Caution - Arizona Airspace and Borders

Darryl sent me an email on this topic and my reply reiterates what
Andy has already has said: the FAA's National Flight Database (NFD)
does not contain border data, and this is why the "border airspace"
files at www.justsoar.com/public/sua/ and www.justsoar.com/public/openair/
are freely downloadable (use at your own risk, blah blah blah).

(The US/Mexico and US/Canada files are at the end of the listings,
after all the US states.)

The individual state border files on my web site were created by
taking publicly available ESRI ShapeFiles from the US Census web site
and running them through a shapefile-to-SUA/OpenAir converter.

The international border files were created by snipping out the
appropriate segments of the appropriate individual state files and
stitching them together into new entities of manageable size (hence CA-
AZ/Mexico, TX/Mexico, etc). This was not a trivial process, as some
states ran clockwise, some anti-clockwise, and a few counter-anti-
clockwise (requiring temporary use of a crossover cable on the flux
capacitor). Fortunately it only had to be done one time

Some things that all users of “border airspace” files should
understand:
* User applications (SeeYou, SYM, xcsoar, etc) all insist on closing
“border airspace” files, even SUA with TYPE=BOUNDARY, by connecting
the first and last points in the sequence. This requires adding
fictional points on the “closed” side of the boundary so that no point
on the “open” side of the border lies in the closed polygon. This is
why plots of “border airspace” files look … funny.
* They are approximations. (To wit, how long is the coastline of
England.)
* Pilots who fly near borders must take the time to either append the
appropriate “border airspace” files to the one they’re using, or tell
their software which one(s) to use.

I don't know where the files on the TPE came from, but if John wants
to post mine there or link to them, he is more than welcome to do so.

go fly

tuno