Complete certain tasks to get each achievment:

Ace Killer
Defeat all other Aces.

Ace of Aces
Achieve the highest score in all campaign missions.

Collector
Unlock and collecte all planes.

Hero
Achieve combat excellence and earn all medals.

Survivor
Outlive your enemies in Arcade Mode.

Veteran
Outlive WWII.

Pause game play, then hold LT and quickly press X, Y(2), X. Then hold RT and quickly press Y, X(2), Y. Repeat the code to disable its effect.

Pause game play, then hold LT and quickly press LB(2), RB. Then hold RT and quickly press RB(2), LB. Repeat the code to disable its effect.

Hold LT + RT and quickly press X, LB, RB, Y(2), RB, LB, X at the main menu.