REWARDS - Respect, $15,000, High Noon for C.R.A.S.H. unlocks
Drive to the airport, go through the front gate and head towards the hangar with the plane you need to steal. If you need any armor, there's a pickup in a corner in the hangar of the plane you need. Get in the plane and get on the runway, then take off to the north and follow the yellow blip.
If the blip is pointing up, then fly up a bit. If it's pointing down, then lower your plane a bit. Once you spot the plane, bank until you get behind it. You must pass through the red circle above the plane, which will trigger a scene where CJ jumps out of your plane and lands on the Forellis' plane.
Once you get in the plane, you'll have to take out the men onboard. Take cover, then peek out every little bit and kill the hitmen. Once all four are dead, the pilot will sneak from behind, so kill him when you get the chance to. Once all 5 men are dead, CJ takes control of the plane. Fly back to the airport and land anywhere on the runway to complete the mission.