What happened
During the fourth leg of a scheduled five-leg mission, a cargo flight departed under night instrument conditions. At the time of departure, local observations reported a broken cloud ceiling at 500 feet above ground level and light snowfall. A preceding flight had noted that moderate snow was falling and that cloud entry occurred at approximately 200 feet above ground level. Prior to takeoff, the aircraft's tail and wings had undergone de-icing procedures.
Radar tracking showed the flight lasted approximately 45 seconds. Data from an aircraft performance radar study indicated that the aircraft type reached an altitude of roughly 1,130 feet mean sea level, which equates to about 400 feet above ground level. During this phase, the aircraft was traveling at 114 knots with a left bank of 29 degrees. The flight subsequently entered a descent, impacting the terrain at an airspeed of 155 knots with a pitch angle of -16 degrees, a left roll of 22 degrees, and a vertical descent rate of 4,600 feet per minute.
Findings
Post-accident analysis of the airframe and engine showed no mechanical anomalies that would have prevented standard operation. The study confirmed that engine power output was consistent with the values specified in the pilot's operating handbook. Additionally, the center-of-gravity position was found to be within limits and did not negatively impact the controllability of the plane, while elevator deflections remained within the functional range.
Investigators determined that the load factor vectors experienced by the crew could have created the illusion of a climb while the aircraft was actually descending.