The deaths this week of two climbers on Aoraki/Mt Cook, and another pair on Sabre Peak in Fiordland, have further highlighted the dangers of mountaineering in New Zealand’s alpine environment.  Six climbers have been killed in the past four weeks across the two peaks, in a summer climbing season that is verging on New Zealand’s most deadly.  Last month, well-respected guide Thomas Vialletet and his American client Kellam Conover died after falling from the western slopes of Aoraki/Mt Cook while attempting a grand traverse of New Zealand’s highest mountain.  Vialletet was known as a highly skilled alpinist.  Only weeks before the accident, Vialletet had guided climbers across Aoraki’s demanding East Ridge in a 25-hour round trip from Plateau Hut. In a social media post, Vialletet believed it had been a decade since the route was last guided.  He died attempting to traverse one of the most dangerous routes on the country’s most dangerous mountain.    Thomas Vialletet. Photo / Supplied  A Givealittle page has raised almost $150,000 to support Vialletet’s partner Danielle and their two young children.  Two more climbers died on the north buttress of Sabre Peak, Fiordland, last weekend.  They were 28-year-old Connor Scott McKenzie, a dual citizen of New Zealand and Canada, and 23-year-old Australian citizen Tanmay Shetankumar Bhati. Both men lived in Australia.  The most recent deaths are believed to have been caused by an ice avalanche on Aoraki/Mt Cook. They had taken a route from Pinnacle hut, Linda Glacier, to the summit.  On Wednesday, search teams utilised a RECCO SAR detector, suspended under a THL helicopter.  “A visual investigation of this area has led to the determination that the overdue climbers have been caught in a significant ice avalanche within a known icefall hazard zone on the upper Linda Glacier,” said Inspector Vicki Walker, Aoraki area commander.   “Because of the scale and volume of material involved, we don’t believe this avalanche was survivable.”  New Zealand’s tallest peak Aoraki/Mount Cook at sunset. Photo / George Heard  The worst climbing season in recent memory was in 2015/16, when seven mountaineers perished. Since then, it has largely trended down, with four deaths in the past four seasons.  Since 2008, 15 climbers have died summiting Aoraki/Mount Cook. There have been six people who have died on guided climbs and seven on recreational climbs. It’s not yet clear which category the most recent deaths belong to.  Many who succumb are never found.  Sally Jones is operations manager at the Department of Conservation Aoraki/Mount Cook. Among her responsibilities is coordinating the search and rescue team.  “They’re consummate professionals and I’m incredibly proud of them,” she said. “We don’t work alone. For this response, we have been really well supported by the police. They’ve been in the room with us since we’ve built a profile and then as we executed the search as well. And we’ve been well supported by our pilot from the helicopter line.”    A SAR helicopter at Aoraki/Mt Cook. Photo / George Heard  Each search takes its toll on her team, who are laser-focused on achieving the best possible outcome. They are themselves experienced mountaineers, quite familiar with how Aoraki/Mt Cook can catch out climbers of all abilities.  Jones believes it is often underestimated, despite its reputation as New Zealand’s deadliest peak.  “I think it’s because it’s so accessible. You’re not trekking for days and days and days, going through base camps and acclimatising. You can be there fairly quickly. You can fly in and begin your climb within a day, a drive from Christchurch, potentially. And there are no issues with altitude.  “So I think a lot of people underestimate Aoraki because it’s accessible. It’s way more technically challenging than a lot of the well-known int...