Another mid-air emergency has forced a Qantas jet to make an unscheduled landing, this time at Adelaide airport after a door opened during a flight to Melbourne.

The Boeing 737-800 departed Adelaide at 6:08 p.m. local time and returned 37 minutes later, reports said.

There was confusion over what caused the emergency. Passengers said a door opened mid-flight, causing "chaos" in the cabin. But a control room operator at Adelaide Airport, who would only give his name as Sunny, told Times Online the doors covering the wheels did not close properly after take-off. The pilot reported this to air traffic control and returned to the runway — but officials deny that it should be classed as an emergency landing.

The aircraft turned around near Murray Bridge, about 40 miles from Adelaide, and landed safely at 6.45pm. It remained at Adelaide airport while passengers were transferred to another Melbourne flight , the Herald Sun reported.

A Qantas spokesman refused to comment beyond confirming an incident had occurred on the flight

That damage is thought to have been caused by an exploding oxygen canister. A section of the cabin flooring gave way, part of the ceiling collapsed and items flew into the first-class area. Investigators yesterday found debris - believed to be from the canister - in the aircraft

Captain John Francis Bartels, a former pilot with the Royal Australian Navy, and his co-pilot Werninghaus Bernd, put the aircraft into an emergency descent from 29,000ft to 10,000ft and landed an hour later in Manila, to applause from passengers. Qantas subsequently carried out checks on its entire fleet.

It is bad news for the new chief executive of Qantas, which boasts of never having suffered a fatal flight. Dublin-born Alan Joyce took over today, just days after 1,500 staff at the company lost their jobs.