It comes after the consumer watchdog revealed on Thursday that it was taking the Flying Kangaroo to court after alleging it was selling tickets to flights it had already cancelled.

Qantas said in response it was taking the so-called ghost flight allegations seriously and would respond to them in full in court.

However, Cass-Gottlieb gave a series of interviews on Friday where she shed more light on the decision to press ahead with the unprecedented action.

“We consider that this should be a record penalty for that conduct,” Cass-Gottlieb told the ABC.

“We think the penalties should be in the hundreds of millions, not tens of millions, for breaches.”

She said the penalty should be “more than double” the previous record fine handed to Volkswagen in 2019 for $125 million.

Later, Cass-Gottlieb told the SMH the ACCC believes the penalties in consumer law cases have not been high enough.

“If a corporate giant is told to pay $100 million, it is seen as the cost of doing business,” she said.

”We would hope hundreds of millions of dollars would be enough to act as a deterrent to not only Qantas but others if these allegations are satisfied in court.”

The full case will see the consumer watchdog allege Qantas engaged in “false, misleading or deceptive conduct” by selling tickets on its website to more than 8,000 flights departing between May and July 2022 for up to 47 days after those flights had been cancelled.

It also claims that Qantas failed to notify ticket holders of more than 10,000 flights departing between May and July 2022 that their flights had been cancelled for an average of around 18 days, with some notifications delayed for up to 48 days, and that it did not update its ‘Manage Booking’ page for ticketholders when flights were cancelled.

The decision to go ahead with court action came from an analysis of data showing Qantas cancelled almost a quarter of flights between May and July 2022, or 15,000 of 66,000 scheduled domestic flights departing from all states and mainland territories

The watchdog says that for 70 per cent of these cancelled flights, Qantas “continued to sell tickets for the flight on its website for two days or more, or delayed informing existing ticketholders that their flight was cancelled for two days or more, or both”.

In a statement, Qantas said it is taking the allegations seriously and will respond to them in full in court.

“We have a longstanding approach to managing cancellations for flights, with a focus on providing customers with rebooking options or refunds. It’s a process that is consistent with common practice at many other airlines,” the airline said.

“It’s important to note that the period examined by the ACCC between May and July 2022 was a time of unprecedented upheaval for the entire airline industry. All airlines were experiencing well-publicised issues from a very challenging restart, with ongoing border uncertainty, industry-wide staff shortages and fleet availability causing a lot of disruption.”

In a Senate committee hearing on Monday, Qantas CEO Alan Joyce defended high cancellation rates on routes like Sydney-Melbourne and Sydney-Canberra, saying it is better to cancel flights on more frequent routes than leave customers waiting for a lower-frequency flight.

Around 2,300 flights between Sydney and Melbourne across all major carriers were cancelled in the first six months of 2023.