ANC21LA020 · Robinson Helicopter Co R66

The pilot, the sole occupant, was making a personal cross-country flight in the helicopter. According to flight tracking data, the helicopter departed and proceeded on course for about 1 hour 33 minutes. The flight track ended when the helicopter was about 70 nautical miles (nm) from its destination, over open ocean water, at an altitude of 394 ft mean sea level, and at a groundspeed of 132 knots. When the helicopter failed to arrive at its destination, family and friends contacted the Federal Aviation Administration and an extensive search was launched. During the search and rescue (SAR) operation, an inflated yellow pop-out float believed to be from the accident helicopter was located on the ocean surface. The search continued with additional SAR assets; however, minimal debris believed to be from the helicopter was observed in the water, and the search was suspended. Days after the accident, debris was discovered on the shore of an island about 42 nm north from the accident site and identified to be from the helicopter. Most of the helicopter was not located, and it is presumed to have sunk in the ocean waters. The pilot was not located, and an autopsy and toxicology test could not be performed. Weather satellite imagery indicated that as the helicopter approached the vicinity of the accident site, it was likely operating in visual meteorological conditions beneath scattered-to-broken cloud cover. A weather station near the accident site reported wind gusting to 27 knots, which could have led to low-level wind shear conditions. Investigators were unable to determine the cause of the accident with the available information

Verbatim NTSB analysis and probable cause from the NTSB dataset