Robinson Helicopter R22 N7085K accident near Unalaska, Alaska

Probable cause

The pilot’s failure to maintain adequate clearance from terrain during a precautionary landing in whiteout conditions, which resulted in an in-flight collision with terrain.

NTSB analysis

The commercial pilot of the helicopter stated that the purpose of the flight was to transport a telecommunications technician to a cattle ranch on an island. After departing from the airport, while flying overwater, the pilot observed a snow squall with near-zero visibility and decided to return to the airport. On the return trip, while flying in a mountainous valley, another snow squall moved into the area. He stated that due to the deteriorating flight conditions, he conducted a precautionary landing to remote, snow-covered terrain to wait for improved flight conditions. Once the squall passed, he continued to the airport. Several minutes later, another snow squall arrived, and the pilot decided to conduct another precautionary landing. During the landing sequence, the main rotor system downwash resulted in whiteout conditions, and the pilot was unable to recognize any topographical features. The main rotor blades impacted terrain and the helicopter rolled onto its left side. The pilot reported that there were no preimpact mechanical failures or malfunctions with the airframe or engine that would have precluded normal operation.

Text from the NTSB. Open the NTSB docket for ANC17LA011 for the full record.