"The ideal candidate aircraft will be a drop in replacement for the Q300 for seamless integration into the existing Air New Zealand turboprop network, which may include retrofit of the existing aircraft," the airline said.

The plan to seek proposals by March 2022 comes as companies pour more resources into developing cleaner turboprop technology to help airlines meet a challenging industry-wide target of net zero emissions by 2050.

Private equity-owned De Havilland signed a memorandum of understanding last week with hydrogen-electric-engine developer ZeroAvia to develop line production and retrofit programmes for its turboprop models that could be certified this decade.

Another company, Universal Hydrogen, is developing hydrogen conversion kits for Dash 8s and ATR72s and has signed a letter of intent for Dash 8 conversions with Icelandair Group.

Universal Hydrogen signed an agreement last month with Australia's Fortescue Future Industries to develop green hydrogen and logistics hubs in New Zealand.

Air New Zealand said 7% of its carbon emissions in the 2019 financial year came from its fleet of Q300 and ATR72 turboprops, which fly on domestic routes mostly shorter than 350 km (217 miles) and will be the easiest to replace with new-technology planes.

The airline's 23 50-seat Q300s are on average a decade older than its 29 68-seat ATR72s, meaning they will be due for replacement earlier.

Air New Zealand has already signed agreements with Airbus SE and ATR, a joint venture between Airbus and Italy's Leonardo, to study low-emissions aircraft. The airline said on Tuesday it hoped to get a one- to nine-seat low-emissions plane for training or freight missions by 2025.

(Reporting by Jamie Freed in Sydney; Editing by Peter Cooney)

By Jamie Freed