A former air force cadet told a royal commission that rules prohibiting touching were treated as a "joke".

The woman, who joined the Australian Air Force Cadets as a 13-year-old in 1999, told the inquiry that cadets were made aware of the policy but it was not always observed.

The witness, given the pseudonym CJF, told the Royal Commission into Institutional Responses to Child Sexual Abuse that the non-fraternisation policy was not taken seriously.

"It was spoken about or joked about quite frequently," she said.

"We weren't allowed to touch each other. We had to maintain blue book distance. We would hit each other with the book because that was maintaining blue book distance."

The inquiry into sexual abuse within the Australian Defence Force has previously heard a former cadet, Eleanore Tibble​, committed suicide at the age of 15 after being falsely accused of fraternising with an instructor in Hobart.

In her statement tendered to the commission, CJF said AAFC adult staff members at her squadron in Sydney did not follow the fraternisation policy.

"Though staff members were aware of fraternisation it was not monitored and there was little consequence or punishment if a cadet engaged in fraternisation," she said.

CJF, who went on to become an adult instructor with the AAFC, told the commission she was intimate with a navy cadet instructor following a cadet rifle training activity when she was 17.

"We went back to his house after one of the shoots and he brought us alcohol and there were other navy cadet instructors at his home at the time when the incident took place," she said.

The hearing before Justice Peter McClellan​ is scheduled to run until Friday.

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