Breach the next door and kill all enemies to clear the LZ. From here, you have two options again: Provide Air Support or Stay on the Ground.
Boost your partner up to the chopper then make your way to the left. Follow the catwalk to reach the other rooftop. Your partner will provide covering fire from the helicopter's machine guns. Engage the enemies then take the stairs ahead. Turn around to the enclosed building and enter it to find the RPG trooper and take him out.
Wait for your partner to destroy the antenna. Once it crashes, the iron gate to be blown open. Get to the other side then vault to the antenna and head towards the crash site. Kill the lone enemy there then head towards your partner. The cartel chopper will return and aim its guns towards you so kill the pilot before it kills you. Once done, just enter the rooftop building and breach the door to complete the section.
Take out the highlighted targets as your partner moves below. Make use of the explosive barrels and gas tanks below to take out multiple targets. An RPG trooper will give you a hard time. Since you can't reach him, continue providing air cover to your ally until he successfully take out the RPG trooper. Once your objective is updated, destroy the antenna for your partner to continue. Kill the enemies on the other rooftop to assist your wounded allies until a cartel chopper appears and shoots your own helicopter down.
After the scene, kill the cartel chopper pilot and enter the building. Continue inside to complete the section.