Air New Zealand will cut its planned schedule and operate 1.5 per cent fewer seats than originally planned during the next six months.

The airline says it is taking proactive measures to protect customers' travel plans as sickness continues to cause disruption.

And in a move that will anger former crew hoping to get their jobs back, the airline is exploring expensive "wet leasing" aircraft with crew for the busy summer period.

The airline said most customers who experience a flight change will be transferred to another flight on the same day for domestic travel, and for international travel, on the same day or a day either side of their original booking.

Where customers cannot be accommodated within these timeframes, they may change their booking online, opt into credit or request a refund.

Those customers with changes will start to see them from today and will be automatically transferred to another flight. Those with further onward connections may also be disrupted and "we will work through these directly with impacted customers".

Air New Zealand chief executive Greg Foran said making these changes now gives customers advance notice and will help the airline provide a service that's more reliable during its rebuild.

"Like many airlines around the world, we've been ramping up our operation at a time when Covid and the flu continues to impact the aviation industry. Looking at the disruptions our customers and staff have faced over the past five weeks, we've made some adjustments to reduce short-notice cancellations in the months ahead."

Sickness has been three times normal levels and the airline is still in the process of bringing back its biggest planes, Boeing 777-300s.

"While we did factor sickness into our ramp up plan, we've seen the highest rates of crew sickness in over a decade. We see these challenges continuing not just for crew, but for our whole operation, and so we're making proactive changes to address them."

Air New Zealand has used charter operator Hi Fly previously to plug gaps. Photo / Supplied

Foran said reducing the number of flights means the airline will be able to have crew on standby to cover illness, which has not been possible lately.

The airline is "pulling out all the stops" to minimise disruption and provide surety for our customers over the next six months.

"We have rehired or brought on more than 2000 pilots, airport staff, cabin crew, contact centre and engineers, and we're going as fast as we can with recruitment and training."

The airline was also exploring options to lease a crewed widebody aircraft for the busy summer period.

"We know customers want the Air New Zealand experience, and that's what we want to deliver too. But at the moment we're stretched to capacity and making sure our customers are able to travel is our top priority. The lease of an additional crewed aircraft may help us achieve that."

In the summer of 2017-18 the airline wet leased aircraft from specialist Hi Fly from Portugal to plug gaps caused by the grounding of Boeing 787 Dreamliners which needed engine repairs. T

Air New Zealand's domestic and international schedule will be operating at 90 per cent of pre-Covid capacity for the next six months.

Advice to travellers:

What should I do if my flight changes because of these schedule changes?
• If your domestic flight has changed and you have not been given a flight on the same day, then you will be able to request a change online under Manage my Booking, opt into credit or request a refund.

• If your international flight has changed and you have not been given a flight on the same day or on a day either side of your original booking, then you will be able to request a change online under Manage my booking, opt into credit or request a refund.
• If you have booked through a travel agent, you will need to contact them if changes are needed, or to request a refund if eligible.

When can you get a refund?

• For other controllable events like staff sickness, engineering or operational requirements, a refund may also be available when Air New Zealand is unable to provide an alternative flight within the timeframes stated above.
• For disruptions outside of the airline's control (e.g. weather), where the alternative flight offered is not suitable, customers can opt into credit or if they purchased a refundable ticket, they will be eligible for a refund or where a refund is required by applicable legislation.

- Grant Bradley, NZ Herald