Another possible solution is what I call a "Hop" system. It is slightly more complicated and would take a lot of getting used to by players.
An aircraft can travel a set number of units of distance. We'll just go with "miles". Whether it marches/attacks/patrols it cannot exceed the maximum amount of miles. Lets say an aircraft has a max range of 100 miles. and he wants to attack a target that is 60 miles from his base. Under what I have explained earlier it wouldn't be able to happen because that target has exceeded the "Halfway Point" of the maximum ranged and the aircraft wouldn't be able to make it back to its previous base UNLESS there is another base occupied by the same player or ally of that player that is within 40 miles of the intended target. The player could select "add target" and then select "march" to a closer base to land the aircraft. Again this is more complicated and would take a lot of effort just to plan an air attack. It isn't really a good idea however it does open the door to other ideas or discussion.
-BOP-
