I just tried this mission again to see what I did.
After taking off slow down to about 125 knots (you don't have to drop your bombs), and follow the cargo plane. Through the rest of the mission, don't touch the throttle.
When you see the first plane straight ahead, shoot it down, then turn right to take down the second plane. Turn back left and you should see the cargo plane. Keep following it.
When you see the next two planes, again take on the one ahead of your first, then turn left and take out the next plane. Turn back right, and you should see the cargo plane still on it's way towards the enemy base.
Before it gets there it will turn left, and after a little while turn left again to fly over the West lake. Just fly towards it and you won't lose it to win the mission.