Speaking from the Manila airport, passenger Dr June Kane says she heard a loud bang from underneath the plane, and saw debris fly through the cabin.

"I'm looking at the plane now and on the left hand side, just forward of the wing, there's a gaping hole from the wing to the underbody," she said.

"It's about two metres by four metres and there's baggage hanging out so you assume that there's a few bags that may have gone missing."

Dr Kane says she heard the bang while the plane was flying over the South China Sea.

"There was a terrific boom and bits of wood and debris just flew forward into first (class) and the oxygen masks dropped down," she said.

"We were told that one of the rear doors, a hole had blown into it, but I've since looked at the plane and there's a gigantic gaping hole in the plane.

"It was absolutely terrifying but I have to say everyone was very calm."