All campaign missions and planes
At the main menu, hold L + R and quickly press X, White, Black, Y(2), Black, White, X to unlock all campaign missions and planes.
Invincibility
Pause the game, then hold L and quickly press X, Y(2), X. Then, hold R and quickly press Y, X(2), Y. Repeat the code to disable its effect.
Increased damage by weapons
Pause the game, then hold L and quickly press White(2), Black. Then, hold R and quickly press Black(2), White. Repeat the code to disable its effect.
All Missions, Medals and Planes
At the main menu, hold Left Trigger + Right Trigger and press X, White, Black, Y, Y, Black, White, X.
Desert recon
After successfully taking the first three pictures of the ships, continue to the desert. Watch your radio signal when it picks up. You should have the two bars to be all fullly green. When that happens, you can pick up the camp on the radar.