My old carrier used 747-400s on routes from JFK and ORD to HKG on Polar routes. I know of a few guys, because of low fuel temps during the winter months, who either descended to a lower and hopefully warmer altitude, or increased the mach to around .88 or .89, thereby generating a slight increase in ram air temperature. I seem to recall that a few guys had to stop in Bejing for fuel due to the increased burnout that resulted from the higher speed.

I did the JFK to HKG route for six months or so, but only in the warmer months, so I never had to face the condition.

However, the 777 is not capable of these speeds in cruise.

Going through 777 requalification school at TK, and since the carrier at that time was contemplating using the 777 on these Polar routes, I asked an instructor about possible fuel icing problems since the "mach increase technique" was not an option for the airplane. His statement to me was that the system was designed so that the fuel temperature wouldn't get to the point of ice formation.

Not for one second did I believe him.

The only thing I really know for certain about this accident is this those BA pilots did one heck of a job. Real professionals.