The captain of the AirAsia plane that crashed in December was out of his seat when the jet’s co-pilot apparently lost control, Reuters reported, citing two people familiar with the investigation.

The Airbus A320 jet plunged into the Java Sea while flying from Indonesia to Singapore on Dec. 28, and the investigation is likely to focus on training, procedures and maintenance, the news organization reported.

All 162 people on board the plane were killed.

Indonesian officials, however, reportedly stress that it is too early in the investigation to draw a detailed picture of how events unfolded.

According to Reuters, Captain Iriyanto was out of his seat and conducting an unusual procedure on the Flight Augmentation Computer (FAC) when his co-pilot, Remy Plesel, lost control. By the time Iriyanto returned, it was too late to save the plane.

Iriyanto reportedly had previously flown on the A320 airbus and experienced a faulty FAC, which he apparently went to fix. Reuters was unable to offer independent confirmation of the faulty device.

After trying to reset the device, pilots pulled a circuit-breaker to cut its power, Bloomberg News reported on Friday.

``You can reset the FAC, but to cut all power to it is very unusual,'' one A320 pilot, who declined to be identified, told Reuters. ``You don't pull the circuit breaker unless it was an absolute emergency. I don't know if there was one in this case, but it is very unusual.''

Pulling the circuit breaker is also an unusual move because the captain would have had to rise from his seat.

AirAsia said it will not comment while the matter is under investigation.

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