The 2575ha blaze in the Orroral Valley is believed to have been started by an army helicopter in Namadgi on January 27.
The MRH-90 Taipan helicopter was looking for landing spots for other firefighting teams, when its landing light may have started the fire.
But the inquiry will specifically focus on the 45 minutes it took between the fire starting and ACT emergency services being notified of the blaze's location by the army.
Defence personnel didn't pass on the location of the fire until they'd landed their helicopter at Canberra airport some 45 minutes later.
ACT Chief Coroner Lorraine Walker will head the inquiry, which is due to run from Monday to Thursday.
Speaking in 2021 when the inquiry was announced, Ms Walker said it was critical the fire was given a thorough examination.
"It is in the public interest that all relevant matters concerning the cause and origin of the fire – and the actions taken to respond to it – are fully considered," she said.
"In light of reports which have been provided to government to date, it is my intention at the present time that the inquiry be limited to the approximately 45 minutes between the ignition of the fire and the subsequent communication of its location to the ACT ESA."
The Department of Defence didn't release the findings of an internal investigation into the matter.
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