A database that provided faulty predictions on headwinds is being blamed for the bumpy start to Air New Zealand's flagship service to and from New York.
The airline blamed extreme weather for disruption to a non-stop flight from New York to Auckland on Sunday.
Fifteen customers,who were supposed to travel on Prime Minister Jacinda Ardern's flight, had to agree to take alternative flights, to lighten the load in the face of unusually strong headwinds on the way.
Sixty-five passengers on the inaugural flight arrived in Auckland last Monday without their bags, while passengers on a flight - departing from New York on Friday - were told they would have to stop over in Fiji so the plane could refuel.
The winds eased and the flight was able to bypass Fiji.
Air New Zealand chief operational integrity and safety officer David Morgan said the airline had planned for two years in the expectation of a successful launch of its Auckland-JFK airport route.
Flight plans to determine payload had been run over the past year and the airline was hopeful "it had the numbers right".
However, some factors had arisen such as significantly higher headwinds plus the inability to use Ohakea Air Force base as a backup and the need to fly around cyclones.
"It's not a good look and we're very sorry that our passengers have been disrupted particularly with the bags."
David Morgan says the airline planned the flagship route for two years before its launch. Photo / Lydia Lewis
The databank Air New Zealand used as part of its planning for information such as weather forecasts had misled the airline, he said.
"We've been using a database that our flight planning provider and also Boeing use and as a consequence of that we've actually found seasonal winds, particularly in North America, have been significantly higher."
The airline industry uses what is called the 80 percentile while Air New Zealand has struck the 98 percentile which was "quite extraordinary", he said.
That has meant capacity has been capped on the route; this month it will be a maximum of 180 which may be extended to the rest of the year while around 260 passengers can be flown on the outward journey.
Morgan was confident that reduced capacity would lessen the risk of problems although with winter approaching in the Northern Hemisphere it was anticipated winds would get even stronger.
Asked if airfares might be reduced because of the disruptions and uncertainty, he said the reality was the airline needed to make the new route pay its way.
Air New Zealand has new aircraft on order that will help address ultra long haul issues.
