During the "Brave New World" mission, you will reach what appears to be a waterway. Work your way through it and kill all the enemies. When you get to the end, you will see your squad. Two helicopters will drop enemies. Pick up one of the laser guided rocket launchers. Aim the laser as best as you can on the helicopter. If done correctly, it will explode. Keep the laser targeted at all times on the helicopter or the rocket will miss. The rocket launcher takes about several seconds to reload and has two rounds per magazine.