questions about who exactly is to blame for flight 901. >> everybody has got opinions, but a lot of the evidence just has never been considered. >> but one thing both reports agree on, weather was a key factor. >> the record shows that they had thought they could get into clear air below the cloud at about 2,000 feet. >> a weather condition called sector whiteout made the flanks of mount erebus seem to disappear. the optical illusion caused the approach to lewis sound to look identical to the approach they believed they were flying over mcmurdo sound. >> they were seeing what they expected to see, a cloud base above them, a bay or whatever in the front, mountain to either side of them. exactly what they expected to see. >> these whiteout conditions are