A logbook of missing aircraft that was kept in the old Jackson's Control Tower SAR room, was a sobering tome to peruse. There was way over 600 allied aircraft still missing, of which a large number would have of course perished due to enemy action, while many were cfit or water.
Sharpie, during the war in PNG, Allied casualties due to sickness and tropical diseases versus enemy action were on the a ratio of 10:1, i.e., ten soldiers were 'lost' to disease for every one lost to enemy action.
I can't recall where I read this, but I understand that wartime Allied aircraft losses due to weather, mechanical failure etc versus enemy action in the PNG area were at about the same ratio. This probably wasn't the case in the first 12 months, when the Japanese were in the ascendency, but after that, I can well believe those figures.