Late in the day on January 15, a male lead climber was attempting to climb the Second Flatiron, a low 5th-class climb with many possible variations. The leader climbed a full rope length and could not find an adequate anchor. He untied from the rope to try to climb further to find viable anchors. The second started climbing, assuming he was on belay, and then slipped, fell, and tumbled 40 feet, getting airborne in the process. Rescue involved 800 feet of high-angle evacuation to a ground team, followed by a mile of lower-angle evacuation to an ambulance.
It seems as though a lack of experience and available protection led the lead climber to believe the best option for the completion of their climb was to untie and begin a free solo to find suitable anchors. It seems there was a lack of communication between the leader and second, both for the action of untying from the rope, and for the second starting to climb. (Source: Daniel Lack, Rocky Mountain Rescue Group.)