Hold down the ALT button and go into 'Reference'. Keep holding it down. Click on the ghosted out 'Fly' button and you can fly any plane you wish.
U.S. Navy Fighters
Another one is to hold down the right ALT, CTRL, and SHIFT buttons and go into Reference. Scroll through the fighter planes until you see the Atomic Moth (oooh). You can fly that!
Thanks to Revolution reader Bryce Renfro!