cazatou,
OK, I will try once more.
At point A, where your impressive list of impressive witnesses were, I am prepared to accept, with absolutely no doubt whatsoever, that there was fog with a visibility of less than 20 metres.
At Point B, about 1 mile away from Point B and close to where Mr Holbrook was, the weather would appear to be within RW VFR limits but I cannot be sure about that. I have no doubt whatsoever that the visibility was nothing like it was at Point A. Even allowing for apparent variations in Holbrook's testimony between BOI and HOL, it is clear that the weather at Point A was very different. You seem to be suggesting that these differences in his story mean that his testimony should be totally disregarded. (You seem to have a similar attitude to S.L. Burkes evidence on airworthiness too).
Conclusion: The visibility at Point A cannot be used to determine gross negligence "at waypoint change" i.e. Point B.