There is an issue with CTD in Billund EKBI in Prepar3D v5.1 which apparently is caused by an issue with SODE and/or Simconnct. LM and the developer of SODE are aware of the problem and are working on a solution. Please see this thread:

https://www.prepar3d.com/forum/viewtopi ... 6&start=15

A temporary solution is to add the following entry to the [SIM] section of the Prepar3D.cfg:
AdaptiveSimGroupEnable = False