Heatseeker

SR-71 Blackbird:
Successfully complete the Pilot bonus objective for the final mission (Mission 4.5-Final Count Down) to unlock this secret plane.
gfmh vpgwa, yirWurd77.

The Big One (SR-71 Blackbird Weapon Pack):
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: Both the SR-71 Blackbird plane and "The Big One" weapon pack can both be unlocked at the same time if playing under 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).
Wurd77.

Hint: Landing your plane:
When you are told you need to land your plane, make sure you look for some blue rings floating around close to where you need to land. Slow your plane down (by using your airbrakes) and fly through the blue rings. This will deploy your landing gear and you will then be able to land your plane successfully.
Wurd77.

Hint: Aircraft:
Complete the bonus objective in the indicated mission under the listed difficulty setting to unlock the corresponding aircraft.

F-15 Eagle V1: Mission 1.3 under the Rookie difficulty.
F-15 Eagle V2: Mission 2.3 under the Pilot difficulty.
F-16 Falcon V1: Mission 1.3 under the Rookie difficulty.
F-16 Falcon V2: Mission 2.1 under the Pilot difficulty.
M-27 Flogger V2: Mission 1.2 under the Pilot difficulty.
MiG-27 Flogger: Mission 1.1 under the Ace difficulty.
MiG-29 Fulcrum V2: Mission 2.3 under the Rookie difficulty.
MiG-31 Foxhound V1: Mission 1.3 under the Ace difficulty.
MiG-31 Foxhound V2: Mission 2.1 under the Ace difficulty.
T-45 GOSHAWK: Mission 1.1 under the Rookie difficulty.
Yak-141 Freestyle: Mission 1.2 under the Ace difficulty.

Hint: Weapon Packs:
Complete the bonus objective in the indicated mission under the listed difficulty setting to unlock the corresponding aircraft.

Air Attack (for MiG-27 Flogger V2): Mission 1.1 under the Pilot difficulty.
Circuit Breaker (for F-117 Nighthawk): Mission 2.2 under the Ace difficulty.
Circuit Breaker (for F-22 Raptor V2): Mission 2.4 under the Ace difficulty.
Cluster Bomber (for F-16 Falcon V2): Mission 1.3 under the Pilot difficulty.
Long Ranger (for F-15 Eagle V2): Mission 2.1 under the Rookie difficulty.
Multirole (for SU-27 Flanker V2): Mission 2.3 under the Ace difficulty.
Multirole (for Mig-31 Foxhound V2): Mission 1.2 under the Rookie difficulty.
Naval Fighter (for MiG-29 Fulcrum V3): Mission 2.4 under the Rookie difficulty.
Rocket Attack (for MiG-29 Fulcrum V2): Mission 1.3 under the Rookie difficulty.