Chug, there seems to be an impression that the AAIB are not routinely involved in military accident investigations. Based on my knowledge of military accident investigations over the last 12 years or so, I would say that the AAIB have been involved in the vast majority of them. The only reason I can think of where the AAIB might refuse is when the health and safety of the investigators cannot be guaranteed. Even then I have personal knowledge of an AAIB investigator who was helcoptered into an active war zone to undertake a very rapid investigation of the aircraft wreckage.
Regarding the involvement of the civil Police, consideration has to be given to the fact that their primary role is the investigation of crime, not the investigation of the cause of the accident. For fatal accidents, the Police of course have to report their findings to the Coroner but as a general rule, these rely heavily on the Service Inquiry findings (or the HSE when they are involved). I have to say that Police involvement often leads to severe delays in the investigation; reprehensible when other aircrew potentially remain at risk of technical problems.
EAP