The NSW Bushfires Coronial Inquiry has heard back-burning deployed in an effort to control a deadly bushfire that killed three people on the NSW south coast was "appropriate".
The second stage of the inquiry is further investigating 17 bushfires during Black Summer to identify systemic issues around bushfire management.
This week NSW Coroner Teresa O'Sullivan is hearing evidence about the use of back-burning as a containment strategy for the Currowan fire in the days leading up to the catastrophic events of New Year's Eve 2019/20.
The Currowan fire started in late November, but within a month it had merged with four other fires to cover an area of some 315,000 hectares.
The court heard fire crews had established an eastern containment line from Milton in the south to Nowra Hill in the north, in an effort to stop the fire spreading east across the Princes Highway and into densely populated coastal communities.
On New Year's Eve, the fire broke the containment line and crossed the highway, killing three men who were protecting their homes.
The court heard fire crews carried out a number of back-burning operations on December 30 and 31 around Porter's Creek Road and the Yatte Yattah area.
Counsel assisting Donna Ward said the inquiry would hear from residents who claimed the back-burn was responsible for the loss of property.
"Witness statements from within the brief offer different opinions as to whether the fire that impacted upon individual properties came from the strategic back-burn or from the Currowan fire front or spot fires from either of these," she said.
Ms Ward said the varied experiences of residents and firefighters on the ground reflected the chaotic path of the fire.
"There is no single or universal experience of the fire or back-burn," she said.
"It is important to remember that the fire didn't proceed in a uniform fashion. Topography, vegetation, and weather conditions from place to place also played a role.
"What is beyond dispute is that the fire was relentless in its size and its impact."
The inquiry will later this week hear from independent bushfire expert Geoff Conway, who will provide evidence about the decision to carry out back-burning in light of the forecast severe weather conditions prior to News Year's Eve.
"[Mr Conway] has concluded that the eastern containment strategy was appropriate in the circumstances at the time of its planning," Ms Ward said.
"He suggests the incident management team could not have had any confidence that they would have access to the number of firefighters, firefighting vehicles, and aircraft needed to safely and effectively protect the people and assets that would come under threat if they were to limit themselves to relying on purely defensive strategy."
'Most challenging day of my career'
David Palmer, the Acting Incident Controller for the Currowan fire on December 30, told the inquiry they carried out a risk assessment on whether to continue back-burning.
He told the court if they failed to provide sufficient "depth" to the containment line through back-burning, there was a risk the fire front could grow to become "many kilometres long".
"At the end of the day, the determination is that we must attempt to get this back-burn to secure the eastern containment line," he said.
Mr Palmer told the inquiry the experience was the toughest of his career.
"We lost a fire unit that day. They rolled over and they were just able to escape before their vehicle was run over by fire," he said.
"A couple of volunteers who were protecting their property were significantly burned and ended up having to be airlifted to hospital.
"Certainly the most challenging day of my career."
The inquiry continues.
