REWARDS - $5,000
This can be one of the most frustrating missions in the game. You have to destroy 5 couriers with a RC Baron. The RC Baron only has a limited amount of fuel, so you must be quick with this mission. X increases the throttle, while Square decreases it. L2 and R2 make it turn left and right, while L1 fires its machine guns. Even though it sounds easy, the plane is damn hard to control, in my opinion.
Head to the nearest marker on your radar and drop behind the van. Open fire and blow it up. If the driver gets out of the van, you'll have to kill him too. Once you take care of that van, head to the next nearest blip, which should be a bike. After the bike, the next nearest blip should be another van. The northwest one is the third van and the northeast one is another bike. Hopefully, you can shoot them while in the air to save time. Once all 5 are done, you'll have to fly back to Zero's store's roof with the remaining fuel.
Some of the guys will fire back at you with what seem like AK-47s. This presents a problem since your plane doesn't take too much punishment before becoming a fiery ball of nothing. Watch out for the stoplights, trees and power lines when flying. Also, don't try to hit the ground too much. You get $5000 when you pass this mission.