What happened
During the final stages of an ILS approach toward the destination airport, the aircraft encountered significant difficulties maintaining its flight path. Despite the application of maximum engine power, the pilot was unable to stay on the required glidepath. Prior to the impact, the crew and passengers noted that the aircraft was experiencing notable vibrations and shuddering. One passenger observed ice accumulation on the rear section of the left wing. The aircraft eventually struck trees and the ground roughly 10 miles west of the destination airport.
Records indicate that the pilot had engaged in several communications with the Fort Dodge, Iowa AFSS, including one transmission on December 27 and four on December 28. Before departure, the pilot had received flight service briefings and had spoken with flight watch.
Findings
Evidence suggests the aircraft was operating in an environment characterized by severe icing. Weather forecasts for the flight route had specifically warned of moderate to isolated severe icing conditions occurring from 7,000 feet down to the surface. Witnesses on the ground also reported observing severe icing conditions in the vicinity at the time of the accident. The accumulation of ice likely contributed to the loss of control and the inability to maintain the glidepath during the descent.