NTSB Identification: CEN10LA556
14 CFR Part 91: General Aviation
Accident occurred Friday, September 17, 2010 in Duluth, MN
Probable Cause Approval Date: 04/12/2011
Aircraft: ROBINSON HELICOPTER COMPANY R44 II, registration: N145DM
Injuries: 1 Minor.

NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

According to the pilot, he lifted the helicopter into a hover and subsequently established a 600 foot-per-minute rate of climb at 60 knots airspeed to depart the area. As the helicopter climbed out, he reported a sinking feeling in the seat and noticed that the vertical speed indicator displayed a descent. The pilot increased the engine power but the helicopter continued to descend. The pilot could not discern his exact height above the water because of the night lighting conditions and thought that the helicopter was higher off the water than it was; as a result, he did not flare prior to impact. A witness reported that the liftoff and initial climb also appeared normal and that the helicopter appeared to be level and remain in controlled flight the entire time. A postaccident examination of the airframe and engine revealed no mechanical malfunctions or failures that would have precluded normal operation. The witness commented that the conditions were dark at the time of the accident, but there was a distinguishable horizon. The light wind reported at the time of the accident and lack of convective activity in the area is inconsistent with a downdraft or microburst condition.

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

The pilot's failure to identify and arrest the helicopter's descent due to spatial disorientation.

Full narrative available

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