First choose the A-10 as your plane. Wait for the Good Luck message to disappear from the screen, shoot your 30mm cannon one time, then hold down the X button. Keep it held down and the message, ''Super A-10'' will appear on the screen to confirm that the cheat worked. Now your weapon will be much more powerful.
Extra Missles and Fuel
Pause the game with controller 1 and then enter the following code on controller 2: A - B - A - B - Select - A. Then you should get more missiles and fuel.