Mount Hutt ski-field will not be changing its policy towards skiing off piste after two deaths this season.

A 54-year-old Christchurch woman died in Christchurch Hospital after falling about 500m down a valley while skiing with her daughter at the Canterbury field yesterday afternoon.

Her daughter, who witnessed the fall, raised the alarm but the woman died from her injuries just before 5pm.

On June 17 a 21-year-old American woman died from serious chest and head injuries last month after she slipped on ice while skiing off-trail at the ski field.

Three days earlier a 60 year-old man died when his car slipped off the Mt Hutt access road.

Mt Hutt Ski Area manager Dave Wilson said today that it would not stop skiing out of bounds but reiterated advice that skiers should assess conditions and their own ability before skiing off trail.

"We try and encourage people if they are going to go out in the back country to check in with the ski patrol," Mr Wilson said.

The out of bounds area was too big to patrol and it was up to the individual to look after their own safety.

Mr Wilson said the two deaths this season was unheard of and ski-field staff had found it hard to deal with.

"I've been here for 10 years and having one [death] is unusual," he said.

Before this season the last death at the ski-field was in 2005 when an Australian man, Harry Brian Wylie, fell to his death while skiing off the main trails.

Responding to calls to make helmets mandatory for all skiers, Mr Wilson said it was definitely an option but there needed to be a lot of discussion and research before a decision was made.

The woman who died yesterday was wearing a helmet but the American woman was not, he said.

It was impossible to tell if a helmet would have saved her life, Mr Wilson said.

Yesterday's death was being investigated by the ski-field staff in conjunction with police, he said

The woman's daughter had been spoken to but the family would be given time to mourn before she was interviewed again as part of investigations, Mr Wilson said.

Her name would be released once relatives had been informed.