The report, issued by the National Transportation Safety Board, says another pilot who had flown the same route about 20 minutes before the 10:30 a.m. crash reported a moderate amount of ice had accumulated on his wings and windshield during his approach to Friedman Memorial Airport in Hailey, just outside of Salmon. The area lies in central Idaho near the Montana line.
Fred Villanueva, of Farmington, and Raymond Ingram, of Salmon, died when their Cessna 208B, owned by Salmon Air, crashed in a field about 10 miles south of that airport.
A witness reported seeing the plane flying low with the right wing tilted down as the plane continued to lose altitude.
"The witness then noted that the wings rocked back and forth a couple of times before the nose of the aircraft dropped near vertical to the terrain," states the NTSB report.
The witness also reported hearing the engine running steadily until impact.
Weather reports at the airport about 45 minutes earlier showed a temperature of 45 degrees, light snow and mist, scattered clouds at 2,000 feet, broken clouds at 4,500 feet and overcast skies at 6,000 feet, according to the report.
The last communication with the plane came at 10:20 a.m. when the Hailey tower cleared the Cessna 208B for landing and asked the pilot if he had the airport in sight.
The pilot answering the call, presumably Villanueva, reported that he could not see the airport and was still navigating by instruments, states the report.
Transcripts of communications with the pilot during the flight have been requested by NTSB investigators to determine how much knowledge he had about the weather conditions as he flew, said NTSB investigator Debra Eckrote. The airplane's maintenance records and the pilot's flight history also are under review, she said.
A manual for the Cessna Caravan states that anti-icing and de-icing equipment that is properly installed meets federal regulations but is not designed to "provide protection against freezing rain or severe conditions of mixed or clear ice."
The Cessna 208B is under investigation by the NTSB for its wing design, which allows ice buildup - which can cripple the plane's ability to stay aloft - in light to moderate icing conditions.
Eight accidents involving Cessna 208B aircraft with similar characteristics to Monday's crash are the focus of a review by the NTSB. The results of the study, which has been under way for more than a year and a half, are expected to be released next week.
mwestley@sltrib.com
