an unusually steep ascent, Transport Minister Ignasius Jonan told reporters after a parliamentary hearing in Jakarta where he said the jet climbed at several thousand feet a minute.
The voice recorder shows that the plane’s pilots were talking in the cockpit and no explosion is heard, Nurcahyo Utomo, an investigator with Indonesia’s National Transportation Safety Committee, said separately. An initial report on the loss of the QZ8501 and its 162 passengers and crew will be issued by next week, according to the leaders of the probe.
“There’s a possibility of airplane malfunction, a possibility of the human factor,” Utomo said. “There’s no explosion like in MH17 in Ukraine,” he added, refering to the Malaysian Airline System Bhd. Boeing 777 thought to have been shot down over the eastern European country in July.
Jonan’s comments regarding a stall during a fast ascent — which he said were based on radar readings and automatic data transmissions rather than the flight recorders — point to possible parallels between the AirAsia crash on Dec. 28 and the loss of Air France (AF) Flight 447 in the Atlantic in 2009.
The AirAsia plane disappeared from radar screens en route to Singapore from Surabaya, Indonesia, after the pilot sought permission to climb from an altitude of 32,000 feet because of thunder clouds. The local weather office has said the jet’s engines could have been affected by ice formation inside the storm, citing meteorological conditions over the Java Sea.
In the case of the AF447, airspeed sensors on the Airbus A330 registered a false drop in speed readings after becoming iced up in thunder clouds. The readings caused the autopilot to disengage, forcing the pilots to fly the jet manually, with the result that they pulled the plane up too steeply and lost lift, sending it nosediving into the ocean and killing everyone on board.
Ice was also identified as a probable factor in last July’s crash of an Air Algerie MD-83 in Mali, France’s BEA air crash investigator said in an interim report. It described the zone where the plane flew as “active and highly dynamic, creating risks of severe icing and/or severe turbulence.”
Agency to Close
Investigators also want to examine the plane’s fuselage, which has yet to be lifted from the seabed, he said.
Listening to the voice recorder, investigators heard communication between other aircraft and air traffic control that overlapped with the AirAsia pilots, which was “disturbing because the voices are loud.”
Jonan said today he intends to shut the Indonesian agency responsible for coordinating aircraft flight slots in three months. That’s after the AirAsia flight took off on a Sunday, without a Transport Ministry permit to fly that day.
The government has since suspended the license of AirAsia for that route, found other airlines in breach of permits and removed officials involved from the ministry, AirNav Indonesia and state airport company PT Angkasa Pura 1.
The airline made an administrative error in flying QZ8501 on Sunday, AirAsia Indonesia Chief Executive Officer Sunu Widyatmoko said Jan. 13. The carrier didn’t inform the Directorate of Air Aviation on the schedule revision, he told parliament in a hearing.