FALL ON ROCK, CHOCKS PULLED OUT

Quebec, Gatineau Park Escarpment

On May 14, 1989, Henry Marsden (25) was leading a 5.10b route up a thin crack in the ’Ron and John’ cliff. The lead was protected by five wired chocks: R.P.s and taper locks. At the top, about 12 meters up, he fell. As the rope tightened, it pulled out the chocks starting from the bottom. Then finally when the top piece pulled out, there was no backup protection, and he fell to the ground, where he suffered a fractured sternum and strained back muscles. (Source: Henry Marsden, Ottawa)

Analysis

Zippering is caused by the inability of ordinary chocks that are placed for downward loading to withstand an outward pull. In principle, a remedy would be for the belayer to sit closer to the rock face, but in this case, he was already closer than two meters, and it would have been difficult to do better. Zippering could be prevented by placing a camming device at the bottom of the climb, one that would not pull out sideways. Another possibility is to climb on two ropes, alternately clipping into each one, so that only half the runners would be pulled outward. (Source: Henry Marsden)