ABC journalist Mark Willacy was on board QF520 en route to Brisbsane.

He said the pilot assured passengers the right engine had been shut off but that it was still leaking.

“I've flown for 40 years and been on hundreds of flights and that was the scariest one I've been on,” he said.

“When [the plane] couldn't seem to take the altitude that a normal flight would … that was the most frightening moment for me.”

Willacy said an off-duty pilot was sitting among passengers and stepped up to help the Qantas pilot after the explosion.

“He was looking out at the engine to try and help the pilot, who was actually in the cockpit,” he said.

Passengers were instructed to disembark the plane once it landed.

"When we hit the ground, everyone burst into cheering and applause."