Paladin's Secret Achievement / Trophy Guide
Government Plane Wreck is the fifth expedition. The starting location is randomized. Look for a rusted plane wreck (has a brown color tone). It's the body of the plane and still has two wings on it. There's also a blue ladder leading up inside the wreck.
Enter the plane wreck. Interact with the Laptop on the ground level, it's next to the only enemy on the ground level. This opens a secret vault upstairs. Go to the upper level of the plane wreck where 1-2 enemies are standing and interact with the vault door at the end of the room. The secret Sam Fisher Outfit is behind that door.