Engineers from Australian carrier, Qantas, are investigating what caused the problem that led to a plane on route to London being diverted to Frankfurt on Aug. 31.

A spokeswoman says the Boeing 747 from Singapore was diverted when the captain was alerted to a vibration in one of the engines.

She says the engine was shut down as part of standard procedure and the plane landed safely in Frankfurt.

One of the passengers onboard, Andrew Negline, says there was a large bang in the middle of the flight.

"We all woke up to a huge bloody bang and a lot of noise and shaking in the plane and they shut that engine down and then about four thirty, five o'clock, they told us we were diverting to Frankfurt," she said.