Instructions
Start the "False Idols" mission.
Drive to the bridge that connects Staunton and Shoreside. Drive around the curve and look at the left side of the road for a large concrete block with a piece of the metal bridge attached to it. You need to get on top of that concrete block.
Drive toward the base of the block, which has a sloped bottom and creates a jump for your car or motorcycle. Get out of the car on top of the block.
Walk toward the metal support that attaches to the bridge. Continue walking past the big red light.
Turn to your left once you pass the light. When you will see a building without a roof next to the bridge, you can jump down onto the space.
Wait for the helicopter to pass by. Be sure you are standing on the pilot's side.
Grab the pilot and pull him out of the helicopter. Get inside the helicopter.
Stay in the helicopter until after the mission has failed. The helicopter is now yours to keep and fly.