Now that it's real, she's a little frightened.

Ms Finney expects the inquiry to show exactly what went wrong before her son, David, took his own life in 2019.

"I'm frightened of seeing what my son went through, I'm frightened of seeing what help he didn't get when he was so obviously outspoken about mental health issues and PTSD," she told AAP.

"I'm frightened of finding out why he died when he didn't have to."

Prime Minister Scott Morrison has outlined the scope and timing of the inquiry to be led by an ex-police officer, a former judge and a psychiatrist.

Mr Morrison said the royal commissioners would be sensitive and effective.

"One of the sensitivities in doing this was the veterans community and families and others were concerned it might be someone from a military background or something like that, and that would make them anxious."

They will look at all aspects of service, including what happens when people leave the armed forces.

The availability and quality of health and support services will be examined, as well as other issues faced by ADF members such as housing and employment.

The commission will also be able to look at any previous death by suicide, including suspected suicides.

Australia Defence Association executive director Neil James was pleasantly surprised with the inquiry's scope.

"Many people thought they'd weasel out of this by rigging the terms of reference and they appear not to have weaseled out of it, probably because of the public outrage that would cause," he told AAP.

Mr James was also pleased the commission would investigate the role played by the defence and veterans' affairs departments.

"There are too many laws, they are too complex and their administration is too bureaucratic," he said.

Ms Finney said David would be proud "because this is what he wanted".

"He wanted every veteran to feel safe to feel supported and that's what we'll keep fighting for," she said.

RSL national president Greg Melick said the organisation stood ready to help diggers who came forward to assist the inquiry.

"The royal commission's going to stir up a lot of memories for a lot of people," he told AAP.

The commission is due to deliver its interim report in August 2022 and a final report the following June.

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