On September 2, 1993, at approximately 1512 hours mountain daylight time (MDT), a Cessna A188B "AgWagon," N21861, registered to Agwagons, Inc., and being operated and flown by William R. Ferguson, a certificated commercial pilot, collided with terrain while applying Roundup over an agricultural field. The aircraft was destroyed and the pilot suffered serious injuries. Visual meteorological conditions existed at the time and no flight plan had been filed. The aerial application flight was to have been operated in accordance with the requirements set forth in 14CFR137 and had departed a field near the accident site at approximately 1503 hours. The aircraft departed with 20 to 25 gallons of fuel and 140 gallons of chemical. The pilot reported that while maneuvering in preparation for a spray run "an area of down air was encountered." He stated that he increased propeller RPM to maximum and "the throttle was brought up." The pilot reported that 100 to 110 gallons of chemical remained at the time of the event and that he dumped approximately 30 to 40 additional gallons. The pilot reported that "before anymore load could be dumped, the ground was impacted in a flat, level attitude." During an interview with an FAA Inspector, the pilot stated that "he dumped part of his load, applied full power, but the aircraft continued to mush out." Additionally, he reported that there was no indication of any malfunction with the aircraft (refer to attached FAA Form 1360-33).