BOAC
Admit, to mention these words might be somewhat misleading. The assumption that they were flying on just flight plan data and reporting to ANC ATCC via a radio relay station might be correct. The opposite might be correct as well and via some detached RADAR station ANC can see them on RADAR ??? But the question still is unanswered: Based on which factual information the clearance for a direct course to a RNAV position connected with an instruction " to maintain at or above 2000ft" was transmitted to the crew ??
My basic assumption in this case is to believe that all of the person involved in this accident knew all about the weather conditions and the terrain situation much better than one at hindsight can determine.