Originally Posted by Mofomat

Yes, planes are more economical the higher they fly, but this flight also does not cruise at the normal speed, so the engines are not using the same amount of fuel either. It could be swings and roundabouts. Also, there is little choice if AF want an overnight NRT-CDG flight. Because NRT closes quite early at 2200. This flight (AF277) is scheduled to leave the gate at 2155 and arrive at the gate in CDG at 0425. If it flew at normal heights and speeds then it would arrive in CDG way before 0425.

I suppose AF believe the extra attraction of an overnight NRT-CDG outweighs the extra costs of the inefficient profile of the flight.

I am an air traffic controller, and I handle this flight on every night shift. When it enters my airspace in the vicinity of Hamburg, it is normally at 28,000ft and the pilots will refuse any direct "because we will arrive in Paris too early". It seems strange to see, with all that empty (normally very busy during the day) airspace, this AF flight following every twist and turn of the airway.