Monday, July 5, 2010

An ‘unlucky’ winter

[Reproduced from the May 2010 issue of Wilderness Magazine]

The winter of 2009 saw the Southern Alps’ backcountry cloaked in some of the best snow seen this millennium. But the siren song of all that untracked powder belied what was often a very well hidden trap – and for too many people, a lethal one.

The season had begun spectacularly in May with over a metre of snow falling and surprisingly staying . Skiers across the country were understandably elated. Many simply couldn’t wait and resorted to hiking up the as-yet unopened ski resorts for some of the best skiing of the season; light, dry shin-deep powder under bluebird skies – before winter had technically even begun.

However, according to Mountain Safety Council spokesperson Hamish McCrostie, it was that six week stretch of bluebird days that followed that were to haunt backcountry users.

“That sustained cold weather makes the snow weak; it turns it sugary. Then once you get a bit of snowfall or wind-deposited snow on top, that weak cohesionless snow just acts like ball bearings,” he said. “When you get enough weight on it, the snow on top will release and the whole lot will run down hill.”

The question is how much is ‘enough weight’? Depending on a host of terrain variables like steepness, curvature, rockiness, elevation and angle to the wind, any particular slope could accumulate differing amounts of snow that would stress the buried weak layer by different amounts.

Over the course of the winter, some slopes would avalanche spontaneously under the weight of new snow; others would bond together with the warming influence of the sun. But a lot of slopes would lay waiting for some external force to set them in motion. On July 24, a party of four heliskiers enjoying feather-light fresh powder in the Ragged Range would provide precisely that force.

Llynden Riethmuller, John Castran and his son Gus were on their last run of a day heli-skiing, when as Castran puts it, the snow “just opened up around me”. They’d overloaded the weak layer.

As they rode the disintegrating slab of snow downhill, two more slide paths released nearby, culminating in a triple slip that overtook the skiers. Riethmuller was buried under half a metre of snow and Castran almost two metres deep.

The two men, who were both wearing avalanche transceivers, were quickly located by their guides. Castran survived and was skiing again the next day. Riethmuller died at the scene, possibly due to a pre-existing medical condition.Earlier in the day he had reportedly exclaimed: “You don't get much closer to heaven than this.”

Less than 24 hours later snowboarder Sam Deavoll set off from the Remarkables ski area, past an avalanche advisory sign showing the danger as ‘High’, to ride a backcountry chute above Lake Alta, ominously named ‘the terminator’.

As he dropped into the chute, his weight overloaded the same buried weak layer, releasing a massive avalanche. But, in what was aptly described by the Otago Daily Times as ‘the ride of his life’, he somehow managed to stay ahead of the debris as it ran the full length of the slope and out onto the lake’s frozen surface.

A few moments later the weight of the avalanche debris broke through the thin layer of ice. If Deavoll had been caught up in the slide he would have almost certainly gone to the bottom of the lake making it two fatalities in two days.

Nine days later on August 2, after another storm cycle dumped 75cm of fresh snow, further stressing the snow pack, brothers Frazer and Ryan Campbell traversed from the Coronet Peak ski area boundary, after also having seen an avalanche advisory sign showing the danger as ‘High’ for a twilight run down Dirty Four Creek. Neither was wearing an avalanche transceiver or carrying shovels or probes. By their actions it could reasonably be assumed neither had attended any sort of avalanche education.

As the pair descended the bowl they triggered a medium sized slide, setting around a thousand cubic metres of snow cascading towards the valley floor. Miraculously Frazer managed to stay clear of the debris, but Ryan who was ahead by three metres was carried down into a tight gully and deeply buried. It took a team of rescuers two hours working under floodlights (at some risk of further avalanches themselves) to find him.

After a post-mortem of Campbell’s body, Otago-Southland coroner David Crerar said his death was a result of “severe respiratory failure due to extensive severe chest and lung injuries caused by the massive weight of snow and ice in the avalanche and had been determined to be not survivable and almost instantly lethal.”

Campbell’s parents said Ryan was a victim of bad luck. He’d been “in the wrong place in the wrong set of circumstances” and was “a thrill-seeker, not a risk-taker”.

By this stage many of the more educated backcountry skiers and boarders were opting not to ‘risk take’, or ‘thrill seek’, or go into the backcountry at all for that matter. Despite that, there were still more incidents to come.

By August 14, the avalanche risk finally dropped a little and was listed by the Mountain Safety Council as ‘Moderate’ in the Ragged Ranges when Johnny Morgan, who had been hailed as a hero for his swift work rescuing the survivors of the July 24 slide, set off for a day’s heli-skiing with four clients.

While investigating a run, Morgan was hit by a small slide and swept down a steep gully. Despite being only partially buried, and receiving immediate medical treatment Morgan would succumb to the injuries incurred in the tumble. This slide, Morgan’s second for the season, would be described by survivors as ‘a freak accident’.

Three days later another group of heli-skiers on the Richardson Mountains would be caught out, with one client buried two metres deep. The skier was immediately dug up and flown to Queenstown Lakes District Hospital suffering from hypothermia but alive. Statistically speaking the likelihood of surviving a burial that deep is about one-in-four.

The tragic deaths of Llynden Riethmuller, Ryan Campbell, and Johnny Morgan and the spectacular near misses were well publicised but they were by no means isolated incidents. The Queenstown region in particular recorded 18 involvements that caught or buried 10 people - and that’s just the ones that were reported.

With the popularity of backcountry pursuits growing each year, there is a strong impetus to figure out what’s going wrong and to prevent a repeat in 2010. As you can imagine, there’s a lot of theories out there.

As this goes to print, last year’s fatalities are still the subject of a coronial inquiry with recommendations expected some time in July. If there’s a repeat of last year’s snow conditions that may be too late for some people.

There’s heated speculation regarding the heli-skiing incidents under the watchful eye of experts. The cynical point of view says some guides are becoming blasé about the risks and some operators are bowing to commercial pressure to take people on steep, deep slopes, when they’d be safer on more mellow terrain – or in the pub.

On the other hand, industry insiders point to the fact that the mountains will always present a certain level of hazard and that statistically even if you eliminate 99% of the risk, the 1% will eventually catch up with you if you spend enough time out there. In the case of some heli-skiing operations that’s several decades.

The situation regarding amateur backcountry users is equally complex. A culture has developed in many parts of the alpine sports community that is prepared to hike for steep untracked snow, just outside of the resort boundary, operating under the misconception that near the resort is nearly as safe as the resort.

However, as Treble Cone Operations manger Rosco Davies puts it, “Once you step outside the boundary, you’re into the Stone Age,” he says, “It might be only forty steps past an arbitrary line, but that makes the difference between controlled and uncontrolled – and that can be the difference between safe and dead.”

Numerous avalanche involvements in this resort-adjacent backcountry are leading to resorts considering a North American approach to boundary management, where ski resort boundaries are policed. This would be quite a big change for New Zealand which has long tradition of free and unrestrained access to the backcountry.

McCrostie says, “Resorts are unlikely to restrict access to the back country.” However he cautions, “Some may choose to limit access options by erecting fences with gates and providing much more ‘in your face’ information at those access points”.

In fact, Wanaka’s Treble Cone ski field already has its backcountry gated and it closes that gate on days with high or extreme avalanche danger. Last season no avalanche involvement occurred at the field.

Treble Cone is fortunate in having only one main access point to the backcountry; other ski fields have dozens.

Davies says another way to improve things might be to look at New Zealand’s five-step avalanche warning system. He says experts, like American Bruce Tremper are suggesting a two-part scale that gives one rating for the likelihood of releasing a slide, and another for the consequences if you do.

“While the likelihood of setting off an avalanche last winter was reasonably low, if you did set off one it was very large, and probably not survivable,” he says. “Other years we can have a higher hazard where you’re pretty likely to release an avalanche, but if you do they’re only five or ten centimetres deep - something that might take you for a scary ride but you’ve got a good chance of surviving uninjured.”

A system that covered both factors would give people a clearer understanding of what they’re letting themselves in for, but it does assume that people will actually look at the warnings - unlike in the cases of Deavoll and Campbell.

A salient point in avalanche incidents is the misattribution of ‘luck’ in media coverage. People who avoid avalanches are ‘lucky’. People caught have had ‘their luck run out’, or were ‘at the wrong place in the wrong set of circumstances’, or were involved in a ‘freak accident’.
All of which runs against the seemingly obvious reality that luck is not what keeps you alive in avalanche terrain; making the right decisions is. As McCrostie puts it, “If you make good decisions, you make your own luck.”