Richard Woodward, vice president of the Australian and International Pilots Association, told The Australian: "She was sitting in the cockpit for a large percentage of the flight. I think it was naive and silly."
He said that pilots were angry about the incident and added: "It takes a lot of work to become a professional pilot. She came on dressed as a pilot."
He explained that the chief concern was that, in the event of an emergency, the woman many have been called upon to help with the flight - and said that lawyers were in the process of sending a letter of complaint to Qantas.
The Age reports that the plane's captain was put in a difficult position because he had to decide whether to leave the woman behind or allow her on board. He has since raised his concerns in a report to Qantas operations.
Qantas spokesman Andrew McGinnes confirmed that the woman was wearing "parts" of a pilots uniform, but could not explain why.
He said: "We're examining precisely why this happened, however it's clear that the staff member was on the flight deck for operational reasons and was not in any way trying to deceive the flight crew, who knew the staff member wasn't a pilot.
"The staff member had the proper security clearance and appropriate documentation to be on the flight deck and there is no suggestion of improper behaviour on the aircraft."
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