just play through the DLC storyline till you get to the america's next top scientist mission, first you need to drive tera to the given destination and then you need to defend that location and the truck, ultor will come with BEAR's and masaki but you have an annihilator with a lot of rockets available in the area so you should be fine.
After tat jane valderama will call you to meet her with the truck watch out because ultor will be tailing you , after that you need to shoot down 6 ultor helicopters a cutscene will play and you will get the achievement afterwards.