On July 30, 2007, a Christen Industries Inc. A-1 (registration N661FB) was involved in an aviation accident near Elm Springs, SD. Investigators recorded the probable cause as: The pilot not maintaining clearance from the rising terrain. A factor contributing to the accident was the rising terrain. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
An airplane struck rising terrain while maneuvering on a public use animal control flight. The pilot reported unusual stick pressure changes before impact. No mechanical anomalies were found.
Accident Details
An airplane impacted rising terrain while maneuvering on a public use animal control flight. The pilot reported that he had turned south and initiated a shallow descent to maintain a constant altitude above down-sloping terrain. As the flight continued, the pilot noticed a slight rise in the terrain and believed there was sufficient altitude to clear it.
Pilot Statement
According to the pilot, "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."
Investigation Findings
Flight control continuity was confirmed after the accident. An examination of the airplane's systems revealed no anomalies. No other contributing factors were identified in the investigation.