Battle: Los Angeles

Watch the Video!!!!

Info prior to watching the video: The rocket launcher spawns on the highway overpass in the second mission and must be used to fight the airsupport unit. After obtaining the rocket launcher exit the rooftop and watch the two minute video below. Play on an easy difficulty in order to minimize enemy health. If you need to restart and you will start in the exact spot this video starts (this could interfere with other achievements so use with caution)

Just a note for those of u like me who followed the above guides and even when u manage to get both with one shot the achievement doesn't pop. apparently this has happened to several people and it happened to me, this achievement is evidently randomly glitched. Personally I tried over and over and even when obviously i killed both aliens with one shot it just didn't pop. If u are having this issue try this: in dashboard go over to system settings, select memory and go into storage device settings (of whichever device u have your saved game on, if u have multiple devices) and delete the save game file under Battle:LA, clear your cache (hit "Y" when selecting main memory unit) and start all over again. The game is fairly short so there's not too much time to devote before you're back to the section u need to be at. After starting a fresh game i got it first try by following the directions in the other solutions. Just figured id upload a solution for the few of u who may have the same issue! hope this helps!

I did this on Easy mode because I'm almost positive that enemies have less health on Easy. The best place to get this achievement is after you fought two battles with an air unit (one on a bridge and the other behind a cracked wall area). Switch to your other weapon and take out the enemy in front of you and on the roof. Two more enemies will spawn on the roof. After these four enemies are dead, switch to rockets and turn left. Down this corridor, two aliens will pop out from either side. This is your chance to aim a rocket at the ground between both of them. If you timed it right, you should kill both with one rocket and get the achievement. Also keep in mind that if you don't get it, simply restart checkpoint as it will put you right back at the foot of the ladder with rockets again.

The easiest way of getting this achievement is the one I used whilst playing on 'EASY' mode on the last mission.

After you have destroyed the second attack craft, fill up on RPG ammo and climb down the ladder.

You now have to cross a broken bridge, where as you do so an alien drops at the end of the bridge in front of you as you get half way across, with one other dropping down mid-right in front of you.

Kill both of them and proceed to the end section of the final mission (this is were your Sgt. talks at you like he's in a badly dubbed martial art film).

At this point he will tell you to get in the HMV and use the 50 cal. to destroy the enemy attack craft. DO NOT GET IN IT - instead wait until you see the aliens that spawn in front of you start to hide behind the cars on the left or in the middle.

Wait as the aliens will eventually bunch up on the cars (usually one in front & one behind a car) shoot them or the car with the RPG and the achievement will pop.

Hope this help.

This achievement requires you to kill 2 enemy aliens with a single rocket.

About 3/4's through the second level, after you blow the gas station up, you will encounter a flying enemy ship and an available rocket launcher on a highway overpass. You will get about 3 or 4 hits and the ship will fly away to another location. You will run up a set of stairs and you will be able to finish the ship off. At this point SAVE your rocket! You will exit this area, go down a ladder and encounter a few more enemies. After the are finished, you will will be in a tight alleyway. Arm your rocket before you advance. Once you cross the line of the building, 2 aliens pop out. Aim at the ground between their feet and kill them.

If you fail to kill them, and only knock them down, restart to checkpoint. You will have to kill 4 enemies before you can hit these two again. Adjust your aim and fire again. Keep trying, and you will get it. This has proven to be the easier method.

The achievement will pop once they are killed by the rocket. If the achievement doesn't unlock immediately, you did not kill them.

Message me for any questions.

I'm not 100% certain but after trying quite a few times i get the feeling you may have to use only the rocket to kill the two enemies, when i did it two or three times an ally got a couple shots off and it didn't award me, as soon as i blew two up before anyone got a shot off i got the achievement!
just a thought in case people are finding it hard to get even when they kill two enemies?