Ian McBeth, Paul Hudson and Rick DeMorgan came to Australia to fight the devastating bushfires and died when their large air tanker crashed fighting a fire on January 23, 2020.
The Australian Transport Safety Bureau (ATSB) released its report into the crash in the Snowy Mountains region of NSW on Monday.
It found the RFS sent the aircraft to an area with unfavourable conditions, without aerial supervision, and relied on the pilot to assess the risk without providing all the information required.
The pilot of the aerial supervision plane had declined the job due to poor weather conditions and the crew of a separate Boeing 737 had reported they would also not be returning to the fire-ground.
The ATSB said the crew of the Lockheed EC-130Q large air tanker that crashed was very likely not aware of those two decisions made by other pilots.
"While this was only one risk factor among others that would be considered by the crew when accepting a task, having this information would have allowed them to make a more informed decision about the weather conditions," the report said.
The forecast and actual weather conditions in the region on the day of the crash were hazardous, gusting winds, likely exacerbated by the fires and local terrain.
The crew assessed the conditions were unsuitable and were instead sent about 58 kilometres to the east, where conditions were much the same.
The ATSB found the aircraft likely stalled as it climbed after dropping fire retardant on the Good Good fireground near Peak View, north of Cooma.
The RFS and the aircraft operator shared responsibility for risk mitigation in firefighting operations, which necessarily take place in a high-risk environment, the ATSB said.
A number of issues were identified with risk mitigation in the bureau's report.
Coulson Aviation, the Canadian company contracted to operate the tanker for the RFS, did not have adequate operational risk assessments or a maintained risk register.
The company has improved its risk assessments and procedures and training for pilots who encounter windshear in response, the ATSB said.
The RFS had limited policies and procedures for large air tankers and their supervision, and no procedures for deployment without supervision.
There was also no policy to manage task rejections or to communicate those rejections internally or to other pilots in the area.
The RFS advised the ATSB it would commission reports on airspace management, establish a co-ordinator for air tankers, audit records on qualified pilots, and review its safety doctrine among other measures.
However, the bureau said the RFS had not yet committed to adopting any safety precautions that would reduce the risks associated with issues identified in its report.
It recommended the agency address its absence of policies on aerial supervision and the communication of task rejections.
The ATSB said its investigation was delayed and limited due to no recording of the accident on the cockpit voice recorder, which only contained audio of a flight in the US from 2019.
