Past Section Night content
Avalanche Awareness
On 22 June our Wellington Section Avalanche Educator, Aviette Musin, gave her annual Avalanche Awareness talk to a packed crowd at the Southern Cross. Her talk covered the following topics:
- the avalanche problem
- weather, terrain, snowpack and how these relate to avalanche conditions
- travel: decision-making about route selection and safe travel techniques
- understanding the NZ avalanche advisory
- trip planning and preparation.
A quick recap of the key points from the night:
- 90% of avalanche incidents are triggered by the victim or someone in the victim’s party.
- Slab avalanches are:
•A cohesive layer of snow that slides as a unit on the snow underneath.
•The most common type to be triggered by people and responsible for the majority of injuries and deaths.
•They tend to release once the victim or members of their party are on the slab, often breaking above and taking them along with it.
Slope angle is the most important factor in determining whether a slope may avalanche. Most slab avalanches are triggered on slopes between 30° and 45° with 38° being the angle most prone to avalanche. This is also the perfect slope angle to ski! Similar to a black run on a ski area. Aviette really hammered home the importance of getting good at estimating slope angle so we can recognise when we are in or going into avalanche terrain. Use an inclinometer when you are in the hills to practice and get your eye in. Aspect and altitude also impact whether a slope is likely to avalanche or not.
A useful thought process to cultivate is:
- “Is it avalanche terrain?”
- “Could it avalanche?”
- “What human factors are affecting our decisions?”
Studies into avalanche accidents have found that the victims often had the skills and knowledge to recognise the signs of unstable avalanche conditions but chose to go anyway. We need to stay alert to the human factors which lead us to make bad decisions.
Aviette covered how to move safely in avalanche terrain (spacing, visual contact, islands of safety, safe travel routes, communication and escape routes).
She was at pains for us to understand that a transceiver, shovel and probe are rescue equipment, not safety equipment i.e. having them on you doesn’t keep you safe. And if things do go wrong, you only have minutes to live if you are buried in an avalanche. If you are wearing a transceiver, you have a significantly higher chance of being found quickly, but only if the people with you know what to do. So make sure to practice, practice, practice… transceiver searching but also probing and shovelling techniques.
Aviette showed us around www.avalanche.net.nz and took us through the New Zealand Avalanche Danger Scale. Most people get caught or die on days with considerable avalanche risk. Moderate risk also requires skill to manage. Don’t go when the danger is high or extreme.
Compare it to the likelihood of being stabbed in a bar. Would you go into a bar if you had a low chance of being stabbed? How about a moderate chance of being stabbed? You’d probably think twice. Considerable chance? You’d probably go find another bar.
Trip planning (every trip needs a plan, even a short ski beyond the ski area boundary):
- Plan your trip: Seek local knowledge, plan the route you will take and the amount of time you can reasonably expect it to take.
- Tell someone your plans: Tell someone your plans and leave a date for when to raise the alarm if you haven’t returned.
- Be aware of the weather: Check the Avalanche Advisories at www.avalanche.net.nz and the local weather conditions at www.metservice.com
- Know your limits: Before you go, make sure you’ve selected a trip that’s suitable for you and your group. If you’re not sure about this then ask a local.
- Take sufficient supplies: Always carry a transceiver, shovel and probe – and regularly practise using them.
To learn more, check out the learning tab on www.avalanche.net.nz for online training, course providers and videos.
Aviette encourages following the weather and avalanche forecasts for several days in a row, as this is a great way to learn how the weather impacts avalanche danger.
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