2015-11-06: TSB#A86C0119: Keystone Air Services, Flight 104, a Piper PA-34-200 Seneca, C-GZTZ
, was operating on an instrument flight rules (IFR) flight plan from Winnipeg to Swan River. The aircraft departed Winnipeg International Airport at 1855 central standard time (CST). On board were the pilot and one passenger. Flight 104 had been cleared to cruise at 6,000 feet above sea level (asl) by air traffic control (ATC), but, in order to stay above cloud, the pilot requested a change of altitude to 8,000 feet asl. Thirty-five miles from Swan River, the pilot commenced the descent to the Swan River Airport. There was no evidence of ice formation while descending through a layer of cloud between 7,500 and 6,000 feet asl. After entering cloud at 5000 feet asl, the airspeed indicator decreased to zero. The pilot used a flashlight to check the outside air temperature (OAT) probe and windshield for ice and noted that there was over an inch of ice on the OAT probe. Ice began separating from the propellers. The pilot applied power and raised the nose to climb, but the aircraft began to vibrate and the airspeed continued to read zero. The pilot adjusted the attitude to maintain flying speed, which resulted in a continuous descent in icing conditions. The windshield became covered with ice, and the descent continued until the aircraft struck some trees approximately 10 miles from the airport. The accident occurred at an elevation of 1,830 feet asl at lat 51deg58'N, long 101deg02'W, at 2030 CST during the hours of darkness. 3.1 Findings 1. Shortly after entering cloud, the aircraft was unable to maintain altitude due to a rapid and heavy accumulation of ice. 2. The pilot descended into cloud in conditions conducive to icing. 3. The aircraft was not equipped for flight into icing conditions. 4. The weather forecast indicated that conditions would be below that required for single-pilot IFR operation for destination but acceptable for alternate selection. 5. The passenger was not wearing a seat-belt. 6. The occupants were not wearing the shoulder harnesses installed in the aircraft. 7. The flight was not operated in accordance with the company's operating certificate. 8. The pilot was certified and qualified for the flight in accordance with existing regulations. 9. The aircraft was certified, equipped, and maintained in accordance with existing regulations and approved procedures. 10. There was no evidence of fire either before or after the occurrence. 11. The weight and centre of gravity were within the prescribed limits. 3.2 Causes The pilot initiated flight into forecast icing conditions in an aircraft that was not certificated for flight in icing conditions. When icing was encountered, the pilot did not detect the formation of ice on the aircraft in time to take effective corrective action.