BELL 407BRISTOW US LLC

The pilot of the helicopter departed on the flight to transport the passenger to an offshore platform; several minutes before the accident, he transmitted a pilot report describing a cloud ceiling about 700 ft above ground level and 6 statute miles visibility. Onboard data indicated that the helicopter entered a descending left turn from about 300 ft above ground level that continued until the helicopter impacted a marsh. The turn to the north was not consistent with the intended route of flight. The characteristics of the turn as it tightened over the last 25 seconds of the flight (increasing roll, decreasing pitch, and vertical descent rate) are consistent with the pilot experiencing spatial disorientation and loss of control. The restricted visual references resulting from the low cloud ceilings and flight over a body of water that lacked significant contrasting terrain features would have been conducive to the development of spatial disorientation; and the low altitude in which he was flying would have limited his available time to recover. Postaccident examination revealed no mechanical anomalies that would have precluded normal operation.