Wānaka’s alpine community is in mourning following the death of local mountain guide Thomas Vialletet and his client on Aoraki Mt Cook on Monday evening (November 24).

Thomas, an IFMGA-qualified mountain guide, and his client died following a fall near the summit of Aoraki/Mount Cook at approximately 11.50pm on Monday, the NZ Mountain Guides Association (NZMGA) reported. 

The pair were part of a team of four, including two guides and their two clients, who were completing a grand traverse of Aoraki/Mount Cook.

The other two members of the party were successfully brought down unharmed from the summit ridge.

NZMGA president Anna Keeling said Thomas was a respected and valued member of the NZMGA. 

“[He was] an integral part of our guiding community,” she said. 

“NZMGA’s focus is now on those most affected, and our priority is supporting the family, including [his] partner and children, as well as our wider guiding community during this extremely difficult time.”

Thomas was the co-owner of Wānaka-based guiding company Summit Explorers with his wife Danielle. The pair have two young children.

Aoraki Mt Cook PHOTO: Wānaka App

While some national media reported that Wānaka Search and Rescue’s (SAR) Alpine Cliff Rescue team was involved in the rescue, Wānaka SAR chair Raewyn Calhaem confirmed that was not the case.

“There was a misunderstanding and I believe that the helicopter came into Wānaka to collect a member of the Aoraki ACR team,” she said.

“Although not part of SAR, Thomas was well known and respected with the guiding and mountaineering community in Wānaka. Our thoughts are with his family at this sad time.”

Mountain Safety Council (MSC) chief executive Mike Daisley said this time of year is the busy mountaineering season, with many climbers heading into the mountains.

“Recent fine weather has drawn many mountaineers to the high alpine, with multiple guided and recreational teams summiting Aoraki/Mount Cook over the past week,” he said.

“Current conditions on the mountain are considered ideal for mountaineering, with firm overnight snow conditions and well-filled glaciers following early spring snowstorms.”

In December 2024, three climbers, including two guides from the United States and Canada, died while climbing Aoraki/Mt Cook. Their bodies were never recovered.

“These mountaineering fatalities are a reminder of the high-consequence environment of our alpine mountains, especially our highest peak,” Mike said. 

“Mountaineering has very little margin for error. Even the most qualified professionals cannot eliminate all risk.”

NZMGA says a formal investigation into the incident will take place in due course.

“There will be an opportunity for the NZMGA to understand and share more about what happened in this tragic accident,” Anna said.

Both MSC and NZMGA offered their sincere condolences to the families of the deceased, and the wider alpine and guiding community.

A givealittle page has been created to support Thomas' partner, Danielle, and their two young children.