Did the airline file a flight plan that took account of the weather en route from Surabaya, Indonesia, to Singapore?
There are two ways of making a radical change of flight plan like that.
In compliance with the flight plan, the 777 was at 33,000 feet.
On the report of this attack, the flight plan would be changed, for safety.
Accordingly, in that period it was shown incorrectly on any computer print-outs of the flight plan.
He filed a flight plan that would return him to his home, and in due course arrived there.