RAPPEL ERROR—DID NOT SECURE RAPPEL ANCHOR SLING
Colorado, Eldorado Canyon State Park
On May 6, after belaying his partners down a 20 to 30 foot cliff, the victim (39) fell about 30 feet while rappelling. A Ranger found a red sling girth hitched around a tree with no knot in it. Apparently the victim placed the red sling around the tree and added a descending ring, but did not securely tie off the sling. The descending ring, rappelling device and locking carabiner were all securely attached to the victim.
Know the appropriate knots to use. And always double check them. (Source: J. W. Wilder, Park Ranger)