Flight CG8572, en route to Wewak and Vanimo, was grounded at the Madang airport for two hours.
The flight's captain explained to passengers that, by law, they will not take off unless all passengers are accounted for and confirmed on the manifest.
The confusion started in Lae, Morobe Province, when the airline company's ground crew allegedly issued seat numbers that were already occupied by passengers from Port Moresby, bound for Madang, Wewak and Vanimo.
The Madang ground crew reportedly made the same mistake.
Because of this, the two flight attendants had to place these new passengers in other seats.
After all the Madang passengers had boarded and the manifest cross-checked, they realised an adult passenger was missing.
The flight attendants had to go through the list again with each passenger. After an hour and a half, the missing passenger was identified.
The plane refilled and by 6.15pm, taxied off the runway for Wewak with the overly frustrated passengers.
It touched down at Boram Airport, Wewak, at 7pm, making it the first big engine plane to land at the airport at night.
The Vanimo passengers spent a night in Wewak.