Pilots on a Qantas Airways’ flight shut down one of its two engines after an issue on approach to Perth on Monday night, but the Airbus aircraft landed safely, the airline told Reuters on Tuesday.

The Airbus A330-200 aircraft requested a priority landing and taxied to the gate under its own power, a spokesperson for Australia’s largest airline said.

Australian media quoted passengers on the Melbourne to Perth flight as having heard a loud noise or bang from one side of the plane.

Qantas engineers are inspecting the aircraft, the carrier said.

“We know this would have been unsettling for customers on board and we thank them for their cooperation and understanding,” Qantas said.

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Engine failures are rare events, but twin-engine planes are designed to fly on one engine and pilots are trained to do so.

The twin-aisle aircraft is 21 years old, according to aviation intelligence provider ch-aviation.