Qantas plane flies with an extra engine on the wing

You've probably never thought too much about how to quickly transport a 10-tonne plane engine, but Qantas has the answer.

Just strap it to the wing of a Boeing 747.

Qantas Flight 63 took off from Sydney with an extra Rolls Royce turbofan attached to the left wing between an inner engine and the plane's body. The engine was not powered; it just came along for the ride to Johannesburg, South Africa.

"We're undertaking this rare task to get our customers and our aircraft on their way as soon as possible — rather than shipping this engine across by boat or chartering a freighter aircraft," Qantas said in a statement.

Since the additional engine adds extra weight and drag, the flight had to make a stop in Perth for more fuel.

"Additional drag is caused by air travelling around the spare engine during flight and, to counterbalance this, our pilots are trained to use the flight controls to ensure the aircraft flies straight, level and safely," the airline said.

Perth Airport shared a video of the plane landing.

The engine is destined to power another of Qantas' Boeing 747s once it reaches Johannesburg. The last time the airline transported a plane engine in this way was in 2011, according to 9 News Australia.