This chapter consists of an on-rails sequence in a hijacked helicopter. You're armed with a machine gun that has unlimited ammo.
The pilot will start by hovering alongside an office building. Armed guards inside the building will shoot through the windows and continuously fire at you. The biggest threats here are machine guns and RPGs. There will be a distance marker pointing at any enemy that is wielding a machine gun or an RPG, so be sure to prioritize these targets.
As soon as a machine gunner appears, direct your fire at him to take him down before he can do any damage. You may be covered inside the helicopter while not shooting, but you can still get hit, so an unanswered machine gun will down you in no time. Once the machine gunner is down, cease fire and wait for the helicopter to move on. Reload your machine gun in the meantime.
You'll face an RPG launcher-wielding enemy as the helicopter hovers outside the next set of windows. The RPG launcher can destroy your helicopter, so you must kill this enemy quickly.
As soon you're able to spot the enemy with the RPG launcher through the windows, spray him with your machine gun and then take cover. You'll face another machine gun-wielding enemy when the helicopter moves up, so gun him down quickly and then get back behind cover to avoid taking unnecessary fire. You'll face another RPG in the next room; shred him as soon as he's in your sights and then immediately cease fire. You'll face one more machine gunner before the pilot pulls away from this building.
Surviving the first set of MGs and RPGs
A gunship will appear when the pilot reaches the next building. The white bar in the distance marker pointing to this gunship indicates how much damage it has sustained. You must completely deplete the meter to destroy the gunship.
Attached to the gunship is a powerful turret that can rip you to shreds if you aren't careful, so exercise extreme caution here. The key is to wait until the gunship stops shooting before returning fire. Then, as soon as it begins shooting again, cease fire and wait for its fire to lull again before popping back out to continue shooting.
Shooting down this gunship may take awhile, but its weapons can kill you very quickly if you aren't careful, so be patient. Keep the target reticule trained on the gunship for as long as possible to do the most damage.
Shooting down the first gunship
Once you've managed to shoot down the gunship, the pilot will ascend to a higher floor. Surviving this floor is a bit tougher, as you really need to clear out as many of the guards on the floor as you can before the pilot moves on to the next set of windows. Take aim as your helicopter flies alongside the building and open fire as soon as the first batch of enemies is visible through the glass. Spray the RPG user as soon as he appears.
Reload your machine gun when the pilot moves past the first set of windows, then immediately take aim and start firing at the next batch of enemies. You'll face two RPGs here, so direct your machine gun fire at them as soon as their distance markers appear to quickly put them down. Reload your weapon again when the pilot pulls away from these windows and then take to killing the last batch of enemies.
Surviving the second set of RPGs
When the pilot pulls away from the building, cease fire and wait for another gunship to appear. Deal with this gunship just as you did the first: keep behind cover until its fire lulls and then begin returning fire, keeping the target reticule trained on the gunship until it starts shooting again. Repeat this to stay alive and destroy the chopper.
Destroying this gunship may take a bit longer since it tends to hover behind the large signs on top of the building. These signs are destructible, so if the gunship's shots are being blocked by it, feel free to chip away at the sign with your machine gun.
Shoot the gunship out of the sky to complete the chapter.
Shooting down the gunship at the helipad