Spring skiing avalanche on Cascade Saddle
Two skiers who triggered a spring avalanche in extremely high consequence terrain on Cascade Saddle, Mt Aspiring National Park, were lucky to survive.
One of the skiers, Finn, shared his personal account with the NZ Mountain Safety Council (MSC) in the hope others will learn from their experience.
It was 1.15pm when me and my mate Cam were descending from Mt Tyndall via the Cascade Saddle Track in Mt Aspiring National Park on 7 November when we triggered a loose wet avalanche in extremely high consequence terrain.
We arrived at Aspiring Hut on 6 November at about 11pm. Cam, another mate Richie, and I went over our intentions for the next day of skiing. We reviewed the weather and avalanche forecast and did a practice with our transceivers. There had been a recent snowfall the day before, and we assumed multiple natural loose wet slides following this snowfall, given temperatures had risen.
The Aspiring region avalanche forecast on the NZ Avalanche Advisory for 6 November was moderate (danger rating 2 on the 5-point scale), noting the loose wet risk. We assumed the next day would also be moderate with the same risk factors given the weather was similar to the day before. Unknown to us, the danger was downgraded to low on 7 November.
We left the hut at 4am planning on arriving at the snow line on sunrise. Our objective was to ski Mt Tyndall and the Isobel Glacier via the Cascade Saddle Track.
The snowline was about 200m below where the Cascade Saddle Track meets the ridge. The snowpack was thin and had a thin crust, and it was relatively ‘fluffy’. About 40% of our steps were not penetrating the snowpack more than 15cm, meaning it was firm; and the rest would break right through up to our knees or mid-thigh, meaning it was soft. About 20 minutes into walking up the snow, Richie decided to turn back. He was uncertain about any loose wet risk as his heavier bodyweight was impacting him more in the soft snow and he felt he had a higher chance of triggering a small loose wet avalanche in, what we perceived as high consequence terrain.
Cam and I were feeling really good and had a chat about the conditions. We decided while it was steep and fairly high consequence terrain, we could mitigate the risk by returning back through the section below the ridge early, skiing fast through it to the safe points, such as the tussock islands, and by skiing on the avalanche debris line from yesterday. We also knew any loose wet would be slow to trigger and would likely be below the skis.
There had been two loose wets from the day before on our ascent line that we could see. Cam and I hit the ridge at 8:40am in blue bird weather. On the ridge, the snowpack was much more consolidated, and our boots never went into the snowpack below 15cm. We saw a few loose wets from the day before on the opposite face – the east facing, same aspect as Cascade Saddle. We decided we were feeling good for the summit and set a hard deadline turnaround time for midday. We made fair progress skinning up and summited at 11:50am.
The snowpack along the entire ridgeline to the summit was consistent and felt very secure. There was no avalanche debris on the entire route up the Isobel Glacier, and the only debris we crossed was right at the start. We gave ourselves an hour and a half to ski down having set our midday deadline based on the fact we didn’t want to ski the ‘crux’ section of the descent, where we had identified the loose wet risk, after 1:30pm.
We had a fantastic ski back down to the pylon on the Cascade Saddle Track. At the pylon we had another assessment of our descent. We hadn’t seen any roller balling on the face we planned to ski or our previous route, or any loose wets on the same aspect on other faces.
It was only a short descent to the end of the snowline, around 200m of which there were two spots of high consequence terrain we planned to ski through quickly. We planned our route with safe zones and decided to proceed with Cam to ski first.
Only 10m into the first ski, Cam triggered a size 1 loose wet avalanche. He stayed calm and skied straight to the safe zone just managing to stay out of it. It went slowly but really picked up momentum as it went. We both watched as a ton of snow slid off the Cascade Saddle cliff below us. This is the exact same point there have been multiple fatalities. We were both calm and safe but obviously in fight or flight mode. If Cam had been a few metres to his left when it went, or had he made a turn a second earlier this could have been a different story.
At this point, we assessed the situation and had five options.
- Continue our ski out. We knew we could ski the line of the avalanche debris relatively safely. However, we still had around 200m of similarly high consequence terrain to cover, and although it wasn’t quite as bad, it was the same snow and conditions the avalanche had run on. We decided this wouldn’t be safe.
- Find another descent path. We had scouted other descent routes on the way up and tried to find areas we could scramble down tussock or rock. However, we couldn’t find a route where we didn’t have to cross the same face where we had triggered the avalanche. If we had gear to abseil, we might have been able to manipulate the snow below us if we were fixed on a line. However, it would have been very difficult to build a strong snow or rock anchor here even if we did have the gear, plus neither of us were confident enough with that snowpack type to control it.
- Build a snow cave and try again the following morning. The snow wasn’t deep enough for a snow cave and we would have had to walk back up to the glacier to dig one. We could have just dug a pit but there was rain forecast that night. We also thought the avalanche danger wasn’t going to fall that much if it did rain.
- Walk out the Dart Valley. We were very close to choosing this option, but we were shaken up and didn’t have any overnight gear or more than a snack bar or two between us. We also saw another loose wet had naturally released right on the path out to the Dart Valley that day and rain was forecast. In hindsight, carrying an emergency shelter and a little extra food would have been helpful and potentially made this option a more realistic choice.
- Call emergency services.
So, we decided our safest option was to call for help. Since we were in the National Park, we had to call emergency services and we couldn’t ask for a recreational pickup from a helicopter company.
We went over all of our options together and while our lives weren’t in immediate danger, we decided the risk for us was too high, so at 1.50pm we sent an inReach text to my dad to ask for a non-urgent pickup. I really didn’t want to choose this option as we have heard many stories about people taking advantage of the amazing search and rescue services we have in New Zealand. But in the end, we decided this was the only safe option for us to get home.
Due to the rain and cloud forecast for that night, they came relatively quickly, and we were picked up from the Cascade Saddle Track at about 3.30pm.
Upon reflection of the trip
In New Zealand, we are so lucky to have such competent, fast-responding emergency services for the backcountry. It’s incredible they are a free service. We will of course donate generously to LandSAR following our rescue as we are incredibly grateful for their help. Our Garmin inReach was also critical. It allowed us to pass on all of the details to search and rescue and the NZ Police, and importantly communicate our situation was non-urgent.
I have been following the NZ Avalanche Advisory all year, checking every couple of days and have learnt so much from this amazing public service as well. Hopefully this story can contribute to their exceptional work.
Upon reflection of the trip, I have been going over all the options and talking them through with others more experienced than me. What decisions should we have made differently? What did we do wrong? Should we have turned around on the first snow face? Should we have walked out the Dart Valley? Of course, there are always things you could do in hindsight, such as having an emergency shelter and some extra food, but in balance I am confident we stayed calm and made the right decisions in the moment.
One of the assessments we could have done better was on the snowpack warming speed. The snow that avalanched was under cloud the entire morning until 30 minutes before we skied it, despite us being in bluebird conditions. We thought this would be the same, or less risk than direct sunlight, but upon discussions post-rescue, we learnt we got this wrong and that the shallow snowpack would warm up faster under cloud. I am not sure if this would have changed our decisions but is one of the many things we learned that day!
We can’t articulate how grateful we are to LandSAR, NZ Police and Alpine Heli for the rescue, and the NZ Avalanche Advisory and NZ Mountain Safety Council for the avalanche forecasts and backcountry safety information.
Stay safe out there team!
MSC's recent research project Above and Beyond, believed to be a world-first, explored the culture, behaviours and attitudes of the New Zealand mountaineering community towards avalanche safety.
The analysis of avalanche fatality data from 1999 to 2018 confirmed there have been 27 avalanche fatalities in Aotearoa, with 19 (70%) of them involving mountaineers.
The research team identified 16 recommendations aimed at improving avalanche safety amongst the mountaineering community, including increased information sharing and more open and regular dialogue amongst the community.
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