The pilot of a small plane radioed that he couldn't maintain altitude because of mountain wind currents shortly before the plane crashed in northwest Wyoming, killing all four people aboard, federal investigators say.
A preliminary report from the National Transportation Safety Board released this week also says the pilot reported that a trace of ice was forming on the plane and that he was encountering light turbulence.
The crash killed the pilot, 40-year-old Luke Bucklin of Minneapolis, his 14-year-old twins Nate and Nick, and his 12-year-old son Noah.
It took searchers a week to find the wreckage after the single-engine Mooney M20 crashed on Oct. 25 in the Wind River mountains.
Bucklin took off from Jackson at about 1 p.m. and radioed ground controllers about 40 minutes later that he was flying at about 14,000 feet, that he was encountering light turbulence and that ice was forming on the plane, the report said.
About 10 minutes later, Bucklin radioed that he couldn't keep the plane at a steady altitude because of "mountain wave activity," up-and-down wind currents over the peaks.
Ground radar indicated the plane had descended to about 13,300 feet by the time of that transmission, and the plane crashed shortly after that, the NTSB said.
The wreckage was found on a mountainside at about 11,100 feet elevation, six miles southeast of Gannett Peak, Wyoming's highest at just over 13,800 feet.
The NTSB said aviation weather reports predicted turbulence and icing along the route Bucklin listed in his flight plan.
Bonnie Harris, a friend of the Bucklins, said the family had been in Wyoming for a wedding and family vacation. Luke Bucklin's wife, Ginger Bucklin, and the couple's youngest son flew home separately on a commercial flight, Harris said.
Luke Bucklin is president and co-founder of the Bloomington, Minn.-based Web development company Sierra Bravo Corp.
The NTSB report said Bucklin's pilot license was current and that he was instrument-rated, meaning he was qualified to fly by instruments when visibility was poor.
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