An Airbus Helicopters EC135 that crashed near Cooranbong, NSW, in 2015 did so because the pilot continued flight into non-visual conditions, according to an Australian Transport Safety Bureau (ATSB) report released this week.
VH-GKK was on a flight from Breeza to Terrey Hills on 15 November 2015 with pilot and two passengers on board when it crashed into terrain 10 nm NNW of Cooranbong. No-one survived the impact.
Radar data and images from a passenger's camera showed that the pilot had already diverted to land in a clearing due to adverse weather, but after 40 minutes continued the flight.
"The ATSB found that the pilot departed an interim landing site under the visual flight rules in marginal weather conditions," the investigation report states. "The pilot likely encountered reduced visibility conditions leading to loss of visual reference leading to the collision with terrain.
"It is almost certain that the pilot made the right turns in response to the weather conditions and it is possible that the pilot lost visual contact with the ground and climbed to ensure that he maintained terrain clearance. Given the weather conditions, at the point the radar returns dropped out, it is unlikely that the pilot was able to remain in VMC.
"It is possible that pilot was reversing track to return to the interim landing area."
The pilot was a PPL(H) with low-flying and night visual ratings, but did not have an instrument rating. An examination of the wreckage did not reveal any faults or failures with the aircraft that may have contributed to the crash.
"Weather-related general aviation accidents remain one of the most significant causes of concern in aviation safety," the ATSB said in their safety analysis. "Avoiding deteriorating weather or instrument meteorological conditions (IMC) requires thorough pre-flight planning, having alternate plans in case of an unexpected deterioration in the weather, and making timely decisions to turn back or divert.
"Pressing on into IMC conditions without a current instrument rating carries a significant risk of encountering reduced visual cues leading to disorientation. This can easily affect any pilot, no matter what their level of experience.
"In the event of inadvertent entry into IMC, pilots are encouraged to contact air traffic control for assistance."
The full accident investigation report is on the ATSB website.