I worked a couple summers for a crop duster neighbor as a flagger in the field. He put booms and a belly tank on a Piper Super cub when he got started and later bought a plane called a Grumman Ag Cat. Years later he built up a business of twin engine aircraft flying cancelled checks along with other charter and air freight services. Some time ago when the UPS workers went on strike he took on some extra business flying freight during the strike. He was flying to Tennessee one trip with fright and crashed into the side of a mountain. He had many many hours of flying and it was hard for everyone to figure out at first what happened with all his experience, but the investigation of the wreck concluded he simply ran out of fuel.