Forgive me if this has been asked before, but who controls International Airspace?
I know that say when you fly from the UK to the US, you fly over the atlantic, which is classed as international airspace, so who guides the aircraft when it is in this area? Same goes for places like the pacific and Arctic circle. How do airlines pay to use this airspace? and it is it cheaper for an airline to use as much international airspace as possible?