Air Transport

Papua New Guinea's Accident Investigation Commission has released a preliminary factual report into August's crash of a commercial aircraft in which all 13 on board died.

The report says at the time of the accident there was "extensive areas of very low and middle-level layered cloud in the area, embedded with thunderstorms and associated severe turbulence".

"The forecast indicated widespread areas of rain, which had consistently interrupted normal operations in the area throughout the morning of the accident."

It says earlier that day other aircraft were either diverting back to Port Moresby or holding due to the poor weather.

"At about 1055 on 11 August, the pilot of the de Havilland Twin Otter, registered P2-MCB, reported departure from Jacksons Aerodrome, Port Moresby on a charter flight to Kokoda" in the Papua New Guinean highlands, says the commission, referring to an Airlines of Papua New Guinea aircraft.

"On board the aircraft were two crew and 11 passengers" and the aircraft was due to arrive at Kokoda at 1120, it says.

But about 11 kilometres (6nm) from its destination, the aircraft crashed into the eastern side of the Kokoda Gap, a steep and heavily wooded mountain, says the commission.

The aircraft was destroyed on impact and all those on board died, it says.

Search teams found the wreckage at 0810 on 12 August, it adds.

The commission is now investigating with the assistance of the Australian Transport Safety Bureau, it says.

It adds, the investigation will: examine the items recovered from the accident site, review relevant operational documentation, review of the aircraft's weight and balance, look at the forecast and actual weather conditions at the time of the accident, conduct interviews with relevant persons and organisations and review the risk controls and potential organisational influences that may have contributed to the accident.

There was no flight recorder equipment on the Twin Otter "nor was it required to be so by aviation regulation," it says.

Papua New Guinea is known for its mountainous terrain and inclement weather.