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Avalanche perspective from a heli-ski guru.


Here is a photo I took of an avalanche encounter that turned out just fine, but it was not part of a guided program and we ended up where we should not have been.

While skiing at CMH Revelstoke last week, the guides let us know, in no uncertain terms, that the avalanche conditions were very unstable.  We found ourselves ripping run after run of awesome powder, but the guides directed us exactly where to ride, chose terrain conservatively, and explained much of their thought process to us skiers and snowboarders.  However, I know there is much more going on behind the scenes so I asked Colani Bezzola, the Mountain Safety Manager for CMH and a 36-year veteran heli-ski guide, to share some insights into the system CMH uses to keep us safe out there.

TD: Most of the time while heli-skiing, we meet the guides, go skiing all day, and rarely do we see them dig pits or do much obvious snow stability testing while skiing.  Why is that?

CB: While guiding, we continuously observe the mountain, present and  recent avalanche activity, the weather,  how the snow reacts while skiing and while standing in it or while approaching certain terrain features. While guiding a group of skiers we may look at the surface snow layers and do some quick surface stability tests by ski cutting on top of rolls and by digging a quick test profile. Many of these actions and observations occur continuously even if they are not obvious to you. Being aware of your surroundings and elements is how guides stay alive during a life in the mountains. 

TD: So how do you fit more extensive snow profiles into the high-speed heli-ski program?

CB: To do more extensive snow profile observations and tests we need a bit more time.  On any given day, one guide in each area is designated as Snow Safety Guide.  He doesn't guide a group that day and dedicates his time in the field to check out terrain, runs, snowpack layers and changes with full snow profiles while also doing stability tests.  He may do avalanche control and testing with explosives, look for wind-transported snow, wind loaded pockets, and check out the skiing quality in terrain that we may not have visited for a while.

TD: From what I can tell, the guides feel that just because they bomb something, it is not necessarily safe to ski.  A bomb is pretty violent.  How could a slope slide on a skier after not sliding under the force of a bomb?

CB: We do very limited and selective avalanche control and testing with explosives compared to ski areas or road avalanche operations. Mostly we use explosives to protect helicopter landings and pick ups and remove potential avalanche threats that may run into skiing terrain.
  If we deploy explosive charges on a slope and it doesn’t slide, the questions always remain:

  • Have we applied the trigger (explosive) to the right spot?
  • Have we "tickled" the weakness, the "sweet spot"? 
  • How deep is the potential unstable layer and how stiff is the slab over it? 

If we cannot answer all these questions completely after a slope resists an explosive trigger, we tend to decide on the side of caution. From experience we know of avalanches that occurred naturally sometime after we deploy explosive charges, and without obvious additional trigger; as well as incidents where skiers (additional triggers) have found the "sweet spot" near places where explosives had been applied recently.

TD: Wow, snowpack is a feisty critter.  Can you briefly describe how CMH guides observe and record ongoing changes in the snowpack?

CB: All avalanche, stability tests, snowpack, snow profile and weather observations, hazard and risk assessments are captured in CMH's "SnowBase" database system, shared between all our heli-ski areas, which allows the guide teams to monitor, track and recall the developments in the avalanche, snowpack and hazard history for the winter and gives them a collective tool to help make the appropriate risk management decisions on a daily, run-by-run, and pitch-by-pitch basis.

TD: If somebody is interested in snow science and avalanche forecasts, can you suggest resources for them?



Backcountry Avalanche Awareness  Jamieson, Bruce. 1989, rev. 1997.  Canadian Avalanche Association. Revelstoke, Canada.

Free Riding in Avalanche Terrain, Jamieson, Bruce & Jennie McDonald.. 1999.  Canadian Avalanche Association. Revelstoke, Canada

The Avalanche Handbook,  Dave McClung and Peter Shaerer, 1993. Third edition, 2006.  Available from Mountaineers Books 

Snow Sense, A Guide to Evaluating Snow Avalanche Hazard,  Jill Fredston and Doug Fesler, 1994,  The Mountaineers, Seattle, WA.

Staying Alive in Avalanche Terrain,  Tremper, Bruce. 2001. The Mountaineers, Seattle, WA. 

Web Links:

Canadian Avalanche Centre

University of British Columbia Avalanche Research Group - central site for international avalanche information centres. 

Cyberspace Avalanche Centre

Northwest Weather and Avalanche Center

Colorado Avalanche Information Center

Utah Avalanche Center


Hey VirginiaSkier, 
Rob Whelan follows avalanche beacon technology for CMH. In his spare time he is a guide at CMH Kootenay. He had this to say regarding your question: 
The new Orthovox 3+ beacon should be hitting the market any time now, and there is a lot of excitement about this new offering from one of the industries leading players. 
The 3+ expands on the functionality of the S1 - the Flip-Phone styled device released in 2007-2008. Personally, I found that while the S1 could perform as promised, the physical package and the bewildering array of icons never impressed me. It could manage multiple burial situations up to 3 burials, but beyond that it struggled, and the user was forced to return to a strategic search strategy (Micro search strips or equivalent). 
A lot of R&D went into the S1, but I have not seen it widely used in Canada - possibly due to price and likely also due to stiff completion from the Barryvox Pulse. The S1 platform is what has lead to the 3+ with some interesting additional features. 
The feature that makes this device so "findable" is that it has internal sensors that sense the orientation of the antennae. The worst-case scenario for a searcher is when the buried beacon's antenna is in a vertical orientation. Range is reduced, and pinpointing can be difficult. Since the antennae in the 3+ are orthogonal (at 90 degrees to each other) there will always be one antenna that has a better orientation relative to the surface. The 3+ uses the antenna with the most favorable orientation as the transmitter. Great idea. 
I have not had a chance to test this device yet, but it is an intriguing concept and theoretically should work. My concern would be that since there is limited space in the shell of the beacon to place two antennae, and the laws of physics dictate that the longer your antenna the better your range will be, that they have had to compromise on the overall range to make this work. Most beacons have one long antenna that is the transmitter. 
The disappointment with the 3+ is that is does not incorporate a second high speed data channel, such as is found in the Pulse. This technology dramatically improves the performance of multiple burial searches and allows for the devices to work in a networked environment. 
I suspect that this second high speed data channel will become a standard feature of future generations of avalanche transceivers. Right now, since there is no accepted standard for the data transfer protocol, it remains a proprietary feature of the Barryvox Pulse. Look for this to change in the future as the manufacturers battle it out over various solutions - the VHS / Betamax equivalent in the Beacon world. 
I'm looking forward to trying the 3+ in the field. CMH always has a beacon training session with the guides. As you can imagine, you get 100 of the world’s best heli-ski guides together and there will be some serious testing going on. Guides are fussy about their beacons. 
Stay tuned. 
Posted @ Saturday, October 02, 2010 8:55 AM by Topher Donahue
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