Seymour says there will be some follow-on effects, particularly in flights from Australia, where it appears they have been more badly affected.
The outage - caused by an update to a piece of software run by US cybersecurity firm CrowdStrike - caused Windows computers around the world to crash on Friday, cancelling flights, disrupting transactions and stopping people from accessing their online banking accounts.
People were left stranded at petrol stations because they had no cash to pay for fuel, while stores were forced to close their doors.
Meanwhile, retailers are anxiously opening their stores, Retail NZ says.
Retail NZ chief executive Carolyn Young told RNZ many stores would be "opening first thing in the morning and looking for this to be resolved".
"Largely it's out of our hands," she said.
The outage would have an impact on business confidence, which was already shaky thanks to the high cost of living and the official cash rate, she said.
Queenstown caught up
About 300 passengers at Queenstown Airport were caught up in the global outage.
Airports, banking and payments systems, retail outlets, local councils, Hato Hone St John — and more — were reportedly affected in New Zealand as computers crashed around the world last night.
Queenstown Airport sustainability and corporate affairs general manager Sara Irvine said check-in for Qantas and Jetstar flights and some parking payments were affected.
Air New Zealand check-in continued as normal.
And Qantas staff were able to manually check passengers in, she said.
"More than 300 passengers have been affected.
"Some have had their flight cancelled.
"The airline staff on the ground are working to look after those passengers affected. However, the global IT outage is affecting multiple systems, so there are some challenges.
"We apologise for the inconvenience and greatly appreciate passengers’ understanding."
In an update this morning Ms Irvine said the issues affecting check in and travel at the airport had largely been resolved.
"Flights are operating as scheduled at Queenstown Airport today, however there may be some network disruptions or delays as a result of the global IT outage. Please check for updates with your airline."
She said check-in kiosks and automatic bag drop units were operational, and their website and terminal screens had not been impacted.
"If you were impacted by cancellations or delays last night your airline will contact you directly to resolve."
A Queenstown Lakes District Council spokeswoman yesterday said the council was not experiencing any issues with its streetlights or infrastructure monitoring, but was "closely monitoring for any change".
St John national ambulance controller Doug Gallagher said the service immediately implemented an "urgent software update" when learning of the issue.
The organisation’s communication centres were expected to be back to business as usual after the update last night, but St John was experiencing a high volume of calls.
Calls that were not immediately life-threatening might experience a delay, he said.
Air NZ chief customer and sales officer Leanne Geraghty said as of 8pm its flights were operating normally.
"We understand some customers will be experiencing payment issues if they are with impacted banks.
"We are continuing to work through any further potential impacts to our systems and operations and will provide updates to our customers when required."
She asked people to only call the airline if they had travel booked within the next 48 hours.
Retail NZ's Carolyn Young said transactions using eftpos were going through, but contactless and credit transactions were intermittent.
"This is a live issue that is developing as we speak where we only have visibility of what is happening in New Zealand.
"Our advice to retailers is to keep up-to-date with news on this global issue, advise customers of the current challenges being experienced at point of sale and not all transactions will process smoothly."
University of New South Wales Sydney School of Computer Science and Engineering Prof Salil Kanhere said the global IT outage appeared to have been caused by an issue with the CrowdStrike antivirus software, which impacted Windows machines with the software installed, causing them to crash.
"An update to their software appears to have been rolled out globally without proper testing.
"Antivirus software is typically given access to a deep set of permissions ... on computers to protect against viruses and malware.
"The flip side, however, is that if this very software malfunctions, then it can crash the computer, as we have observed with this outage."
Prof Kanhere said the incident "appears to violate every good software engineering practice we know".
"It also points to the need for mechanisms that can protect a computer's operating system from potentially misbehaving anti-virus software."
- RNZ/hamish.maclean@odt.co.nz
