Force of nature: Why flying back from New York was always the hard part for Air NZ

Air New Zealand uses 787-9 Dreamliners on the New York route. Photo / Brett Phibbs.

Air New Zealand was reminded brutally early what it has known for years - flying from New York to Auckland in one leap is hard.

While the inaugural flight to New York with VIPs and media went smoothly, the return journey (with some international media on board) didn't go well for 60 passengers who had their bags offloaded at JFK Airport and had to wait more than a day to be reunited with them. The PR blowback was inevitable given the interest around the long-awaited flight.

On the New York-Auckland flight (NZ1), It came down to a matter of weight. The quickest solution to losing an estimated 1.5 tonnes of weight for the 14,200km flight that was facing a combination of weather and other operational issues was to offload bags.

In the lead-up to the flight the Herald reported that pilots face vast tunnels of wind, jet streams that blow at up to 400km/h in the upper troposphere, formed when cold and hot air meet. Blowing from west to east, jet streams hundreds of kilometres wide snake around the planet for thousands of kilometres and will influence the route's commercial viability.

The airline analysed more than 10 years of weather data in the lead-up to the flight to help establish the operational and commercial viability of the route.

The jet streams are largely invisible and blow hardest in winter when the temperature difference between cold and warm air is at its greatest. Aircraft which fly through them face turbulence described by one pilot as being like those dull staccato bumps experienced on flights from the United States as they approach New Zealand. In some cases, flights can be routed around them.

In the lead-up to the flight Air New Zealand was planning for the 14,185km flight to New York (NZ2) could average 16 hours and 30 minutes and the return journey on NZ1 will take 17 hours and 40 minutes. Flight Aware data shows NZ2 took 17h 12m while NZ1 was quicker, taking 16h 53m.

It turned out that while jetstream winds were strong over the US at the weekend, and the return flight time suggests they were not the big issue. The flight path had to be altered because of cyclones off different corners of the United States (Puerto Rico and Alaska), increasing the amount of fuel that was needed to provide a margin for safety.

The New York non-stop services were launched with fanfare at the weekend. Photo / Supplied

In the lead-up to the service, Air NZ chief flight operations and safety officer David Morgan said the flight was always going to be a challenge but it had a playbook to work from.

"It'll be an operational challenge. Like Chicago [where the airline started flying in 2018] it's an ultra-long range operation and we've had to consider the implications of that, particularly as we're getting into busy airspace and particularly in winter where's there some challenging operational conditions."

The airline has also flown Dreamliners out of Boeing's Charleston plant, not too far south of New York.

But as with any ultra-long range (ULR) operation, the main consideration is the weight on the plane. No matter how advanced the technology is in the lightweight carbon fibre 787s and how efficient the engines are, the physics of flight are unavoidable, especially into a headwind.

"It's the old story — as soon as you start putting weight onto the aeroplane, you reduce the range of the aircraft. And so the amount of weight that we can lift off the runway is defined by the length of the flight on the day," said Morgan, who has been with the airline for 37 years.

Air New Zealand's aircraft configured for the trip has 275 seats, depending on whether it had planned around selling up to 60 of those seats fewer for the return trip.

This was the case on NZ1 at the weekend, where 202 seats were sold. There was no cargo in the belly either.

Chicago operations, suspended since the pandemic but being reinstated soon, had provided an invaluable operational guide.

There are a string of big alternative airports across the US mainland on the New York route should flights have to divert, several with an Air New Zealand presence. Across the Pacific, Honolulu, Rarotonga and Nadi could be stops, and in this country Ohakea and Christchurch are alternatives to Auckland. The temporary closure of Ohakea earlier this week meant that alternative airport was not an option and so the fuel equation had to be changed.

The New York flight is so long that if need be, new crew could be flown to an alternative airport and a stopover would be a "gas and go" operation. Morgan said it was a bit like a Formula 1 pit stop, with the length of time on the ground dictated by how quickly fuel can be pumped into the plane.

Chicago operated for about 15 months, and flights out of there went smoothly although one had to be cancelled when a Polar vortex snow storm hit and no aircraft could be refuelled.

The non-stop flights to New York are a big part of Air NZ's North American push. Photo / Supplied

In New Zealand, the Civil Aviation Authority has to approve any new destination.

"In this case Air New Zealand must be able to provide evidence that the flight can be carried out safely," a spokesperson said earlier this year. "Safely, in a case like operations to New York, involves many different aspects including: aircraft suitability for the route, engineering assessments, navigational capability, communications requirements, air traffic control, contingency planning, briefings and aerodrome assessments, training for operational personnel, crew rest requirements, flight planning and meteorology."

Boeing says that although the listed maximum range of the 787-9 is 7565 nautical miles (14,010 km), some airlines have been able to safely operate the aircraft beyond that. For example, Qantas has operated both the Perth-London (7830 nm) and Brisbane-Chicago (7730 nm) routes, while Air Tahiti flew the 787 between Tahiti-Paris with a range of over 8500nm.

Airplane configurations, including the number of seats, the weight of the seats, the number of galleys and amount of catering for passengers, all impact the range capability of aircraft and all are customised to meet the needs of the airline for their passengers.

"Additionally, leveraging various operational procedures designed to minimise fuel consumption and increase range capability are ways that airlines can extend the range of the airplane," Boeing told the Herald.

Air New Zealand's head of network strategy, Andrew Skilling, said earlier this year that during most of the pandemic teams across the airline including networks, fleet, flight planning and sales, have been working on the critical question — how to maximise the return on a route like New York.

"It's going to be payload constrained so it's right at the edge of the performance capability of the aircraft. So how do we make sure that we can squeeze every bit of juice out of the lemon?"

To lighten the load on the way back to New Zealand, passengers could be re-routed through the airline's other gateways, he said in the lead-up to the launch.

New Dreamliners on order will be able to fly even further with full loads. New aircraft due for delivery from the 2025 financial year will be specially kitted out for ULR lights, and emphasis on the premium offering, with up to 42 newly designed business class seats instead of the 27 in the herringbone layout on existing planes.

The new planes are due to have 257 seats, and subject to regulatory approval six bunk-style Economy Skynest spots. While Air NZ is going more premium for the long routes, it isn't going as far as Singapore Airlines which flies the longest route in the world between Singapore and New York. On its Airbus A350ULRs it has just 161 seats, all Business or Premium Economy.

Air New Zealand is now reviewing what happened with NZ1 and to help minimise the chances of a repeat.