Caution - Arizona Airspace and Borders

Turnpoint Exchange includes airspace files. The airspace files listed
under Arizona Soaring Association were not provided by ASA, are not
approved by ASA, and are known to not properly depict the location of
the US Mexico border.

In the file asa_2010_sua.sua the border is defined by the Southern
boundary of the following airspace - R2301W, R2301E, Sells 1 MOA, Ruby
1 and Fuzzy MOAs. The border is undefined between W Nogales and
Evelyn. It is then defined by the Southern edge of Tombstone C MOA
and Tombstone B MOA, and is then undefined all the way to El Paso.

A review of the current sectional chart will show that each of these
airspace areas extends to, and it terminated by, the US Mexico border.

The polygon closing line to the South of these airspace areas does not
represent the location of the border.

An airspace file that does properly depict the US Mexico border is
available to ASA contest series and South West Soaring Championship
contestants from the scorer.

Andy

On Sep 9, 8:14*am, Andy wrote:
Turnpoint Exchange includes airspace files. *The airspace files listed
under Arizona Soaring Association were not provided by ASA, are not
approved by ASA, and are known to not properly depict the location of
the US Mexico border.

In the file asa_2010_sua.sua the border is defined by the Southern
boundary of the following airspace - R2301W, R2301E, Sells 1 MOA, Ruby
1 and Fuzzy MOAs. The border is undefined between W Nogales and
Evelyn. *It is then defined by the Southern edge of Tombstone C MOA
and Tombstone B MOA, and is then undefined all the way to El Paso.

A review of the current sectional chart will show that each of these
airspace areas extends to, and it terminated by, the US Mexico border.

The polygon closing line to the South of these airspace areas does not
represent the location of the border.

An airspace file that does properly depict the US Mexico border is
available to ASA contest series and South West Soaring Championship
contestants from the scorer.

Andy

So why not just send John Leibacher the right file? He does an amazing
job of quickly posting files to the turnpoint exchange.
John Cochrane

On Sep 9, 7:14*am, John Cochrane
wrote:

So why not just send John Leibacher the right file? He does an amazing
job of quickly posting files to the turnpoint exchange.

Because I do not have the right to distribute the data except, as
scorer, to participants in the contest.

It's a long story and I don't have time now.

Andy

On Sep 9, 7:22*am, Andy wrote:
On Sep 9, 7:14*am, John Cochrane
wrote:

So why not just send John Leibacher the right file? He does an amazing
job of quickly posting files to the turnpoint exchange.

Because I do not have the right to distribute the data except, as
scorer, to participants in the contest.

It's a long story and I don't have time now.

Andy

And it will become the wrong file on the next update.

Darryl

On Sep 9, 7:39*am, Darryl Ramm wrote:
On Sep 9, 7:22*am, Andy wrote:

On Sep 9, 7:14*am, John Cochrane
wrote:

So why not just send John Leibacher the right file? He does an amazing
job of quickly posting files to the turnpoint exchange.

Because I do not have the right to distribute the data except, as
scorer, to participants in the contest.

It's a long story and I don't have time now.

Andy

And it will become the wrong file on the next update.

Darryl

I was the one who discovered the problem when I nicked an airspace
boundary during a recent contest. It's a complex area near the
international border with several MOAs and restricted military
training areas. In examining the data, I find the US/Mexico border is
displaced about 1 nautical mile south of the actual border (perhaps
because the data are based on ADIZ data). SeeYou and SeeYou mobile
clearly show the border in the wrong place. Two MOAs that are
adjacent to the border are correctly shown. The whole southern border
of Arizona is shown at latitude 31 degrees 19 minutes instead of 31
degrees 20 minutes. This 1 minute difference may be the ADIZ border
definition, but I am not sure. I am sure that the indicated border is
in the wrong place (it's obvious if you look at Nogales, for example).

Andy (our scorer) finds that scoring programs do not properly display
the border at all. Clearly, the use of closed polygons to display
lines has some problems.

Our two concerns a

1) There are errors in the database that show airspace boundaries in
the wrong place.

2) Scoring programs (Winscore, for example) handle the airspace files
differently than the navigation problems (such as SeeYou Mobile) and
may plot garbage. The result may be penalizing pilots for airspace
violations that did not occur, or vice-versa.

One major message, though, is to take the warnings on the files
seriously - do NOT use them for navigation purposes! That's what
charts are for.

Mike

On Sep 9, 9:02*am, Mike the Strike wrote:

Andy (our scorer) finds that scoring programs do not properly display
the border at all. *Clearly, the use of closed polygons to display
lines has some problems.

Not quite true. The airspace file the scorer is using depicts the
border in a way that I believe to be correct.

I used Cambridge Aero Explorer Plus to display both airspace sources
and have emailed you the screen captures. I used Aero Explorer Plus
because it was created by Byars and depicts the airspace in the same
way as Winscore. The program has the ability to overlay multiple
airspace files which Winscore (to the best of my knowledge) does not.

Anyone else wanting to see the screen captures is welcome to drop me
an email.

Andy

On 9/9/2010 9:02 AM, Mike the Strike wrote:
One major message, though, is to take the warnings on the files
seriously - do NOT use them for navigation purposes! That's what
charts are for.

How do you compare an IGC file to a paper chart? Can the pilot state "I
was legal according to my paper chart" and get away with it? I thought
the standard for contests was the pilot flew according to the turnpoint
and airspace files the contest provided, so pilots, scoring program, and
the contest managers were all using the same data.

--
Eric Greenwell - Washington State, USA (netto to net to email me)

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