Another day, another Qantas scare

The Canberra-bound plane returned to the terminal and passengers were transferred to another flight. 

A Qantas spokeswoman says QF850 had problems with its air conditioning duct unit.

"It was a routine return to the terminal due to an air-conditioning fault," she said.

"Rather than delay passengers further a replacement aircraft was arranged and the flight took off just before 1pm."

The incident is the latest in a recent run of scares for Australia's national airline.