Civil Aeronautics Board, Aviation Accident Report: Beechcraft C-18-S on 1 September 1959 (1960 | portal)
“ Surface winds along the route were westerly of less than five knots, becoming northwesterly ten knots at 2,000 feet and northerly ten to 15 knots between 5,000 and 10,000 feet above mean sea level. Over the northern two-thirds of the route occasional light icing would have been experienced in the clouds above the freezing level to 11,000 feet. Turbulence was unlikely except for possible light turbulence near Tanana. Over the remainder of the route and in the McGrath area light icing was present in the clouds and in precipitation above the freezing level. ”
