N8512QAir Tractor AT-802A · 2003

The pilot reported that while practicing stop-and-go landings with a crosswind condition, the tricycle-geared weight-shift control (WSC) airplane "weathervaned" to the right upon touchdown. In an attempt to correct for the weathervane, the pilot applied right pedal, the airplane departed the runway to the right, and tipped over coming to rest on the right leading edge of the wing. The airplane sustained substantial damage to the wing keel.

A Federal Aviation Administration (FAA) aviation safety inspector who responded to the accident site reported that he observed no mechanical malfunctions or failures with airframe and engine that would have precluded normal operation and none was reported to him by the pilot.

In the recommendation section of the National Transportation Safety Board Accident/Incident Reporting Form 6120.1, the pilot stated that the accident may have been avoided if he had additional training that concentrated on ground handling and crosswind condition operations.

The FAA has published the Weight-Shift Control Aircraft Flying Handbook FAA-H-8083-5 (2008). This handbook discusses crosswind landing procedures for WSC airplanes and states in part:

When in final approach, the wind correction angle (crab angle) is established by heading toward the wind with the wings level so that the aircraft's ground track remains aligned with the centerline of the runway. This crab angle is maintained all the way to touchdown, when the rear wheels hit first and rotate the carriage and wing around so the front wheel touches the ground with the carriage going straight. However, if in turbulent air or pitched forward during the touchdown, with the front wheel touching the ground first, the pilot should lightly control the steering of the front wheel to be headed in the direction the carriage is going. WSC carriage front landing gear typically has camber that tends to steer the front wheel naturally in the direction of travel, so a light touch on the front wheel as it touches the ground allows it to find its own direction of travel. Once the front wheel is on the ground, lower the nose to keep the WSC on the ground and steer as required down the center of the runway.

The procedure for the wing during the roundout is the same as that for normal and turbulent roundout and touchdowns. The exception is that after touchdown the windward wing should be lowered slightly so the wind cannot get under it to flip the WSC aircraft during later landing roll and taxi.