Are you talking about an airbase on an island or a coastal territory?
If you are talking about a coastal territory, AND that territory is also being attacked by land units from an adjacent territory, then it is possible for the airbase to be taken and the scramble aircraft to survive. In that case, the scramble aircraft would need to find another landing space within ONE (1) space, a friendly territory or carrier, or they are destroyed.
However, if you are talking about an island, it would be impossible for the scramble planes to survive yet still lose the airbase because the entire attacking force would be amphibious and the landing could not take place until that sea zone has been made friendly. In that case, the scramble planes would already be destroyed by the attacking force.