Another Qantas plane had to turn around after a flight from Fiji to Sydney had to return after reports of fumes in the cabin.
It comes only days after the Qantas flight QF144 from Auckland to Sydney had engine failure and issued a mayday call midflight.
The latest incident on Sunday marks the fifth occurrence in as little as a week for the airline.
Passengers on the Fiji-Sydney flight were however unconcerned about returning to Nadi International airport.
One told Australia's The Today Show that they "prefer it when the flight turns around."
Another said "They probably had a reason. It wasn't our flight."
The flight which was already an hour late had to divert after 45 minutes into the journey.
Turnaround flights have cast the spotlight on the airline but Qantas Domestic Chief Executive Andrew David says perspective is needed to examine what's happening.
"We understand that when you hear reports of planes turning around, it's concerning. But people can be assured that aviation is built on safeguards.
"One of those safeguards is that if something isn't right, we take a conservative approach to the problem rather than pressing on."
In other Qantas airline troubles, a Sydney to Fiji flight last Thursday turned back after reporting mechanical problems.
A Melbourne to Sydney flight returned to the runway on Friday, and a domestic flight from Melbourne to Canberra was turned back after 10 minutes of air time on the same day.
