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Strategic Digging - Avalanche Rescue

Shoveling is the slow part of an avalanche rescue. Practiced rescuers with modern transceivers and probes can often locate a buried a victim in minutes, but then the hard part of the extraction (digging) begins. Without a strategy it usually takes more than 15 minutes to extract someone buried even a meter deep – especially if the snow is hard. And non-strategic digging often requires more than an hour to extract a victim who is two meters under the snow.

Yet the 15-minute mark is an important benchmark. The most quoted research from Europe derived its stats from 422 buried victims and suggests that about 90 percent of the people buried for less than 15 minutes can be revived (CPR  may be necessary). After 15 minutes, survival rates drop precipitously with only about 30 percent of the victims surviving after 35 minutes. Those who live longer than 35 minutes almost always have an air pocket that sustains them and the European stats show that 20 percent of these victims will still be alive after 120 minutes. Then comes the final plunge with only 5 percent of those buried surviving past 130 minutes. 

Put this together with the fact that brain damage often starts to occur after 10 minutes, and the need to find and uncover avalanche victims really, really fast cannot be overstated. Every minute counts. It’s important to locate a victim quickly, hence the importance of practicing with your transceiver (the newer digital transceivers are easier and faster to use) and pinpointing the victim with a dedicated probe (3-meters long probes made of quality aluminum or stainless steel are recommended). This being said, drastically shaving time from the digging process is where you’re most likely to save lives.

Last year, we posted information developed by Bruce Edgerly and Dale Atkins about strategic digging. This article is good information to review as an introduction to the digging topic. Also, watch this strategic digging video. Key points about this version of strategic digging:

  • Leave the probe in place. Starting on the downhill side of the probe and from a distance that’s 1.5 times the burial depth, dig in toward the probe.
  • Initially kneel down and throw snow sideways rather than downhill. This ‘starter hole’ (which is really more of a terrace) should be about as wide as your wingspan (a tad wider if two of you are shoveling side by side) and should create a terrace that takes you about half way to the probe. Stand up as the terrace gets deeper, and keep digging and throwing snow to the side until the hole (terrace) is waist deep. 
  • Now start digging out the rest of the area between you and the probe. Rather than moving this snow to the side, throw it downhill beyond the starter hole you’ve already created.
  • If there are two diggers, you can greatly accelerate the time needed to reach the victim. There are different techniques but the video above shows a simple, effective strategy. Have the two shovelers start downhill of the probe with the back shoveler working at a distance of 1.5 the probe-strike distance downhill of the victim and the front victim working more immediately downhill of the probe. Both shovelers should throw snow to the side until their respective holes are waist deep. At this point the front shoveler starts throwing snow on the back shovelers terrace and the back shoveler throws it downhill.
  • Upon reaching the victim determine how you’re going to uncover the head and face as quickly as possible.

We’ve learned of improvements on the digging front that speed-up recovery by using the V-Shaped Snow Conveyor.  A December 1, 2010 article from Earn Your Turns, states the strategic digging techniques developed by Edgerly and Atkins have been a major improvement but, “they could not report on average excavation times since these varied between 15 and 40 minutes based on the shovelers conditioning and motivation.”

However, Manuel Genswein, a long-time instructor of professionals working in the avalanche rescue and avalanche prevention fields, developed an improved technique, and has quantified excavation times around the Snow Conveyor Method. In ‘rock hard’ snows, average excavation times for burial depths up to two meters was under 20 minutes. These times were based on rescues in very hard snows and using people of different gender, age, and physical conditioning. The article concludes, “With times like that, if you’re buried and your friends utilize this method, you stand a fighting chance of living.”

Additional resources:  Read an even more detailed article about this technique by Manuel Genswein.

Manuel Genswein also derived information about commonly used backcountry shovels and how those shovels fared cutting into hardened avalanche debris. Specific shovels made by Black Diamond, Ortovox, Mammut, G3, Stubai, Pieps, Backcountry Access, and Voile were tested and only shovels using 6061 alloy and T6 heat treatment of the aluminum withstood the abuse of continued chopping through hard and frozen snow. Most of us skiing and snowshoeing in the winter are most concerned about performing a companion search immediately after a slide and before the snow has refrozen...so we may not need shovels quite to the standard Genswein recommends. Then again, when the lives of friends and loved ones are at stake, maybe we should have complete confidence in our shovel's ability to handle all snow condition. We'll discuss these shovel findings and try to put them into more context in an upcoming post.