All environments
Press Down, Up(2), Down, Left, Right, L, R, L, R at the menu with "Continue" and "New Game" options. The phrase "Secret code accepted" will be spoken to confirm correct code entry.
All planes and missions
Press Y(3), X(3), L, R, Black(2), White(2) at the menu with "Continue" and "New Game" options. The phrase "Secret code accepted" will be spoken twice to confirm correct code entry.
Easier Dogfight
When playing the earlier planes, esp. against the Japenese, you will find yourself getting shot at from behind an awful lot. An easy way to avoid this is to suddenly cut back your throttle to almost stall, make your plane pitch forward and then quickly change your throttle to wide open. When you do that make your plane point to the sky. The persuing plane will shoot by you, making you the hunter. This will not work with the 262 and Komets, as they have a better turn radius than most of the slower planes.
Level select
Press X(3), B(3), Y, X for the first part of the code at the menu with "Continue" and "New Game" options. Then, press Black(2), White(2) for the second part of the code. The phrase "Secret code accepted" will be spoken to confirm correct code entry.
More instant replay views
Press Up, Down, Left, Right, R(2), L(2) at the menu with "Continue" and "New Game" options. The phrase "Secret code accepted" will be spoken to confirm correct code entry.
Various Codes
On the screen with New Game/Continue, enter these cheats quickly:
God Mode - UP, DOWN, LEFT, RIGHT, LEFT, LEFT, RIGHT, RIGHT, L, L, R, R, WHITE, BLACK.
Infinite Ammo - UP, RIGHT, DOWN, LEFT, UP, RIGHT, DOWN, LEFT, L, R.
Fat Head - RIGHT, UP, LEFT, DOWN, RIGHT, UP, LEFT, DOWN, RIGHT, L, R, L, R.
Unlock All Insta-Action Stages - UP, DOWN, LEFT, RIGHT, L, R, L, R.
All environments...