USAF I believe conducts 2 separate investigations - one, more military, to blame someone and the other, a safety investigation, to see what went wrong and what lessons can be learned. Perhaps someone could confirm and explain?
Of course, it is not too dissimilar in places like France/Italy/Spain (that don't have the UK's adversarial legal system). In these counties, the investigating Judge does the digging with the help of accident investigators but it is he who will decide if there is a criminal case to answer. I can't quite remember the ins and outs but I have a good article somewhere that explains why in some countries/organisations, blame gets lamped on someone - usually the poor sod in control - the last piece in the jigsaw - the one nearest the scene of carnage who often part of it.