AT FIRST the Melbourne multi-millionaire John Castran thought he had escaped the avalanche unscathed, unaware that metres away his Sydney skiing companion was dead.

Buried under more than 1.8 metres of snow on a New Zealand mountain range, Mr Castran, 53, could still move his arms and legs. But then the snow shifted and he was crushed.

Pinned beneath the overwhelming weight of what moments earlier had been featherweight powder snow, Mr Castran realised he did not have enough oxygen to yell for help.

The real estate agent survived the avalanche at Ragged Range, near Methven, west of Christchurch, yesterday, but a NSW businessman, 61, whose name has not been made public, was killed.

As Mr Castran ran out of air, he too thought he would perish under the ice. “You choke with the snow, you can’t breathe, you’re suffocating … it’s like being poured into plaster of Paris. The only thing I could move was my tongue, to push the snow away from in front of my mouth.

“I thought: ‘I’ve only got a little bit of air here, I’ve just got to use all the air very, very carefully’. So I just shut myself down totally.”

Mr Castran had been on a heli-skiing trip with his son Angus, 23, as well as the NSW man and two guides from the tour company Alpine Guides.

The snow had been perfect, the sky clear blue, and the group had completed four ski runs before their chartered helicopter dropped them at the remote Arrowsmith Ranges.

“It’s one of the most spectacular places you’ve ever seen, absolutely breathtaking country up in the ranges about 6000 to 8500 feet [2600 metres] above sea level,” Mr Castran said.

The man who was killed when the avalanche hit about 1pm had said to Mr Castran: “You don’t get much closer to heaven than this.”

The first guide skied ahead of the group to check for danger, then signalled for the men to follow.

“I was skiing down and all of a sudden the whole side of the mountain just let go,” Mr Castran said.

“I thought I might be able to out-ski it and ski off to the side, but the whole thing was happening so quickly and the snow went straight over the top of me.”

A dull rumble like thunder signalled that avalanche warnings issued for the area that day had been accurate.

“The first thing that comes over you is just this incredible adrenalin, and you want to scream. But if I screamed I was going to use up too much oxygen,” Mr Castran said.

“I thought: ‘I’ve just got to be smart’. And I was very lucky that I could just turn my mind off and put myself into another place.”

As the air drained away it became “frighteningly peaceful” under the snow. About 30 metres from where Mr Castran lay, his son had dug himself out from waist-high snow and was using a search and rescue beacon to find his father.

Angus said the tour group had been trained by guides to find each other using beacons they had pinned to their chests.

One of the guides was able to find the dead man within five minutes. He was free within “seven to eight” minutes, but efforts to revive him failed.

A tour guide and director of Methven Heliski, Kevin Boekholt, said: “He was around a metre down and he had his head up and he had no snow in his mouth. He was under the snow but there’s a lot of air in snow. He shouldn’t have died.”

It took Angus and the second guide about 15 minutes to find Mr Castran’s position. They used avalanche probes to feel for him beneath the snow and a rescue shovel to dig him out.

Angus said he feared the worst when they pulled his father from the snow, unconscious and blue.

Speaking from a motel room last night, Mr Castran said he was uninjured apart from a black eye and having “the stuffing taken out” of him.

He said he and his son were experienced heliskiers and their companion, who they had met that day, regularly travelled the world for the adventure of the high-risk sport.