Unions representing Air New Zealand's aircraft maintenance engineers, aircraft logistics and related staff have served notice of a planned strike four days out from Christmas – on the airline's busiest travel day of the year.

The Aviation and Marine Engineers Association and E tū, notified the airline yesterday evening of a total strike by almost a thousand unionised employees on Friday December 21. The unions have also advised to expect further industrial action.

Close to 42,000 customers booked to travel domestically and internationally on 21 December alone now face potential flight cancellations.

In a statement released by Air New Zealand, the average income of the maintenance engineers, logistics and other staff to strike is $115,000 and around 170 of them earn more than $150,000.

Work undertaken by this employee group includes carrying out scheduled aircraft maintenance, unscheduled repair work and signing off aircraft prior to departure, as well as managing the availability of aircraft parts and related activities.

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 percent pay increase followed by a further three percent increase after 12 months, with a further pay review in mid-2021, says Air New Zealand.

'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,” says the airline.

'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 (taking shift workers to six weeks a year), free reserved car parking spaces within 500 metres of their workplace, and the right to renegotiate terms just prior to the busy Christmas season again next year.

Air New Zealand General Manager Aircraft Maintenance Viv de Beus says the news is extremely disappointing and it appears the engineers are deliberately using Kiwi families' much anticipated Christmas holidays as a bargaining chip.

"We know how important summer holidays are for our customers who look forward to being able to gather with friends and family at this important time of year. It would be devastating to see the holiday plans of more than 40,000 hardworking Kiwis and international visitors ruined.

"We have only been in negotiations with this group for six weeks so industrial action is entirely premature. We remain committed to working closely with the engineers' unions to reach a reasonable agreement and avoid strike action if at all possible."

Air New Zealand will communicate with customers booked to travel on 21 December closer to the travel date if these workers go ahead with their strike action. 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 as this fleet is maintained by a separate work group.

SunLive has contacted the AMEA union for comment.