What happened
On 11 September 2004, a Robinson R44 helicopter, registration SE-JHJ, crashed in the Orremossen area of Vättlefjäll, north-east of Göteborg, Sweden. The flight began at approximately 13:35 hrs when the pilot departed Alingsås for Göteborg after a refueling stop.
During the flight, the pilot began flying in circles and changing course as the aircraft approached the hilly terrain of Vättlefjäll. At approximately 14:00 hrs, the pilot contacted Säve tower to inquire about the weather, expressing an intention to attempt flying through a patch of rain. Shortly thereafter, the aircraft entered a state of uncontrolled flight. The impact was violent, resulting in 3 fatalities and the total destruction of the aircraft.
The investigation
The Swedish Accident Investigation Board (SHK) examined the wreckage, meteorological data, and radio communications. The technical investigation of the Robinson R44 revealed no mechanical failures or engine issues. However, evidence indicated that the helicopter experienced severe mast-bumping, which caused the main rotor to strike the forward section of the airframe, leading to the aircraft's disintegration in mid-air.
The investigation also reviewed the pilot's credentials and the prevailing weather conditions. At the time of the accident, a warm front was moving across the area, causing a sudden drop in cloud base to between 200 and 400 feet and reducing visibility significantly. The investigation noted that while the pilot had completed necessary training, the administrative process for his formal class authorization was still pending due to delays in document transfers from the United Kingdom.
Findings
- The primary cause of the accident was the rapid deterioration of weather conditions combined with the pilot's failure to recognize that the flight could no longer be safely completed under VFR conditions.
- The pilot lacked instrument flight training, making it impossible to maintain control once the aircraft entered the clouds.
- The pilot's experience with Swedish weather conditions was limited, which likely hindered his ability to anticipate the severity of the incoming front.
- The helicopter was subjected to intense mast-bumping during the uncontrolled descent.
- Ambiguities in the existing VFR weather minima regulations contributed to the difficulty in making a timely decision to terminate the flight.