JP
You wrote:
the only possible explanation is that they were off track but of course did not realise it
With no CVR and no survivors, I find it unsettling that you are able to reach this conclusion. Yes the hillside they hit was in cloud and yes the position of impact appears to have been a couple of hundred yards to the right of the original intended track, but that does not mean that the crew thought they were on track or that they had
decided to fly over the Mull. Indeed, the fact that the Corran waypoint had been selected is significant evidence that they
intended to make the necessary 7 deg turn to the left to fly VFR towards Corran. For some unidentified (and unidentifiable) reason, the aircraft did not make that minor course alteration to the left and there is, therefore, uncertainty surrounding the cause of the crash. The fact that the aircraft hit a cloud-covered hill whilst the crew was attempting to navigate VFR is not proof they flouted any rules or that they were negligent in any way. It is, I concede,
possible that they were negligent, made a stupid decision to ignore the icing restrictions extant at the time, decided to cruise climb over the hills and didn't even manage to continue to fly in a straight line. However, it seems to me that, in a court of law, it would be impossible to prove this 'beyond reasonable doubt' let alone 'beyond any doubt whatsoever'. I've a feeling you're going to disagree, but a negligence finding in these circumstances (lack of evidence) is surely preposterous, unless one is trying to protect the reputations of Air Marshals.