A MAN who faked his qualifications to work on Qantas aircraft was living in a delusional parallel universe, a court was told yesterday.

For 10 months Timothy McCormack, 27, fooled Qantas into believing he had passed Civil Aviation Safety Authority exams and was a licensed maintenance engineer. During the deceit he checked Boeing 747 jets for maintenance and confirmed they were safe to fly.

He pleaded guilty in September to 42 charges, including faking his exam results and forging his licence. He also faked character references that were tendered to the court last month. Yesterday a character reference was presented from Senator Bill Heffernan, who wrote describing McCormack's family as being of "unblemished character, hard-working, committed, honest".

However, the Crown prosecutor, Paul McGuire, said it spoke volumes that Senator Heffernan did not extend the compliments to McCormack, and he objected to portions of the reference that offered a medical opinion on McCormack.

The NSW District Court heard that among the references McCormack had faked was a rewritten version of one legitimately provided by his former school counsellor.

A psychologist, Jill Farrelly, said McCormack was a pathological liar, which impaired his ability to control his behaviour.

"He said he wanted people to think the best of him, so he could never say anything negative about himself," Ms Farrelly said.

McCormack's lawyer, Sydney Jacobs, said he was living in a "perfect parallel universe".

"My client is trying to create for himself this mythological place where he had greater status and where he could in fact hide from his utter self-loathing."

The judge, Mark Marien, said it was likely he would impose a full-term custodial sentence. "This is someone who not only was carrying out maintenance on Qantas jets carrying large numbers of people, but was actually certifying work done by other people. It's the potential of the harm that could have been done."

He adjourned sentencing until December 17.