Ian McArthur has also become the latest person to raise concerns about the use of air tankers to suppress the Orroral Valley blaze in the hours after it ignited in Namadgi National Park in late January.

Mr McArthur was the ACT Rural Fire Service's deputy chief fire control officer from 1986 until 2001 and has more than 40 years of fire management experience with territory and Victorian authorities.

In a submission to the ACT Legislative Assembly's inquiry into the bushfire season, he said ACT authorities overstated the threat the Orroral Valley blaze posed to Canberra's southern suburbs.

Maps published on January 31 showed the Orroral Valley fire could reach residential areas if the worse-case scenario eventuated.

The agency, in particular commissioner Georgeina Whelan, was widely praised for its public messaging at the height of the emergency, which included frequent live-streamed press conferences and social media updates. As the fire loomed over the ACT's southern outskirts, the agency organised community briefings and helped door knock homes in Tuggeranong.

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The scale public messaging was widely seen as an attempt to avoid the errors made during the horror 2003 Canberra bushfires.

But Mr McArthur said in his submission that the messaging went "too far the other way" during this summer's emergency, and was akin to "crying wolf".

"Anyone with a basic understanding of weather patterns and the ability to read a map would know the likelihood of the fire reaching the southern suburbs was very low," he said.

"The messaging should have gone along the lines of: 'there is a large fire to the south of Canberra but there is no immediate or foreseeable danger but Canberra citizens will be kept well informed.

"What went out to the public created unnecessary fear, confusion and panic."

Mr McArthur's comments echo those made by volunteer firefighters in an internal review conducted in the wake of the fire season.

The agency has repeatedly defended its handling of the emergency, including its public messaging, affirming that it was proud of how it kept Canberrans safe and informed during the ACT's worst fire season since 2003.

Mr McArthur, who worked in bushfire research after graduating from ANU in the 1970s, said that while the Orroral Valley fire appeared to be managed well overall, there were questions about the early response.

He said the use of air tankers was "questionable", arguing that dropping fire retardant was expensive and ineffective. He noted his involvement in early research on aerial firefighting, which he said found the tactic was not a "cost effective" tool for suppressing fires.

A senior volunteer firefighter and well-known local farmer have expressed similar concerns to the inquiry about the reliance on air tankers to fight the Orroral Valley blaze in its early stages.

Fire crews battling the blaze in the hours after it ignited had to leave the fireground while they waited for the retardant drop, costing them time that could have been spent attempting to contain the emerging fire.

Mr McArthur told The Canberra Times that the agency should have sent as many tankers and plant machinery as possible into Namadgi National Park in the crucial first few hours.

"Once the fire gets past a certain stage the air tanker is just not going to put it out," he said.

"I don't think the response was right."