When you start find the door to the aeroplane (the door with the bridge).

Go to the edge closest to the back of the plane (try not to fall off).

Stay on the edge, then turn around and look at the plane wing and you will see boxes under it.

Run and jump and land on them, then go prone and go next to the plane tyre.

You will see a little crack between the tyre - camp in there!

Warning - when in there you can't get out.