It might be useful to have combobox in the segment properties to specify the preferred target type if available.
Options maybe be:
Fighter
Bomber
Vehicle
Ship
AAA
Your formation may run into a collection of bombers with fighter escort all in your activation range at the same time.
You may want your Hurricane flight to concentrate on the bombers and you Spitifire flight to concentrate on the 109s.
You could put it on the flight, but I suspect on the segment would give you more flexibility. A flight may prefer different targets are different points in it's route.
