Originally Posted by CPH-Flyer

I am sure BA does not take the longer and thus more fuel consuming route for the fun of it. But weather and volcanoes are probably not the reason, as all other HND/NRT flights to Europe that day took the route via the Pacific and north of Canada. With the exception of ITA to Rome and Turkish to Istanbul, but they always take the western route.

So whatever operational reasons BA had, they affected no one else.