when you make the config.cpp for a map, you can only define one usuable airport, so every time that a plane is given an order, it taps into the config.cpp and trys to use it. However, there is some hope, as some planes (ie: Su w/e number) seem to be able to take off anywhere, and the computer uses this to its advantage. However, most of the time they will try to taxi to the active airport and take off there.
Because of the way Operation Flashpoint is scripted, it doesnt take into account the possibility of very large planes, so automatically uses rules with the lighter aircraft. And these then obviously conflict with the rules in the addons config.cpp - is there no hope? :-\