A Napier family is stuck in Wanaka and unable to get a flight home after a 72-hour travel extension ended on Friday night.

Shane Cockerill has been calling Air New Zealand since Wednesday, waiting an hour each time only to be told there were no seats available.

The family is one of an unknown number of domestic travellers caught out in New Zealand's snap lockdown that started on midnight Tuesday.

Cockerill and his elderly parents were holidaying in the resort town when they were notified that their return flights from Queenstown to Napier (via Auckland) were cancelled.

Air New Zealand says it added eight flights departing Queenstown on Friday to get Kiwis home, five of them to Auckland and three to Wellington.

That's on top of four extra services added to existing flights out of the resort town on Thursday.

Air New Zealand CEO Greg Foran says they had estimated about 600 people required flights out of Queenstown after the initial 48-hour extension, and were confident the additional 900 seats would cover those who needed it.

Many of the flights were booked out but there were 60 seats available on one Queenstown-Auckland service, and more than 100 on the last Queenstown-Wellington service on Friday.

"Changes in alert levels are not new to us; we have planned and prepared for it," Foran said.

The national carrier will be running a reduced schedule for the next four days for essential workers and cargo."We'll then reassess our schedule in line with any further government decisions," the CEO said.

For Cockerill's family, a flight next Wednesday is available for booking on the airline website, but he is worried that may be cancelled as well if alert level 4 is extended.

"I could drive into Wanaka and get food so yeah, we're ok, but it's just been frustrating."

They are staying put in their Wanaka timeshare with a rental car, and Cockerill's 85-year-old mother has enough medication for now.

"Being in Wanaka, it's a pretty beautiful spot. We're doing okay."