Hi SKADI thanks for the guidance. I really appreciate your input. I have experience of the B105 SAS mode 20 odd years ago and that would be my frame of reference. The EC135 started out as the BO108 on the drawing board.
So in your experience you think the EC135 SAS is an improvement on the B105 system?
I fully agree that the safest option is with ATT and coupled vertical mode. My problem is I need to justify the extra costs of the ATT.