Piper J3C N7009H accident near Grand Bay, Alabama

Probable cause

A loss of engine power during initial climb due to carburetor ice that formed during an extended ground delay, and the pilot's failure to use carburetor heat before initiating the takeoff.

NTSB analysis

Before departing on a local flight, the pilot idled the airplane for about 5 minutes to let the engine warm up. During the takeoff, about 40 feet above ground level, the airplane "seemed to quit climbing" and the engine rpm was decreasing. He pushed the throttle full forward, verified the carburetor heat was off, and the fuel shutoff valve was on. Realizing that the airplane would not clear trees and powerlines ahead, he aborted the takeoff and the airplane touched down about 100 ft before the end of the runway. The airplane continued off the runway and through a wooden fence.

Postaccident examination of the engine revealed no evidence of preimpact mechanical malfunctions or failures that would have precluded normal operation. The weather conditions at the time of the accident were conducive to the formation of serious carburetor icing at glide (idle) power settings. Thus, it is likely that during the ground delay, a period during which the engine would typically be operating at low power, carburetor ice formed, and subsequently resulted in a loss of engine power during the initial climb. Had the pilot used carburetor heat before the takeoff, he might have eliminated the ice.

Text from the NTSB. Open the NTSB docket for ERA20LA023 for the full record.