As one who once served in the RAF and who has been a member of a Board of Inquiry (that is the 3-person team convened to investigate Service accidents), I would join the voices of restraint on here. The simple truth is that no one knows what happened yet, and it is appropriate such a short time after the death of one of the RAF's finest young men to be sensitive to his family and the countless people close to the Red Arrows who will have been devastated by this tragic event. I fully understand the natural desire of people to know, and indeed the massive public interest in such a high-profile event, but everyone has to be allowed a period of privacy for even a short time at a time like this. If we have genuine news or insight, that is great - but surely it can wait for a day or so as a mark of respect.
From recollection, it is the duty of the President of the Board to issue a 48-hour signal which will outline the initial, but not binding view, of what actually happened. That may just say, 'Cause Undetermined'. If the military Board of Inquiry do not know, then the chances of anyone on here knowing more would seem slight to me.