Mates Rates, how peculiar? I was sure PX operated into Kieta in recent years?
The Wikipedia page only mentions Aropa Airport RW 14/32 1,645 meters, asphalt.
https://en.wikipedia.org/wiki/Aropa_Airport
However Google Maps indicates the previous Kieta Airport is now the "Aropa Airport" south of Kieta on the road to Buin.
You may be referring to what appears on Google maps as "Arawa Airport", in the middle of Awara township. It was originally very short, Twin Otter or Islander strip however the Provincial Government permitted only MAF and Bougair to operate. At one stage they hauled logs onto the strip to stop outsiders landing there.