Limited planes not possible

[JtD]

There is a total plane limit, not a in-use limit.

So if you set it to 1, 1 player can take it and no one else will get to choose the plane. If the player lands the plane intact at the same base, he (or someone else) can use it again. If the plane gets destroyed, damaged or is landed on another base, it is no longer available.

It has always worked like that for me. Maybe if you posted the mission file it would be possible to take a closer look.