Tagron:
The principal requirement for a VMC descent below MSA is that safe terrain clearance must be maintained by visual means throughout the descent.
But isn't it also a basic requirement than in VMC, a visual letdown below MSA first requires a positive visual confirmation of one's exact position? I was under the impression the crew was only able to form a visual confirmation (in their minds at least)
after they had descended below the cloud layer and could see the terrain to the left of their track, most of which (including Erebus) was not visible at 16,000 ft. (My memory could be wrong here.)