What happened
On July 22, 2015, a Piper Malibu PA-46-310P, registration N4BP, impacted runway 27 at Wittman Regional Airport (OSH) in Oshkosh, Wisconsin. The flight was operating as a personal flight under Part 91 regulations, traveling from Benton Harbor, Michigan.
During the approach, the pilot was following special arrival procedures in effect for the EAA AirVenture airshow. While on the right downwind leg, the pilot observed a twin-engine aircraft taxiing onto the runway and beginning its takeoff roll. Air traffic control instructed the pilot to adjust the landing point from the "green dot" to the "orange dot," which was approximately 1,000 feet from the displaced threshold.
Although the pilot considered performing a go-around, he decided to continue the approach. As the aircraft descended to approximately 250 to 300 feet above ground level, the pilot reduced power. This maneuver caused the airplane to enter a stall. The aircraft impacted the runway in a nose-down, right-wing-low attitude, causing the right wing to separate from the fuselage and resulting in a post-impact fire.
The accident resulted in 3 serious injuries and 2 minor injuries; there were 0 fatalities.
The investigation
An examination of the engine and airframe revealed no mechanical failures that would have prevented normal operation. The JPI EDM-930 engine monitor recorded the flight, showing that manifold pressure and engine RPM decreased sharply just before the recording ended at 0tk44.
A video study of the flight showed the aircraft was at approximately 180 feet above ground level when it began the turn to the base leg, descending to roughly 130 to 140 feet during the turn. The study calculated the aircraft's inertial speed decreased from 98 knots to below 70 knots during the final 8 seconds of flight.
Technical analysis of the aircraft's performance indicated that while the wings-level stall speed at maximum gross weight was 59 knots, the stall speed increases significantly with bank angle. At a 60-degree bank, the stall speed was 86 knots, and would have been even higher at the steep bank angle observed by witnesses.