On Dec 21, 11:01 pm, Tuno wrote:
2KA,

I haven't dived into the gory details of the NASR, but after browsing
the SUA table of the primary data, the format descriptions for all the
tables, and the class B-E shapes in the "Additional" data, I have the
following observations:

* The APT table can be used in conjunction with the FAA NFD (what I'm
using onwww.justsoar.com) to provide the comm frequencies missing
from the latter. (They have a common key.)

* Similarly, the SUA table provides active times missing from the NFD,
for Restrictive, Alert, and MOA areas.

(Alas the good news seems to end there.)

* The SUA table does not provide precise descriptions of the
restrictive areas. Arcs and circles, instead of being described by
[center, radius, begin point, end point, and direction to travel], are
lists of approximated points. They are not suitable for navigation
purposes, and I believe the NASR description even says so.

* The shapes data (for class B-E) have nice vector renderings (I used
TNTatlas), but this data appear to be 2 dimensional only, and also not
suitable for navigation purposes. (To be useful for navigation, top
and bottom elevations must be provided.) It seems this data are useful
only for 2D plotting. Also, at least the Class B file is out of date;
I got the 20 Dec 07 - Feb 08 download, but it still has the old
Phoenix Class B.

I don't want to discourage you from your project, but potential users
should be aware of these limitations.

I do think that creating an airport turnpoint list from the APT table
would be very useful. I hope you don't mind if I add this feature to
what I provide on justsoar.com.

2NO

2NO

What you say about the SUA is absolutely true. The line segments are
accurate, but arcs and irregulars are only approximate. I hope the
FAA will add them.

The shapefile descriptions actually do include the elevation data you
mention, as well as the name of each segment. The shapefiles are
currently beta only; the FAA says they will be official and updated
regularly sometime in mid-2008.

Please do add the airport turnpoint list to turnpoint.com. I'll send
over some of my source code for comparison, so you can see how I
handle things like unique short name generation.

2KA

2KA