Join Air New Zealand Business class upgrade loyalty program: Enroll in Air New Zealand's frequent flyer program, Airpoints, and accumulate points by flying with the airline. As you earn more points, you may become eligible for complimentary upgrades based on your membership tier.

1. Bid for an upgrade: Air New Zealand offers an option called "OneUp" where you can bid for a premium class upgrade. This feature allows you to place a bid for an upgrade on eligible flights, and if your bid is successful, you'll enjoy the benefits of a higher class cabin.

2. Pay for an upgrade: If you desire a more comfortable and luxurious experience, you can inquire about available upgrade options directly with Air New Zealand. Depending on availability, you may be able to purchase an upgrade to a higher class.