Flight paths question

[jessandjon2005]

Hi everybody, hope you are well.

Just curious, but does anyone know the reason why some flights out of London Heathrow/Gatwick go to Orlando straight over Cornwall and out over the Atlantic directly, wheras some go up over Scotland and Iceland?

Its something that's always baffled me and intrigued what the real answer is and why?

Is it anything to do with land/safety, because one going one way and another plane going another wouldn't make that statement factual, so does anyone have the answer please?

Just find it VERY interesting, as gone both ways on numerous occasions and wandered why, as surely the Iceland route is longer and more costly to the airline so why would some go this way and other airlines do not?