AS350B N3597T accident near Tahoma, California

Probable cause

The pilot's loss of helicopter control due to settling with power while maneuvering for takeoff.

NTSB analysis

The helicopter was being used to transport passengers and equipment for an off-road automobile event in a remote mountainous area. The airline transport pilot picked up two passengers, and the subsequent 3-minute-long inbound flight and landing into the wind at the helispot were uneventful. The pilot reported that, after a third passenger boarded, he initiated a vertical climb to clear trees. He reported that he expected and felt a "bump" as the helicopter encountered a headwind above the trees, and he then began to initiate a left turn for a downwind departure. As the turn progressed, the helicopter rapidly descended back to the ground, and, unable to maintain altitude, the pilot attempted to ditch the helicopter into trees and down-sloping terrain. The helicopter struck a rock slab and rolled onto its side, during which time both the pilot and a passenger sustained serious injuries. Postaccident examination did not reveal any anomalies with the airframe or engine that would have precluded normal operation, and both the pilot and operator reported that there were no mechanical malfunctions or failures.

The pilot attributed the loss of lift to a wind gust; however, the closest weather reporting station, about 14 miles away, reported light wind. Further, a weather simulation was performed to estimate wind and turbulence conditions in the area of the accident. The results revealed a low potential for turbulence with wind, which closely matched the conditions reported by the weather station, at the time and location of the accident.

The fuel load could not be definitely established; however, given the helicopter's estimated gross weight, it was likely operating very close to or slightly above its hovering ceiling. Therefore, it is likely that the pilot attempted to hover the helicopter out of ground effect at an altitude above its hovering ceiling, which resulted in it settling with power.

Text from the NTSB. Open the NTSB docket for WPR14FA324 for the full record.