Swerving the 'highways in the sky' from London to New York goes smoothly, says air traffic control

Simon Calder | The Independent | 18 March 2021

The UK's air-traffic control authority has revealed that deleting the prescribed "highways in the sky" between Britain and the US went smoothly - as well as saving time and fuel and helping the planet.

For over half a century, all planes flying across the North Atlantic have travelled along clearly prescribed tracks.

This "Organised Track Structure" (OTS) enables air-traffic controllers working for the UK's air-navigation provider Nats, and its counterpart Nav Canada, to channel aircraft along up to 12 tracks. Nats says they help to provide "a predictable operating environment".

But a recent study found that all the OTS options are sub-optimal. Some aircraft spent almost 20 per cent longer in the air than they needed, representing an extra hour in flight.

With traffic levels lower than they have been since the start of the century, Nats is now actively trialling abolition of the OTS system.

The first day with no westbound tracks was 9 March, and it went without a hitch.

Highways in the sky

Jacob Young, manager of operational performance for Nats, said: "Traditionally, aircraft follow the tracks at pre-agreed speeds and flight levels in order to allow us, and our [Nav Canada] friends in Gander, to keep them safely apart in an environment without any radar coverage.

"It is a blunt instrument that sometimes doesn't allow the airlines the flexibility to choose their own preferred route, speed or level."

The tracks are typically adjusted daily to try to take advantage of the jetstream - the wind that constantly rotates from west to east around the world, sometimes exceeding 200 mph.

The most efficient way to fly across the Atlantic is the routing that exploits the "wind field" - the moving map of wind speed and direction - to minimise the "air distance", which is the key variable for fuel burn and CO2 emissions.

Surfing the jetstream

Researchers at the University of Reading concluded that transatlantic jets which "surf the jetstream" - taking full advantage of winter winds - can cut fuel burn and emissions by up to one-sixth.

A team led by Professor Paul Williams calculated the savings by analysing all 35,000 flights between London Heathrow and New York JFK in December, January and February last winter.

They calculated that more than 20 minutes could typically be saved from a New York-London flight.

What Professor Williams called "literally a free ride from the atmosphere" would cut costs for airlines as well as reducing emissions.

Eye in the sky

Using satellite technology known as ADS-B ("Automatic Dependent Surveillance-Broadcast"), controllers are now able to track transatlantic planes constantly.

Mr Young said: "What came as a surprise was just how natural the transition to a fully random route environment was for our operational teams. The OTS that we all know so well and utilise on a daily basis was gone, yet there was no significant increase in workload.

"The same aircraft turned up making requests in much the same way that we had seen in the past. The only key difference was there was no specific core, no single or multi-lane highway crossing the sky, and aircraft routes looked less ridged and more 'natural' as a result.

"What's especially pleasing is that we did not receive a single query from our airline customers - not a single pilot question or phone call clarifying what was expected from them.

"I anticipate that we will see several days, both west and eastbound, where we have zero tracks over the coming weeks and months.

"We're working with the airlines to understand what difference it makes to their flight planning, both in the low traffic environment we're currently living through, but also via simulating how that would translate once traffic levels begin to return."

The '75 per cent' summer

Until 2020, London Heathrow to New York JFK was the busiest intercontinental air route in the world.

While travel between the US and UK is currently extremely limited, airlines are preparing to resume European flights at scale.

Nats has a working assumption that air traffic in summer may reach three-quarters of the record levels achieved in 2019.

Juliet Kennedy, the operations director, said: "We are planning operationally for 75 per cent of 2019 traffic this summer.

"It's by no means certain that traffic will reach those levels, but we do know that if - and when - the industry gets the green light, the airlines will be up and running very quickly indeed.

"We have always said that airspace won't be a constraint on the restart. But we don't know which routes may open up, whether there will be a surge in bookings for the May half-term, whether there may be regional differences if devolved governments open routes at different times... and of course people might not feel confident about travelling.

"If airline routes and schedules are not dissimilar to 2019 we can handle 75 per cent with current social distancing measures in place in our ops rooms."

Nats is running simulations at its centres at Prestwick in southwest Scotland and Swanwick in Hampshire "to restore confidence for our controllers".