being the idiot i am i just realised, the very fact you can see further from higher up blows FET out the water. how can the vp at the horizon suddently get further away because you are higher up. altitude doesnt create better eyesight. infact you will be looking through more air particles.
this is the sort of thing that stops people even thinking twice about FET. i have never had a moment when i thought "wow yeh they are right FET could be possible".
i have seen many posts from the FES claiming "ofcourse you can see further at altitude!". well yeh you cant deny that, the question is why and how?