Indonesian air crash investigators said on Monday they had not so far found evidence that the pilot of an AirAsia jet had left his seat, or that power to an automated control system was shut off, shortly before the aircraft plunged into the sea.
Two sources familiar with the investigation had told Reuters that Captain Iriyanto was out of his seat carrying out the unusual procedure of pulling the circuit-breaker on a flight computer when his co-pilot apparently lost control of the Airbus A320.
AirAsia flight QZ8501 vanished from radar screens on December 28, less than half-way into a two-hour flight from Indonesia's second-biggest city of Surabaya to Singapore. All 162 people on board were killed.
“Up until today, there is no indication yet that the captain left his seat as reported by Reuters,” Ertata Lananggalih, an investigator with the National Transportation Safety Committee (NTSC), told Reuters at the team's office in Jakarta, referring to the story published on Saturday.
People familiar with the investigation had earlier told Reuters that investigators were examining maintenance records of one of the plane's automated systems, the Flight Augmentation Computer (FAC), and how the pilots may have reacted to any outage.
Bloomberg News reported on Friday that the pilots of the crashed plane had tried to reset the FAC during the flight, and had then pulled a circuit-breaker to cut power to the device.
People familiar with the matter told Reuters it was the Indonesian captain who took this step, rather than his less experienced French co-pilot, Remy Plesel, who was flying the plane.
NTSC investigators disputed on Monday that the circuit breaker was pulled.
“Up until today, there is no indication or evidence yet that the circuit breaker was pulled,” Lananggalih said.
The NTSC declined to elaborate further, saying the accident was still under investigation.
However, a document prepared by the investigation team and reviewed by Reuters indicated the FAC system and the cockpit circuit breakers were among the issues of interest to the probe.
The schedule document listed more than 30 items for discussion. Along with more general points such as “wreckage recovery” and “maintenance review,” it included the entry “FAC engagement and failure understanding” and another entry related to pulling “CB,” a common abbreviation for circuit-breakers.
“This is .. just inventory. It is to make the investigation easier. There are maybe 40 or 35 things that have to be discussed,” said Tatang Kurniadi, chief of the NTSC, when asked about the list.
“It is not just circuit breakers. This is the first plan...it could change again because of developments. This was prepared in the first week of the investigation.”
The checklist made no mention of pilot seats or movements in the cockpit.
Investigators have said it was too early to say whether the accident involved pilot error or a mechanical fault.
AirAsia declined comment. The airline said previously it would not comment while the crash, its first ever fatal accident, was under investigation by the NTSC.
Indonesia has released some factual details of the circumstances of the crash, but has not made public the preliminary accident report it submitted to the International Civil Aviation Organization last week.
Although more is becoming known about the chain of events, people familiar with the investigation warned against making assumptions on the accident's cause, which needed more analysis.
Safety experts say air crashes are most often caused by a chain of events, each of which is necessary but not sufficient to explain the underlying causes of the accident.