Incident Overview
A twin-engine turboprop aircraft, returning from a medical evacuation (MEDEVAC) mission, crashed near the Thompson Airport in Manitoba. The flight had originated from Coral Harbour, Northwest Territories, and had just completed a patient transport to Churchill, Manitoba. At 2257 central daylight saving time (CDT), the aircraft departed Churchill for a night instrument flight rules (IFR) flight back to its base at Thompson.
The en route segment was conducted at an altitude of 18,000 feet above sea level. Approximately one hour after departure, the crew initiated an approach to Thompson Airport and remained in radio contact with air traffic control (ATC) until about 2359 CDT.
Navigation Beacon Failure and Wreckage Discovery
Shortly after midnight (0001 CDT), the Hotel non-directional beacon (NDB), located 3.4 miles northeast of the airport, stopped transmitting. Ninety minutes later, the search and rescue satellite system (SARSAT) detected an emergency locator transmitter (ELT) signal from an area northeast of the airport. Thompson Airport staff, who had been dispatched to investigate the failed beacon, discovered the aircraft wreckage in and around the NDB transmitter compound. Emergency responses were initiated by airport and local authorities.
Probable Cause and Contributing Factors
The official investigation determined that the flight crew lost altitude awareness during the localizer back course approach and allowed the aircraft to descend below a mandatory level-off altitude. Contributing factors included the crew's deviation from a published approach procedure, ineffective in-flight monitoring of the approach, rapidly developing localized fog conditions, and, probably, pilot fatigue.