I checked in FlightAware for a track of the flight and found this:
Alaska Central Express (KO) #51
IŽd like to say now there is even more than a mystery why they had to hit that mountain. The Speed / Altitude graph clearly shows they were at a safe altitude until few minutes before the crash.
As well, aside of all RNAV related questions it appears they initially where flying on an airway, most probably established on a radial of AKN VOR and having DLG ahead of them. Plus the RADAR coverage.
Big, big question WHY !!!