This long tunnel will be following a giant line that you can only see by getting high up. Planes take cargo to where the tunnel is built.
The only custom object I did not make is Boof69's stopsign object. There are three spawns that are reachable by pressing [X] on your keyboard.
I did not notice that by default the group of metal crates scattered around the airport were lifted up!
And uh, avoid landing on any flickering scurfaces; they Bite!!