Brian
We have been here before.
The BOI into an aircraft accident is the Convening Officers BOI and He/She delegates the investigative function to a team of specialists who are experienced on that type of aircraft. The team are invited to give their OPINION as to the cause of the accident but this is not binding on the Reviewing Officers in the same way as the opinions of investigating Police Officers are not binding on Magistrates, Judges or Juries.
The BOI findings are commented on by Specialist Staff Officers from each Branch in respect of their specialities and passed through their Heads of Branch to SASO and thence to AOC and AOCinC.
It is NOT unusual for a BOI to be reconvened with a different President because the original one has made a complete "Pigs Ear" of the investigation. I recall one BOI years ago that was reconvened twice!!
The aim of the BOI is to investigate the circumstances surrounding the accident - not to allocate blame. There are, unfortunately, accidents where it is apparent that basic rules of Airmanship and Discipline have been ignored and the Convening Officers are left with no option but to lay the cause of the accident upon those who have failed to comply with those rules.
I remain convinced that this was one such accident.