So, you want to get your hands on Grand Theft Auto V's most advanced airplane? Well, you've come to the right place. As of now, there's just about no way to fail at stealing this vehicle when using the following trick.

Head to the military base, but be sure that you're playing as Franklin. Bring a fast car along with you, and drive against traffic along the way so that you have your Special bar filled by the time you arrive. You'll need to use Fanklin's Precision Driving skill during your approach. 

Drive full speed at the military base, and pop Franklin's ability just as you smash through the small gate at the checkpoint. Cut to the first right, and then blaze a quick left immediately after. Drive up the runway, with your special ability still working. With the speed of your car and the help of Franklin's Precision Driving, you should be able to reach the P-996 Lazer jet before the alarm is ever sounded. Hop out of your car and into the jet, and then blast off.

For a bonus rush, when you part the plane, head into the hangar next to Trevor's house. Pull all the way to the back of the hangar, quick save, and you'll have a second P-996 Lazer jet in your garage to play around with.