The man had been fighting a blaze that had burned through more than 1600 hectares when he crashed near Pipers Brook, about 40km north of Launceston, on February 14.
A preliminary Australian Transport Safety Bureau (ATSB) report, released on Friday, noted an air crew on board a Fireboard 460 observed the pilot’s chopper miss a water drop on a small hot-spot.
“Suspecting UHX’s pilot was encountering an in-flight difficulty, and wanting to avoid any potential conflict with the approaching helicopter, the air attack pilot initiated a climbing 360-degree turn,” the ATSB report stated.
“After completing the turn the air attack pilot trailed UHX and observed the helicopter descend toward an open paddock where it impacted the ground.”
A witness at the staging area on the ground said the helicopter missed the hot-spot when releasing its water before it started descending, entering a hover before it rapidly “yawed” twice before disappearing from view below the treeline.
The term yaw refers to an aircraft twisting or oscillating on its vertical axis.
The pilot, who was the sole occupant, was killed in the crash, with the helicopter destroyed from the impact and a fuel-fed fire, the report says.
ATSB director of transport safety Stuart Macleod said the report detailed factual information established in the investigation’s early evidence collection phase.
However, he said it did not detail analysis or findings, which will be outlined in the investigation’s final report.
“As the investigation progresses, the ATSB will continue to analyse the flight profile, further examine helicopter components including the engine, transmission and tail rotor gearbox, consider witness accounts, and analyse accident imagery and video footage,” Mr Macleod said.