Last night Air New Zealand told 180 passengers on its direct New York service it would need to make a detour to Fiji. However, hours later, the flight continued as planned, directly to Auckland.

This is the second time the airline has announced a detour it didn't end up making.

NZ 1 arrived an hour behind schedule in Auckland this morning. Annoying perhaps, but a huge improvement on the announced five-hour delay and unscheduled 'gas and go' on a divert to Nadi.

Citing "strong headwinds" the airline said that it was already planning alternate travel plans for passengers ahead of the departure at 10pm local time.

"Our priority is getting customers to where they need to go safely. It'll mean a short stop in Nadi to refuel and swap over crew, which means NZ1 will arrive into Auckland around 5 hours later than expected."

NZ1 sailed past its scheduled reroute to Fiji, without having to refuel. Photo / Screenshot, FlightRadar24

This is the second time the airline has apologised preemptively for disrupts to the New York direct service. Twice it has not needed to make the stop.

You might wonder how seriously the airline is taking its own refuel disrupts. The answer is 'pretty seriously'.

Ahead of the first rerouted service on 23 September, eagle-eyed plane spotters saw an unusual A321 service NZ6050 fly to Fiji. With 3 hours flight time, there and back, it spent just 50 minutes on the runway. It was speculated that the unscheduled service was carrying replacement crew for the New York service, which cancelled its 'gas and go' at the last minute.

A spokesperson for the airline confirmed that this flight was part of "the contingency plan in place for NZ1."

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After operational issues with weight and fuel estimations on the 18-hour flight, it has been said that the airline is pushing the envelope on what the 787-9 Dreamliners are capable of.

Due to prevailing weather patterns and jet stream wind direction, the route from New York to New Zealand is slower and requires more fuel than the outwards, northbound service NZ2.

So far, despite the repeated threats to divert, all JFK to Auckland services have been able to fly direct.

Chief safety officer David Morgan thanked passengers for their understanding, who were told of the planned divert ahead of leaving New York.

"Weather can change, especially over the length of an ultra-long haul 17.5 hour flight across the Pacific. In this case the crew were able to re-plan the flight based on updated weather conditions, flying our customers safely to Auckland, without the need to refuel in Nadi."

Even less predictable are the luggage woes of passengers. On the first flight from New York 60 passengers' luggage was offloaded to make additional fuel allowance, following reports of adverse weather.

"While we can't control the weather, we can plan for it and using our standard contingency plan to refuel means we get our customers safely to their destination," chief operating officer Alex Marren told the Herald.

The airline analysed over a decade of weather data and prevailing wind patterns while assessing the viability of the service.