Accident Overview
On June 9, 2017, about 0820 mountain daylight time, a Robinson R44 II helicopter, registration N590GG, impacted terrain near Douglas, Wyoming. The helicopter was operated by Wagonhound Land and Livestock Co, LLC under 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed. The pilot and two passengers were not injured, while a third passenger received serious injuries. The helicopter sustained substantial damage.
Flight Sequence
The pilot reported refueling at Converse County Airport (KDGW) with calm winds. After departing with one person, they flew about 25 miles to a lodge to pick up two additional passengers. The pilot shut down the helicopter for boarding and estimated a steady west wind at 12–15 knots. They then departed for sightseeing en route to a ranch and stockyard. The pilot climbed to 1,000 feet as they passed KDGW, where the automated weather station reported wind variable at 3 knots.
Approaching the cattle stockyards, the pilot observed crop status, fields, and irrigation machinery. Noting trees, pond surfaces, and ground track indicated calm wind, he selected an approach course to avoid a barn and work crews, aiming for a clear spot near water tanks.
Impact and Conditions
During the approach, the pilot saw normal power and glide path indications, with last airspeed 30 knots at 100 feet above ground level. Below 50 feet, a sudden, abrupt high rate of descent occurred. The pilot manipulated controls; the low rpm light illuminated and warning horn sounded. He stated there was no time or altitude to lower the collective and regain rpm. The helicopter impacted terrain and rolled to the side when the left skid failed. The engine continued running, and no prior mechanical malfunction or failure was reported.
After the accident, the pilot observed a steady northwest wind estimated at 15 knots, creating a downwind condition for the approach. He believed the high rate of descent resulted from an "advance gust" or "wind shear" as the wind shifted from calm to a tailwind. The calculated density altitude was 7,015 feet, and the helicopter was near maximum gross weight of 2,500 pounds.