Drive to the Airport. You can enter the runway any number of ways; the ramp at the east entrance, the weak fence at the west end from the road along the beach leading from Los Santos Customs, or the weak piece of fence on the right side of the west entrance see picture. Once inside the airport drive toward the designated hanger and stop a good distance away. Get out of your car, take cover, and pull out your sniper rifle. DO NOT use explosives because you run the risk of blowing up the Titan and failing the mission. Pick off as many of the Merryweather guards as you can, some of them will advance on your position with pistols. Take out closer enemies first then the rest that take cover inside the hanger. Once you have cleared enough of them out get back in your car and drive into the hanger, stick to the left side. Equip an assault rifle and fight any guards inside the hanger, beware of the mercenaries on the catwalks above and the ones that spawn in the back of the hanger behind the semi truck. If you get shot up make sure to take cover and use some Snacks. Move the semi truck and trailer out of the way and enter the Titan.