Immediately when the level begins, run up to the pillar in front of you for cover. Enter wall mode and equip Shadow as your weapon. Spin out to the left and kill the first man. Exit wall mode and wait until the second man comes at you, then kill him. There will be more men. Stand back and kill them from near the pillar. If one gets close enough, it helps to use him as a shield. After men stop appearing from the helicopter, equip your M4 and target the man across the room on the raised section of the level. Do not target anyone on the highest balcony. Run at him while firing. Be careful -- he has a rocket launcher. Run side to side. Also be careful not to run past the fountain. If you do, the helicopter will be able to shoot you. After killing that man, make sure no one else is appearing from the helicopter. Get the rocket launcher that is in front of the fountain. After that, equip your rocket launcher and run back to the point on the ramp where it starts to decline. This ramp is near the beginning and between the two pillars you started near. Manually aim at the helicopter from here. If you cannot hit it, move forward until you can. Do not miss with the rocket launcher, as it will take even longer to defeat the helicopter. Use every gun you have and all your ammunition on this. It does not do much, but it does work. After all your ammunition is used, go left and act as if you are going up the balcony stairs. Go up them to the first platform and get the pistol. The last man you have to kill will also be there. After you have killed him, run back to the ramp and shoot the helicopter with all your ammunition again. The pistol will appear again in the exact location. Get the pistol again. There will not be any more men. Go back to the ramp again. Shoot the helicopter with all your ammunition. Keep repeating this until the helicopter is defeated.