Carburetor ice and subsequent engine power loss led to fatal accident near Smithers, BC

From: Transportation Safety Board of Canada

On May 4 2019, a Cessna 182E from Lakes District Air Service Ltd. was conducting a fire surveillance flight near Smithers, BC, on behalf of the BC Wildfire Service, with the pilot and three crew members on board. Approximately three hours into the flight, the pilot transmitted a Mayday before communication was lost. Shortly after, the Canadian Mission Control Centre received an emergency locator transmitter signal. A resulting helicopter search located the aircraft wreckage in a forested area approximately 50 nautical miles north of Smithers, BC, near the Babine River. The aircraft had collided with trees and terrain and was destroyed. There was no post-impact fire. One crew member survived the crash, while the pilot and the other two crew members were fatally injured.

The investigation determined that the aircraft was operating at a low engine power setting and in atmospheric conditions conducive to carburetor icing, which likely resulted in ice forming in the carburetor. The ice would have initially reduced the engine’s ability to produce enough power to maintain altitude and eventually led to a complete loss of power. It was also determined that the aircraft did not have, nor was it required to have, a carburetor air temperature indication system. This system indicates when conditions are conducive to carburetor ice formation before ice begins to accumulate, thus prompting pilots to take appropriate remedial actions.

Following the initial engine problems, the pilot indicated an intention to land at Silver Hilton Steelhead Lodge airstrip. However, the airstrip was not in the aircraft’s global positioning system database, and, as a result, it is likely that the pilot was unable to locate it in sufficient time to conduct a safe landing before the engine failed. The Babine River nearby was in freshet and no gravel bars or open shorelines were visible. In such circumstances, pilot training at Lakes District Air Service Ltd. suggested forced landings should be made into trees, not water.

The investigation found that if aircraft equipped with carburetors are not equipped with a carburetor temperature indication system, there is an increased risk that pilots will not be aware that they are in conditions in which carburetor ice accumulation is possible and consequently will not take the appropriate remedial actions in time.

See the investigation page

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