He died on November 23, 1998 at the age of 35 after his rope failed while performing a "controlled free-fall" jump from the Leaning Tower rock formation in Yosemite National Park. The failure was investigated by the National Park Service with assistance from Chris Harmston, Quality Assurance Manager at Black Diamond Equipment. Harmston concluded that a change in jump site angle probably caused the ropes to cross and entangle, leading to the rope cutting by melting.[2] Miles Daisher, who was with Osman when he made the jump, stated that the ropes used in his fatal jump had been exposed to inclement weather - including rain and snow - for more than a month before the fatal jump, but that the same ropes were used for several shorter jumps on the previous and same day, this was said to be his last jump before he retired