What happened
On 22 August 2008, a Staaken Z-21 Flitzer, registration G-FLIZ, was performing a private flight approaching Runway 05 at RAF Lossiem to land. Based on the windsock, the pilot estimated a left crosswind of approximately 11 knots. During the approach, the pilot maintained a left wing low attitude and an approach speed 5 knots above normal to account for the wind.
The aircraft touched down on its left main wheel first. Following touchdown, the pilot closed the throttle while maintaining left aileron to prevent the right wing from dropping. As the right wing and tail descended, the left wing rose abruptly, causing the aircraft to swing sharply to the right. The pilot attempted to use right rudder and engine power to stabilize the aircraft, but the motion continued. The aircraft completed an approximately 80-degree turn before pitching forward, at which point the propeller struck the runway and the aircraft came to rest upside down. The pilot was able to unbuckle the harness and exit the open cockpit without injury.
The investigation
The investigation examined the aircraft's mechanical condition and the pilot's control inputs. It was noted that the pilot had applied right rudder after touchdown to counteract the left aileron input. The investigation also looked into the physical positioning of the pilot, noting that the position of the left leg may have restricted the ability to apply full left aileron.
Findings
- The aircraft sustained damage including a broken propeller, an engine shock-load, scuffed upper wing skin, a crushed rudder and fin, and a buckled right main wheel.
- A gust of wind likely lifted the left wing at a rate exceeding the available roll authority.
- The pilot's use of right rudder to counteract the left aileron prevented the application of full left aileron, contributing to the loss of control.