|Hevilift Twin Otter DHC-6-300/400 similar to the aircraft reported crashed (Hevilift)|
Carrying nine people, the flight had been travelling from Woitape in Goilala district to Port Moresby as it came down near Mount Lawes, about 20 kilometres north of the capital.
The Australian pilot was killed along with the co-pilot and a passenger, both of whom were PNG nationals.
In a statement, Hevilift said it would be "conducting a thorough investigation" and was "cooperating with all relevant authorities to determine the cause".
"Hevilift’s thoughts and sympathy go to the families of those who have died in the crash and the company will continue to provide every assistance to the survivors," it said.
A Twin Otter belonging to Airlines PNG (Flight 4684) crashed in bad weather on 11 August 2009 at Kokoda, killing all eleven passengers and two crew.
A Nepal Airlines Twin Otter (9N-ABB) crashed in February this year, while a further three fatal or serious incidents occurred in 2013.
The first Series 100 de Havilland Canada (DHC) Twin Otters began flying in the mid-1960s and proved very popular with short haul operators. Productuion of the DHC Otters (Series 300) ceased in 1988.
Revised and updated Series 400 aircraft were introduced by new manufacturer, Viking, in 2007.
Twin Otters were once widely operating in regional Australia, but are now confined to Pacific Islands airlines in Solomon Islands, PNG, Vanuatu, NZ and Fiji