Aeronca 7AC N65HM accident near Hanson, Massachusetts

Probable cause

A loss of engine power due to carburetor icing, the pilot's decision to turn back to the runway shortly after takeoff, and his failure to maintain airspeed during the turn, which resulted in an exceedance of the airplane's critical angle of attack, and subsequent aerodynamic stall.

NTSB analysis

The commercial pilot and passenger were departing on a local personal flight in the single-engine airplane. Review of airport security video showed the airplane level off about 100 ft above ground level as it passed the departure end of the runway. The airplane then entered a left turn and descended to ground contact. Damage to the propeller blades was consistent with a lack of engine power at the time of impact; however, examination of the wreckage revealed no evidence of preimpact mechanical anomalies that would have prevented normal engine operation. Based on the temperature and dew point about the time of the accident, the conditions were favorable for serious carburetor icing at a glide power setting.

Video showed that the airplane operated on the ground at an idle engine power setting for about 7 minutes before takeoff, and it is probable that carburetor ice formed during this time, subsequently resulting in the loss of engine power during the initial climb. Following the loss of power, the pilot attempted to turn back to the runway with insufficient altitude and, during the turn, failed to maintain airspeed, resulting in an exceedance of the airplane's critical angle of attack, an aerodynamic stall/spin, and impact with terrain.

Text from the NTSB. Open the NTSB docket for ERA18FA230 for the full record.