The unions representing Air New Zealand's engineering and logistics workforce have confirmed they have served a three day strike notice to the airline.
The action is scheduled for December 21, 22 and 23.
Union members voted in favour of industrial action last week. The union says the strike action relates to Air NZ's "low offer and requests for cuts to sick leave and overtime".
The airline and union members were involved in negotiations until late on Monday evening.
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Savage, Head of Aviation at E tū, says the decision to strike was not taken lightly.
"While the bargaining team is trying hard to get a workable offer, the union members are steadfast in their commitment to taking industrial action if necessary."
A third day of negotiations will begin on Wednesday morning.
Air NZ says the airline will do all it can to get customers where they need to be this Christmas.
"We know customers are very concerned about their travel plans at this important time of the year, and unfortunately we are not in a position to provide certainty at this time," Air NZ's customer experience manager Anita Hawthorne said.
"We would like to reassure customers that we remain committed to mediation with unions and we are still hopeful of reaching a resolution which sees strike action averted."
But the airline can't rule out delays or cancellations due to the strikes
"We are working on contingency plans to keep our flights moving the best we can if, as a worst-case scenario, strike action should go ahead - unfortunately some disruption would be inevitable though."
Air NZ said customers who have travel booked on the days affected should sign up to their travel alerts system and keep a close eye on their flights details.