MB - I don't think you understand the 40 degree elevation actually. Work out please (someone did it way back here) what difference a 6nm change in altitude would make in angular terms over a distance of 22000nm +? Un-measurable, I suggest. Altitude has very little to do with it. The 'red arcs' are probably drawn as ground position but would be near as dammit the same at 40,000' - a 3-D 'corridor' if you like.