Correct me if I'm wrong, but isn't a "cloud break procedure" a procedure designed to allow a descent through cloud to get visual beneath a layer? After completing the cloud break procedure terrain avoidance would still be visual, and impact at 6,000' in sector whiteout is just as possible, especially if you are not where you think you are. VFR procedures require the pilot to use visual observations to ensure separation from the terrain. Even just one minute after you have made a positive visual fix you are navigating using dead reckoning procedures, and if you're below the lowest safe the only source of positive terrain clearance information is by visual observation.
Prospector, the conditions you describe (sky clear) are far, far greater than CAVOK. It is my understanding that under a solid ceiling at 20,000' even with 100km visibility (also well in excess of CAVOK conditions in this location) "sector whiteout" could still occur with the same results. Unlike reduced visibility or cloud, you can't see sector whiteout coming - you can only recognize it when you are in it AND you are expecting it AND you know what signs (or lack of) that you are looking for.
Whilst the conditions may have been unsuitable for scenic viewing in the McMurdo area, the weather could well have been quite suitable a few miles away. Whilst I don't have any Antarctic nor Arctic experience, I do have a lot of experience in VFR tourism operations, and I would be very surprised if localized weather did not occur in these regions like it does everywhere else that I've flown. To condemn the crew based on the weather in another location (even if it was their eventual destination) is irrelevant.
Ultimately, there are numerous things that if the flight crew had done differently the accident would not have occurred on this particular flight. However, the same can also be said for Air New Zealand, the New Zealand Civil Aviation Authority (what ever it was called) and even the US military. Even the open door policy could well have distracted the crew at a critical time.
It is the company's responsibility to ensure that the flight crew are route qualified - and it is the company's performance is this regard that lined up many of the holes (the lack of detailed information on whiteout, the lack of information on the use and limitations of weather radar for ground mapping of surfaces covered by dry snow, the alteration of the waypoints combined with the ambiguity [polite way to put it] of the route in relation to Mt Erebus).
I still have some trouble with the concept that the crew should be completely exonerated for their contributions to the accident. At the end of the day a perfectly serviceable aircraft crashed into the side of a mountain, and if the crew's job is not to prevent that, what is it? However, given what I have read I am not comfortable to condemn the crew to being any of 'reckless', 'careless' or 'negligent' - the outcome proves that some of their decisions were wrong, but given the same training, briefings and company procedures without the benefit of hindsight would other professional pilots have done the same thing? I'm damn sure some would have.
W