At the fortress' jamming device, next to it is a door mounted to the bottom of the fortress. Fly up inside and destroy the four boxes that will take down the shields of the cannons. Fly back down. Go around and fly to the highest point. Take out the cannons with your missiles. Jarvis will tell you to go inside. Tap into the computer and come back out, then destroy the four engines and the top of the craft. Go back inside to another door, then open the big loading bay door and fly inside. There may be a couple mines dropped on the city below. Destroy the mine and go back into the loading bay doors, then destroy the big blue cannon to go inside. Straddle between the two orange power engines to complete the level.