On May 19, 2003, about 1750 Pacific daylight time, an unregistered Sabre Trike 330 airplane stalled during an inadvertent takeoff near Jean, Nevada. The pilot, who did not hold a pilot certificate, was operating the borrowed airplane under the provisions of 14 CFR Part 91. The airplane sustained substantial damage. The pilot, the sole occupant, received fatal injuries. Visual meteorological conditions prevailed and no flight plan had been filed. The owner reported in a written statement that he was selling the airplane to the pilot. He demonstrated how it was assembled, and then demonstrated the airplane in flight. The pilot/buyer then put on his helmet and sat in the airplane. Two of his friends, and the owner, advised the pilot not to takeoff, to "just taxi." The pilot said he was not going to fly. While the pilot/buyer was taxiing, the airplane's speed increased. The airplane "went up" about 100 feet and then "[was] going straight to the ground." The airplane began to "come out of it" and the owner turned away. Shortly thereafter, the airplane impacted the ground. One of the pilot's friends witnessed the accident. He reported the airplane "went up too fast, stalling, losing control, then smashing to the ground." The owner was not aware that the airplane did not comply with the requirements of Federal Aviation Regulation (FAR) 103, which specifies the requirements an aircraft must meet in order to operate as an ultralight vehicle.