Jwscud;
You make an interesting point. I have been questioned by the AAIB following a commercial air transport accident. I can't remember the exact words of the statement they read out before the questioning started but it was along the lines of "we are here to determine what happened. We are not part of any disciplinary process, however the results of our report may be used by your employers, the CAA or police if they believe you have been negligent in any way."
The problem I came up against was that the inspector had effectively decided in his hotel room the night of the accident, and the night before interviewing me what had caused it and accused me of a gross error in my performance calculations. Luckily I had friend with me from BALPA and he realised the inspector's mistake. By that time I had been questioned for two hours fifteen minutes without a break.
When the inspector's mistake was pointed out the rest of the interview went quite quickly (about another hour and a half) what really helped us was when we were able to put the FDR data into a simulator and show exactly how the aircraft behaved. I was shocked at how similar the outcomes were.
A year later the report came out and the P2 and I were gratified to see that there was nothing we could have done, but thanks to the spoutings of a late unlamented journalist some mud stuck.
I learned a couple of lessons from my experience:
1. I had been quite seriously injured, but in the trauma/shock of the aftermath didn't realise it and was not in fact fit to be interviewed.
2. NEVER, EVER GO INTO AN AAIB INTERVIEW WITHOUT KNOWLEDGABLE REPRESENTATION OR A LAWYER. The AAIB are not infallible, but they are exceptionally good. I have visited a couple of times since, both as an interested party and to answer some questions about a later accident I was involved on the periphery of. They are highly dedicated people, but when you prove them wrong they listen and learn.
SND