mikeran
Always nice to see new interest in this matter. May I suggest you go to the archive section and read All that has been said about it before posting again. Most of your questions have been answered.
With respect to why the aircraft did not fly airways, you may be surprised to learn that military helicopter pilots do not hold the required procedural instrument ratings to do this. Furthermore, the icing clearance of the Chinook Mk2 prohibited flight in IMC below +4 degrees C.
The point made above is the crux of the matter. Negligence is something which must be proved beyond any doubt whatsoever, not just used as a convenient cause when no other can be found.