Slovak Investigation of 2024 Robinson R44 Raven I Emergency Landing in the High Tatras (OK-STR)

Incident Overview and Investigation Authority On 25 May 2024, a Robinson R44 Raven I helicopter with registration OK-STR was involved in an accident in the High Tatras region of Slovakia. The event was investigated by the Air and Marine Investigation Unit (Letecký a námorný vyšetrovací útvar) of the Slovak Ministry of Transport under the case number SKA2024003. The investigation was conducted in accordance with Slovak civil aviation law, European Union Regulation 996/2010, and ICAO Annex 13. The operator and owner of the aircraft was Industry-logistik s.r.o., and the flight was classified as general aviation for sport and recreational purposes. ## Flight Details and Sequence of Events The helicopter departed from Ružomberok Airport (LZRU) with the pilot and two passengers on board for a recreational flight over the High Tatras. The planned landing site was the departure airport, with a scheduled landing time of approximately 16:15 UTC. During the flight over the High Tatras ridges, the pilot experienced a drop in main rotor RPM. After an unsuccessful attempt to restore full engine power, the pilot decided to make an emergency landing. The selected landing area was covered in icy snow and was not sufficiently stable. This instability caused the helicopter to tilt to one side, resulting in the main rotor blade contacting the ground and the aircraft overturning onto its right side. The final position of the helicopter was approximately 150 meters south of Chata pod Rysmi. ## Personnel, Injuries, and Aircraft Damage The pilot, a 49-year-old Czech national, held a Private Pilot Licence (Helicopter) and a Light Aircraft Pilot Licence. The pilot sustained minor head injuries, while the two passengers were uninjured. All occupants evacuated the helicopter without external assistance. The helicopter sustained extensive damage as a result of the overturning. No third-party damage claims were reported to the investigation unit. ## Aircraft and Meteorological Information The Robinson R44 Raven I, serial number 1933, was manufactured in 2008 by Robinson Helicopter Company, USA. It is a four-seat, single-engine light helicopter with a two-blade main rotor and a two-blade tail rotor, powered by a Lycoming O-540-F1B5 engine. The aircraft was registered in the Czech Republic and was equipped for Visual Flight Rules (VFR) day operations only. It did not have a Flight Data Recorder (FDR) or Cockpit Voice Recorder (CVR), as this equipment is not mandatory for this category of helicopter. At the time of the accident, the weather in the area of Chata pod Rysmi (2,250 m above sea level) was mostly partly cloudy to cloudy, with no precipitation. The air temperature was 4 to 5 °C, and the prevailing wind was from the south at 3 to 5 m/s, with gusts up to 10 m/s. Horizontal visibility was approximately 70 km. The investigation noted that turbulent airflow, influenced by the local orography and the orientation of the rocky ridges, caused sudden changes in wind direction and speed in both horizontal and vertical directions.