rcwild
07-01-2005, 09:21 AM
A group was descending a canyon in California's San Gabriel Mountains. The incident occurred at the tallest waterfall in the canyon, believed to be approximately 100 feet. The rope used to set up the rappel was believed to be 200 feet long. The rope was rigged toss-n-go (rope was threaded through the rappel ring, ends brought together, then both strands were thrown over the edge). It was not possible to see the bottom from the top, but the group was confident that the rope would reach. The first person down took the group's additional ropes with him to rig the next rappel.
The first three people rappelled without a problem, but became aware of a developing issue. The rope had enough stretch to reach the bottom when it was weighted. When not weighted, it was about six feet short and the ends were uneven. As each of the first three people rappelled off the end of the rope into the water, the ends became more uneven. This happened because their rappelling devices came off the short strand while continuing to create friction on the longer strand, pulling on it. They realized that each subsequent descent would make it worse and feared that the situation could result in (a) someone taking a severe drop, and/or (b) the rope being pulled through the anchor, stranding the remaining group members at the top of the rappel.
Visual communication was not possible between people at the top and bottom of the rappel. The group did not have walkie-talkies. Some members of the group had whistles, but they had not discussed signals. The three people at the bottom considered their options and decided to attach a second rope to the end of one of the strands, then use the other strand to pull the second rope to the top. To accomplish this, they knew the existing rappel rope would need to be weighted so they could reach the dangling ends. When the fourth person started his rappel, two people entered the water. One stood on the other's shoulders. It proved more difficult than anticipated to connect the rope and assist the fourth person off the rope.
In the meantime, the people at the top grew concerned because the fourth person was on the rope for a long time. When the tension finally came off the rope, the fifth person descended far enough to figure out what was going on, ascended back to the top and reset the ropes.
ANALYSIS AND LESSONS LEARNED:
This incident did not result in any injuries, but it does illustrate several issues that should be addressed in similar situations.
1) Confidence in the length of the rappel was high because the canyon had been pre-scouted. Confidence in the length of the rope was also high. However, considering the small margin for error (100-foot rappel, 200-foot rope), more thought should have been given to the possibility that the rope might be too short.
2) Circumstances warranted setting up either a block or a contingency anchor instead of toss-n-go: (a) the small margin for error in rope length, and (b) the number of beginners in the group. There were people in the group who questioned the rigging in their own minds, but did not speak up. When roles are pre-defined as "leader" and "followers", or when a beginner feels somewhat intimidated by the expertise of someone with more experience, there is a risk that alternate solutions are not presented for consideration, or worse, that risks are not brought to the attention of the group.
3) If a block or contingency anchor was used, it would have been okay to send the other ropes ahead to the next rappel. Using blocks and contingency anchors, extra rope is available at the top of the rappel to deal with problems. When the decision was made to rig toss-n-go, one rope, at least 100 feet long (the length of the rappel), should have been held back at the top, just in case. This is standard practice for professional guides, but not among recreational canyoneers.
4) Carrying whistles is a very good idea, especially in Class C canyons. Unfortunately, they won't be of much use unless signals are discussed in advance.
5) All canyoneers should know how to ascend a fixed rope and carry appropriate equipment to do so. If anyone in the group had descended to the end of the short strand of rope, and that end was at a dangerous height, he/she needed the option to ascend back to the top.
The first three people rappelled without a problem, but became aware of a developing issue. The rope had enough stretch to reach the bottom when it was weighted. When not weighted, it was about six feet short and the ends were uneven. As each of the first three people rappelled off the end of the rope into the water, the ends became more uneven. This happened because their rappelling devices came off the short strand while continuing to create friction on the longer strand, pulling on it. They realized that each subsequent descent would make it worse and feared that the situation could result in (a) someone taking a severe drop, and/or (b) the rope being pulled through the anchor, stranding the remaining group members at the top of the rappel.
Visual communication was not possible between people at the top and bottom of the rappel. The group did not have walkie-talkies. Some members of the group had whistles, but they had not discussed signals. The three people at the bottom considered their options and decided to attach a second rope to the end of one of the strands, then use the other strand to pull the second rope to the top. To accomplish this, they knew the existing rappel rope would need to be weighted so they could reach the dangling ends. When the fourth person started his rappel, two people entered the water. One stood on the other's shoulders. It proved more difficult than anticipated to connect the rope and assist the fourth person off the rope.
In the meantime, the people at the top grew concerned because the fourth person was on the rope for a long time. When the tension finally came off the rope, the fifth person descended far enough to figure out what was going on, ascended back to the top and reset the ropes.
ANALYSIS AND LESSONS LEARNED:
This incident did not result in any injuries, but it does illustrate several issues that should be addressed in similar situations.
1) Confidence in the length of the rappel was high because the canyon had been pre-scouted. Confidence in the length of the rope was also high. However, considering the small margin for error (100-foot rappel, 200-foot rope), more thought should have been given to the possibility that the rope might be too short.
2) Circumstances warranted setting up either a block or a contingency anchor instead of toss-n-go: (a) the small margin for error in rope length, and (b) the number of beginners in the group. There were people in the group who questioned the rigging in their own minds, but did not speak up. When roles are pre-defined as "leader" and "followers", or when a beginner feels somewhat intimidated by the expertise of someone with more experience, there is a risk that alternate solutions are not presented for consideration, or worse, that risks are not brought to the attention of the group.
3) If a block or contingency anchor was used, it would have been okay to send the other ropes ahead to the next rappel. Using blocks and contingency anchors, extra rope is available at the top of the rappel to deal with problems. When the decision was made to rig toss-n-go, one rope, at least 100 feet long (the length of the rappel), should have been held back at the top, just in case. This is standard practice for professional guides, but not among recreational canyoneers.
4) Carrying whistles is a very good idea, especially in Class C canyons. Unfortunately, they won't be of much use unless signals are discussed in advance.
5) All canyoneers should know how to ascend a fixed rope and carry appropriate equipment to do so. If anyone in the group had descended to the end of the short strand of rope, and that end was at a dangerous height, he/she needed the option to ascend back to the top.