Piper PA 18-150 N9720P accident near Nikiski, Alaska

Probable cause

The total loss of engine power due to carburetor icing, which resulted from the pilot’s failure to use carburetor heat while operating at low-power settings in an area conducive to carburetor icing.

NTSB analysis

The pilot reported that he had flown the airplane for about 20 to 30 minutes to survey the area for possible landing sites. After choosing a landing site, the pilot completed the prelanding checklist, cycled the carburetor heat on, and then placed it in the "off" position. When the airplane was established on short final for landing, the engine lost total power. The pilot attempted to restart the engine by switching fuel tanks and applying carburetor heat, but engine power was not restored. The airplane subsequently collided with rising terrain, which resulted in substantial damage to the fuselage and wings. A postaccident examination of the engine revealed no evidence of any preimpact mechanical problems that would have precluded normal operation.

Another company pilot, who had landed his airplane at the same location only minutes before the accident airplane approached, stated that carburetor ice accumulated during the descent. Further, the atmospheric conditions at the time of the accident were conducive to the accumulation of carburetor icing at glide and cruise power settings. Therefore, it is likely that, as the pilot reduced engine power, carburetor ice formed, which caused the engine to lose power.

Text from the NTSB. Open the NTSB docket for ANC15LA005 for the full record.