Thornbird - a thorough reading of the AAT decision shows a number of things. In the first instance, I saw a number of points where the decision was against CASA, either because their evidence could not be corroborated or the line of attack they took was not able to be backed up. To my reading it was a considered and balanced decision reached.
I would think if CASA could find criminal charges, I am sure they would persue them, if nothing else to wave around headlines. Standard practice for a government regulator. But the AOC suspension is not about a raft of convictions - its about the confidence CASA has that the operator was safe.
There is plenty in the AAT decision that shows this operator was an accident waiting to happen. The pressures to do jobs fatigued, the "go up and see what its like" attitude to icing and poor weather, the implied resistance to adding MR entries. You might argue these are subjective, but there were enough pilots and witnesses for the AAT to find these conditions existed. But then on top of this the history of the operator shows even when given time and opportunity to fix issues raised in audits they did not. The way they dodged and tried to shift issues between their two AOCs shows they were not interested in fixing them, they were more interested in dodging blame. To my mind, CASA actually took too long to bring this to a conclusion and it cost three people their lives.
I am not saying there is not a case for review of the way CASA operates. There seems to be plenty of examples raised on this forum alone where power is unchecked and the right of reply is limited, as well as examples of vendettas and personal issues escalating to administrative action. But if you are going to argue that, don't use the recent AAT decision - there was more than enough in that to show CASA took the correct action.