I should have taken the next arc as an example, as the self-consistency in the previous open-air case is resolved, when a spherical Earth is used.

But for the next arc the self-consistency of the open-air arc can not be resolved by a switching from the WGS84 ellipsoid to the FAI spheroid.

*## 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
* comment HLT without any warranty
* fix start or endpoint of arc as old radii are 69.739 and 69.910 (sphere 69.974 and 69.980 )
DP 28:26:09 N 100:20:26 W
V D=-
V X=29:21:39 N 100:46:18 W
DB 28:26:09 N 100:20:26 W, 28:54:07 N 099:45:24 W
* comment HLT without any warranty
* fix start or endpoint of arc as old radii are 59.832 and 59.990
* (sphere 59.983 and 59.940 )