Police are calling them heroes but Queenstown couple Erik Bradshaw, 37, and Christine Ryan, 32, say they were just members of a team of strangers pulling together in extraordinary circumstances.

The couple have been praised for their attempt to save Irish climber Donal Deery and comfort his seriously injured partner, Helen McClemmens, after a fall on the Cascade Saddle in the Mt Aspiring National Park.

But the couple, who had never been involved in a serious rescue, said they just went onto autopilot when they discovered the pair had fallen more than 250m into a rocky gully.

Their presence on the saddle was a "piece of luck on an unlucky day", Mr Bradshaw, of Queenstown, said yesterday.

The rock-climbing couple were walking down the Cascade Saddle when they were told by an American tramper there had been an accident.

The man said he had passed another man, Tom, who was running to the Mt Aspiring Hut to raise the alarm.

"He didn't know what to do, whether to have a look or not. We were about to have lunch but went down and saw slip marks on the snow. Then we saw a scarf, then Helen in the gully," Ms Ryan said.

Although the pair did not have search and rescue training, they set off their personal locator beacon.

The Irish couple fell over a steep part of the route but she and Mr Bradshaw were able to scramble down rocky ledges to Ms McClemmens.

Mr Bradshaw put her in a sleeping bag. They abseiled a further 15m to assess Dr Deery, who had slid into a tunnel of snow.

Ms Ryan then climbed back up to get a sleeping bag.

About 40 minutes later, Dr Deery stopped breathing and Mr Bradshaw started mouth-to-mouth resuscitation, thinking he would stop after 10 minutes.

But then he heard the helicopter coming so continued for 50 minutes, wedged between rocks and snow, supporting Dr Deery so the fatally injured man would not slip further down the mountain.