I tried some co-op tonight. Brilliant first mission, lots of street and building-to-building fighting, shooting rockets at vehicles, etc. The 2nd mission, which you will have to complete to unlock the rest of them, is helicopter piloting/shooting. I crashed nearly immediately 5 times. Then the game somehow switched me into the gunner's seat and my squadmate got his chance to crash. Eventually, he was able to fly for a bit but crashed at what felt like the end of the level. Frustrating and annoying, to the point where we are hesitant to try again. Maybe this was what DICE considers a "helicopter training mission," but making a difficult vehicle level the hinge-pin of the co-op campaign is a design mistake.