So I've been playing at this for a bit now... and I'm at the point where there are no guys on the roof, just me and the helicopter firing rockets at me... I've been running around the room search. There just isn't a JAW. Wtf?

Thats happened to me, the first time I played there were lots of JAW's but the second time there weren't any, probably a glitch. Don't worry though, if you shoot the heli enough it will come down but it will require management of ammo. good luck

there is a jaw if you look aroud on a corpse

JAWS are dropped by the Cell operators when they jump down from the above windows, you can see on there backs they are wearing them.

The problem is most likely that you are killing the Cell guys that have JAWs while they are up on the roof and their bodies and the JAWs they are carrying are not falling down to where you can reach them. But the game isn't spawning more of them because it registers that there are rockets available on the map.

When you see a Cell carrying a launcher, wait for him to repel down on a rope before killing him. Although, I have always had a rocket on me during this part of the game, so it never spawns any rocket guys if you already have them on you.

JAWs like to be invisible sometimes (another bug) but can still be pickd up - if all elese falls just throw anyting at the damn chopper ,this works a treat

scan the room and you should find one.

Yeah I think what lunarf1264 said is probably right... and if so, that's pretty crap.

I had this problem. Shoot the guy operating the turrent in the helicopter. The chopper will return and you have to do it again but once you've shot both gun operators it takes off and says it's going down with damage or something.