Amateur-built CHALLENGER N1666R accident near Oshkosh, Wisconsin

Probable cause

The pilot’s failure to maintain adequate airspeed during the base to final turn and his exceedance of the airplane’s critical angle of attack, which resulted in an aerodynamic stall.

NTSB analysis

The airplane was landing on the ultralight field when the accident occurred. The pilot stated that she made a wide base to final turn because she was unsure about the placement of the runway. Although the pilot added power, the airplane entered a left descending turn until the left wing contacted the ground near the beginning of the runway's displaced threshold. The airplane then spun left and slid rearward on the ground until it contacted a chain-link fence.

The pilot reported that there were no mechanical anomalies with the airplane that would have precluded normal operation. The pilot's statement, along with a ground-based video of the accident, revealed that the pilot failed to maintain adequate airspeed and exceeded the airplane's critical angle of attack during the base to final turn, which resulted in an aerodynamic stall.

Text from the NTSB. Open the NTSB docket for CEN18CA291 for the full record.