Raytheon 58 N345PG accident near Dixon, Illinois

Probable cause

The pilots’ improper decision to continue flight in icing conditions after the deicing boots could not shed accumulated ice, which resulted in a temporary loss of airplane control.

NTSB analysis

The two pilots, one of whom was a flight instructor, were conducting a cross-country flight in instrument meteorological conditions. The pilot reported that, during the climb to 8,000 ft mean seal level (msl), light ice accumulated on the wings' leading edges. Activation of the deicing boots eliminated about 30 to 40 percent of the ice. The airplane then climbed to and leveled off at 10,000 ft msl, at which point, the engine speed "fluttered" and the airplane then rolled "quickly to the left" and entered a descending spin. The flight instructor applied control inputs, and the spin was arrested about 2,500 ft msl. The pilot landed the airplane without further incident.

Postaccident examination and testing of the airplane revealed no mechanical anomalies that would have precluded normal operation. The examination revealed substantial damage to the right wing and elevator control surface, which was consistent with forces sustained from excessive accelerations; radar data showed that the airplane descended 7,500 ft in about 30 seconds. A weather briefing for the flight showed that an airmen's meteorological information for moderate icing conditions was in effect and that light showers, rain, and snow were forecast throughout the area about the time of the accident. The deicing boots were unable to shed the accumulated ice, which adversely affected the airplane's performance and resulted in the temporary loss of airplane control. The pilot reported that he did not fly in such weather conditions unless accompanied by an experienced pilot.

Text from the NTSB. Open the NTSB docket for CEN15LA021 for the full record.