"It wasn't easy to find him and things weren't looking good for him once we did," said Mike Mclintock, from Garden City Helicopters, who said the man had fallen about 200 metres.
"The team had to airlift him out of there and work to stabilise him at the patrol rooms but the head injuries were really extensive," Mr Mclintock said.
"They were limited as to what they could do so they took him straight to hospital."
A Christchurch Hospital spokeswoman confirmed today that the man had died on Sunday night.
Mr Watkins said the man's family had been notified and a sibling had flown to Christchurch to be with him when he died.
"The shame thing about it all is that their holiday was wrapping up," he said.
"Today (Monday) they would have been heading home after a good time but that's sadly not the case."
James Young, manager of Mt Cheeseman Ski Area, said Tarn Basin was popular with experienced skiers and snowboarders, especially after a snow dump, when conditions were "fabulous".
But it had been two weeks since a big snow fall and, with several melt-freeze cycles, it was "firmer than it looked".
"Like many of the back basins, it would have looked very inviting but the conditions probably weren't as good as they seemed to the eye," Mr Young said.
He said he believed the three men were "competent enough to be in there, from what I can gather, but it was probably tougher going than they realised".
With several months of skiing ahead, and hundreds more Australians expected from across the ditch, the manager urged caution by all who opt to enter unpatrolled areas.
"Wear crash helmets and consult with snow safety officers before you head into any back-country areas so you understand what the conditions are," Mr Young said.
"That is vitally important."
The man is the third Australian to die on New Zealand's ski slopes in three years.
Sydney businessman Llynden Riethmuller, 61, died in July 2009 when he was buried in an avalanche in a remote Southern Alps valley.
Tasmanian neurologist Stan Siejka, 51, died when he skied out of control at Porters ski area in Canterbury two months later.
The latest case has been referred to the coroner.
- AAP