For more than 70 years, the American Alpine Club has published an annual collection of hard lessons learned, the Accidents in North American Climbing (ANAC). The periodical includes tables cataloging injuries, deaths, key causes and other relevant information. As a longtime climber expecting my first child, I took an interest in risk and accident data. But the official ANAC tables didn’t show the most dangerous causes by type of climbing, or reveal relationships between factors. Curious about those statistics, I analyzed the text of each ANAC-published accident from the past 30 years using a background in data-journalism and the natural-language-processing concepts I’ve acquired working in the field.
In this article you can find the results—data from 2,770 accident narratives, starting in 1990. No data set is perfect, so these results should be taken with a grain of salt, not as definitive hard stats.
This is not an AAC project. With that said, I’m thankful to AAC editors Dougald MacDonald and Bryan Simon for consulting on the project, and also to my friend Nicholas Cohn-Martin, a data and research analyst and climber.
What Type of Climbing is Most Dangerous?
In an examination of all roped rock-climbing accidents, trad climbers reported about three times the number of accidents as sport and toprope combined. The following analysis, and pie chart, exclude alpine and mountaineering incidents, which represent a separate climbing discipline with added dangers, and which deserve further study. We will call this category “Trad ex-ALP,” since it is for trad climbing but not alpine/mountaineering climbing.
Trad ex-ALP accidents make up 63 percent of all roped accidents, with sport and toprope together making up 20 percent. There are “unknown” cases because accident reports aren’t always clear, and I aimed to be conservative in tagging, preferring false negatives to false positives.
It’s not definitive that trad is three times as dangerous—as stated earlier, this is not a truly random sample—only that it is three times more dangerous in the context of the published accidents. Other missing information includes the total number of climbing days that are spent on each discipline.
A trend worth noting is that in the first two decades of data, trad accidents were roughly five times as prevalent in the accident narratives as sport and toprope combined. Since the 2010 Accidents, they have been instead about twice as common—trad still has a much larger count.
That trend directionally lines up with data from the Outdoor Industry Association’s latest reports, which estimate climbing activity within two large umbrella groups of styles by surveying thousands of people online. In 2017 and 2018, the first years that the OIA surveyed Americans about both sport/bouldering and trad/ice/mountaineering, the group found a larger amount of the trad group, with greater than 2.5 million participants each year, compared with greater than 2.1 million people each year participating in sport and bouldering. Both ranked below the estimate of indoor-climbing participants, at 5 million plus.