The Transportation Safety Board blames thick smoke as a cause in a fatal helicopter crash last summer in northern Manitoba.

The helicopter crashed on Canada Day July 2013 into the waters of Gull Lake, about 50 kilometres west of Gillam.

The report said when the chopper went down, winds shifted and moved smoke from nearby forest fires into the Gull Lake area. Rain also likely played a role, but the report also says a mechanical failure with the aircraft cannot be ruled out. That's because major portions of the wreckage, including the engine, were never recovered. The pilot, a 69-year-old man from B.C., was killed in the crash.