What happened
The pilot was conducting a visual approach for landing in extremely cold conditions, with an ambient temperature of eight degrees Fahrenheit. During the base turn phase of the approach, he applied full carburetor heat to clear the engine of potential ice accumulation. As he transitioned onto the final approach, he determined that his altitude was too high and reduced the engine power below 1000 RPM for a duration of approximately 10 to 20 seconds.
Shortly after reducing power, the pilot observed an excessive sink rate. When he attempted to add power to correct the descent profile, the engine failed to respond, and the power output did not increase. Unable to arrest the descent, the aircraft landed short of the intended runway threshold and collided with a snowbank.
The investigation
Post-accident examination of the engine and its associated components revealed no evidence of pre-existing mechanical malfunction or failure. The lack of response to throttle input was attributed to carburetor icing caused by the combination of low power settings and cold, moist air conditions, despite the prior application of carburetor heat.
Findings
- The pilot reduced power below 1000 RPM during final approach in cold weather.
- Carburetor ice formed, causing a loss of engine power.
- The aircraft landed short and impacted terrain due to inability to regain thrust.
- No mechanical defects were found in the engine components.