OSHKOSH (NBC 26) — The National Transportation Safety Board has determined that a July 29, 2023, crash of a North American AT‑6D near Oshkosh, Wis., was caused by an aerodynamic stall/spin after the pilot failed to maintain airspeed while maneuvering. Both the pilot and passenger were killed and the airplane (N49961) was destroyed when it impacted Lake Winnebago outside Wittman Regional Airport.
What happened
- Date/time: July 29, 2023, about 9:05 a.m. CDT.
- Location: Over Lake Winnebago near Oshkosh (Wittman Regional Airport operations were underway for EAA AirVenture).
- Aircraft: North American AT‑6D, N49961. Registered owner/operator: Texas Warbirds LLC.
- Occupants: Pilot (30‑year‑old female) and one passenger — both fatally injured.
Investigation findings
- ADS‑B and winds‑aloft data show the airplane climbed to about 3,900 ft mean sea level, leveled, then performed a right turn followed by a left turn. During these maneuvers the airplane decelerated. Calibrated airspeed fell from about 110 mph to a recorded low of 87 mph just before the rapid descent.
- Calculations indicate the airplane’s load factor rose to about 1.8 g during the second turn; at the airplane’s loaded weight this produced an accelerated stall speed near 89 mph. The NTSB concluded the airplane slowed to a speed consistent with its accelerated stall speed, exceeded its critical angle of attack and entered a rapid descent and spin. A witness in a boat reported seeing the airplane in a flat spin to the right until it struck the water.
- Post‑recovery examination of the airframe, engine and systems revealed impact damage but no preimpact mechanical anomalies that would have prevented normal operation.
Probable cause The NTSB’s probable cause statement: “The pilot’s failure to maintain airspeed while maneuvering, which resulted in the exceedance of the airplane’s critical angle of attack and an aerodynamic stall/spin.”
Additional details
- The airplane broke into pieces on impact and came to rest in about 20 feet of water.
- The pilot held a private pilot certificate with about 687.8 total flight hours, including about 33 hours in the AT‑6 type. The airplane last received an annual inspection on July 19, 2023.
- The NTSB docket for this accident is CEN23FA332. Toxicology testing was performed as part of the investigation.
Safety context The NTSB report highlights a common risk: during steep turns or abrupt maneuvering, airspeed can decay and load factors increase, raising the aircraft’s stall speed. Accelerated stalls and spins remain a significant hazard, particularly at low altitude where recovery may not be possible.
