The RNFSAIC works independently of the chain of command whilst it is conducting an investigation. Their reports stand for themselves and are never altered or amended. The role of the RN BOI is to determine the "events leading up to the accident", draw conclusions and make recommendations. Again whilst appointed by the chain of command they acted in an independent way. The key is the difference in philosophy between the RN and RAF. IMHO the RN chain of command have always been able to stand back and not second guess BOIs, and accept their findings. If they (the CoC) have disagreed with the BOI then it was always stated in a seperate document and the BOI report remained uninfluenced and untouched. The RN do not conduct formal oral briefings of the CoC (where influence may be brought to bear one might think) during the BOI but they do keep the CoC informed of key issues that affect airworthiness or safety. The RN system is excellent and has withstood many an investigation and inquest.
I noted that the RN BOI/RNFSAIC teams gained significant praise from both the coroner and families during the PORTLAND inquest.