What happened
On 18 May 2008, a Piper PA-22-160 Tri-Pacer, registration G-ARDT, was conducting a private flight from Oban to the Northside airstrip near Aberdeen. During the approach, the pilot noted a surface wind of 350 degrees at 12 knots, which necessitated landing with a tailwind. To utilize the shelter provided by nearby trees and the upward slope of the strip, the pilot performed a turn toward the windsock.
While established on final approach with full flaps and an indicated airspeed of 65 mph, the pilot attempted to initiate a go-around at approximately 50 feet above the ground. During this maneuver, the pilot intended to reduce the flap setting from full to half. However, the pilot accidentally retracted the flaps to the up position. This caused the aircraft to sink rapidly while tracking over rising terrain.
The aircraft touched down and bounced violently, striking the windsock with the right wing. The left wing subsequently struck the door support structure of an adjacent polytunnel. The aircraft continued along the strip, running over a dry stone wall before coming to a halt. The impact resulted in one serious injury and one minor injury to the passengers, while the pilot was unhurt. The aircraft sustained substantial damage and was destroyed.
The investigation
The AAIB examined the mechanical operation of the aircraft's flap system and the flight path. The investigation established that the aircraft's flap lever, which functions similarly to a handbrake, lacked a mechanical stop or baulk to prevent the pilot from moving the lever directly from the full position to the up position.
Findings
- The pilot accidentally retracted the flaps completely while attempting to adjust them to a half setting.
- The aircraft's flap control mechanism lacked a physical barrier to prevent accidental retraction from full to up.
- The landing strip's significant uphill slope and the presence of obstacles, including telegraph lines and a polytunnel, contributed to the severity of the impact.