What happened
The aircraft departed from an airport and returned for landing at a private airstrip. The runway surface consisted of wet grass and featured a significant topographical challenge: the final third of the runway sloped downward in the direction of travel.
Upon approaching the threshold, the pilot initiated the landing flare approximately one-quarter of the way down the available runway length. Due to the combination of the wet surface conditions and the downhill gradient, the aircraft failed to stop within the paved or grass limits. It continued its forward momentum past the end of the usable runway area.
The aircraft eventually left the ground surface and entered a ditch located immediately adjacent to the departure/landing zone. The ditch was approximately six feet deep. The impact with the ditch brought the aircraft to a halt.
The investigation
Examination of the site revealed that the wet grass conditions likely reduced tire traction. The downhill slope in the last third of the runway contributed to the inability to decelerate effectively using standard braking techniques. No mechanical failures were reported as contributing factors to the overrun.
Findings
The primary factors leading to this incident were the wet runway surface and the downhill gradient on the final portion of the airstrip. These conditions exceeded the aircraft's stopping capability for the given landing distance.
All four occupants aboard the aircraft escaped without injury. The structural damage was confined to the airframe interaction with the ditch.