Carbon Monoxide, Failure to Ventilate Tent, Weather, Fatigue, Alaska, Mount McKinley

Publication Year: 1987.


A party of six climbers from Switzerland departed for their ascent of Mount McKinley on May 29,1986. Four members planned to climb the West Buttress while the other two intended to climb the Cassin. On June 6 the four member team of Rolf Rauber (23), Paul Kolly (37), Siegfried Beyeler (30), and Bruno Beyeler (22) reached the 4350 meter camp on the West Buttress. Rauber came to the NPS medical/rescue tent to have his eyes examined due to minor irritation. Rauber was examined by Dr. Wade Henrichs and later talked with Ranger Roger Robinson. Rauber appeared in good spirits and condition with very minimal effects from the altitude. The four made a carry and placed a cache at 5200 meters on June 7. Both Bruno Beyeler and Rauber felt quite tired from the day’s work, returning after seven hours at 2030. At 2100, Rauber came by the medical/rescue camp to borrow some duct tape to repair Kolly’s overboots. Robinson noticed that Rauber still appeared in good spirits, though he seemed somewhat tired. Bruno was affected more by altitude, experiencing minor AMS as reported by his brother Siegfried. Bruno and Rauber mentioned to Kolly and Siegfried that they would like to sleep in and not to disturb them until the afternoon of June 8. Kolly and Siegfried were camped about 35 meters from Bruno and Rauber, with snow walls over one meter circling the tents. These walled-in tent sites were previously built by other climbing parties, which was why they camped this distance apart. At 2120 Bruno and Rauber told Kolly and Siegfried that they were going to make dinner and go to sleep.

The weather remained unsettled with the overnight low of approximately -14°C. Light snow fell most of the night with occasional gusts of ten knots. Not until early evening of June 8 did the conditions begin to improve and the clouds lift for better visibility.

Siegfried and Kolly slept until noon, but were not alarmed when they observed no

activity coming from their companions’ tent site. Not until early evening did they become somewhat suspicious about this inactivity. At 1900 Siegfried and Kolly went over to check on Bruno and Rauber. Siegfried shook the snow from the top of the tent and pulled open a vent flap. (Siegfried reported that he had repeatedly warned Bruno and Rauber to leave the two top vents open.) He then noticed that the tent sagged because the guylines were loose, another common mistake he had repeatedly instructed the two to avoid. No voice contact was made, so Siegfried unzipped the entrance to find both Bruno and Rauber unconscious and cold. Kolly hurried over to the medical/rescue camp calling “Doctor, doctor.” VIP Dr. Wade Henrichs and Ranger Roger Robinson were contacted and rushed back to Bruno’s and Rauber’s tent at 1910 where they found the two cold and lifeless. It was felt by Dr. Henrichs that the two had been dead for 18–24 hours. At 1920 Robinson called the Talkeetna Ranger Station informing Ranger Scott Gill of the situation. Dr. Henrichs continued to examine the two individuals in the vestibule area of the tent and concluded that they had died of carbon monoxide poisoning the evening before. Robinson and Henrichs observed that Rauber’s Bluet stove had burned out its fuel at a medium to low heat cooking a pot of soup. The control knob on the stove was found on with a small thick portion of soup in the double cooker container. It appeared that the soup had boiled for a period of time. A used Bluet cartridge was found next to the stove along with dirty cups and opened food packets. It appeared that Rauber and Bruno had already eaten most of their dinner and were in the process of heating soup when they were overcome by carbon monoxide. Kolly mentioned that they usually had tea or soup after dinner. It also apeared that they may have put on another cartridge over the course of the meal which would mean that the stove burned for an additional three hours.

Bruno and Rauber were found in their sleeping bags within arm’s reach of the stove. It appeared Bruno was sleeping, as he lay on his side, while Rauber lay on his back, apparently in control of the stove.

Due to the poor unsettled weather, Ranger Robinson decided that an air evacuation would not be reasonable, so chose to coordinate a ground evacuation. The rescue team consisting of Ranger Robinson and ten volunteers began their descent on June 9 in stormy weather, arriving at Kahiltna Base Camp the next evening. The bodies were flown out that evening. (Source: Roger Robinson, Mountaineering Ranger, Denali National Park)


This tragedy reminds us of the extreme danger of the odorless gas carbon monoxide (CO) when using combustible appliances in closed spaces. Cases of CO poisoning on Denali were reviewed last year also (see ANAM, 1986). Either the climbers ignored the warning signs of CO toxicity such as headache or nausea, perhaps attributing them to the altitude, or were overcome with such a high concentration of CO that there were no toxic symptoms prior to unconsciousness, which is possible but unlikely. CO poisoning among mountaineers is probably much more common than realized. The effects of CO and altitude hypoxia appear to be additive, and thus CO exposure at altitude is more dangerous than at sea level. Recent measurements by William Turner and Bill Sumner, on Denali, found toxic levels greater than 750 parts per million of CO near the stove in tents, snow caves and igloos. A major factor in producing CO is the damping effect on the flame of having the pot too close to the flame, and having water drop onto the flame from condensation on the pot. Keeping the pot warm and adding snow slowly to warm

water thus produces much less CO than filling the pot with snow. Climbers cooking in shelters should try to minimize condensation on the cooking pot.

Adequate ventilation is the key to removing CO from a shelter. The Swiss climbers’ tent was made of apparently unbreathable material, and closing the vents sealed the tent as well as their fate. The same could happen when cooking in a tent completely buried by snow, or in an igloo with glazed ice walls on the inside. In a tent, ventilation is a function of the wind in the area of the vent opening. When cooking in a snow cave or igloo, the vent must be at least of ski pole basket-sized diameter, should be placed directly above the stove, and can be sealed when not cooking in order to maintain warmth. Climbers with symptoms of mountain sickness must be especially careful. CO poisoning should be considered in anyone unwell at altitude if using a combustible appliance in a closed shelter. Treatment is to stop the CO production and have the victim, if conscious, hyperventilate in fresh air. Descent to a lower altitude, administration of oxygen and forced hyperventilation by mouth to mouth breathing may be required for comatose victims. (Source: Dr. Peter Hackett, Denali Medical Research Group)