complete chapter 13 and then complete the Free Mission at Shinjuku
How:
this will then unlock a fighter jet for all your sky missions just go to the dragon select menu and go down the choas dragon levels till you see ??? that is the jet but remember you can only use it in sky missions.
all you have to do is reapet the level until your weapons are powerful level 4 is the max level of your weapons the level is easy so it shouldnt take to long.
