Terror as plane plunges 20,000ft

Some passengers vomited when oxygen masks had to be used as the Melbourne-bound Qantas Boeing 747 plane prepared to make an emergency landing at Manila in the Philippines.

Passengers spoke of hearing a loud bang and debris flying into the first class cabin as the plane's flooring gave way, part of the ceiling collapsed and the plane reportedly plunged 20,000ft.

The aircraft touched down safely at Manila at 11.15am local time and all 346 passengers and 19 crew disembarked normally.

Manila airport operations officer Ding Lima told local radio the plane lost cabin pressure shortly after take-off on the Hong Kong to Melbourne leg of its journey and the pilot radioed for an emergency landing.

He said: "There is a big hole in the belly of the aircraft near the right wing, about three metres in diameter.

"Upon disembarkation, there were some passengers who vomited. You can see in their faces that they were really scared."

Dr June Kane, from Melbourne, said: "There was a terrific boom and bits of wood and debris just flew forward into first (class) and the oxygen masks dropped down.

"On the left-hand side, just forward of the wing, there's a gaping hole from the wing to the underbody. 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. It was absolutely terrifying, but I have to say everyone was very calm."

Peter Gibson, from Australia's Civil Aviation Safety Authority, told ABC Radio that initial reports indicated a problem with air pressure in the cabin.