Qantas has thanked passengers for their cooperation after they were evacuated via slides in Sydney when haze filled the cabin of their Airbus A330 after it was forced to turn back due to a hydraulic fluid leak.
Qantas said passengers on the Sydney-to-Perth flight had experienced the "very unusual and probably alarming experience" after flight 575 returned to Sydney shortly after takeoff at 8.45am on Sunday.
About 20 minutes into the flight, its captain received an alert for one of three hydraulic systems on the aircraft.
"The captain elected to return to Sydney and the aircraft landed safely shortly afterwards. No emergency was declared," the airline said in a statement on Sunday afternoon.
"Once the aircraft was back on the gate there were reports of a thick haze in the cabin, likely caused by hydraulic fluid entering the air conditioning unit.
"While customers may have thought it was smoke, there was no fire."
The captain ordered an evacuation of the aircraft and passengers exited by emergency slides and the aerobridge into the terminal, Qantas said.
"Two passengers were treated for injuries sustained from using the slides and another passenger was taken to hospital as a precaution. Some customers reported sore eyes and itchy throats."
Qantas Fleet safety captain Debbie Slade said the airline understood the incident would have been a "very unusual and probably alarming experience for our customers".
"We thank them for giving crew their full cooperation," Ms Slade said in a statement.
"The crew did a great job of putting their training into action and following the procedures for a set of circumstances like this.
"We'll investigate exactly what happened, including liaising with Airbus, before this aircraft is returned to service."
One passenger described the incident on Twitter as "terrifying".
"Just had to evacuate my flight to Perth after engineering issues. Everyone had to exit the plane via slide onto Sydney tarmac after the cabin filled with smoke and the captain screamed evacuate," she tweeted.
The Civil Aviation Safety Authority and the Australian Transport Safety Bureau have been notified of the incident, Qantas said.
The airline says it will assist the bureau with its investigation.
"Qantas is providing support to customers on the affected flight and managing some delays to other flights that occurred as a result of this incident," the airline said.
"The airline extends its thanks to all customers for their patience and understanding."
Australian Associated Press