On July 30, 2007, about 0700 mountain daylight time, N661FB, registered as a Christen Industries Inc. A-1 airplane, operated by the State of South Dakota, sustained substantial damage when it impacted rising terrain while maneuvering near Elm Springs, South Dakota. Visual meteorological conditions prevailed at the time of the accident. The public use animal control flight was being conducted under 14 Code of Federal Regulations Part 91. No flight plan was on file. The pilot and passenger sustained minor injuries and went to a hospital. The local flight originated from the Wall Municipal Airport, near Wall, South Dakota, at 0615. The pilot stated in his accident report that he had turned and was heading south. He said that he had begun a shallow descent to maintain a constant altitude above the terrain, which was lowering toward a river bottom. The pilot's accident report, in part, further stated: As we continued to descend I noticed a slight rise in the terrain and determined that we had plenty of altitude to clear that rise and continued on with my southerly flight path and shallow descent. As we approached the slight rise in the terrain the pressure in the stick changed very quickly with a movement in the pitch axis only. The pressure came back immediately and then there was another pressure change in the stick that was a little more pronounced. This movement was identical to the other in that it was a pitch change only; there was no movement in the roll direction. After the second time the pitch change changed I made a remark to the gunner and the crash took place. At 0652, the recorded weather at the Rapid City Regional Airport, near Rapid City, South Dakota, was: Wind 150 degrees at 7 knots; visibility 10 statute miles; sky condition clear; temperature 21 degrees C; dew point 17 degrees C; altimeter 29.97 inches of mercury.