Ultimate Hikes will conduct an internal investigation after a 74-year-old Japanese woman on a guided walk with the company got lost on the Milford Track.
The woman was part of a group on the third day of a five-day trek from Te Anau to Milford Sound when she left the track for "unknown reasons'' on Friday afternoon.
She had left Pass Shelter after a lunch stop about 12.45pm and had a conversation with another walker about 1pm.
Alarms were raised at 5.20pm when she had not arrived at Quintin Lodge.
A ground search was launched at 6.30pm, during which the entire track was covered, and emergency services were notified a short time later.
About 15 Land Search and Rescue (SAR) volunteers from Invercargill and Te Anau as well as Police SAR staff were put on standby to begin a full search on Saturday if the woman was not located.
Ultimate Hikes general manager Noel Saxon said the Te Anau-based SAR helicopter, piloted by Sir Richard Hayes, joined the search about 11pm when the land-based search and a heli-search by Ultimate Hikes failed to locate the woman.
She was found about midnight on the Arthur Valley side of the MacKinnon Pass, in thick bush, by employing thermal imaging night vision equipment.
However, due to her location she could not be extracted, so Mr Saxon and two guides were lowered into the area with supplies and hiked to reach her.
They got there about 1am and stayed with her until she was rescued on Saturday morning.
Mr Saxon said the woman had done "the right thing by realising she was lost and hunkering down until help came''.
She had a sore ankle, but was otherwise uninjured and rejoined her group on Saturday night for dinner.
Police praised the professional and immediate response of the Ultimate Hikes and Milford Track staff, and the professionalism of the crew on the helicopter for locating the woman in "difficult terrain''.
Mr Saxon said he and the team involved in the rescue were "really pleased'' the woman was safe, well and in good spirits.
"We are very pleased that she did all the right things once she realised she was lost - she made herself as comfortable as she could and then waited, rather than risking trying to find her way back in the dark.''
