Your calculations are probably right, however Ron's plane could of gone down 3.1 miles from Revelstoke. One radar report/sighting near Spences Bridge could be anything from another plane in area, to a Penguin with ruffled feathers! One 'beep! bird' or tracked all the way? Guess that factual info about this report is in the pipeline? Other airplanes in area at the time? No flight plan common in area? Area generally busy with air traffic? Traffic operating from unlicenced fields? Normal pos reporting ops for the area? Just questions, although i tend to agree with your synopsis.
Regards all, happy new year.
NB: Make me happy? A result on the fate of two missing people and the hope that 2008 doesnt bring us anything more to look at.