What happened
On 9 September 2006, a Zenair CH 250, registration G-BIRZ, was performing a private flight from Perth to Glenforsa Airstrip on the Isle of Mull. After a two-hour stay at the airfield, the pilot prepared for the return journey. Although the weather appeared clear, the airfield manager noted surface winds from 140º at 8 knots, gusting to 12 knots.
During the takeoff roll on Runway 07, the pilot struggled to maintain the aircraft's heading despite applying full right rudder and into-wind aileron. As the aircraft reached a speed of approximately 50 mph, it began to veer uncontrollably to the left. The aircraft briefly became airborne in a high nose-up attitude, reaching a height of 10 to 15 feet before the left wing dropped. The aircraft then struck the airfield's perimeter fence, penetrated it, and slid down a slope to come to rest on the beach below.
Both occupants of the aircraft escaped the wreckage without injury.
The investigation
Investigators examined the aircraft, the site of the impact, and witness accounts from several pilots and the airfield manager. Photographic evidence and witness marks on the grass were analyzed to determine the aircraft's path. The investigation also considered the airfield's topography, specifically the transverse slope of the runway which leads toward the shore.
Findings
- The pilot's inability to maintain directional control was likely due to the crosswind being at or near his personal limit.
- While the aircraft would typically weathercock into the wind, the combination of engine torque, slipstream effects, and the runway's downward slope caused the aircraft to yaw left.
- The high nose-up attitude observed by witnesses likely increased drag and reduced airspeed, leading to a stall that caused the left wing to drop.
- The aircraft sustained severe damage to the airframe, engine propeller, port wing, and landing gear, rendering it beyond economic repair.