HISTORY OF FLIGHTOn July 27, 2020, about 1045 central daylight time, a Cessna A188 airplane, N53163, was destroyed when it was involved in an accident near Corsica, South Dakota. The pilot was fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations (CFR) Part 91 aerial application flight. According to the operator, the pilot had started with the company about 3 months before the accident. On the day of the accident, the pilot flew about 2.5 hours practicing spray operations with loads of water. The accident occurred on his third flight of the day. According to witnesses, the pilot had completed two passes over the field. After he completed the second pass, the pilot entered a turn to return for another pass when the airplane suddenly nosed over and impacted the ground. One of the witnesses noted that the airplane entered a descending spiral before impact. Two witnesses heard a loud noise from the airplane before seeing it "nosedive." The sound was similar to a "backfire" or "an over-inflated tire bursting." All three witnesses stated that the airplane appeared to be flying normally before the accident occurred. PERSONNEL INFORMATIONThe pilot received a Part 137 agricultural endorsement on May 8, 2020. WRECKAGE AND IMPACT INFORMATIONThe airplane came to rest in a bean field. The forward fuselage was fragmented, and the aft fuselage was buckled consistent with impact forces. Both wings exhibited leading edge crush damage and localized deformation. The empennage remained attached to the fuselage. The flight control surfaces remained attached to the airframe. A postaccident examination of the airframe and engine revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation. MEDICAL AND PATHOLOGICAL INFORMATIONToxicology testing performed by the Federal Aviation Administration’s Forensic Sciences Laboratory identified 1.3 ng/ml of carboxy-delta-9-tetrahydrocannabinal (THC-COOH) in the pilot’s blood. THC-COOH is the primary inactive metabolite of tetrahydrocannabinal (THC). THC is the psychoactive compound in marijuana. In addition, THC-COOH, 11-hydroxy-delta-9-THC (an active metabolite of THC), pheniramine (a sedating antihistamine), and albuterol (an inhaled drug used to treat asthma) were identified in the pilot’s urine.