Avalanche Balloon Packs Current Status at the Canadian Workplace

Transcription

1 Avalanche Balloon Packs Current Status at the Canadian Workplace August 2012 Principal Investigator/Applicant Pascal Haegeli RS2010-IG33

2 Avalanche Balloon Packs Current Status at the Canadian Workplace March 2012 Revised August 2012 Canadian Avalanche Association & Avisualanche Consulting (Pascal Haegeli) Project Number: RS2010-1G33

3 Acknowledgements We would like to thank everyone who provided the research team with information about the effect of avalanche balloon packs in avalanche involvements. Special thanks goes to the British Columbia Coroner Service and particularly Tom Pawlowski for their support of this research project. We would also like to thank all the avalanche professionals and operators who took the time to talk to us about their concerns and experiences with the operational use of avalanche balloon packs at their work place. Two anonymous reviewers provider valuable feedback to an earlier version of this report. This research was supported with funds from WorkSafeBC through the FOCUS ON TOMORROW program. i

4 Table of Contents Acknowledgements... i Table of Contents... ii Point Form Summary... iii Executive summary... iv Report... 1 Part I: Analysis of Canadian avalanche incident records... 3 Methodology... 3 Project findings/outcomes... 6 Part II: Examination of avalanche incidents resulting in worker fatalities...10 Methodology...11 Project findings/outcomes...12 Part III: Overview of concerns and operational experience within the professional Canadian avalanche community...15 Methodology...15 Project findings/outcomes...17 Implications for future occupational health research...22 Application for policy and prevention...23 Knowledge translation and exchange...24 References...26 ii

5 Point Form Summary Part I: Analysis of Canadian Avalanche Incident Records The data collection efforts resulted in 34 well-documented Canadian avalanche incidents involving avalanche balloon packs. Seventy-one individuals were significantly involved in these incidents; 46 (65%) of whom were carrying an avalanche balloon pack. A univariate examination of the complete sample showed that the use of avalanche balloon packs increased the survival rate among individuals seriously involved in avalanches by 27 percentage points from 56% for non-users to 83% for users. Additional factors affecting survival rates were avalanche size, elevation band, relative location of victim when slab released and whether victim was an avalanche professional or amateur recreationist. However, the small size of the dataset prevented a meaningful multivariate analysis to properly isolate their contributions. A qualitative examination of incidents where avalanche balloon pack users were fully buried and/or killed highlighted configurations where the effectiveness of the device might to be considerably limited (e.g., victims who were located low on the slab at the time of release; avalanches with terrain traps in runout zone). Part II: Examination of Avalanche Incidents Resulting in Worker Fatalities Since the winter 1996/97, there have been eleven worker fatalities in Canada. A primarily qualitative assessment of the incidents indicated that the use of an avalanche balloon pack might have been able to prevent or reduce the severity of the involvement in two cases (18%). In five cases (45%) an avalanche balloon pack would likely have not made a difference, and the available evidence was inconclusive in four cases (36%). Part III: Overview of Concerns and Experiences with Operational Use of Avalanche Balloon Pack within the Canadian Avalanche Community 150 individual avalanche professionals and 90 operators completed an online survey. The use of avalanche balloon packs has been growing exponentially within the Canadian avalanche community. Participants without operational avalanche balloon pack experience are foremost concerned about acquisition cost and possible ergonomic impacts, followed by concerns about practicality and impact on the efficiency of operations. Indirect effects on other safety aspects of their operation were of least concern. Guides and heli-ski guides in particular were significantly more concerned than their colleagues. Many of the concerns related to avalanche balloon packs of guests. Participants with avalanche balloon pack experience were significantly less concerned about the potential negative effects of the device. Defining formal policies on avalanche balloon pack use by professional seems premature due to preliminary nature of this research and the current dynamic product development environment. iii

6 Keywords Avalanche balloon pack Avalanche survival Avalanche worker Avalanche accidents Operational avalanche safety iv

7 Executive summary Prior to the publication of this study, all of the existing research on avalanche balloon packs has been based on the European experience. While those studies validated the efficacy of avalanche balloon packs, the fundamental differences between the Canadian and European experience of working in avalanche terrain precluded the adoption of any of the derived European recommendations. Examples for these differences include the greater use of helicopters in avalanche work in Canada, increased access to forested terrain, and the higher incidences of trauma in avalanche fatalities. The goal of the present study is to provide a comprehensive Canadian perspective on the pros and cons of the use of avalanche balloon packs for the safety of avalanche workers. The study includes two separate accident analyses. The first looks at Canadian avalanche incidents involving avalanche balloon packs to determine how well these devices perform in the Canadian context. The second focuses on past avalanche accidents resulting in worker fatalities to retrospectively examine the possible impact of avalanche balloon packs on worker safety. In addition, the study includes a survey of Canadian avalanche professionals, which aims to assess the existing concerns about the operational use of avalanche balloon packs, and compares those concerns with the experience of operations that have adopted the device. Part 1: Analysis of Canadian avalanche incident records The focus of this analysis is to determine if there is a significant difference in survival rates between Canadian avalanche victims with and without avalanche balloon packs. As well, the effect of the devices on the severity of burial depths was considered, and whether the use of avalanche balloon packs leads to higher rates of trauma a common opinion among Canadian avalanche professionals because of the greater use of forested terrain in this country. Victims with inflated balloon packs are riding on top of the avalanche, which could increase their exposure to the danger of impact with trees or other obstacles. For the present analysis, only incidents where the victims with avalanche balloon packs were considerably involved in the avalanche s flow (e.g., knocked over by the slide) and/or were buried by the avalanche were included in the dataset. This approach ensures that the analysis only included cases where avalanche balloon packs had a realistic chance to affect the outcome of the involvement. The control group for the analysis included individuals without avalanche balloon packs who were seriously caught in the same well-document avalanches. While this approach results in a relatively small control group, it reduces the influence of reporting biases and ensures comparable data quality for both cohorts. The dataset for the present analysis comprised 34 incidents involving 71 individuals 11% (8 of 71) were non-mechanized backcountry skiers or snowboarders, 44% (31 of 71) were mechanized backcountry skiers, 1% (1 of 71) was a ski patroller, and 44% (31 of 71) were snowmobile riders. The overall survival rate for the dataset was 73% (52 of 71) with a significant variability between the activities. Survival rates for ski patrolling, non-mechanized backcountry skiing and snowboarding and mechanized backcountry skiing and snowboarding were 100% (1 of 1), 88% (7 of v

8 8), and 87% (27 of 31) respectively. The survival rate for the snowmobilers was significantly lower at 55% (17 of 31). This difference is likely linked to the lower reporting rate of non-fatal avalanche incidents among recreationists. Among the 72% (51 of 71) individuals equipped with an avalanche balloon pack, 10% (5 of 51) were not wearing it at the time of the avalanche (all of them had taken the pack off to access personal gear prior to the avalanche). Among the 46 individuals wearing an avalanche balloon pack at the time of the accident, 63% (29 of 46) were able to successfully deploy it. Thirty-seven percent (17 of 46) chose not to deploy, or were unable to do so during the avalanche involvement. While the individuals who did not wear their avalanche balloon pack at the time of the accident were included in the control group, victims whose avalanche balloon pack did not deploy during involvement were grouped with those who successfully deployed their packs during an involvement. This perspective treats the non-deployments as device failures and includes their outcome in the performance measure for of the device. Following this approach, a univariate analysis of the complete dataset yielded a survival rate of 56% for non-users and 83% for users. While users of avalanche balloon pack users experienced significantly shallower burials, no significant difference was detected in the trauma rates between users and non-users of the device. It is important to note that avalanche balloon packs are only one of the factors affecting the survival of the avalanche victims in the data set. Other significant factors include the source of incident information, size of the avalanche, the elevation band where it occurred, whether the victim was caught in the avalanche s start zone, track, or runout zone, and whether the victim was a professional or a recreationist. While the dataset was too small for s meaningful multivariate analysis, two additional survival rate analyses were performed with reduced datasets in an attempt to at least partially control for these additional influences. Both of these analyses confirmed the result of the overall analysis. Despite the overall increase in survival rates, there were also a number of complete burials and fatalities with fully deployed avalanche balloon packs. A qualitative examination of these cases clearly highlights the limitations to these devices when the user is located low on the slab when the avalanche was released and in the presence of terrain traps in the runout zone. Part 2: Examination of avalanche incidents resulting in worker fatalities This analysis looked at ten avalanche incidents involving 11 worker fatalities in Canada from October 1996 to December A worker is defined as an individual performing their primary job duties in avalanche terrain and getting paid, or actively training to obtain certification for future employment. The primary source of information was Avalanche Accidents in Canada Volume 5 by Jamieson, Haegeli, and Gauthier (2010). To retrospectively examine the possible impact of avalanche balloon packs, this analysis examined these incidents with respect to four criteria: the relative location of the victim when the avalanche released, the distance the victim was carried by the avalanche; the character of the runout zone; and the cause of death. The total number of negative indicators in regards to these criteria was used to assess whether an avalanche balloon pack could have likely reduced the severity of the incident. vi

9 This primarily qualitative assessment indicates that the use of an avalanche balloon pack might have been able to reduce the severity of the involvement in two cases (18%). In five cases (45%) an avalanche balloon pack would likely have not made a difference. The evidence was determined to be inconclusive in four cases (36%). Part 3: Overview of concerns and operational experience within the Canadian professional avalanche community In the first phase of this research, 24 open-ended personal interviews with key informants representing all segments of the Canadian professional avalanche community were conducted to develop a comprehensive picture of the existing concerns about the operational use of avalanche balloon packs. These interviews revealed 16 indirect impacts falling into four main categories: safety aspects; ergonomic concerns; practicality challenges; and other concerns. A detailed online survey was subsequently developed to more broadly sample the avalanche community. While participants without avalanche balloon pack experience at their workplace were asked to express their concern about the possible indirect impacts, participants who regularly use the device at work were asked to comment on their personal experience. Survey questions also differed between individual workers and operators of avalanche safety programs. The survey was completed by 150 individual professionals and 90 operators. Survey participants were categorized into five industry segments: guiding; control work; other field programs; avalanche training; and search and rescue. Twenty-three percent of survey participants reported regularly or always using avalanche packs. However, since participation was likely biased towards avalanche balloon pack users, the true percentage of users is likely lower. Participants were most concerned about the cost of acquiring the devices and their possible ergonomic impacts, primarily due to the additional weight. Participants with experience using the device at their workplace were significantly less concerned about the ergonomic challenges. The practicality of avalanche balloon packs in the workplace was another significant concern, with the focus of this concern varying widely between the participants. There were consistently higher levels of concern from the guiding community particularly heli-ski guides and operators. These concerns are most likely related to the fact that this group deals not only with their personal avalanche balloon pack, but also with avalanche balloon packs of their guests. Application for policy and prevention Despite the limited sample size, the findings from Part 1 indicate that avalanche balloon packs can reduce risk. However, the analysis also highlights where the efficacy of the device is limited. Risk management is a multi-faceted challenge for avalanche professionals. Blanket regulations or recommendations for the use of avalanche balloon packs may not address the various safety needs and challenges of the professional community. However, the use of avalanche balloon packs is growing quickly and new manufacturers are entering the market. The increased competition among manufacturers has the potential to boost innovation that will address the current ergonomic and practicality concerns as well as lower the cost of the device. This development will result in a natural increase in the use of avalanche balloon packs by both professionals and recreationists. It may be premature to write policy on the use of avalanche balloon packs in such a dynamic product development phase. vii

10 Report The initial concept for avalanche balloon packs, also known as avalanche airbags, was invented in the late 1970s in Europe (ABS, 2011). While the first commercial product was available in the European market in 1991 (Brugger et al., 2007), the introduction of the safety device to the North American market was considerably delayed due to a stream of regulatory hurdles. In comparison to other avalanche safety devices that aim to accelerate the search and extrication phase of an avalanche rescue, the goal of avalanche balloon packs is to prevent burial through the process of inverse segregation. Typical accident avalanches are gravitational granular flows that segregate in a way that larger particles are more likely to be found near the surface while smaller particles move towards the base of the flow (Kern, 2000). The effectiveness of this process primarily depends on the relative size difference of the particles within the flow. With the inflated balloon(s), an avalanche victim, who is already a rather large particle in an avalanche, becomes an even larger particle that can take full advantage of the segregation effect. As long as the user of the avalanche balloon pack is flowing freely within the avalanche debris, the separation effect will be moving the victim towards the surface despite its higher density. Since asphyxia through burial of the airway in snow is the primary cause of death in avalanches (Hohlrieder et al., 2007; McIntosh et al., 2007; Boyd et al., 2009) and the time window for successful live recoveries is only 10 to 20 minutes long (Brugger et al., 2001; Haegeli et al., 2011), avoiding complete burial has great potential for improving avalanche survival. The effectiveness of avalanche balloon packs is supported by various credible scientific studies, which included the theoretical evaluation of the concept of inverse segregation in the context of avalanches (Kern, 2000), field experiments where crash test dummies with inflated avalanche airbags were exposed to artificially triggered avalanches (Tschirky & Schweizer, 1996; Kern et al., 2002; Meier & Harvey, 2010) and statistical evaluations of accident records 1

11 comparing the mortality rates of avalanche victims with and without avalanche balloon packs (Tschirky et al., 2000; Brugger & Falk, 2002; Brugger et al., 2003; Brugger et al., 2007). Whereas the majority of these studies were conducted in Europe, experience and numerous studies have shown that the avalanche safety context in Canada differs significantly from the situation in Europe. Examples include the higher significance of trauma in avalanche fatalities (Boyd et al., 2009), the shorter survival phase in the Canadian avalanche survival curve (Haegeli et al., 2011), but also the higher prevalence of helicopter use in avalanche work and the greater access to forested terrain. These differences unfortunately prevent the direct adoption of European recommendations on avalanche balloon packs (ICAR, 2006) without a thorough examination of their strengths and weaknesses within the local Canadian context. The goal of the present research was to address this significant knowledge gap by compiling a comprehensive overview that assesses the value of avalanche balloon packs for Canadian avalanche workers and explores the challenges and barriers for their adoption within the complete context of risk management at their workplace. More specifically, the research project examined the following three research questions: 1. How well do avalanche balloon packs perform in Canadian avalanche accidents? 2. Would the use of avalanche balloon packs have likely made a difference in the outcomes of recent avalanche accidents involving worker fatalities? 3. What are the existing concerns about the operational use of avalanche balloon packs in the professional avalanche community in Canada and how do they compare with the experience of operations that have adopted avalanche balloon packs? This report will provide short summaries on the methodologies and research finding for each of the three research questions before concluding with a general discussion of the overall implications of this research and its possible application for policy and prevention. 2

12 Part I: Analysis of Canadian avalanche incident records The goal of this part of the project was to collect detailed information on Canadian avalanche incidents involving avalanche balloon packs and to conduct a preliminary statistical analysis on the effect of avalanche balloon packs on the survival rate of individuals seriously involved in avalanches in Canada. More specifically, the project aimed to address the following three research questions: 1) Is there a significant difference in the survival rates between avalanche victims with and without avalanche balloon packs? 2) Are avalanche balloon packs able to significantly reduce the severity of burials? 3) Does the use of avalanche balloon packs lead to higher rates of trauma? While the first research question tries to answer the ultimate question about the effectiveness of avalanche balloon packs, the second question explores the performance of the process of inverse segregation in real-life situations. The last research questions aims to examine a common opinion among Canadian avalanche professionals. Being closer to the surface layers of the avalanche, victims with inflated avalanche balloon packs may travel faster and farther with the more quickly moving surface layers of an avalanche. Depending on the position of the victim (head first versus feet first) and the presence of obstacles (e.g., trees or rocks), the use of avalanche balloon packs could therefore lead to a higher occurrence of injuries. Methodology The incident records used for the present study were collected from a range of sources. From 1991 to 2010, the WSL Swiss Institute for Snow and Avalanche Research SLF collected information on avalanche incidents involving avalanche balloon packs worldwide in collaboration with ABS Peter Aschauer GmbH, the manufacturer of ABS avalanche balloon packs. By 2010, this dataset contained a total of six Canadian avalanche incidents involving avalanche balloon 3

13 packs (Zweifel, 2011; pers. comm.). In the spring of 2009, Ilya Storm of the Canadian Avalanche Centre (CAC) collected a preliminary list of Canadian incidents involving avalanche balloon packs. This information was augmented using the following four methods: Reports of the British Columbia Coroners Services were scanned for the use of avalanche balloon packs in any fatal avalanche accidents in British Columbia. The online survey examining the perspective of Canadian avalanche professionals (Part III of this study) included questions about personal experiences with avalanche balloon packs in emergency situations. Public avalanche forecasters at the CAC scanned incoming avalanche incident reports for information about avalanche balloon packs. The CAC added a new form to its online incident reporting wizard ( ca/cac/bulletins/incident-reports/submit) in the winter of 2010 to allow recreationists and avalanche professionals to submit information on the use of avalanche balloon packs in avalanche incidents in a consistent manner. Any indications of incidents involving avalanche balloon packs were followed up, if possible, with personal interviews with the accident party, rescue personnel, or accident investigators to confirm the involvement of avalanche balloon packs and gather detailed information. Despite extensive efforts, it was not always possible to collect sufficient information on all incidents to allow a meaningful analysis. In total, the data collection effort resulted in 43 welldocumented incidents between 1999 and 2010 involving a total of 92 individuals. Detailed narratives of each incident are included in the appendix of Haegeli (2012a). For the proper interpretation of the statistical results it is critical to understand that avalanche accident datasets are inherently incomplete and biased towards more serious incidents involving fatalities, serious injuries, or multiple victims. These types of avalanche accidents are 4

14 generally better-known and documented in greater detail. While smaller involvements in the professional avalanche community are commonly reported through channels such as the InfoEx or InformalEx, these reports often lack the necessary details to be included in a statistical analysis. Small avalanche incidents of recreationists without fatalities commonly remain unreported. The results of a statistical analysis critically depend on what types of avalanche involvements are included in the dataset. For the present analysis, only serious involvements were considered, which were defined as individuals who were unable to remain standing during their involvement, were considerably involved in the flow of the avalanche and/or were buried by the avalanche. This criterion ensures that that the analysis include cases where a deployed avalanche balloon pack had a realistic chance to affect the outcome of the involvement. Individuals who were only marginally involved in the avalanche (e.g., only slightly moved and remained standing upright, skied out of the avalanche) were excluded from the dataset. To examine the effectiveness of avalanche balloon packs in emergency situations, it is necessary to have a reliable control group of individuals who did not wear avalanche balloon packs during their avalanche involvements. For the present study, the control group consisted of individuals who were seriously caught in the same well-documented avalanches as the avalanche balloon pack wearers included in the analysis. While this approach reduced the influence of possible reporting biases and ensured the data quality for both cohorts is comparable, it also resulted in a relatively small control group that is biased towards larger avalanche incidents. Pearson chi-squared tests were used to compare nominal data between users and nonusers of avalanche balloon packs. The Wilcox rank-sum test was applied to ordinal and nonnormal data for pair-wise comparisons. The Boniferroni correction was used to adjusted p- values of multiple pair-wise comparisons. We considered p-values of less than 0.05 to be statistically significant; p-values between 0.05 and 0.10 were interpreted as marginally significant. 5

15 Project findings/outcomes After insignificant involvements were excluded, the dataset consisted of 34 avalanche incidents involving a total of 71 individuals. Eleven percent (8 of 71) of individuals were nonmechanized backcountry skiers or snowboarders, 44% (31 of 71) were mechanized backcountry skiers, 1% (1 of 71) was a ski patroller, and 44% (31 of 71) were snowmobile riders. Seventy-two percent (51 of 71) of individuals were equipped with an avalanche balloon pack. Among them, 47% (24 of 51) were using ABS products, 35% (18 of 51) Snowpulse balloon packs, and 8% (4 of 51) Backcountry Access (BCA) balloon packs. In 10% of the cases (5 of 51) the brand was unknown. As of January 2012, there were no documented avalanche incidents in Canada involving any WARY products (formerly AviVest). Among individuals equipped with avalanche balloon packs, 10% (5 of 51) were not wearing them at the time of the avalanche. All of these individuals took their avalanche balloon packs off to access personal gear prior to the avalanche. Among the 46 individuals wearing avalanche balloon packs at the time of the accident, 63% (29 of 46) were able to successfully deploy their avalanche balloon pack. Thirty-seven percent (17 of 46) chose not or were unable to deploy their avalanche balloon pack during the avalanche involvement (Table 1). This number is considerable higher than what has been reported in previous studies (Tschirky et al. (2000): 20% (8 of 40); Brugger et al. (2003): 12% (7 of 60) and Brugger et al. (2007): 20% (7 of 35)). TABLE 1: REASONS FOR NON-DEPLOYMENT OF AVALANCHE BALLOON PACKS Reason for non-deployment Number of cases No attempt by wearer 3 (18%) Unable to grab release handle 2 (12%) Maintenance issue 2 (12%) Unsuccessful attempt 7 (41%) Unknown reason 3 (18%) Four of the known unsuccessful deployment attempts identified significant weaknesses in the involved avalanche balloon pack design, which have since been addressed by the manu- 6

16 facturers. All Snowpulse avalanche balloon packs now use a closed venturi system and Backcountry Access avalanche balloon packs are equipped with the Easy Pull Kit. More details on all incidents are available in the appendix of Haegeli (2012a). Nineteen individuals lost their lives during their avalanche incident, resulting in an overall survival rate of 73% for the dataset. Survival rates vary significantly among activities, with high values for ski patrolling (100%; 1 of 1), non-mechanized backcountry skiers and snowboarders (88%; 7 of 8), and mechanized backcountry skiers (87%; 27 of 31). The snowmobile sample exhibits a survival rate of 55% (17 of 31), which is significantly lower than the other activity groups (Pearson chi-squared test p-value = 0.046). This difference is likely linked to the lower reporting rate of non-fatal avalanche incidents by amateur recreationists in general and snowmobile riders in particular. Only five of the 13 known snowmobile avalanche incidents involving avalanche balloon packs (38%) did not include fatalities. The effectiveness of avalanche balloon packs can be assessed by comparing the survival rate of users and non-users of avalanche balloon packs. However, the evaluation critically depends on the decision of whether to group individuals whose avalanche balloon pack did not deploy during the involvement with users (i.e., successful deployments) or with non-users (i.e., individuals not equipped or not wearing their avalanche balloon pack). The common approach is to group individuals whose avalanche balloon pack did not deploy with the individuals who successfully deployed their safety device. This perspective views avalanche balloon packs that did not deploy as failures of the safety device and the consequences of these failures need to be included in the overall assessment of the device. This perspective was used in the existing studies on avalanche balloon packs by Tschirky et al. (2000) and Brugger et al. (2007). The survival rates in the present dataset using this perspective were 56% for non-users and 83% for users, which represents a statistically significant absolute increase of the survival rate of 27% (Pearson chi-squared test: p-value = 0.03; 95% confidence interval: 4% to 49%). Detailed information on 7

17 the degree of burial is known for 93% (66 of 71) of the involved individuals. A Wilcox rank-sum test indicated significant differences in the degree of burial (p-value = 0.002) with users of avalanche balloon packs experiencing significantly shallower burials. The use of avalanche balloon packs is not the only factor affecting the survival rate of avalanche victims. Ideally all contributing factors would be included in a multivariate analysis about avalanche balloon packs to properly isolate the individual effects. However, since the small size of the available dataset prevents a meaningful multivariate analysis, the present analysis was limited to a series of individual univariate analyses to offer first insights into the other factors affecting survival in the dataset. A Wilcox rank-sum test revealed that avalanches resulting in fatalities were significantly larger than the avalanches of survivors (p-value = 0.006). While the median avalanche size of survivors was 2.0 according to the Canadian avalanche size classification (CAA, 2007), the median size of avalanches resulting in fatalities was 3.5. The terrain character of the incident location also had a significant impact on the survival of avalanche victims. A Pearson's chi-squared test of elevations bands alpine, treeline, and below treeline showed that the survival rate at treeline (58%) was significantly lower than in the other elevation bands (p-value = 0.036). However, no significant differences were observed in the survival rates of victims with and without terrain traps in the runout zones (Pearson's chi-squared test: p-value = 0.468). An examination of the relative location of victims start zone, track and runout zone when the avalanche was triggered revealed that the survival rates were significantly reduced for individuals caught in the track or runout zone of the avalanche. (Wilcox rank-sum test: p-value = 0.020). In the present dataset, the difference in survival rates of amateur recreationists and avalanche professionals (69% versus 100%) was marginally significant (Pearson's chi-squared test: p-value = 0.094). This difference is likely a reflection of the expected underrepresentation of amateur accidents without fatalities in the present dataset. 8

18 In an attempt to at least partially control for these additional influences, the dataset was reduced to only include incidents where both users and non-users of avalanche balloon packs were involved. The reduced dataset consisted of only six incidents with a total of 35 involvements, which represents 49% (35 of 71) of the complete victim dataset. Within this sample, victims wearing an avalanche balloon pack had an 80% chance of survival, 24 percentage points higher than the 56% survival rate of non-users. While this improvement was not statistically significant due to the small sample size (Pearson's chi-squared test: p-value = 0.347; 95% confidence interval: -8% to 56%), it is in the same range as the estimate from the complete sample. Even though the described results indicate that avalanche balloon packs are able to reduce the severity of burials and increase survival rates, critical burials (i.e., burials with impaired airways) and fatalities do occur despite completely inflated avalanche balloon packs. In the complete dataset, 24% (7 of 29) of the individuals with a fully deployed avalanche balloon pack were critically buried and 17% (5 of 29) did not survive their avalanche involvement. While this dataset is too small to offer conclusive statistical evidence, a qualitative examination of these incidents indicates that the effectiveness of avalanche balloon packs is reduced in larger avalanches, when victims are caught in the track or runout zone of the avalanche and when terrain traps are present. In the complete dataset, all fatalities died from asphyxia. No significant differences were observed in injury rates among the survivors with different degrees of avalanche balloon pack usage (Pearson chi-squared test: p-value = 0.863). The results of this research reveal that the avalanche balloon packs can improve survival rates among avalanche victims in Canada. The calculated improvements in survival rates are comparable to those published in European studies. However, due to the small sample size and the inability to conduct a multivariate analysis, the present analysis can only be viewed as 9

19 preliminary. Furthermore, it is important to critically examine the underlying assumptions when interpreting the present results and comparing them with others studies. The most important aspects are what type of avalanche involvements were included in the dataset, the character of the control group, and whether non-deployed avalanche balloon packs were included in the analysis with users or non-users of avalanche balloon packs. Despite the overall increase in survival rates, the examination of complete burials and fatalities with fully deployed avalanche balloon packs also highlights possible limitations of the device. A more detailed description of this study is provided in Haegeli (2012a). In addition to the results discussed in this report, the extended research report also examines the effectiveness of avalanche balloon packs by contrasting deployed balloon packs against non-deployed avalanche balloon packs and non-users. Furthermore, it contains the narratives of all welldocumented avalanche incidents included in this analysis. Part II: Examination of avalanche incidents resulting in worker fatalities Although there are no published studies to date explicitly contrasting the characteristics of fatal avalanche incidents involving workers versus amateur recreationists, it is reasonable to assume that there might be considerable differences between these two user groups. The advanced avalanche safety systems of professional operations allow workers to more systematically monitor and manage avalanche hazard than amateur recreationists. As a consequence, avalanches resulting in worker fatalities might be of different character and severity than the avalanches that typically kill amateur recreationists. In addition, survival chances of workers might be higher due their intimate familiarity with the avalanche phenomenon and the more sophisticated rescue resources and capabilities available in professional operations. All of these differences make it problematic to draw conclusions about the effectiveness of an avalanche safety device for worker safety exclusively based on studies that examined incidents of workers and amateur recreationists together. The goal of this part of the present study is to examine the 10

20 characteristics of recent avalanche incidents that resulted in worker fatalities to provide a better understanding of the potential benefits of avalanche balloon packs for the safety of workers. Methodology Since survival chances in an avalanche involvement are affected by a wide range of factors, assessing the potential benefits of an additional avalanche safety device retrospectively is a challenging task. However, the analysis of Part I of this study offered some initial insights about conditions that are favourable and unfavourable for the performance of avalanche balloon packs in emergency situations. An examination of avalanche accidents involving worker fatalities with respect to these conditions can offer a first understanding about the potential effectiveness of avalanche balloon packs for worker safety. The study period for this part of the project was October 1996 to December 2011, which roughly coincides with the use of avalanche balloon packs in Canada. The term worker fatality was defined as an individual who was killed in an avalanche incident while pursuing their primary job responsibilities in avalanche terrain. They could either be getting paid at the time of the incident or could be actively training to obtain certification for future employment. The primary source of information for the present analysis was Avalanche Accidents in Canada Volume 5 by Jamieson et al. (2010). This publication offers the most comprehensive description of fatal avalanche incidents in Canada between the winters of 1996/97 and 2006/07. The collection of supplementary data from additional first-hand sources was beyond the scope of the current study. Using results of Part I of this study as a foundation, the present analysis examined the identified avalanche accidents involving worker fatalities with respect to four aspects: a) relative location of victim when avalanche released, b) distance carried by avalanche, c) character of runout zone, and d) cause of death of victim (Table 2) to examine whether conditions were favourable or unfavourable for the performance of an avalanche balloon pack. The final assess- 11

21 ment on whether the use of an avalanche balloon pack would have likely been able to prevent or reduce the severity of the incident was assigned using the guidelines described in Table 3. TABLE 2: CRITERIA FOR ASSESSMENT OF WORKER FATALITIES Criterion Relative location of victim when avalanche released Distance carried by avalanche Character of runout zone Cause of death of victim Description A frequent observation among the incidents involving full burials or fatalities with fully deployed avalanche balloon packs was that the victims were caught by the avalanche in the lower parts of the slope. Furthermore, the statistical analysis in Part I of this study showed that victims caught in the track or runout zone of the avalanche have a significantly lower survival rate. This observation is likely caused by two separate factors. First, individuals lower on a slope are first hit by the turbulent and more violent front part of the avalanche, while individuals closer to the fracture line are immediately involved in the more laminar tail of the avalanche. Second, the potential volume of snow available for burial is much greater for a victim in the front part of the avalanche than in the tail. Together, these two factors can counteract the benefit of an avalanche balloon pack and lead to burials despite their use. To be sorted to the surface of an avalanche through the process of inverse segregation, an avalanche victim needs to be fully involved in the flow of an avalanche for a considerable amount of time or distance. Victims who are carried for only short distances might therefore not be able to benefit from this safety device. Whereas avalanche balloon packs are designed to reduce the severity of an avalanche burial, terrain traps, such as depressions or sharp transition in the runout zone of an avalanche can considerably increase the likelihood of a deep burial and potentially overcome the benefit of inverse segregation. Furthermore, cliffs, trees or other obstacles in the path and runout zone of the avalanche increase the chance of victims sustaining live threatening traumatic injuries. Even though some of the existing avalanche balloon pack products claim to offer some protection against trauma, it is not main purpose of this safety device. Avalanche victims whose primary cause of death was trauma would likely not have survived their avalanche involvement even if they had they been wearing an avalanche balloon pack. TABLE 3: GUIDELINES FOR EVALUATION OF POSSIBLE IMPACT OF AVALANCHE BALLOON PACKS ON WORKER FATALITIES Evaluation Description Possibly positive impact The absence of any negative indicators was interpreted as that an avalanche balloon pack might have had a positive impact on the outcome of this incident. Inconclusive Fatalities with only one negative indicator were interpreted as inconclusive. Likely no impact Two or more negative indicators were interpreted as a sign that avalanche balloon packs would likely not have been able to make a difference in the outcome of the incident. In addition, fatalities with trauma as their primary cause of death were automatically assigned to this category since preventing trauma is not the main goal of avalanche balloon packs. Project findings/outcomes There have been eleven worker fatalities in ten avalanche incidents in Canada during the study period (Table 4). Sixty-four percent (7 of 11) of the victims were guides, 27% (3 of 11) were avalanche technicians and 9% (1 of 11) was a researcher. Among the guides, 57% (4 of 7) where either tail or apprentice guides. Forty-five percent (5 of 11) of the victims were working at an outdoor worksite when they were caught in the avalanche, 36% (4 of 11) were heli-ski guiding, 9% (1 of 11) were snowmobile guiding and an additional 9% (1 of 11) were guiding in a non-mechanized backcountry environment. 12

22 TABLE 4: LIST OF AVALANCHE INCIDENTS INVOLVING WORKER FATALITIES SINCE 1996/97 Date Location Activity Worker Worker Fatalities Negative indicators Assessment 13-Jan-1999 Bone Creek Heli-skiing Tail guide 1 2 No impact 31-Mar-1997 Mt Switzer Heli-skiing Guide 1 0 Positive 16-Apr-1998 Sa Dena Hes Mine Outdoor worksite Researcher 1 1 Inconcl. 7-Jan-1999 Ningunsaw Pass Outdoor worksite Avalanche technicians 2 0 Trauma Positive No impact 19-Mar-2000 Wasp Creek Heli-skiing Guide 1 1 Inconcl. 12-Jan-2002 Parker Ridge Outdoor worksite Avalanche techn. 1 2 No impact 10-Feb-2002 Mt La Forme Heli-skiing Tail guide 1 1 Inconcl. 20-Jan-2003 Tumbledown Mountain Backcountry skiing Apprentice guide 1 1 Inconcl. 27-Mar-2003 Mt Brewer Snowmobile riding Guide 1 2 No impact 14-Jan-2006 Lizard Range Outdoor worksite Tail guide 1 2 No impact The median size of avalanches in the present sample of worker avalanche fatalities was 3.0. Thirty percent (3 of 10) of the avalanches were size 2.5, 50% (5 of 10) were 3.0, and 20% (2 of 10) were 3.5. Detailed information on the location of the victim when caught was available for nine of the 11 worker fatalities. In 44% of the cases (4 of 9), the victim was close to the fracture line when the avalanche released. In the other 56% (5 of 9), the victim was either in the path or the runout of the avalanche. In three incidents examined in this analysis, the victims were only carried for a short distance, possibly limiting the ability of inverse segregation. The worker fatalities in the Bone Creek and Mt Brewer incidents were carried for an intermediate distance of approximately 100 m. All the other victims were carried over substantial distances of at least several hundred metres, providing considerable time for the sorting process. Information on the character of the runout zone was available for ten of the 11 fatalities. In 40% (4 of 10) of the cases, the runout zones were open and smooth without any obvious terrain traps. Trees were present in the runout zones at Parker Ridge and Lizard Range (20%; 2 of 10), but according to the available information, they did not affect the outcome of the incident. The remaining four incident sites (40%; 4 of 10) exhibited significant terrain traps that led to 13

23 deeper burials and contributed considerably to the fatal outcome of the incidents. According to the available information, only one of the worker fatalities died from trauma. Based on the currently available information, the use of an avalanche balloon pack might have had a positive impact on the outcome of 18% (2 of 11) of the assessed worker fatalities (Table 4). In 45% (5 of 11) of the cases, an avalanche balloon pack would likely not have made a difference and in the remaining 27% (3 of 11) of the fatalities, the available information was insufficient for a conclusive assessment. Even though wearing an avalanche balloon pack might likely have not prevented the burial of the victim in the Sa Dena Hes Mine accident due to the short travel distance in the avalanche, the inflated avalanche balloons might have offered an obvious landmark for a quick location of the shallow burial by the inexperienced companions. There are no indications that any of the victims would have been worse off during their involvement had they worn an avalanche balloon pack. The evaluation presented in this study should only be viewed as preliminary. A retrospective analysis based on information that was not explicitly collected for the research question at hand should always be viewed with caution. Even though Jamieson et al. (2010) offer the most detailed descriptions of the relevant accidents, the original data collection process of the authors did not focus on the potential effect of avalanche balloon packs. However, in the opinion of the research team the collection of additional first-hand information on the examined accidents would have been extremely time consuming and would have likely only resulted in marginally improved assessments. Even though the approach used in the present study aimed to provide a systematic review of the known incidents involving worker fatalities, it is currently not possible to eliminate a certain degree of subjectivity in these qualitative assessments. 14

24 A more detailed description of this part of the study is provided in Haegeli (2012b), which also contains detailed narratives and discussions of all ten incidents involving worker fatalities. Part III: Overview of concerns and operational experience within the professional Canadian avalanche community All of the existing research on avalanche balloon packs, including Part I and II of this study, has so far focused exclusively on their effect on avalanche survival. However, this important safety aspect is only one of many ways how the operational use of avalanche balloon packs can affect avalanche workers and avalanche safety operators. The operational use of avalanche balloon packs has far-reaching consequences for many other operational aspects and the decision to implement their use requires a comprehensive evaluation of all the involved advantages and disadvantages. This part of the present study aims to close this knowledge gap by providing a comprehensive and systematic review of the existing concerns and experiences about the operational use the work place in the Canadian avalanche community. Methodology A mixed method approach (Creswell, 2009) was used to derive a comprehensive perspective on the advantages and disadvantages of the operational use of avalanche balloon packs by Canadian avalanche workers. In the formative first phase of this research, the research team conducted 24 open-ended personal interviews with key informants representing all segments of the Canadian professional avalanche community (February 16 and April 22, 2011). Based on the collected information, the research team identified 16 possible indirect impacts of operational avalanche balloon pack use that fell into the four main categories: i) Safety aspects; ii) Ergonomic concerns; iii) Practicality challenges; and iv) Other concerns (see Table 5 for complete list and detailed description of items). 15

25 A detailed online survey was subsequently developed to examine the topic of avalanche balloon packs in a more quantitative fashion and with broader participation from the professional avalanche community. The survey was designed to dynamically select questions based on the TABLE 5: LIST OF POSSIBLE INDIRECT IMPACTS OF AVALANCHE BALLOON PACKS ON AVALANCHE SAFETY OPERATIONS Categories Safety aspects Ergonomic concerns Practicality challenges Other concerns Impact Risk compensation: The potential safety benefit of avalanche balloon packs might be cancelled by avalanche workers exposing themselves to a higher level of avalanche hazard to providing better service (i.e., risk compensation or risk homeostasis; Wilde, 2001) Situation awareness: The repeated attention required for the use of a personal avalanche balloon pack and/ or when dealing with avalanche balloon packs of guests has the potential to significantly distract avalanche professionals and reduce their situation awareness (Endsley & Garland, 2000; Klein, 2003) of the existing hazard conditions. Emergency deployment: The active release of an avalanche balloon pack might be a considerable distraction during a time when an avalanche victim might still have the chance to escape an involvement. In addition, the avalanche balloon pack might not deploy properly. Trauma rate: The effect of the inflated avalanche balloons in an avalanche involvement might put their wearer in a position more susceptible to trauma injuries. Helicopter safety (operators only): Helicopter safety can be affected by avalanche balloon packs during flight, but also when handling the avalanche balloon packs around a running helicopter on the ground. Effects from personal avalanche balloon packs: The additional weight and the suboptimal ergonomic fit of avalanche balloon packs have the potential to considerably increase the long-term wear and tear on an avalanche worker's body. Effects from handling avalanche balloon packs of guests: The repeated loading and unloading of avalanche balloon packs for guests can further increase the long-term wear and tear on a guide's body Functionality of avalanche balloon pack: Functionality as a regular backpack for working in avalanche terrain Leg loop/crotch strap (individual avalanche professionals only): Practicality of using the leg loop/crotch strap to secure the avalanche balloon pack to the wearer Preparation for flight (individual avalanche professionals only): Practicality of additional work required to prepare personal avalanche balloon pack for flight (i.e., securing trigger handle) Accidental deployments (operators only): Impacts of accidental deployments of avalanche balloon packs on efficiency of field program. Efficiency of field program (operators only): Impacts of regular use of avalanche balloon packs on efficiency of field program. Maintenance concerns (operators only): Concerns about time commitment for regular maintenance and tracking of avalanche balloon packs. Additional non-field related logistics (operators only): Concerns about additional logistical challenges, such as establishing drying and/or storage space or the refilling of empty gas canisters. Cost concerns: Concerns about the capital investment associated with the implementation of avalanche balloon packs and an operation or for personal use. Liability concerns (operators only): Concerns about possible liability claims related to malfunctioning avalanche balloon packs that could be traced to maintenance errors or training omissions. 16

26 characteristics of participants. Individuals without experience with avalanche balloon packs at their workplace were asked to express their concern levels about the 16 possible indirect impacts, while participants who regularly use the device at work were asked to comment on their personal experience with these potential issues. Survey questions also differed between individual avalanche workers, who are in charge of their personal safety only, and operators of avalanche safety programs, who have much broader responsibilities including the safety of staff. The online survey (see for survey instrument) was launched on June 6, 2011, with various professional organisations from the Canadian avalanche community encouraging their membership to participate in the study. The majority of participants completed the survey in June and July, but the survey remained open until October 20, 2011, when the final sample for the analysis was drawn. Pearson chi-squared tests were used to compare nominal data between users and nonusers of avalanche balloon packs. The Kruskal-Wallis rank-sum test was applied to ordinal and non-normal data for comparisons of multiple groups. We considered p-values of less than to be statistically significant; p-values between and were interpreted as marginally significant. Project findings/outcomes During the study period, 150 survey participants completed the online survey as individual avalanche professionals and 90 responded to the questions from the perspective of an operator. To better understand the range of possible impacts on avalanche workers, survey participants were categorized into five industry segments that differ in their immediate need to enter avalanche terrain and their responsibilities to provide safety to others (see Table 6 for description of segments and number of survey participants). 17

27 The use of avalanche balloon packs has grown considerably over the past few years (Figure 1). Participating avalanche professionals reported to regularly or always using avalanche balloon packs in 23% (79 of 354) of their work situations (multiple responses per survey participant possible). However, since survey participation was likely biased towards avalanche balloon pack users, the true percentage of users within the community is likely lower. Since not TABLE 6: LIST OF INDUSTRY SEGMENTS AND NUMBER OF SURVEY PARTICIPANTS (INDIVIDUAL AVALANCHE PROFESSIONALS AND OPERA- TORS) WITH AND WITHOUT OPERATIONAL AVALANCHE BALLOON PACK EXPERIENCE. Segment Description Ind. av. prof. Operators with without with without Guiding Any type of avalanche safety operation where guests are guided through avalanche terrain (mechanized and non-mechanized ski guiding, snowmobile guiding). Entering avalanche terrain with individuals under their care. Possible economic consequences Control work (Control) Other field programs (Field) Avalanche training (Train) Search and rescue (SAR) Small field teams with immediate responsibility to secure avalanche terrain for the public or other workers (ski areas, highway operations, consultants doing operational forecasting). Possible economic consequences Small field teams without immediate responsibilities for the protection of others (public avalanche forecasters, research). Lower pressure to enter avalanche terrain. Involved in avalanche safety education for avalanche workers (e.g., CAA ITP) or recreationists (e.g., CAC AST). Involved in search and rescue. Generally entering avalanche terrain under conditions of elevated hazard to secure others. Total all operators participated in the survey, their responses on avalanche balloon pack use did not provide a meaningful overview of the operational adoption of avalanche balloon packs of across the Canadian avalanche community. A closer look at the adoption attitude of individual avalanche professionals using a modified precaution adoption scale (Weinstein & Sandman, 2002; FIGURE 1: DEVELOPMENT OF REGULAR AVALANCHE BALLOON PACK USE AMONG PARTICIPATING AVALANCHE PROFESSIONALS 18

28 FIGURE 2: AVALANCHE BALLOON PACK ADOPTION ATTITUDE OF PARTICIPATING INDIVIDUAL AVALANCHE PROFESSIONALS McCammon, 2009), shows that in addition to the 22% who are regularly using the safety device in their workplace, 30% believe it is a meaningful device, but have not implemented their use (Figure 2). The significantly higher level of adoption among field technicians was primarily caused by the regular use of avalanche balloon packs by a single research team. An overall comparison of the expressed concern levels by individual avalanche professionals and operators regarding the possible impacts of regularly using avalanche balloon packs showed that both groups are most concerned about the associated acquisition costs and the possible ergonomic impacts. Among the ergonomic issues applying to all avalanche professionals, participants were most concerned about long-term wear and tear due to the additional weight of avalanche balloon packs. Concern levels were significantly lower among field technicians and avalanche awareness instructors, who typically spend less of their day carrying their backpacks than other avalanche professionals. The absolute highest level of ergonomic concern was expressed by heli-ski guides about the possible impacts from handling avalanche balloon packs of guests. Among the individual avalanche professionals and operators with avalanche balloon pack experience, roughly half reported to be aware of at least some ergonomic impact from wearing a personal avalanche balloon pack. Only about one-quarter of the experienced heli-ski guides reported any personal impact from handling avalanche balloon packs of guests. 19