On June 17, 1997, approximately 0915 Pacific daylight time, a Cessna A188, N9766V, being operated by Eagle Cap Aviation of La Grande, Oregon on a 14 CFR 137 aerial application flight for mosquito control, crashed near Richland, Washington. The aircraft was substantially damaged in the crash and a subsequent fire. The airline transport pilot of the single-seat agricultural aircraft escaped the aircraft without injury. Visual meteorological conditions prevailed and no flight plan had been filed. During an interview with a Federal Aviation Administration (FAA) inspector and in a subsequent written statement, the pilot reported that he was in the process of applying a granular larvacide (brand name Vectovac) along the Yakima River near a park. The pilot stated that this was his third load of the morning and about half of the load of larvacide had been applied at the time of the accident. The load was being applied to the north side of the river at water level. The terrain on the south side rose steeply to about 300 feet above the river. Power lines ran across the river, and additional power lines were strung east of the park at an elevation of about 75 feet. The pilot stated that he was making a turn southbound at the end of a run. The pilot reported that during the turn, he felt the onset of a "stall buffet." The highest terrain with power lines on top were directly in front of the airplane. The pilot stated that to his left were the power lines that crossed the river, however, he lost sight of those wires, but knew they were close. The pilot stated that he chose to continue the turn to the left and hit the terrain instead of chancing a collision with the wires. During the turn, the airspeed and altitude continued to decay. The airplane collided with the ground at minimum speed and wings level. A post-crash fire ignited and consumed the airplane. The pilot reported that there were no mechanical failures or malfunctions with the airplane at the time of the accident, and felt that turns to the right instead of to the left, might have given him a way out to avoid the accident.