The female captain of a Qantas plane was ordered from the controls of a passenger jet last week, just minutes before it was due to take off, after cabin crew suspected she had been drinking alcohol before the flight.
The pilot was suspended and Qantas has since launched an investigation into the incident after the senior pilot recorded a positive reading for alcohol.
The captain has been withheld from operational duties on full pay, but the airline will not comment on what reading she gave or how recently before the flight she had been drinking.
The incident occurred last Monday as the Qantas aircraft was about to depart Sydney for Brisbane.
Flight attendants on the Boeing 767-300 aircraft, which can carry 254 passengers, informed the airline's flight operations managers that they suspected the captain of the plane had been drinking.
The aircraft had already been pulled back from the domestic terminal and was taxiing towards a runway for take-off when Qantas management made the decision to stand down the captain from command of the plane.
The 767 returned to the domestic terminal where the captain was taken off the plane and a replacement pilot was found to fly to Brisbane
It is rare for pilots to be removed from flying for breaching airline procedure. Qantas has a zero tolerance to pilots recording an alcohol reading of any level.
Fewer than 100 of Qantas's 2200 pilots are women.
The investigation into the captain's alcohol reading is expected to take at least a month. Qantas has informed the air safety regulator, the Civil Aviation Safety Authority, of the incident.
However, it is considered a matter for Qantas rather than the regulator because the testing of the captain was done under the auspices of the airline's drug and alcohol management plan.