Air New Zealand issued a record number of warning letters and travel bans to its customers this year.

Photo: 123rf

More of the airline's passengers had behaved badly towards each other or staff this year. Air NZ said the behaviour included verbal and physical abuse, and over-indulging in alcohol.

The airline issued 15 percent more warning letters, and issued 60 percent more travel bans for between one and five years.

"We want all our customers to have an enjoyable experience and won't tolerate poor behaviour toward each other or our staff, who try to go the extra mile to deliver a world-class uniquely Kiwi experience," David Morgan, chief operational integrity and standards officer, said.

The airline is heading towards its busiest day of the year tomorrow, with more than 60,000 passengers heading away for the holiday break on 600 flights across its network. This is 20,000 more customers than last year's busiest day on the airline's network.

The busiest route will be Auckland-Christchurch, according to the airline.

The airline is calling on customers to show respect to each other and airline staff over the busy summer season.

Air NZ Auckland airports manager Todd Grace is advising travellers to allow extra time to get to and through the airport, and encourages all passengers to take out travel insurance and sign up to the Air NZ Travel Alerts service for information on any disruption.