More scrambles:
At the Options screen, choose a high Defcon level, then repeatedly enter and exit menu screens.

A-7 Corsair:
At the Aero Meet, beat Air To Ground #4

A-7E U.S. Navy colors:
Accomplish twenty carrier landings.

A-10:
At the Aero Meet, finish every surface attack objective.

AV-8B Harrier Jump Jet:
Beat VTOL training releases.

Apache Longbow:
Finish combat training.

Blue Impulse F-86 fighter:
In free flight mode on the Island level, get the Blue Impulse Squadron Icon.

Blue Impulse T2 trainer:
In free flight mode on the Bay level, get the Blue Impulse Squadron Icon beaneath a bridge.

C-1:
At the Aero Meet, finish the Maneuver Objectives.

Cobra:
Finish helicopter training.

F-104J fighter:
Reach a speed of Mach 2.0 or higher.

F-105 drone:
In training mode, fly at least 50,000 feet.

F-14B Test Bed:
Beat Recon Mission 2.

F-15 Aggressor 1:
Get 50 aerial kills.

F-15 Aggressor 2:
Get 100 aerial kills.

F-15 Aggressor 3:
Get 150 aerial kills.

F-15 Aggressor 4:
Get 200 aerial kills.

F-15 Aggressor 5:
Get 250 aerial kills.

F-15 Aggressor 6:
Get 300 aerial kills.

F-15 Aggressor 7:
Get 350 aerial kills.

F-15C:
At the Aero Meet, finish the ACM objectives.

F-15J:
Finish ten scrambles.

F-2A support fighter:
Beat the ACM maneuver objectives.

F-2B:
Finish fifty scrambles.

F-4E Phantom:
Destroy the F-4E Phantom.

F-86:
Spend an hour in training mode.

FA-18 Hornet:
Finish carrier landing training .

Mig-21:
Shoot down the Mig-21 in a scramble.

Mirage 2000C:
Shoot down the Mirage 2000C in a scramble.

Oh-6:
Finish helicopter training.

Su-25:
If ordered by the control tower, shoot it down.

Su-27 (Camouflage) fighter:
Finish recon mission 3.

Tornado:
Shoot down the Tornado in a scramble.

US-1A Search and Rescue Amphibian Plane:
Beat the Scramble mission in which the Marine US-1A has crashed at sea.

Fly over 800 mph:
Get a fast jet and head to the Bay level. Land on the highway and then press forward on the Analog-stick, but don't take off. Engage your afterburners and accelerate, don't take off. If you do it right, you can go faster then 1,000 mph.