Really if I remember correctly from the videos, you only need to hit him with a few shots from the Grenade Launcher (I hope you have BOW gas rounds) and then you hit the button, that'll be enough to send him out of the plane. I think I only used three shots of BOW gas rounds and I was able to beat him. I know, old thread ;>_> you're probably long passed this part...
Splinter Cell HD (PS3)
Oz, The Sopranos, Smallville or The Following (Season 1)