kill the enemies when it's convenient. don't worry about getting them all as long as you can stay alive. RUN to the big grey metal wall and kill the guy behind it, get the key to the jet and go back. As LONG As you can get that key and get to the jet nothing else matters and I promise you there will be plenty of time!! Good luck.
What are you talkin about "kill the enemies when it's convenient."? You act like it takes forever to kill them all off. Killing them all off wont entitle you gettin shot from behind while looking for the key. Your goin to beat the level soon, so you might as well waste ur m-16 bullets. Where's the action if your not going to shoot anybody?