Amateur-built ES N18BG accident near Oshkosh, Wisconsin

Probable cause

The pilot’s failure to maintain adequate airspeed which resulted in an exceedance of the airplane’s critical angle of attack and an aerodynamic stall while maneuvering for traffic spacing.

NTSB analysis

The pilot was flying the airplane on an arrival route when the air traffic controller instructed the pilot to widen the turn to allow for two warbird airplanes to land in front of him. The pilot acknowledged the transmission and stated that he had the two airplanes in sight. Wind was recorded as variable at 4 kts. According to ADS-B data, the airplane turned south, consistent with a modified downwind, then back to the east, and then toward the north, consistent with a base-to-final turn. The airplane was about 975 ft mean sea level (msl) and 84 kts ground speed when it started a turn to the north toward the airport. The last data point recorded from the airplane was about 975 ft msl and 70 kts ground speed, 1.5 miles from the approach end of the runway. According to the airframe pilot operating handbook, the stall speed varies from 59 to 74 kts indicated airspeed at zero degrees of bank.

The airplane impacted a soybean field upright and was destroyed by a postimpact fire. An examination of the airplane, engine, and flight control system revealed no mechanical anomalies or failures that would have precluded normal operations.

Further review of the ADS-B data from the warbird flight showed that the landing Aero L-39 airplane passed well to the east and above the flight path of the accident airplane. A review of the wake vortices generated by the L-39 revealed that the accident airplane would not have encountered the wake of the L-39 before impact.

It is most likely that the pilot did not maintain adequate airspeed while maneuvering to ensure spacing from the L-39 that landed ahead while completing his turn toward final. This resulted in an inadvertent stall and subsequent impact with terrain.

Text from the NTSB. Open the NTSB docket for CEN24FA277 for the full record.