'Remarkable' more did not die in Black Summer: coroner

It is remarkable more people were not killed in the devastating Black Summer bushfires given the unprecedented scale of destruction, a coroner has found.

A long-running NSW inquiry into the disastrous 2019-20 bushfire season has led to a string of recommendations to help prevent similar future losses.

They include new rules for the use of firefighting aircraft, better alert systems and remodelled risk classifications.

The more than two-year probe culminated in a 700-page report delivered on Wednesday, building on the work of multiple earlier inquiries.

State Coroner Teresa O'Sullivan said the disaster, which became known as Black Summer, was one of the most catastrophic on record.

"It was unprecedented in scale and intensity," she said in delivering her findings.

"The sheer scale and ferocity of the fires burning simultaneously meant resources were stretched across the state ... it is remarkable the loss of life was not higher."

The fires killed 25 people and more than 800 million animals were estimated to have perished as their habitats were reduced to ashes.

NSW Rural Fire Service personnel assess a bushfire in Katoomba
The coroner has released a lengthy report on the Black Summer bushfires after two years of hearings. (Steven Saphore/AAP PHOTOS)

Over 5.5 million hectares burned, with thousands of houses and buildings worth as much as $1.88 billion destroyed.

"These figures are important but do not capture the human tragedy or impact upon the community's collective psyche," Ms O'Sullivan said.

At Lidcombe Coroner's Court for the findings, residents of the Blue Mountains, west of Sydney, left disappointed and saying they felt ignored.

Jochen Spencer recalled the trauma of sheltering with neighbours as fire hit Berambing, an event that fuelled the Mt Wilson Backburn Survivors Group's community campaign.

"We put in a lot of affidavits, we put in expert reports ... and it feels like the community voice has not been listened to," he said.

Affected residents hold signs following an inquest into Black Summer
Some residents impacted by the bushfires say they felt ignored in the latest Black Summer inquiry. (Dean Lewins/AAP PHOTOS)

Kooryn Sheaves said her first warning came from residents in a neighbouring village about to be overrun by flames.

"That gave us 15 minutes for the bush telegraph to actually get out there and tell everyone what was happening," she said.

"It's communities who save themselves ... this inquiry was definitely a missed opportunity."

But the coroner reiterated that her purpose was not to assign blame.

More than 780 witness statements were submitted and close to 200 people testified in person, providing a "forensic contribution" beyond their written submissions, Ms O'Sullivan said.

"It was not possible to call for oral evidence from every person that saw, heard or experienced something."

There were a range of causes for the fires including power lines, lightning strikes and out-of-control back-burning.

Among the deaths were US aviators Ian McBeth, Paul Clyde Hudson and Rick DeMorgan Jr, whose air tanker crashed at Adaminaby in the Snowy Mountains.

Their deaths prompted recommendations around the use of the aircraft.

NSW Rural Fire Service air tanker drops retardant on a blaze in 2020
Aerial firefighting decisions and risk management are a focus of the coroner's Black Summer report. (Dan Himbrechts/AAP PHOTOS)

RFS Commissioner Rob Rogers says the recommendations will take time to process.

"We'll be talking to government ... and making sure that when there's a response given to the community on the response to those recommendations it's actually fully informed and we ensure we can absolutely implement them," he said.

Improvements have been made already, including work done on designing safer trucks.

The inquiry recommended fire trucks be designed with better protection against rollovers and falling objects after Geoffrey Keaton and Andrew O'Dwyer died when theirs was hit by a tree at Buxton, southwest of Sydney.

The 28 recommendations are directed to the commissioners of the RFS and NSW Police and chief executive of state-owned Essential Energy which says it has it has been working with the University of Melbourne on updating its Bushfire Risk Classification.

Hearings were held across two years around NSW including in Queanbeyan, Lismore, Armidale, Taree, Cooma and Katoomba, and live-streamed from Sydney.