Ampan,
Bob Thomson, who has been quoted by me a few times in this thread was probably closest to the cause he states
"The captain didn't give attention to problems he might have around there. These people were taking a Sunday drive. When I heard the transcript of the CVR I fell out of my chair. Most of the times Mulgrew had been down there he had gone by sea, and all his travels from Scott Base had been to the south. Hardly anybody ever went into Lewis Bay.
Had they orbited Ross Island they would have seen the cloud. If a pilot is unsure he always goes up, never down. The Co-Pilot on FLT901 never opened his flight bag to look up the co-ordinates. I always had a chart in the cockpit and checked the lat and long readout, but the crew of the fatal flight never referred to it."
Bob Thomson was not qualified aircrew, but he had done more trips to the ice than most, and very often in the cockpit, and he certainly was New Zealands most experienced Antarctic person.