Following three days of negotiations, the unions representing Air New Zealand logistics and engineering workers have come to an agreement in principle.

The mediated negotiations come after strikes were threatened by staff which would disrupt travel over three days from Friday, December 21.

The three days would disrupt travel for 120,000 customers over the three days which are the busiest days in the airline annual calendar.

Air New Zealand chief ground operations officer Carrie Hurihanganui said the airline was focused on achieving a resolution on behalf of its customers.

"We know how important it is to our customers to get where they need to be, particularly at this special time of the year, and the negotiating teams have been working diligently to achieve this result."

Details of the offer will not be released until union members have been briefed of the outcome, E tū said in a statement.

Talks concluded between the two parties at Air New Zealand headquarters at 10pm and the member's core aims have been largely achieved, the union said.

"Industrial action of this nature is always a last resort and so it's a positive sign that we've reached an agreement in principle," Savage, head of aviation for E tū said.

"Unions are democratic organisations so the most important next step is communicating with our members.

"We will be recommending the deal to members at ratification meetings over the coming week – then it's up to the members to discuss and vote on the company offer."

On the Friday alone, Air New Zealand has close to 42,000 customers booked to travel domestically on its A320 jets and internationally faced potential flight cancellations.

The airline had accused just under 1000 engineers of deliberately using Kiwi families' much-anticipated Christmas holidays as a bargaining chip.

It detailed the average income of maintenance engineers, logistics and other staff to strike — $115,000 – angering unions who accused it of taking an unnecessarily aggressive approach.