Mission simulator only. When at the weapon selection screen, hold start and X until the game starts.
Successfully complete the game on easy mode.
During the replays you can press Triangle, Circle, Square, X, L1 or R1 to move the camera around and press L2 and R2 to add filters and blur.
Complete all 52 missions and save the game. Return to the title screen and load the completed save file. The "new file" option will now be an "s-file" option. Choose that option for a mission simulator that allows any mission to be played with any airplane and on difficulty level.
At the title screen where it says "Press Start", press and hold down L1+L2+R1+R2 and then press start and select at the same time.