Get on the car and drive towards your objective. Soon you will be attacked by a helicopter, which you need o destroy. To the right, on the shipwrecks, there will be some enemies equipped with rocket launchers. You can either kill them all, or ignore them completely. After you drive over the broken hull of a ship, you will run into an APC. Once you reach the precipice, ignore the Ceph ship and drive down. Try and kill all of the enemies, and especially the Pinger, by using the cannon mounted on the car.
To the left of the large closed gate, there may be a few CELL soldiers remaining and a turret. Also here, will you find a Blackbox 3/3 on the corpse leaning against the container, and a Datapad 4/5, at the other side of the containers. Now you need to climb the stairs opposite the containers, in order to find a control console to open the gate with.
Cross the gate and take one of the vehicles to the left. Keep killing/passing enemies until you reach a big tunnel which you need to drive into. After you reach the tunnel's other end, you will have to leave the vehicle behind after covering several hundred meters, due to a road block. At the other side of the block, there is a Gauss Sabot Gun. Put it to use and kill the enemies below.
Destroy the command center defense system
You will receive a piece of information from Psycho informing you about your secondary mission. Jump down now and go left. You will reach a narrow passage that leads to your destination point. After you reach the passage's other end, you will notice Ceph attacking the CELL base. You can wait, in hiding, for a moment and let them kill each other out. On the Ceph attacking the base to the left, Use a weapon of a larger caliber. Collect his X-Pac Mortar and fire at the remaining enemies.
After you clear the area, approach the base and use grenades (there is a grenade box to the left of the target) to destroy the generator. Opposite the generator, there is a suit upgrade kit. Backtrack now to the passage that you took to get here, and continue towards your destination point.
On your way there, you will encounter several enemies and, underneath the pipeline, you will find an APC to get on. While driving, you will notice CELL vehicles trying to fight Ceph back. Kill everybody and destroy all equipment. Enter now the opened pipeline to infiltrate the base.