Im gonna say the AA vechicle got a tiny bit buffed since this post.
To be honest not even the Pro league player would have a chance with portable anti air against helicopter.
You lock on and then they release flare and hide under radar. Meanwhile Engineer has limited ammo and they just go after the flare. Fix the ridicilous weak Anti air. its completely useless as it is since launch of the game. the vechicle balance is more correct. The vehicle are powerful but so are the mines and RPG.
With Air vehicle heli are powerful, but the anti air is actually even less useful than the machine gun. its ridiculous weak. The Machine fun is more powerfull anti air weapon than any of the portable anti air missile.