(CNN) The pilot of the plane that crashed and left nine dead in South Dakota took off with limited visibility in snowy and turbulent weather, according to the National Transportation Safety Board.

The pilot initially filed with the Federal Aviation Administration a plan with instrument flight rules (IFR), which describe how an aircraft operates when a pilot is unable to navigate with visual references.

Visibility around the time of takeoff was about half a mile, with moderate snow and icing, along with overcast skies and turbulent conditions, the NTSB said Monday.

The single-engine Pilatus PC-12 was then cleared Saturday to fly from Chamberlain Municipal Airport to Idaho Falls, Idaho, the NTSB said.

Though clearance gives pilots permission to use the runway, it does not suggest that they are necessarily OK to go in the weather conditions they face. The decision to fly or not, in small-aircraft operations, rests on the pilot, CNN transportation analyst Mary Schiavo said.

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