"It could have been deadly," he said. "We were preparing ourselves for the worst.
"She was seriously distressed, really upset. She clearly didn't know where she was, she was out of food and water and that really gave it that sense of urgency."
Before her location was able to be established her phone battery went flat.
Ms Rosli spent the night among rocks and snow and did not move from her location as Search and Rescue and police used night vision goggles to search Tongariro.
It was yesterday morning before rescuers realised she was actually on Ngauruhoe.
Ms Rosli spotted the helicopter and was able to get enough battery life to call police again to tell them searchers were above her location, before her phone went flat again.
The woman had also been spotted by another tramping party as she climbed Ngauruhoe, who told the Mangatepopo Hut ranger, who alerted rescuers.
A police dog handler, dog and search and rescue specialist were dropped to a location and established voice contact with Ms Rosli. She was reached about 8:30am.
"There were some tears, obviously," Mr Shepherd said. "She was quite happy that we found her.
"She was pretty cheerful, and in good spirits and remarkably good physical condition," he said.
Mr Shepherd said he was amazed how resilient Ms Rosli was to have survived the night, as she was only wearing a T-shirt, hoodie and yoga pants. The temperature dropped to 1C overnight.
She was airlifted by the Greenlea Rescue Helicopter and taken to Whakapapa Village before continuing to Taupo Hospital. Mr Shepherd believed she had a sprained ankle but was not suffering hypothermia.
Ms Rosli's group "lost sight of her at the staircase leading out of Mangatepopo valley crater", Mr Shepherd said.
"She went right to the summit and over the top and down the other side."
Liam Schuitemaker, president of the Waikato University Tramping Club, said the club had not organised a Tongariro Alpine Crossing expedition, and Ms Rosli was not a member of the club.
