Lesson 1: Avalanche Survival and Mortality

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Understanding trends and common characteristics of avalanche incidents allows rescuers to develop strategies and procedures that will help maximize survival chances in avalanches. Today, 90% of avalanche fatalities involve people who are recreating in avalanche terrain.

Factors Influencing Survival and Mortality

Causes of Death. The Primary causes of death in avalanche incidents are:

1. Asphyxia (75%) – from a compromised airway in full or partial burials.
2. Severe trauma (24%) – from hitting trees/rocks or being pushed over cliffs.
3. Hypothermia (1%) – from burial length surrounded by snow, or from exposure to cold air. 

Burial Depth. Over 80% of avalanche fatalities are from full burials. The chances of survival are also decreased greatly if the victim is buried 100 cm or greater (<10% at >200 cm).

Terrain and Vegetation Factors. Terrain and vegetation factors significantly affect the potential for death from trauma and the probability of and depth of burial. Some of these factors include:

• Trees and forest density
• Rocks and cliffs
• Lakes and creeks
• Gullies, crevasses, and depressions
• Slope incline and aspect

Environment Factors. Environmental factors showing to affect mortality rates in avalanche burials include:

• Snow Density: Full burials in denser snow leads to higher mortality rates. Snow densities can differ depending on climate and season.
• Air and Snow Temperature: Colder temperatures and full burials lead to a higher probability of hypothermia.

Reducing the Likelihood of Consequences in an Avalanche

Protect Against Trauma:

• Use protective devices such as an avalanche airbag, helmet, and spineguard

Reduce Burial Depth:

• Use an avalanche handbag
• Use releasable gear
• Swim and fight to stay on the snow surface

Reduce Burial Time:

• Use avalanche rescue gear efficiently (transceiver, probe, shovel)
• Shorten evacuation time once located (shovelling technique and equipment)
• Limit number of people exposed to avalanche danger (allows for more rescuers)

Maximize Chance of Survival if Fully Buried:

• Create an air pocket (manually, or with an airbag)
• Use an AvaLung
• Stay calm and conserve oxygen (Easier to do if everyone is well trained)

Avalanche Rescue and Survival Equipment

Avalanche Airbag. Airbag technology is based on the principle of inverse segregation. Avalanche victims who wear and successfully deploy an airbag are more likely to remain on or near the avalanche debris surface, thus reducing burial depth significantly and allowing for rapid intervention.

AvaLung. AvaLungs allow buried victims to draw oxygen from the snowpack through a mouthpiece, and expel carbon dioxide behind them. This reduces the chance of the victim rebreathing carbon dioxide for up to 60 minutes. With normal CO2 levels, subjects are less susceptible to asphyxia and hypothermia.

Helmet. Helmets offer important trauma protection from trees, rocks, and debris.

Transceiver (457kHz), probe, and shovel. Burial time is directly linked to survival; the choice to omit any of these items will severely impact rescue response times. The following list highlights average rescue times by an individual rescuer with various combinations of equipment for the complete extrication of a subject buried 1m deep:

• Transceiver, probe, and shovel: 11 minutes
• Transceiver and shovel: 25 minutes
• Transceiver and probe: 51 minutes
• Transceiver: 1-2 hours

Communication Device. Communication devices such as cell phones, VHF radios, satellite phones, and other two-way satellite communication devices are critical for initiating a rapid and effective AvSAR response. Each of these devices have their limitations; anticipate and plan for them prior to use in an emergency.

Roles of Responders

Onsite Responders. Onsite responders may be members of the involved group, members of a nearby group that witnessed the incident, or members of a responding ski-patrol.

Onsite responders must be proficient in all aspects of companion rescue, contacting and communicating with external responders, be adequately fit, possess the appropriate mindset to function well in an emergency response, and always maintain situational awareness in an AvSAR.

External Responders. External responders are called to an incident as needed to assist with search and rescue efforts. They may include the following:

• Avalanche Dog Team
• Helicopter Sling Rescue Team
• RECCO Searcher or Heli-RECCO Team
• Physician
• Paramedics
• Police
• Coroner/Medical Examiner
• Investigator
• Military
• SAR Technicians

The AvSAR Plan

Agencies and organizations that have workers exposed to avalanche terrain or that may be called on to respond to an avalanche incident must have an AvSAR plan in place. The objective of the AvSAR plan is to provide guidelines for organizing and coordinating various resources and agencies in the event of an avalanche incident. The plan is specific to each agency and organization. All responding personnel must be informed and trained in all aspects of the plan. The plan should be practiced at least once a year.

An AvSAR plan includes:

• Clear and simple directions if an avalanche incident is reported.
• Expectations, roles, and responsibilities of staff/volunteers.
• Priority actions for the various stages of the rescue response.
• Prompts for a dispatcher and/or initial responders to ensure that all details are included.
• Complete list of internal and external resources with up-to-date contact information.
• Call-out lists of key AvSAR personnel (in order of priority).
• List of available equipment resources with specific locations.
• Methods to track all resources that have been contacted, and are on standby, responding, or waiting for assignment.
• Demobilization plan.

Steps of an AvSAR Plan. Following these steps ensures that all rescue components are included, and that a safer, more efficient, and effective response is facilitated.

1. Record Incident Details. The information gathered from a call for assistance should accurately describe what occurred. This allows responding personnel to analyse the incident’s chain of events, determine appropriate actions, and assess which resources are needed immediately and which resources may be needed in the future.

The initial incident details are recorded on the Initial Avalanche Report Form, which must be readily available in the field books of all AvSAR Personnel.

In addition, a Communications Log is needed for documenting the chronology of information flow as the rescue is initiated and carried out.

2. Initiate Response/AvSAR Plan. A communication plan that contains protocols for contacting rescue personnel and additional external resources. These protocols are followed to ensure that all parts of the rescue are coordinated and run smoothly.

The person who records incident details must immediately contact the designated person, such as the Search Manager or Incident Commander, and clearly convey the reported information. This person then decides on the appropriate response level and resources needed, and addresses initial responder safety concerns. The dispatcher or personnel assigned to contacting resources and initiating the rescue plan must alert rescue personnel and resources in order of priority.

3. Determine Response Level. Not all incidents require the same level of response. The response level is determined by the Incident Magnitude and Complexity Table: