SYDNEY, Dec 4, 2008 (AFP) - A man who worked as an engineer with Australian airline Qantas after forging his qualifications put the lives of thousands of passengers at risk, a court was told Thursday.

Timothy McCormack posed as a licensed aircraft engineer for almost nine months and conducted 30 maintenance checks on planes leaving Sydney Airport before being exposed in July 2007, the court heard.

The 27-year-old pleaded guilty in September to 42 charges including forging a maintenance engineer's licence - and then faked four character references for the court as it considered his sentence.

Prosecutor Paul McGuire said McCormack became entangled in a web of deceit that could have had "catastrophic" consequences for Qantas passengers flying out of Sydney.

"The potential that arose because an unqualified and failed engineer was carrying out significant work to major systems on an international aircraft directly put at risk the lives of 12,000 people," he said.

Judge Mark Marien noted that McCormack, as a supervising engineer, had been checking the work of other junior engineers working on passenger planes.

"This is someone who was not only carrying out maintenance on Qantas jets carrying large numbers of people, but was actually certifying work done by others without qualification," he said.

McCormack was described by his defence lawyer as a "pathological liar", while a psychologist said he told fantastic stories "to restore a proper sense of self-worth" after his girlfriend left him and took their infant child.

The judge is expected to pass sentence on December 17.