Campaign Mission 8

So I've flown the entire route, stuck to the waypoints and destroyed the enemy chopper, escorted both Meatboy 1 and the CH-47 all the way back to base but for some reason they don't want to land, think I may have missed a trigger somewhere but can't work out where - as much as it's a nice flight through the mountains it's becoming a bit of a pain having tried 3 times now, any suggestions where I'm going wrong and/or has anyone completed it?

I can`t remember exactly, but I think you have to land at the base where you see the green smoke. Thats the finish point.