If you wish to gain this achievement using the exploit please see here:http://bit.ly/h3WWh5If you wish to gain this achievement legitimately please see here:Once you’ve been debriefed on the mission, talk to Morgan and he’ll give you some items that you’ll need for your squad, now head over to the terminals and choose what you want your squad to be, you’ll need to use both of the terminals before you’re allowed to leave.
Now head North-West toward the goal that states you have to destroy 2 fuel tanks, once you get there just plant explosives on the 2 tanks to finish up this part of the quest, after that you’ll get warped back to the room you were briefed in earlier, choose another command set at the terminals and prepare to leave.
Now head up to the Listening Post, be careful though, there are loads more enemies in this area and some will have heavy weapons like rockets, they’re not hard to take out, but it’s easy to die here if you’re not careful. Follow the train track and go through a broken building, you’ll come to a set of stairs, head up them and enter the building.
Once inside just follow the path all the way though killing enemies as you make your way up to the top, when you get up there you’ll clear the quest, get teleported back to the briefing room again and the achievement will pop!
If you're still having trouble, try checking out the videos below!
*Credit to MahaloVideoGames for the videos