tucumseh
I don't doubt that you believe that your assertions are correct in respect of navigation equipment limitations - however they were meant to be flying VFR. If they were complying with VFR requirements then they should have had ample warning of the hazardous situation that they were in and they should certainly not have been proceeding at such a high speed whilst approaching fog enshrouded high ground . If they were unable to comply with VFR weather limitations then they should have climbed to at least Safety Altitude whilst turning away from the high ground- NO "ifs" and NO "buts".
There is also the question as to whether they were aware as to the actual position of the turning point in relation to the high ground.