Investigators have determined that the crash that killed Steve Fossett was most likely caused by sudden turbulence, the BBC reports. An NTSB probe concluded that there was no malfunction with the adventurer's plane, and that an "inadvertent encounter with downdrafts" caused him to lose control of his aircraft in the September 2007 crash.
Downdrafts of "at least 400 feet per minute" yanked Fossett's plane downward during the flight over the Sierra Nevada mountains, according to investigators. Their probe determined that the plane was still traveling at a high speed when it hit the ground, scattering wreckage over a wide area. No trace of Fossett was found until more than a year after the crash.