I am actually just working on the same problem on same island. The idea is to get an empty plane on the runway at the beginning and accelerate it, then detach it from the ground and place the AI inside, then he will not act as stupid as on the ground, but try to keep the height. Can be done also with AI inside, but he will try to turn to the default airport and move the plane some meter wrong. This can be done with little shaking if you decrease the acceleration value and interval proportionally, but I guess it will eat some bandwidth in MP. I can attach my mission file just when I return home at 1600 CET today, if you wish.