Piper J3C-65 N70585 accident near Rosemount, Minnesota

Probable cause

The pilot's delayed use of carburetor heat while operating in conditions conducive to carburetor icing.

NTSB analysis

The pilot reported that he started the engine and waited for about 10 minutes for the oil temperature to rise before he departed from a grass airstrip. During takeoff, he reported that the airplane “felt slow.” He turned the carburetor heat on, but the engine lost partial power and the airplane "started to sink." He banked to the left to avoid trees. He reported losing altitude, and then the airplane experienced a “stall spin to the left,” impacting a mature corn field. Postaccident inspection of the engine and airframe revealed no preexisting anomalies that would preclude normal operation of the airplane. The observed temperature was 11 degrees Celsius (C) and the dew point was 6 degrees C. The Transport Canada Carburetor Icing chart indicated that at the observed weather conditions the engine was susceptible to “Serious Icing – Any Power.”

Text from the NTSB. Open the NTSB docket for CEN10LA002 for the full record.