Primary finding
Probable cause
The pilot's failure to maintain aircraft control while maneuvering resulting in an impact with terrain. Contributing factors were the gusty winds, downdrafts, and box canyon.
Investigator assessment
Analysis narrative
While heading in a northwest direction at the edge of a box canyon, the helicopter encountered a "very strong burst down draft," and began to descend into the box canyon. The pilot attempted to arrest the descent, but was unsuccessful. Subsequently, the helicopter impacted the base of the canyon and came to rest upright.
Source record
Factual narrative
According to the pilot, the purpose of the flight was aerial photography of wildlife nesting areas. Prior to departure, the pilot checked the weather forecast, which called for calm winds and winds increasing in the afternoon. As the helicopter approached the target area, the winds were "dead calm", and the pilot was "watching for the first signs of wind in the grass on the tops of the cliff areas and in the canyons below." While heading in a northwest direction at the edge of a box canyon, the helicopter encountered a "very strong burst down draft," and began to descend into the box canyon. The pilot attempted to arrest the descent, but was unsuccessful. Subsequently, the helicopter impacted the base of the canyon and came to rest upright.