On January 19, 2005, a Beechcraft King Air 200, with two pilots and two paramedics on board, departed Prince George Airport, B.C., at 12:28 Pacific Standard Time (PST) on an IFR medical evacuation (MEDEVAC) flight to Cranbrook, B.C. The flight was dispatched to transport two patients from Cranbrook to Kelowna, B.C. During cruise flight at 15 000 ft ASL, the aircraft was in icing conditions. The aircraft’s ice-protection equipment dealt effectively with the icing conditions until about 45 min after takeoff, when the aircraft began to accumulate ice at a rate that exceeded the capabilities of the ice-protection equipment. The airspeed decreased to the point that a descent was required and, despite the crew selecting maximum available engine power, the aircraft descended from 15 000 ft to 10 800 ft; below the minimum obstacle clearance altitude (MOCA) for the area. Vancouver ATC issued emergency vectors to guide the aircraft down the Arrow Lakes area to avoid high terrain. Several minutes later, the pilots advised that they were clear of cloud and proceeding to Kelowna. Accumulated ice, up to 6 in. thick, was shed during the approach to Kelowna, where an uneventful landing was made.

Findings as to causes and contributing factors

1.        The pilot-in-command (PIC) did not review the available graphical area forecast (GFA) weather information and was not sufficiently informed to avoid the forecast icing conditions.

2.        The severe in-flight icing conditions caused an ice accumulation that the aircraft’s ice-protection systems were unable to prevent or remove. As a result, the aircraft entered a power-on stall condition and an uncontrollable descent.

3.        The PIC did not detect the severe ice accumulation in sufficient time to alter the flight route to avoid the icing conditions.

Safety action taken

Following an internal investigation into the occurrence, the company, as an interim safety action, distributed a memorandum to advise flight crews to review all available weather data before flights. The company has since developed a syllabus, examination and emergency checklist regarding severe icing, and has implemented them as part of its training program to provide flight crews with more in-depth knowledge of severe icing conditions and exit strategies.