Dalek - I posted a long time ago my analysis of the 'probabilities' of 'getting away' with such an assassination attempt without it going 'pear-shaped', being discovered and the chances of success. It is worth sitting down and asking yourself if it would have been feasible, regardless of equipment which may or may not have been fitted/working/approved or a crew which may or may not have been tasked to test it. Ask yourself the odds that:
a crew would not sense something was wrong from visual cues, abort the mission and report back
the weather would provide EXACTLY the right orographic cloud at exactly the right time
the crew would have pressed on at cruise speed towards a 'murky Mull' relying solely on a reading fed into some black box by persons unknown.
Ask yourself also who tasked it? Who authorised it?
To me the whole question is of passing interest only for these reasons and should not detract from the gross injustice dealt to the deceased crew and families which is the thrust of this thread.
Perhaps we need to keep watching Wiki-leaks?? I guess in the world of bad and failed US plots against other countries, with the known sympathies for the IRA amongst our US 'friends' you just never know!