Close to 1000 Air New Zealand staff will strike four days out from Christmas.
The airline said in a statement the industrial action by the Aviation and Marine Engineers Association and E Tū puts "thousands of holiday plans at risk" on the busiest travel day of the year.
Staff set to strike include aircraft maintenance engineers and aircraft logistics staff.
"Close to 42,000 customers booked to travel domestically and internationally on 21 December alone now face potential flight cancellations," Air New Zealand says.
Yesterday the airline was notified of a total strike by almost a thousand unionised employees on Friday 21 December. The unions have also advised to expect further industrial action.
"The average income of the maintenance engineers, logistics and other staff to strike is $115,000 – more than double the average wage in New Zealand – and around 170 of them earn more than $150,000," Air New Zealand says.
"While the group has received pay increases annually for the past 12 years, it has so far rejected recent proposals by the airline including an immediate two per cent pay increase followed by a further three percent increase after 12 months, with a further pay review in mid-2021.
"Staff have also declined a proposal to standardise overtime pay to 150 per cent of regular pay rate (currently overtime is paid at a mix of double time and time and a half), and a corresponding $6400 one off payment to address the change in rate.
"Only some of this workgroup does regular overtime but the payment would be made to everyone employed under this collective agreement."
Along with pay, claims on the aircraft maintenance engineers’ side have included an extra week of annual leave for employees with five years’ service.
Air New Zealand say they will communicate with customers booked to travel on 21 December closer to the travel date if these workers go ahead with their strike action.
They say customers are asked to avoid calling the airline’s customer contact centre in the meantime as no further information is available at this stage.
Customers booked to travel on Air New Zealand’s regional turbo-prop aircraft fleet will not be affected.