What happened
During the descent phase of the flight, the aircraft struck terrain roughly 14 miles from its intended destination. Radar and meteorological records indicate that the plane descended from an altitude of 16,700 feet to 3,700 feet above ground level while traveling through clouds and active icing conditions. During this period, the aircraft's ground speed decreased significantly, dropping from 268 knots to 92 knots.
The pilot initially notified approach control that the aircraft had emerged from the cloud layer at 5,400 feet. Shortly thereafter, the pilot reported that the airframe had accumulated both rime and clear ice during the descent. Within 13 seconds of this report, the pilot issued a distress call, stating that the aircraft was in trouble and descending rapidly. The final radar contact recorded the aircraft passing through 3,700 feet at a ground speed of 92 knots. An eyewitness reported seeing the aircraft performing unusual maneuvers before it entered a vertical spin and headed toward the ground.
Findings
An airmet for icing was active along the flight path at the time of the accident, and other pilots had reported encountering icing in the vicinity. The investigation noted that the pilot had not requested a weather briefing either before the flight commenced or while in transit. The accumulation of ice during the descent appears to be a critical factor in the loss of control.