California, Berkeley—On March 11, 1956 a group of about 15 climbers that included experienced men as well as novices was practicing lower belaying at Indian Rock under the direction of the outing leader. The belayer was at ground level using a standing seat belay to arrest falls (free jumps from above). The rope passed through a carabiner about 25 feet above the belayer and then down a few feet to a climber on a ledge. On signal the climber would leap off to be arrested by the belayer. For safety a second, upper belay was also used but the belayer was off at an angle of about 30 degrees and hence not too effective. Although several jumps had been made and successfully arrested, on this occasion the rope broke after absorbing most of the energy of the fall but dropped the climber possibly the last five feet. Fred Schaub (20) landed on his back, apparently without serious injury, at least none that could be diagnosed.
Source: William Siri.
Analysis: (W. Siri). The rope used in these practice falls and belays was 7/16 inch diameter nylon. The rope, however, was five years old and had been badly worn in use on local practice climbing and belaying. A study of the rope revealed that about 50 percent of the fibers were only ½ inch long and only 10 per cent of the fibers in the rope had not been affected by abrasion. Ninety per cent of the fibers were less than 4 inches long. Further tests are being made of its ultimate strength. Action is being taken for better inspection of ropes, and to substitute weights for the practice of lower belays.