Mountaineering emergencies on Denali

Transcription

1 Journal of Wilderness Medicine 4, (1993) ORIGINAL ARTICLE Mountaineering emergencies on Denali CLARE LATTIMORE, MS* University ofalaska, Anchorage, College ofnursing and Health Sciences, Alaska, USA Rescue records of 98 mountaineering emergencies were reviewed to evaluate the risks of climbing North America's highest peak, Denali (6187 m). During a 10 year study period ( ) there were 126 search and rescue subjects, including 28 deaths (fatality rate = 4.3 per 1000 climbers; case fatality rate = 22.2%). Increased risk was significant at higher elevations (p < 0.01), on technically difficult climbing routes (p < 0.001), and for European and Asian climbers (p < 0.001). Hazard is inherent to climbing; while prevention of mountaineering injuries is the ideal, development of skilled rescue and medical services is also essential. Key words: mountaineering injuries; rescue; injury epidemiology Introduction Risk of injury, disability, and death are inherent to mountaineering; while dramatic stories of survival situations are plentiful [1,2], systematic study of such emergencies has been rare. North America's highest peak, Denali, poses a unique combination of hazards related to high altitude, arctic climate, treacherous terrain and remote wilderness. Also known as Mt McKinley, this 6187 m Alaskan peak attracts mountaineers from all over the world. Previous research on Denali has focused on high altitude physiology and cold injuries [3,4]. In 1976, a previous study examined the high casualty rate on Denali and a neighboring peak, Foraker [5], but retrospective analysis of morbidity and mortality has otherwise been lacking. The purpose of the present study was to quantify the risks of climbing Denali and to identify factors contributing to the need for rescue from the mountain. Methods Data were collected from the records of Denali National Park and Preserve. The park service maintains extensive archives which include registration records on all climbers, detailed reports of rescues and summary statistics compiled each year. All rescue reports from 1978 through the end of 1987 were surveyed for variables describing emergency situations, rescue missions and outcomes. Registration records on rescued subjects provided demographic information, a resume of each climber's experience, and specifics of group size and type of leadership. A sample of 241 non-rescued expeditions, randomly selected from the registration files, was surveyed for comparison data. Annual *Address for correspondence: POB 144, Unalaska, AK 99685, USA Chapman & Hall

2 Denali emergencies 359 statistics compiled by the park summarized numbers of expeditions and climbers on the mountain, countries represented, routes chosen and frequency of employment of professional guides. These data were used to provide denominators for rescue and fatality rates. Results There were 6580 members of 1554 expeditions on Denali during the study period. Ninety-eight search al}d rescue missions involved 126 subjects, 28 of whom died. The nature of these emergencies is summarized in Table 1. The fatality rate, 4.3 per 1000 climbers, can be compared to a rate of 0.42 deaths per 1000 in Grand Teton National Park [6] and to 29 per 1000 Himalayan mountaineers [7]. Environmental factors All of the routes up Denali involve crevassed glaciers, cold temperatures and high altitude; some offer more climbing challenges than do others. Rescue and fatality rates increased with the difficulty of the climb (Table 2). For every 19 expeditions on the easiest (West Buttress) route, there was one rescue mission; on the most challenging (South Face and Cassin Ridge) routes, one of 11.5 expeditions required help and the fatality rate, 25.8 per 1000, approached that of the Himalayas. Specific areas on the mountain are notorious among climbers for environmental hazards. During this study period,. eight people were injured in falls on a section below Denali Pass known as 'the Autobahn'. Two of these people died. Two teams fell down a couloir on the West Rib known as 'the Orient Express', killing two men and injuring three others. Eight people disappeared in 'the Valley of Death' of the northeast fork of the Kahiltna Glacier, where avalanches and crevasses are major hazards. Of 23 falls where the direction of travel was recorded, 19 (82.6%) happened on descent. Twelve climbers died from falls; five of these were into crevasses. Expeditions usually fly onto Denali, starting their climb from a glacier airstrip at 2100 m. Typically, they spend three weeks on the mountain. Hazards increase with Table 1. Events precipitating mountaineering emergencies on Denali Event" Frequency Subjects/Deaths CFRt Falls Overdue Altitude Cold Avalanches Other Total / * 41/2 28/2 4/0 6/2~ 126/ Each case attributed to single most important precipitor t Case fatality rate, or percentage of SAR subjects killed *Eight of these were probably buried by avalanches Ifprobable avalanche fatalities are included (eight ofthe 'overdue' climbers), the CFR becomes 80% 'These two died ofcarbon monoxide poisoning while cooking in an airtight tent

3 360 Lattimore Table 2. Evacuation and fatality rates by difficulty of ascent route Alaska grade t n Evacuation rate~ Fatality rate Two ** 2.0*** Three and four Five and six * 25.8*** Total Note: values for x 2 were obtained by comparing each category to the others combined (df = 1, n = 6580) t Scale increases with degree of difficulty and hazard; the West Buttress is grade 2, the Cassin Ridge, grade 5 and some south face routes are grade 6 [8,9) *Number of climbers evacuated alive per 1000 Number of deaths per 1000 climbers *p< 0.05, ** p< 0.01, *** p< elevation; half of the emergencies studied developed above 5000 m, where most climbers spend less than 20% of their time. Faulty decision making contributed to 56% of emergencies and judgement errors were more likely to contribute to emergencies at higher altitudes. The mean elevation for cases involving judgment error was 5056 m, and for other cases 4499 m, (t(88) = -2.64, p < 0.01). Human factors The mean age of search and rescue (SAR) subjects was 32 years, with 93.3% male and 6.7% female. Evaluation of the comparison sample of non-rescued climbers showed no significant difference for these variables and neither climbing experience nor employment of professional guides demonstrated a protective effect. European and Asian subjects were at significantly higher risk than were North Americans (Table 3). This was not linked to choice of ascent route; the proportion of foreign climbers on the least risky route exceeded their representation on the mountain. A random sample of 899 individuals registered for the West Buttress included 313 (34.8%) foreign climbers, while 28.6% of all climbers were from foreign countries [10). Frequently, foreign SAR subjects were described as having 'underestimated the Table 3. Rescue and fatality rates by residence Residence n Rescued t (rate) Died (rate) North America Europe Asia Other Total (11.3)** 49(45.1)** 22(46.5)** o 126(19.1) 10(2.0)** 11(10.1)* 7(14.8) ** o 28(4.3) Note: values for x 2 obtained by comparing each continent to all others combined. Yates correction for continuity used when small expected cell sizes encountered (df = 1, n = 6580) t Includes all subjects receiving help and all fatalities *p< 0.005, ** p< 0.001

4 Denali emergencies 361 mountain', implying that they were poorly informed of the risks of Denali, or overconfident of their abilities. Climbing rangers also noted that Asians and Europeans tended to ascend the mountain more quickly than the 1000 ft per day recommended for altitude acclimatization [11]. Perhaps haste was necessitated by long distance travel schedules; US citizens have a higher fatality rate than most European or Asian nationalities in the Himalayas [12]. Costs The park service finances rescues and is sometimes reimbursed by victims. Expenditures were recorded for 88 of the 98 missions (89.8%); these totalled $ Aircraft contracted from private and military sources were the major source of expenses. Although the costs of using military aircraft were calculated, under a mutual aid agreement between government agencies, money did not actually change hands. The military rescue teams view Denali missions as valuable training. A survey of mission summaries at one military base showed that mountaineers accounted for 2% of cases (77 of 2174) and 3.5% of flight hours used (584.7 of ); most of that agency's expenditures were for. missing pilots and fishermen [13]. Other costs to consider are the risks taken by rescuers. Some of the more harrowing missions reported included two 'one skid' helicopter landings, two high altitude hoist operations, and a landing at 5200 m described as a 'semi-controlled crash'. One mission involved a solo climber crossing the summit to save two men near the top of the Cassin ridge, another called for a single rescuer to assist a nearly incapacitated man down this ridge and included a crevasse fall on the way. In 1960, two men died in a rescue attempt on Denali when their plane crashed [1], but no injuries to rescuers were reported during this study period. Discussion Injury control efforts on Denali have focused on preventive education at registration and early intervention by the High Latitude Research Group based at 4300 m on the Kahiltna Glacier. Staffed by medical scientists, this team provides care for injured subjects and assistance with rescues. These measures can be credited for the fact that while the number of climbers on the mountain has recently increased dramatically, rescue frequency has not [10]. Even the best climbers die in the mountains. Further educational efforts should target European and Asian climbers, but experience and knowledge are not protection against certain hazards. Rescues will always be needed. The costs of mountain rescue are sometimes protested, but it can also be argued that this is money well spent. Mountaineers are usually young, healthy individuals with many productive years ahead of them. On Denali, the climbing season is limited to three months a year and the need for rescues of a challenging nature is expected. This is an ideal situation for training individuals in SAR skills. Establishment of a rescue internship program on the mountain would be attractive to rangers and guides from all over the world, and would be a way to provide additional manpower at reasonable cost.

5 362 References Lattimore 1. Waterman, J. Surviving Denali, New York: American Alpine Club, Williamson, J.E. (ed.) Accidents in North American Mountaineering. New York: American Alpine Club, Mills, W.J. and Rau, D. University of Alaska, Anchorage-section of high latitude study, and the Mt McKinley Project ( ). Alaska Med 1983; 25, Hackett, P.H., Roach, RC., Schoene, RB., Hollingshead, K.F. and Mills, W.J. The Denali Medical Research Project AmerAlp ; Wilson, R, Mills, W.J., Rogers, D.R and Propst, M.T. Death on Denali. West 1 Med , Schussman, L.c. and Lutz, L.J. Mountaineering and rock climbing accidents. Physician Sports Med 1989; 10, Shlim, O.R and Houston, R Helicopter rescues and deaths among trekkers in Nepal. lama 1989;261, Everett Jr, B.N. The organization ofan Alaskan expedition. Pasadena: Gorak Books, Waterman, J. High Alaska. New York: American Alpine Club, Denali National Park Service Statistics Hackett, P.H. and Roach, RC. High altitude pulmonary edema. 1 Wild Med 1990; 1, Towne, J. Death and the art of database maintenance. Mountain 1986; 110, Rescue Coordination Center mission summaries, Elmendorf Air Force Base, Anchorage,