World-famous wingsuit flier Dean Potter had strapped his iPhone to the back of his head and hit record before he and partner Graham Hunt jumped from a cliff in Yosemite National Park in what was to be an exhilarating flight through a V-shaped rocky formation—a route that left little margin for error. Twenty-two seconds later the video abruptly stops. The two were killed when they slammed into the ridgeline at 100mph-plus. A National Park Service investigation concluded the May 16 deaths were accidental, but despite the video and photos of the jump, officials consider the specific reason why they died a mystery. Investigators listed several possible contributing factors: indecision, distraction, miscalculation, and air turbulence.
Autopsies found that Potter had struck headfirst and that Hunt hit with the front of his body. Blood samples showed no drugs or alcohol for either man. An unnamed wingsuit flier who investigators consulted estimated that Potter and Hunt had flown through the notch about five times; the flier inspected both wingsuits for the park service and found no equipment flaws. Among other things, investigators noted that Hunt may have been distracted by phone calls and texts he attempted immediately before jumping and that Potter may have seen his partner strike the ground and flinched, or he simply misjudged his elevation. "No one but Potter and Hunt will ever truly know what happened," investigators concluded. The AP obtained the investigation reports through a records request. More of the findings, including the sounds Potter's girlfriend heard, here.