As it seems before waypoint change they were most likely not in fog, thick or otherwise, caz, that doesn't really help. Instead of answering questions that you were not asked, please answer the ones that you were:
So they were in control of the aircraft, flying towards the cloud enshrouded Mull intending as planned to turn left at the "Waypoint Change" but were already Grossly Negligent? Why? Because they were "flying too fast"? How fast was that, caz? The only speed known to any degree of accuracy is the speed deduced from impact damage. Is that the "flying too fast" speed? Why? If you were the BoI President and had done a proper Accident Investigation, that uncovered the Lack of Airworthiness and took into account the evidence of Flight Control malfunction in the wreckage, you would still find the primary cause of the accident to be the Gross Negligence of the pilots before "Waypoint Change" even though they could still have been flying in VMC?
Thank you