Aeronca 11AC N3420E accident near Conyers, Georgia

Probable cause

An encounter with shifting wind conditions, which resulted in the airplane using more runway than anticipated, an aborted takeoff, and subsequent runway excursion. Contributing to the accident was the pilot’s failure account for the potential of variable and shifting wind in his departure planning.

NTSB analysis

The pilot was taking off from a 2,700-ft-long runway and described that during the initial climb, the airplane’s climb rate was insufficient to avoid the trees at the departure end of the runway. The pilot attempted to land on the remaining runway; however, the airplane departed the far end of the runway, impacted a berm, and came to rest in a lake. The airplane sustained substantial damage to the wings and fuselage. The pilot reported that the engine was operating normally and that there were no anomalies or mechanical failures that would have precluded normal operation of the airplane.

Three of the closest official weather stations reported the wind was varying between being a quartering headwind to a quartering tailwind. The pilot reported receiving the weather conditions from an online, publicly available weather station, which reported that a headwind would be present for takeoff. He also provided a plot of the data from that station for the time surrounding accident, and it showed that while the wind direction was reported as he described, it had also begun to vary around that time, and continued to for some time afterward. Based on this information, it is likely that the variable wind conditions resulted in a shift in wind direction during takeoff that changed from a quartering headwind to a quartering tailwind.

Text from the NTSB. Open the NTSB docket for ERA24LA183 for the full record.