NTSB Identification: CHI07CA049.
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Accident occurred Friday, December 22, 2006 in Mosinee, WI
Probable Cause Approval Date: 03/26/2007
Aircraft: Beech 99, registration: N799CZ
Injuries: 1 Uninjured.

NTSB investigators used data provided by various entities, including, but not limited to, the Federal Aviation Administration and/or the operator and did not travel in support of this investigation to prepare this aircraft accident report.

The airplane, on a non-scheduled domestic cargo positioning flight, sustained substantial damage on impact with a snowbank and terrain during landing. The pilot, in part, stated, "I executed a routine [instrument landing system] approach ... during moderate to heavy snowfall at Central Wisconsin Airport. The runway conditions were reported as poor and it was snow covered. A crosswind existed as well as some wind shear as noted during the approach. Central Wisconsin Tower also advised me of a snow berm that remained on the west side of RWY 35 because it was not plowed to the full width of the runway. After I got a visual on the runway lights, I judged the runway centerlines by the runway lights and my position in between them. After the main wheels touched, I let the nose wheel down and I could see via the landing lights that I was close to the berm on my side and I gradually pushed right rudder pedal to steer away from the snow berm. I did not apply any braking action to avoid skidding and I was above 60 kts and had plenty of runway remaining to bleed off speed. Just as I positioned the power levers in the beta range, the left outer main landing gear tire began to make contact with the edge of the remaining snow berm left by the plows. The aircraft then began to yaw to the left and I applied more right rudder to compensate, but to no avail. The nose wheel hit the snow berm and broke off sending the aircraft sailing over the berm. The main landing gear wheels collapsed completely and the aircraft slid to a stop approximately 200 ft. west of RWY 35 off of the runway."

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

The pilot encountering the unsuitable terrain during the landing. Factors were the dark night and the snowbank.

Full narrative available

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