The BALPA decision to appeal the Court of Sessions ruling is welcome regardless of its outcome as we need a second test to ensure all the arguments have been given proper weight. As Flying Lawyer pointed out, this is actually an important case that could affect professional pilots here and in other countries.
Against a background of our trying to apply just culture from inside the blame society we now live in, it is worth remembering that people have died and it is therefore the duty of the Crown Office to determine whether those deaths were unlawful. If the accident had not caused fatalities it is doubtful the Lord Advocate would have asked for the CVFDR as such a request would not have passed the public interest test in the first place.
Fishing expedition or not, there is also the concept of best evidence in play. It would be unreasonable to base a decision to prosecute purely on incomplete (ie redacted) evidence - and it should certainly be grounds for an appeal if you were convicted on the same basis. And here the best evidence is the CVFDR. What may have blurred the lines on this occasion was an operator decision to release FDM data to Police Scotland shortly after the accident, in AAIB's view a move that was contrary to EU law. I am not sure who interpreted the FDM for PS, but I think most people would agree this was a very unwelcome use of the data.
I think all this will hinge on a higher court's view of the public interest test and it is perhaps useful that the decision on this occasion will involve more than one judge, as others may have different views. If the original order stands (and I hope it does not) then maybe the saving grace lies in the conditions Lord Jones attached to release of the CVFDR, which should at least ensure the CVR is not played in open court.
There is plenty more to come on this, including a potential appeal to the European court if this one fails.