I understand from press reports the flight departed Oban at 1130 Monday but was not reported missing till tuesday afternoon....I can only assume therfore after departure from Oban the aircraft never made contact with ATC and therefore no one had any idea the poor guy was in trouble.
"PPrune Radar" mentions the aircraft was seen on radar to make a rapid descent from 5000ft, again I assume this is from data gleaned from radar recordings once it had been decided the aircraft was missing more than 24 hours later!
I guess in this instance it may not have helped the final outcome but at least if the flight had been in contact with the Scottish FIR service or other ATC agency the alarm bells would have been rung some 24 hours or so earlier?
Once again it points out the danger's of flying over the hostile terrain of the mountains and glenns of Scotland without making RT contact with some agency.
Once again all my own opinion on what is a very sad and tragic event.