Cessna 172S LN-KAB Accident on Tisleifjorden, Norway

Overview and Aircraft DetailsOn 24 April 2020, a Textron Aviation Cessna 172S with registration LN-KAB, operated by Hallingdal flyklubb, was involved in an accident at Tisleifjorden in Gol municipality, Viken, Norway. The flight was a private club operation in visual meteorological conditions (VMC) during daylight hours. The pilot, a 51-year-old holder of a Private Pilot Licence (PPL), had 468 total flight hours, including 254 on the type. The aircraft sustained significant structural damage, while the pilot was not injured.## Sequence of EventsThe pilot had planned to land on the frozen surface of Tisleifjorden, a regulated reservoir with a variable water level. Prior to the flight, the pilot had gathered information from an experienced mountain pilot and conducted a personal inspection of the landing area on the morning of the accident. The planned landing zone was approximately 500 meters long and 15 meters wide, marked by tracks from ski-equipped aircraft and snowmobiles. The pilot assessed the surface as having a thin frost layer with low rolling resistance and assumed moderate braking effectiveness. During the landing, the aircraft came to a sudden stop when the nose wheel penetrated the upper ice layer. The main wheels lifted off the ice, the aircraft yawed 30–45 degrees to the left, and the right wingtip struck the ice. The pilot shut off the fuel, ignition, and master switch, and evacuated the aircraft.## Investigation Findings and Ice ConditionsPost-accident inspection revealed that the aircraft had entered an area with a 3–5 cm layer of slush between an upper, partially porous ice layer (8–10 cm thick) and the solid ice below. The main wheels had begun sinking through the upper ice layer approximately 31 meters before the sudden stop, but had resurfaced. Thirteen to 15 meters before stopping, both main wheels and the nose wheel had cut into the ice, with the left main wheel 5–10 cm down and the nose wheel 10–12 cm down. The Norwegian Water Resources and Energy Directorate (NVE) glaciologist noted that the layered ice structure likely formed earlier in the season due to snowfall on frozen water, creating slush ice over a water/slush layer. NVE emphasized that visual inspection cannot reveal internal ice structure or water layers, and that ice conditions can vary significantly across a water body, particularly in regulated reservoirs where water levels change.