Yeh, I thought this crash was a new way for a helicopter too ...
Caz,
with all due respect, had they run inadvertantly into IMC
before they got to the Mull they would have had a chance to do something about it - prescribed actions which you and others are aware of and would surely realise that by the time these pilots had got to flying Chinooks in the RAF they could be relied upon to do the right thing.
We know that they were not in IMC at waypoint change (nearest ground only 600 metres-ish away) or they would not have dumped their local STANS waypoint.
I say that the weather of concern was right on the landmass - it was generated by it.
How do you judge your distance off a cloud/fog bank? - you could see the motley Mull alright, but it could have looked like a blimp made of DPM of unknown size in a whispy cloud.
If you inadvertantly ran into this localised IMC Wx, you'd be stuffed.
So why did they approach so close so fast? Perhaps something was telling them that they had further to go - Flt Lt Tapper would not have been trusting the STANS of the day to better than a mile after a sea crossing so dont worry about errors in the main nav system - try and think of what they could have been referring to, that they would trust because of its intrinsic reliability and which also could so easily be used to mislead them, accidentally or wilfully.
If you'll pardon me being a little didactic, perhaps I should spell it out
C P L S