Avalanche Terrain Exposure Scale

/Avalanche Terrain Exposure Scale
Avalanche Terrain Exposure Scale 2019-10-31T09:32:00+00:00

CAUTION! The Aran Avalanche Centre of the Conselh Generau d’Aran provides information on the conditions of the snowpack through the Avalanche Danger Bulletin and on the terrain characteristics through the ATES maps, and declines all responsibility for the damages that may occur derived from the interpretation and/or use of this information by the users. This information does not replace training, experience and good judgment of users.

Following a serious avalanche accident in Roger’s Pass, Glaciers National Park, BC (Canada) in February 2003, Parks Canada and Avalanche Canada created and developed the Avalanche Terrain Exposure Scale ATES is a cartography that aims to help all winter mountain terrain users to assess the severity of the avalanche terrain in the trip planning . The three terrain classes – Simple, Challening and Complex – describe the degree of exposure to avalanches and their consequences.

The ATES zoning maps are obtained from the analysis of a set of terrain parameters at a given resolution that fails to assess the characteristics of the terrain at a slope scale. For this reason, ATES is not a navigation tool during the trip.

Simple Terrain
Simple terrain has exposure to low angle or primarily forested terrain. Some forest openings may involve the runout zones of infrequent avalanches, but there are many options to reduce or eliminate exposure.

Challenging terrain
Challenging terrain has exposure to well defined avalanche paths, starting zones, or terrain traps.Options exist to reduce or eliminate exposure with careful route finding.

Complex terrain

Complex terrain has exposure to multiple overlapping avalanche paths or large expanses of steep, open terrain. Here, there are multiple avalanche starting zones, many terrain traps below the open terrain and minimal options to reduce exposure.


The boundaries between the different categories of terrain are not an exact line, but there exist transition strips. This is shown in the maps as an area where the colors overlap in a width of 20 m.


Frequent Avalanche Paths

Areas where natural avalanches occur relatively frequently, especially with fresh snow or during melting due to rain or high temperatures.


Suggested Itinerary

Some of the many possibilities that the area offers.

 And in the Google Earth file you can find as well…


Advice for critical decision points

Point in the itinerary where you must decide which option to take according to the conditions and the group. Clicking on a critical decision point displays a set of specific advice for that particular point.


Main summits in the mapped areas.


Huts and shelters



Most common parking spots for the suggested itineraries