AirAsia captain left seat before jet lost control

The captain of the AirAsia jet that crashed into the sea in December was out of his seat conducting an unorthodox procedure when his co-pilot apparently lost control, and by the time he returned it was too late to save the plane, two people familiar with the investigation said. The jet had been suffering maintenance faults with a key flight control computer for over a week, and one person familiar with the matter said the captain had flown on the same plane with the intermittently faulty device just days before the crash.

You can reset the FAC, but to cut all power to it is very unusual. 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.

A320 pilot

Maintenance problems on the Flight Augmentation Computer (FAC), and the way the pilots reacted to them, were at the heart of the investigation. After trying to reset this device, pilots pulled a circuit-breaker to cut its power. The outage would not directly upset the aircraft but would remove flight envelope protection, which prevents a pilot from taking a plane beyond its safety limits, leaving the junior pilot to fly the jet manually in delicate high altitude conditions. Shortly afterwards the junior pilot pulled the plane into a sharp climb from which investigators have said it stalled or lost lift. The Airbus A320 jet plunged into the Java Sea while en route from Surabaya, Indonesia, to Singapore on Dec 28, killing all 162 people on board.

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