Am Samstag, 21. Juli 2012 06:06:42 UTC+2 schrieb Tom S:
On 7/19/12 3:35 PM, hlt wrote:
> This inconsistencies might quite likely result in an disqualification of a pilot.

How would this happen if the pilot and scorer both use the same data?

Because the data is written in a way that it can be interpreted in different ways.

Have a look at an example from the Uvalde data of last weekend, data was now update respectively is no longer available:

*## CRYSTAL NORTH ##
AN CRYSTAL NORTH 0800-0930 & 1300-1430 TUE-FRI O/T BY NTM
AC CTA/CTR
AL 6000 ALT
AH FL 180
DP 28:38:38 N 099:26:26 W
V D=-
V X=27:28:43 N 099:25:04 W
DB 28:38:38 N 099:26:26 W, 28:20:23 N 100:18:24 W

In the case the radius of the arc described by the DB record is 69.739 nm at the beginning and 69.910. In the open air format it is not defined which radius is to be used under these circumstances.

As as side remark:
The same arc is described in a different data format on the same
web page as

POINT=N283838 W0992626
ANTI-CLOCKWISE RADIUS=70.00 CENTRE=N272843 W0992504 TO=N282023 W1001824

So the arc definition in open air is not only not unique, it differs in
addition also from the definition in the TNP format.


The airspace open-air files now at the website use no longer the DB record. The DA record is used in the files currently available for download. With the DA record the Earth model has an even larger impact on the actual position of the arc than with the DB record.