On July 14, 2005, at 2130 central daylight time, an Air Tractor AT-301, N3159N, piloted by a commercial pilot, was destroyed during impact with terrain near Langdon, North Dakota. Visual meteorological conditions prevailed at the time of the accident. The aerial application flight was operating under the provisions of 14 Code of Federal Regulations (CFR) Part 137 without a flight plan. The pilot was fatally injured. The flight departed Robertson Field Airport (D55), Langdon, North Dakota, at an unconfirmed time. The airplane was spraying a field of canola with fungicide just prior to the accident, according to the land owner. The land owner reported that after a spray-run the airplane continued about a half mile beyond the end of the field before pitching-up. The witness did not see the airplane impact the ground due to a ridgeline which obstructed his view of the accident site. An agricultural pilot, who was operating near the accident site, saw the airplane "take a straight line up and arch across the top violently and then it appeared to go straight down." The pilot stated that the airplane did not climb higher than 200 feet above ground level before abruptly pitching to the right and entering the nose low attitude. The pilot did not see the airplane impact the ground due to a ridgeline which obstructed his view of the airplane. Federal Aviation Administration (FAA) inspectors performed the on-site examination of the wreckage. The wreckage was located in a level, open field. The aircraft engine was impacted into the field to a depth of approximately four feet. The FAA inspectors reported that flight control continuity was established between all flight control surfaces and the cockpit. No anomalies were found that could be determined to have existed prior to impact.