On July 13, 1999, at 0718 central daylight time, a Cessna A188B, N731VR, collided with trees and the ground following an aerial application maneuver in Panther Burn, Mississippi. The airplane was operated by the commercial pilot under the provisions of Title 14 CFR Part 137, and visual flight rules. Visual meteorological conditions prevailed and no flight plan was filed for the local agricultural application flight. The pilot received serious injuries, and the airplane sustained substantial damage. The flight originated from a private airstrip in Anguilla, Mississippi, at 0650. According to the pilot, he departed the airstrip with a load of 57 gallons of Fyfanon, a chemical used to spray boll weevils. After performing a series of spray runs, the airplane veered off course, collided with a tree line, then impacted the ground and burned. According to the pilot, he did "not recall" anything with regard to the events leading up to and subsequent to the accident. Following the accident, an FAA inspector and an engineer from the Cessna Aircraft Company attended the accident scene. The airplane was found approximately one and a half miles northwest of the field the pilot was spraying. The airplane traveled on an easterly heading through a line of trees running north to south located 30 feet from the initial ground scar. The fuselage and part of the left wing were found approximately 100 feet east of the tree line. The left wingtip, a portion of the left wing and the left landing gear were found west of the tree line. The right wing was found in the tree line, and the right landing gear was located east of the tree line. The engine was located 75 feet south east of the main wreckage. One of the propeller blades was found partially embedded in a tree, and the second propeller blade was not located. The right wing and fuselage from the instrument panel forward sustained fire damage following a post-impact fire. An examination of the engine was performed. Fuel was present in the fuel manifold. The spark plugs were removed and appeared normal. One of the magnetos was removed and produced spark when rotated by hand. The engine's crankshaft was unable to be rotated. A large section of a tree was found on the engine's left side between cylinders and the push rod housings. A review of the airplane's maintenance records disclosed that the Differential Global Position System (DGPS) installed on the airplane had been serviced on two separate occasions (July 7 and July 12) during the week leading to the accident. The DGPS is installed on a shelf behind the pilot's seat near the shoulder harness attachment point, and was required to be operational for use during the flight under the conditions of the spraying contract. According to stored information downloaded from the airplane's DGPS, the lock on the DGPS was lost shortly after the pilot had completed a right 180-degree turn along the southeast side of the field the pilot had sprayed (see attached map of downloaded DGPS flight track).