Well, I tried adding a move command for when the arrow key is used. This would in theory keep the chopper flying straight. The move command reset the destination by the same distance and angle as the arrow key movement. But it was a huge failure, for whatever reason it sent the chopper heading across the map in the opposite direction.
Map size is big because of music and loading screen, maybe I should remove the music. Wc3 music just doesn't fit with a chopper game though.