How Air NZ is making the New York dream come true
Air New Zealand always said getting back non-stop from New York to Auckland was going to be the hard part. Grant Bradley goes inside the airline’s jet operations nerve centre in Auckland where up to 24 staff work on getting NZ1 home.
Pre-flight
On top of years of planning and allowing for disruption reported in June, preparation for each flight begins by picking the optimal plane which can vary from week to week. Air New Zealand has five Boeing 787-9 planes with a premium heavy cabin configuration dedicated to the New York route their performance varies slightly from week to week and that means picking the right one is crucial. David Morgan, Air NZ chief flight operations and safety officer, says there’s a 540kg weight difference between the Dreamliners as they’re absorbing moisture at around 1kg a day, so the difference depends on their age and when insulation was replaced.
Then the airline assesses in real time the fuel consumption per kilometre of each of the aircraft which varies because the performance of the Rolls-royce Trent 1000 engines varies during their lifetime.
“Either through engine performance or drag coefficient of the aircraft they will all vary,” said Morgan who oversaw the introduction of a total of 14 Dreamliners to the fleet. While the performance is generally consistent, the airline is looking for any rapid change and that will dictate which aircraft is put on the route. The operations team bases the call on an assessment table provided by engineers.
“If the performance changes through 0.1 per cent a week that’s a pop-up for us and what we then do is call up engineering to have a look at the aircraft.”
During the years of build-up to launching the flight, weather trends, dominated by the constant west-to-east jetstream winds, were analysed to build the operational and commercial case for the 14,200km flight. And around a week out from each service, flight planners in the “nerve centre” — the integrated operations centre at Air New Zealand’s Auckland Airport campus — look for specific weather events such as hurricanes, cyclones and during the New York winter, snowstorm warnings that not only affect NZ1 but the Auckland-new York NZ2 flight.
The clock is running
A full day out there’s another weather check using Met Service and offshore forecasters to assess whether NZ1 will have to fly around intensifying weather systems or strengthening jetstream winds. But to add further complexity, these forecasts can also change in the hours before takeoff, let alone while the plane is airborne because it is such a long flight. For one flight this month there was a tonne of fuel difference in the expected requirement 24 hours out and when the flight departed because the winds had changed. This is also when the load planners swing into action. They look at predicted baggage weight and provide an all-up weight, in case passengers need to be re-routed on other flights or luggage needs to be offloaded as happened on the first NZ1 flight.
The extra weight of the Jamaican netball team’s gear resulted in about 60 other bags being offloaded and sent on later.
Around 24 operations centre staff are working in the New York flights at any one time and since September they have built up a body of knowledge, says Suzanne Thimbleby, Air NZ’S head of airline operations. They calculate to “the nth degree” the impact on fuel consumption on the number of passengers, the number of bags that are carried. She says fewer children (who are lighter) have been carried than forecast and average Economy luggage check-in weights are around 21kg — 2kg lighter than allowed, although this may change around Christmas. The airline surveys its passengers’ average weight every four years, (the last domestic survey revealed a 1kg gain).
Making the big call
At 24 hours out these load projections are at this stage handed to flight controllers and, with latest weather, the call is made on whether to activate the Pacific divert plan, as happened on
October 29, after two false alarms. The airline needs the 24-hour window to notify the plan and get replacement staff to Nadi to replace the four pilots and 10 cabin crew. Air NZ’S chief operating officer, Alex Marren, a veteran of operating airlines in the US eastern seaboard, says a quick pit stop can save days of recovery.
During the October 29 touchdown — just 63 minutes — about 20 tonnes of fuel was taken on and crew replaced.
Morgan says the business case for the flight included up to six diversions a year while Marren says even with as few as 180
passengers on NZ1 (not the maximum possible of 275), it remains commercially viable.
While the recovery plan needs to be activated 24 hours out, eight
to six hours out from the scheduled time of departure further variables are being assessed; such as more baggage than expected, and taxi or pushback delays, Thimbleby says.
“If people are turning up with excess baggage — we know down to the kilogram, the crew get their plan, they assess it and do last minute adjustments. Check-in closes one hour out and that’s when the final figures funnel up to the load planner and flight planner and the captain gets the final weights.”
At that point it’s the captain’s call — but they will always consult with flight operations.
The turnaround time is two hours on the ground at JFK Airport when the aircraft is cleaned, restocked and crew rotated. That’s around 15 minutes longer than the average US flight.
‘You’re clear to go’
Morgan says the plane takes on about 101 tonnes of fuel in New York. While the aircraft could take off with more on board, it can’t fit that additional volume into its fuel tanks, although there could be marginal improvements in winter. He explains that while a litre of water weighs 1kg, a litre of jet fuel weighs 780gms.
“But the volume of the fuel will change depending on its specific gravity — as the fuel gets colder in New York you can put more volume into the tanks,” he says.
“What is the limiting factor on these flights is not take-off weight (all flights are taking off about 5 tonnes under maximum) — it’s the amount of fuel you can get in the tanks — payload is restricted.”
At the moment fuel can’t get beyond “volumetric cut-off” — similar to when motorists fill up a car at the petrol station.
Boeing has offered a software tweak that will allow airlines to reduce the air gap at the top of the tanks, something it has yet to activate.
During the 17.5-hour flight the variables keep coming. Weather can change, and mean the aircraft can burn a tonne less fuel than forecast while en-route. Along the way there’s “dynamic air replanning” available to respond to changing conditions and that’s how NZ1 avoided two planned “gas and goes” in Nadi.
Morgan says the work of load controllers who decide where baggage is stored becomes apparent during the ultra-long flights. Taking to a whiteboard in the operations centre, he explains principles of how the highly sensitive aircraft centre of gravity (COG) works. On the smaller A320, it has a range of just 45cm.
“Load control is crucial — the airplane has to operate in a centre of gravity envelope. If it doesn’t it becomes aerodynamically unstable.”
A Dreamliner’s efficiency improves as the COG moves towards the rear, but the tendency is to move forward as fuel is consumed during flight.
The 787 stores fuel in the wings and a centre tank, using fuel from the centre one first.
“The load control people plan to make the centre (of gravity) as aft as possible — if you move it towards the rear of the plane you end up with a plane with less drag and using less fuel.”
The flights have been running three times a week since midseptember and so far have landed with an average of around eight tonnes of fuel left in the tanks, says Morgan.
One lever the airline hasn’t been able to use is sacrificing general cargo. It’s generally the first to go when loads are tight but from the start of operations it wasn’t an option on NZ1. There has only been one flight where there has been bags offloaded.
For passengers who have been “proactively rerouted” through other North American ports, they have been thanked with a $US1500 ($2400) compensation payment and accommodation if required.
Cabin crew are at the front line of handling any disruption and say there’s been challenges but the service has been a success.
President of the Flight Attendants Association Craig Featherby, who is also an inflight service manager, says passengers love the ease of point to point flying without having to transit and, on NZ1, there’s more room to spread out in Economy.
Cabin crew will also have three nights on the ground in New York, more than the minimum rest period of 46.5 hours in the contract.
What’s the future?
NZ Airline Pilots Association president Andrew Ridling says flights have been managed well and conservatively and expects the risk of diverts easing as the airline gets more information and confidence around its longest route.
Featherby is hopeful there’ll be more passengers on the Aucklandbound flights. “The cabin crew hope to see those seats fill, as the more people who choose to fly on this route means an increase in demand, and makes the route more viable long term.”
Further out, new planes will help. The new 787-9s due to enter the fleet from 2024 are specifically designed for the route.