I realise all of this, I was just wondering for a normal 747-400 taking off at sea level for example.
Reason for this is i'm developing a Airline Tycoon game, I have formula to calculate the distance between two points to see it's in side the range of a 747-400 (or any other aircraft in the game) but I don't want to enable people to run it between two small airports.
So what's the min length which you would use?