Stay on the right side area of the train. There will be ramps on the left that will provide serious air for your ride. Change directions mid-air if you have to. Ram the cars and inch your way into the engine. In any case you've missed and ended up on the left, just wait for the train to pass you by, go to the right and keep trying.
Now rev up your engine and swap to Michael. Head under the bridge to check Trevor. Go pull up beside the orange cargo box, plant a sticky bomb, move out and trigger the explosion.
Change to Trevor and provide cover for Michael. First, waste the two baddies in the boats. Use the rocket launcher and shoot the chopper. Utilize the IR feature of the sniper rifle to take down 4 guards on the ridge above you. Next up, hit the two paratoopers before they are able to land.
Rush down the river while shooting back to the enemies nehind you. Destroy the helicopter if you know you can and always make sure to prevent being grounded.
