This October 2007 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.
Aircraft: Cessna 310. Location: Ekalaka, Mont. Injuries: 2 Fatal. Aircraft damage: Destroyed.
What reportedly happened: The instrument-rated private pilot was on a cross-country flight in IMC. He had received a pre-flight weather briefing, but it was limited by his request for wind, temperature aloft forecasts and METAR observations for his route of flight. About 40 minutes into the flight the pilot reported to air traffic control that he was encountering icing conditions at his cruise altitude of 13,000 feet MSL. He requested a lower altitude and was cleared to descend to 11,000 feet. He continued to encounter icing conditions and was cleared to descend to lower altitudes. About 15 minutes after the his initial report of icing conditions, he transmitted “headed towards the runway” followed by “…going down…troubles with engine.” No additional communication was received. The wreckage was located later that day in an open field about two miles west of a private airstrip.
Post-accident examination of the airframe and engine revealed no evidence of mechanical malfunction or anomaly. Ground scars and wreckage signatures were consistent with a stall/mush into the terrain. Weather forecasts and pilot reports for the intended route of flight indicated icing and widespread instrument meteorological conditions. FAA Advisory Circular 91-51A states, in part, “The most hazardous aspect of structural icing is its aerodynamic effects. Ice can alter the shape of an airfoil. This can cause control problems, change the angle of attack at which the aircraft stalls, and cause the aircraft to stall at a significantly higher airspeed…” The AC additionally states “Flight into known or potential icing situations without thorough knowledge of icing and its effects and appropriate training and experience in use of deice and anti-ice systems should be avoided.” According to the manufacturer, the airplane was not certified or equipped for flight into known icing conditions.
Probable cause: The pilot’s improper in-flight planning/decision, his continued flight into icing conditions and failure to maintain an adequate airspeed during the emergency descent for landing.
