The airline began offering flights in and out of Whanganui a couple of years ago when Air NZ pulled out, and since then patronage had increased, Guy said.
Air Chathams were currently working through regulatory requirements with the property owner, and Guy said those talks were progressing well.
They were a "high reliability" airline.
Guy said people were reflecting on the way Air NZ had treated travellers from Kapiti in giving them only three weeks notice before discontinuing services.
"They feel let down with the national carrier."
A farewell for the final flight tomorrow will begin at 6.30am.