California, Yosemite Park, El Capitan. On May 15 Jim Baldwin (24) and Ed Cooper were in the early stages of the climb of the then-unclimbed direct S.W. face on El Capitan (climb successfully completed in November, 1962). Because of the severity of the climbing, the fixed rope technique was being used. Party had been climbing single days, ascending to and descending from the high point every day; party climbed until reaching about 700 feet high, where the piton crack ended, and an overhanging blank wall was encountered for some distance. At this point, the prussiking up and down every day took too long, the party decided to spend its first night on the wall, hanging in slings. The angle of the climbing had been only 75–80 degrees before the overhang was encountered. At the end of the second day, some 56 feet of blank overhang had been overcome. In addition, when the second man removed the bolt hangers and pitons on this overhanging pitch, the rope was fixed so that it descended an additional 90 feet below the hanging belay- stance beneath the overhang. For perhaps 100 feet the rope hung free. It was a single 7/16 inch braided nylon rope of a very smooth quality, manufactured in Canada. It was a scary prussik, and the first test of the prussik was descending it, not ascending it. When coming to the overhanging section, Jim's prussik knots failed to grip simultaneously, and he fell 80 feet to the bottom of the rope where he was stopped when he came to the anchor point where the rope was fixed at the bottom. He suffered severe rope burns attempting to stop himself, and could not climb for three weeks. Inspection of the prussik knots at the base of the climb showed that they had been partly burned through.
Source: Ed Cooper.
Analysis: (Cooper) The ordinary two twists of the prussik knot are not always sufficient. I had for sometime used three twists in my prussik knot whenever presented with a situation that I was not completely familiar with, and this no doubt prevented a similar fall on my part; as I did not know of the fall until I reached the ground. (The rock curved away beneath me at that point.) The smoothness of this particular nylon rope most certainly, and tiredness from a night spent hanging in a sling, perhaps contributed to the cause of the accident. (The safety precaution of having the other end of the rope secured should also be emphasized. If prussiking down is planned, and the other end cannot be secured, the alternative would be to have a large knot near the end of the rope to act as a safety measure, ed.)