Halo MCC Guides:
- All Collectibles / Datapads in Halo Reach.
- The Humble Beginnings of Wiljax Brantley Achievement.
- This is Not the Greatest Lab in the World… Achievement.
- Mind the Skill Gap Achievement.
- HBOrg Special Achievement.
- Keep It Clean Achievement.
We're Gonna Need a Bigger Ship
Fly both the Pelican and Phantom on New Alexandria.
Load up New Alexandria on Easy with preferably two players (it's possible with one, but you can get another achievement as well if you have two, plus two people make it substantially easier). Once you have the objective of shooting down the anti-air turrets at ONI Tower, head to the large building with the red strip around it near the top, to the west of Club Errera. Your friend should be in the side of your falcon.
Land on top of the building and have your friend stand on top of your falcon. Carefully fly down to the back of the building, and there will be a switch on the roof of an overhang just above the red strip. Fly up to the switch carefully and have your friend hit the switch. They will then fall to their death.
From here, fly straight up to the top of the building and land on the top. Your friend should respawn and get back in the falcon. Facing directly opposite the direction of the overhang, head straight forward from this building, and you should see a large ring-like building, with a giant diamond-shaped hole in the middle of it that you can fly through. Fly through this building at height ~950 and your passenger should be teleported into a pelican. Fly through it again and you should be teleported into one as well. This should get you each the achievement.
Now, land the pelicans somewhere flat, and have each player take turns getting into and firing the other pelican's turret. This should unlock another achievement for both of you: The Jorge Can't Have All the Big Guns achievement