Know the ‘no risk’ zone for off-piste skiing!
There are very few quick, simple and accurate rules when it comes to off-piste and avalanche risk management. Indeed, most of the time we advise you to avoid going on automatic quick and simple rules because they are not always accurate and can be dangerous traps (even if they work most of the time). For example, it is dangerous to base decisions simply on the presence of trees on a slope – or to take people and tracks on a slope as signs of stability and safety. It’s been shown that most avalanche accidents could have been avoided if the victims had not let their impulses lead them down the path of such attractive quick, but often inaccurate opinions or justifications.
However, it is now accepted as a simple basic rule that no avalanche of any consequence to you will release on a slope less steep than 30°. This means that if you’re in an area with no slopes of 30° steepness or more around you, below you or above you, you are in a ‘no-risk’ avalanche zone.
A 30° slope is about the equivalent of the steepest part of a red run to ‘normal’ part of a black run in European ski areas. More precise, in the video below, you can see how to do a simple test with your poles to get a very close approximation of a 30° steepness reference point on a slope.
Most official survey maps now outline the slopes of 30° and more to help ski tourers and mountaineers plan their routes using this reference (e.g. French IGN maps).
In summary, this rule is very helpful as a point of reference for us all: non-professionals and professionals. That is why it’s the first point on our Framework.
Making that decision to go steeper than 30° is an important one. It needs to be validated by evidence based on facts, for example by the other points on the Framework.
For non-professionals: Sticking to slopes of 30° and less is a good, clear limit for you to stay in – a safe zone – while you are learning.
For professionals: It’s a good reference point in your decision making process. Ask yourself if you are deciding to go steeper because of clear facts which you have discussed. Or are you moving steeper just because your clients want, or you think they want, you to take them onto more challenging terrain?
Remember: you can have a great, successful day on slopes that are less than 30°.
PS: I’ll be talking about this and more off-piste skiing subjects on this year’s ORTOVOX Off-piste Awareness Tour
PPS: Slush Avalanches. It’s worth mentioning that if you are going to Northern latitudes, such as around the Arctic circle: parts of Alaska, Scandinavia, Greenland, Northern Russia, Slush Avalanches can release and flow on low slope angles (even down to 5° or so). They are not complicated to understand or even to foresee, but you need to inform yourself about them because they can be a danger, especially at times when there is rapid warming spell near the end of winter. They are like flash floods made up of snow and water.