Where we currently are the RAF OSI team and our MEDA investigators work together to get to the root cause of the issues when required to.
A simple tool that needs no training in is called the FAIR model (used to be called the culpability slide/slope/chart), the only problem is there has been the odd time when great discussion has taken place to try and get a person over the 'line in the sand' with a view to some form of disciplinary action, which is obviously not part of Human factors and the 'Just Culture' theme.