Hi Paco! Sorry for the late reply; I've been swamped with school recently and didn't see your post.
(I've been sadly absent from the poetry forum altogether. I'll be back in a week or so.)
The chiasmus in this one is in the airport (people crossing paths), but it's also in the structure of the lines. Check out this thread
for a more complete explanation. The basic idea was something like this:
camraderie (line 1) / shared experience (line 8)
mid-world stop (2) / building full of gates (7)
between two places (3) / not here, not there... (6)
people talk (4) / open their mouths (5)
Thanks for taking the time to comment!