A helicopter accident at Forresters Beach in 2022 has highlighted to pilots the need to be aware of factors that can induce unanticipated yaw, according to an investigation report by the Australian Transport Safety Bureau.
On November 19, 2022, at about 6pm, the pilot of a Robinson R44 was conducting a private flight with two passengers from a property at Jilliby to a function centre at Forresters Beach.
A 40-year-old woman and her husband were being flown to her own birthday celebration with family and friends.
Three people were onboard the helicopter which witnesses said came in low and started spinning out of control before losing altitude and taking out power lines and then crash landing in a ditch on Central Coast Hwy between Cresthaven Ave and Tumbi Rd.
The Australian Transport Safety Bureau (ATSB) investigation report said that during the approach to the planned landing site, a carpark beside the venue, the pilot reported experiencing an uncommanded and unexpected yaw to the right, which was unable to be recovered.
ATSB Director Transport Safety Stuart Maclead said that during the approach to the confined carpark landing site, the helicopter experienced a loss of tail rotor effectiveness and an unanticipated yaw to the right.
“The pilot’s response was ineffective at recovering control – however, the unanticipated yaw may have occurred at a height from which control of the helicopter was not recoverable,” he said.
The investigation report said it could not be established if control of the aircraft was recoverable from the point in the approach that the unanticipated right yaw occurred.
The helicopter subsequently struck power lines before crashing to the ground. While the helicopter was substantially damaged, fortunately the occupants received only minor injuries.
ATSB’s report said that considering Gosford weather observations of a north-east wind at 10 knots, the approach track placed the wind from a direction and at a speed known to be conducive to the onset of unanticipated yaw.
Macleod said it was important for helicopter pilots to be aware of the factors that could induce unanticipated yaw, especially the relative wind direction, and particularly in confined spaces.
“These factors should be avoided, or their influence on the helicopter’s anti-torque system should be managed through positive control of the yaw rate,” he said.
“Depending on the yaw rate recovery may not be immediate, but maintaining the recovery control inputs is the most effective way to stop the yaw.”
Sue Murray