Due to the questions popping up recently on this missions, I'll try to submit a hint in this section so more people will see it.
The problem most people seem to have with this mission is actually getting onto the cargo plane with the bike. The trick is to go straight for it. Don't go off to the side of the plane to avoid the barrels, you'll get blown away by the plane's engines. You have to go straight up the middle and dodge the barrels while gunning the engine. If you do this, you should be able to make it on the plane the first time, every time.
For any of those having trouble with the people inside the plane, remember to use melee type weapons. Chainsaws, brass knuckles, any of that will really work. Just make sure not to use explosives or reckless bullet guns, else the plane will explode on you and you will fail the mission.
Added by: Forgoten_Scars Dec 13th 2010, ID#8042