The Reduction Method

The Reduction Method is a way to assess winter avalanche danger. Its author is the renowned avalanche expert Werner Munter of Switzerland. It consists of a practical aid which we can use when planning winter hikes. While it can sometimes seem that the Reduction Method is too complicated, in reality it involves nothing that can be managed using common human effort. In its most basic version it can be used easily and at any time during a hike. A necessary condition is to have enough information and to consider it in advance using a 3-level approach (“the 3×3 filter”). The essence of the Reduction Method is a simple balance of negative and positive factors of the natural environment and human behaviour in it. If on one tray of the scale we put some negative, undesirable factors, then in the second tray we have to add some positive, protective factors, that can divert the situation in a safer direction. With the reduction method a point value is assigned to certain negative factors during avalanche conditions, and in a similar way to positive factors as well. In the final balance the points are added up; the negative are placed as the numerator of a fraction, of which the positive are the denominator, and the outcome must be less than 1. Even a middle school student can handle such calculations.

What was relatively arduous and complicated was defining which elements should have how many points. Or, in other words, to define what is considered more important and what is less important. W. Munter had indeed quite a bit of work with this aspect, and had to carefully weigh all factors. He operated from the basis of statistical data from long-term observations and a range of mathematical models. In the end, however, this need not interest the common user. What is essential for the end user is to know how many points which elements have.

We have to connect the Reduction Method to the typical three-level approach to observing the situation (also known as the 3×3 filter). when we divide the situation of the hike into three levels, according to the operating distance from which we are viewing the situation. For a better idea, this process is often compared to the mechanics of a camera (zoom), where the photographer gradually goes closer to the scene. The first point of view (1x zoom) is typically named the “regional filter” (this is the “view from home”), the second point of view (2x zoom) is called the “local filter” (this is the “morning view from the lodge window”), and the third point of view (3x zoom) is called the “slope filter” (this is the “view from the event itself”). More on this in the Planning a Hike section of the book. In every one of these filters there is the possibility to apply the Reduction Method. The correct approach should lead us to assess the situation through the filter in which we are perceiving it, and then for us to apply the Reduction Method to the facts determined (that is, to assign the given point value and count points).

One negative factor as part of the Reduction Method is the announced level of avalanche danger. This is due to the fact that the lay public does not have instruments to specifically define the level of avalanche danger (even though methods exist for this, as a rule the messing about of a lay person in the snow is misleading and confusing and would introduce nothing but mistakes).

Here it is therefore necessary to use a reliable evaluation, and an evaluation carried out by a professional mountain rescue service is such. There is also the necessity to have this source of information available. This is one of the few limits of the Reduction Method – it can’t be used in non-civilised, exotic regions.

The Reduction Method is intended for European mountain ranges (Alps), where an international information system of avalanche warnings is available.

More in e-book.

Title Part 4Mountaineering Methodology – Part 4 – The Mountains

ISBN 978-80-87715-10-9

MMPublishing, 2013

Available for download from Apple iTunes (in the Books section).

For example U.S. store – link

Another countries – look on the page Download

See layout.

Another possibility is Google Play. This version is a simplified (as PDF).

Title Part 4 GPMountaineering Methodology – Part 4 – The Mountains

ISBN 978-80-87715-15-4

MMPublishing, 2014

Available for download from Google Play.