On June 5, 1998, at 1958 central daylight time, an Aero Commander S2R agricultural airplane, N1765S, was destroyed upon impact with terrain following a loss of control during approach near Hondo, Texas. The non-instrument rated commercial pilot, sole occupant of the airplane, was fatally injured. The airplane was owned and operated by Rusty's Flying Service, Inc., of Hondo, Texas, under Title 14 CFR Part 137. Visual meteorological conditions prevailed for the aerial application flight for which a flight plan was not filed. The local flight originated from the Hondo Municipal Airport, at approximately 1855. According to local law enforcement personnel who responded to the accident site, the airplane was returning to home base upon completion of an aerial application flight in a corn field on Highway 173, approximately 5.5 miles north of Hondo. The operator confirmed that the airplane had been loaded with "Slam" to eradicate root worm beatles. Witnesses near the airport reported that the airplane was observed in the traffic pattern at approximately 400 to 500 feet agl in the downwind leg for landing on runway 04. Eyewitnesses reported that the airplane "stalled during the turn from base to final" during a visual approach to runway 04. Another witness reported hearing "the sound of the engine power being applied as the pilot attempted to recover from the stall." Witnesses reported that "the airplane impacted in a potato field in a nose low attitude, in a nearly wings level attitude, at a high rate of decent." The airplane came to rest in a westerly heading, in the upright position, approximately 150 yards south of the airport's perimeter fence. Examination of the airplane by the FAA inspector revealed that the forward section of the fuselage was severely compressed. The radial engine separated from the airframe, and the 2-blade propeller was buried in the ground. The "accordion like" damage to the leading edges of both wings was nearly symmetrical. The left fuel cell was compromised. There were no chemicals on board the airplane at the time of the accident. There was no fire. Weight and balance calculations were made using figures provided by the operator, the aircraft maintenance records and FAA medical records. The airplane was found to be within weight and balance limits at the time of the accident. The winds at the time of the accident were reported from 040 degrees at 13 knots, with occasional gusts to 20 knots. A pilot home based at the Hondo Airport reported to the FAA inspector that on the day of the accident he had experienced "noticeable wind shear in the area throughout" on the day of the accident. The pilot added that his employer elected to discontinue flight testing of the unmanned vehicle they were testing earlier that day due to an approaching front and the unstable air. A transient pilot that flew a Piper Cherokee into the Hondo Airport about an hour prior to the accident, also reported "wind induced turbulence while on his approach when within 500 feet of the ground." Official sunset was reported as 2044. An autopsy and toxicological tests were requested and performed. The autopsy was performed by the Forensic Science Center of the County of Bexar, in San Antonio, Texas, on June 07, 1998. The autopsy indicates that the pilot was wearing the seat belts and shoulder harnesses at the time of the accident. The 22 year old pilot was reported to be wearing a flight helmet at the time of the accident. Toxicological tests were negative. At the time of his last FAA physical examination on January 21, 1998, the commercial pilot reported that he had accumulated 950 flight hours. In the enclosed NTSB Form 6120.1/2, the operator estimated that the pilot had accumulated a total of 1,500 hours.