Thunderstrike: Operation Phoenix

Level select:
Enter the options screen. Set "Vibration" to "1" and "Sound effects" and "Music" to "0". Then, hold L1 + L2 + R1 + R2 + Circle + Square. The message "Spooky Cat" will appear in the middle of the screen to confirm correct code entry.
Jim.

Ending bonuses:
Successfully complete the game under the hard difficulty setting. The maniac difficulty setting and a bonus helicopter and will now be unlocked. The bonus helicopter flies, turns, climbs, descends, and shoots faster.

Successfully complete the game under the maniac difficulty setting to unlock a third bonus helicopter, which you can use on any difficulty setting. It has the same top speed and fire rate as the second bonus helicopter, but more armor.
Jim.

AWACS view:
Press Triangle + Up.
Harris.

Target view:
Press Triangle + Down.
Harris.

Weapon view:
Hold Triangle while firing wing mounted weapons.
H. Harris.