The craft position is freezed?
ummm... are you saying that the x, y and z position numbers are not changing? which ones are you using?
FWIW: i kinda would expect that it would appear that they are not changing because there's no terrain around to be measured from...
i do rather agree with Thorsten, though... if all you are wanting is the FlightDynamicsModule then running the standalone JSBSim would seem to be the better option...
"You get more air close to the ground," said Angalo. "I read that in a book. You get lots of air low down, and not much when you go up."
"Why not?" said Gurder.
"Dunno. It's frightened of heights, I guess."