NTSB Identification: SEA07GA142.
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Accident occurred Friday, June 01, 2007 in Loa, UT
Probable Cause Approval Date: 04/30/2008
Aircraft: Christen Industries A-1, registration: N9602R
Injuries: 2 Fatal.
: NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this public aircraft accident report.
The pilot and gunner were participating in a low-level, aerial predatory control operation. They were operating over terrain that was approximately 8,300 feet above mean sea level. While maneuvering in a turn at slow airspeed to make an additional pass over an area with coyotes, the airplane impacted the ground with the right wing tip, and then came to rest inverted. A witness, who was working with the pilot from the ground, was in a drainage wash while the airplane circled overhead. They had just identified a coyote den and there were coyotes traversing up and down the wash. The airplane went out of the witness's view, and then the witness heard the impact of the airplane with the ground. No evidence of any preimpact mechanical anomalies was discovered. Weight and balance calculations showed that the airplane was out of its aft center of gravity limits by 1.6 inches, which would result in less stable flight characteristics, especially during slow flight. Previous accidents involving similar flight regimes have been associated with wake vortices encounters. Although it is possible that the airplane encountered its own wake vortices, this could not be determined with the available evidence. Based on standard atmospheric conditions and the temperatures at the closest reporting stations, the density altitude would have been about 10,000 feet.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: The pilot's failure to maintain an adequate airspeed during low altitude maneuvering flight that resulted in a stall. The pilot's decision to operate the airplane at a center of gravity beyond the rear limit, the low altitude of the flight, and the high density altitude were contributing factors. Full narrative available
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