Successfully complete the Ace bonus objective for the final mission (Mission 4.5: Final
Count Down) to unlock the SR-71 Blackbird's fourth weapon pack. This weapon pack includes
the game's super weapon, the A-SLAMR. The A-SLAMR does not recharge once fired so use it
wisely. Note: The SR-71 Blackbird and "The Big One" weapon pack can both be
unlocked at the same time if playing on the Ace difficulty setting. Just complete both of
the required bonus objectives to unlock the SR-71 and "The Big One" weapon pack together
(instead of separately).