Amateur-built GLASTAR GS-1 N103A accident near Grand Rapids, Minnesota

Probable cause

The loss of directional control during landing because the autopilot engaged for undetermined reasons because water and recovery damage precluded detailed examination of system components.

NTSB analysis

Prior to takeoff from the airport pond, the pilot performed a few high-speed taxi and on-the-step maneuvers with no anomalies noted. After the flight and during the short flight to the intended landing area, the pilot heard two to three aural "autopilot disconnect" voice messages. Because the pilot believed he did not engage the autopilot during the flight, he was uncertain why he was hearing the autopilot disconnect messages and was not overly concerned. During the landing, after the floats contacted the water, the airplane's right wing immediately lifted up, and the left wing tip contacted the water. Subsequently, the airplane nosed over. The pilot reported the weather at the time of the accident as ideal for flying; sky clear and a steady 5-knot wind. Data extracted from the avionics units showed 9 autopilot engagements during the flight; however, the data did not show what caused the inadvertent engagements. It is likely the autopilot engaged during the attempted landing and caused the loss of directional control, but the reason for the autopilot engagement was not determined due to damage to the avionics system caused by water exposure and recovery damage.

Text from the NTSB. Open the NTSB docket for CEN13LA376 for the full record.