"I had about six or eight tumbles and shot off a ledge and landed in some soft snow," Mr Lightbody said.
He said Mr Ittak came charging down after him "like a Viking" after having picked up his mate's ice axe, and was able to stabilise him and get help from a mountain patrol.
He was slowly carted down the mountain in a sled on the back of a snow groomer before the Youthtown Trust rescue helicopter was called in to take him to hospital.
"I was in first stage hypothermia by then and was shivering uncontrollably..and they couldn't give me anything for the pain, so it was pretty harrowing," he said.
His right ankle needed to be reset as the wrench had partially cut his circulation and he now faces surgery, which will either be carried out here or back in Melbourne.
Mr Lightbody said he was a keen cross-country telemark skier, which involves long and narrow skis where the heels lift up, but was told there could be lasting ankle damage that may make it difficult in the future.
Nevertheless, he said he was relieved to have survived the fall and avoid a potentially fatal knock to the head.
He said he had huge praise for the ski field staff and paramedics who helped rescue him and deliver him to hospital throughout the night.
"Also my friend Peter - they are a great bunch of guys."
Mr Lightbody said he had been skiing in the South Island earlier in the year and was keen to return to New Zealand with his family next year.
He was one of at least three people to have taken a tumble on mountains at the weekend.
Aucklander Andrew Blair fell at least 60m in the same area on Saturday, breaking a leg and ribs in the process.
Another man received moderate injuries in a fall of about 300m in the Mt Somers area of mid-Canterbury early yesterday.
- NZPA