"Air New Zealand has been a Pratt & Whitney customer for more than five decades, dating back to when its forerunner, Tasman Empire Airways Limited, operated the Douglas DC-8 powered by the JT3D engine," said Rick Deurloo, senior vice president of sales, marketing and customer support at Pratt & Whitney.
The Connecticut-based company says that since entering into service in early 2016, the GTF engine has demonstrated its promised ability to reduce fuel burn by 16 per cent, to reduce nitrogen oxide emissions by 50 per cent and to lower the noise footprint by 75 per cent.
Air New Zealand had delayed the delivery of the first A321 to get more certainty after engine problems emerged.
"As with new products there are sometimes infancy issues as the engine matures, and no engine is immune to those things. I think now they've reached a reasonably high level of maturity and reliability," head of aircraft programmes Kerry Reeves said last month.
The aircraft, with the tail registration ZK-NNA, is expected to enter commercial service on November 23, operating flight NZ739 from Auckland to Brisbane.
The A321s are 7.5m longer than A320s and will have 46 more seats in a completely revamped interior.
The slimline seats - upholstered with leather from Taranaki - are wider than those on existing A320s.
The middle seat will be 49cm - 3cm wider than the middle seats on the airline's existing A320 short-haul fleet - and the aisle and window seat 47cm - 1 cm wider than now.
Seat pitch (the distance between them, fore and aft) ranges from 29 inches to 33 inches (74-83cm) compared to 30-34 inches in A320s used on international flights.
A second A321neo is also expected to enter service in the coming weeks, while the majority of the remaining aircraft will follow at intervals through until late 2019.
The new A321neos will replace the current A320s that operate Tasman and Pacific Island services.
Air New Zealand has ordered a further seven A321neos for their domestic network, which are expected to be delivered from 2020 to 2024.