User blog comment:Artemis Paradox/The Official Monster Hunter Wikia Help Blog/@comment-144.131.9.151-20111026080747/@comment-969093-20111026102459

Evading the attacks without evade+ isn't impossible but you must time your roll pretty darn well if you want to pull it off. Your position must also be ideal. That's the thing with 1st and 2nd gen evasion. Without evade+ timing isn't enough. You must also know where to be. That way to can roll those retarded tail swings without evade+ for example.

Good luck with Yama. Have a look at Yama Guides (I wrote it, but am going to re-write it someday) and get yourself some important information. I even included something you won't find anywhere else on the net. The deviation in altitude that makes the helikopter attack unavoidable or auto-avoidable.