NATS achieves emissions reductions but increasing air traffic poses an environmental performance challenge

NATS achieves emissions reductions but increasing air traffic poses an environmental performance challenge | NATS,Sustainable Aviation

NATS Swanwick control centre
(photo: NATS)

Mon 25 July 2016 – UK air navigation service provider (ANSP) NATS achieved a reduction of 34,195 tonnes in ATM-related CO2 emissions in 2015, according to its latest annual Responsible Business report, but this masks a tough challenge it is facing to reach an ambitious 2020 goal of reducing overall emissions from aircraft under its control by 10% against a 2006 baseline. Although it has made strides in airspace improvements and procedural changes to aircraft operations, a rebound in air traffic since a downturn towards the end of the last decade has added to the task ahead. NATS’ Head of Environmental and Community Affairs, Ian Jopson, explained the action NATS is undertaking to reduce both carbon emissions and the impact of aircraft noise on communities. As current Chair of Sustainable Aviation, Jopson also outlined the future direction of the UK cross-industry group.


Now over half way through the 10% CO2 reduction programme, NATS has achieved a cumulative reduction of 1.12 million tonnes of CO2 since the programme started in 2008, representing overall savings of around 4.3%. “Clearly,” admitted Jopson, “we still have a lot to do.”


When NATS sat down in 2007 to set its environmental ambitions, there was no benchmark to measure itself against as no other ANSP had – and still hasn’t – set a specific CO2 reduction target. “We didn’t really know if 10% was achievable but it’s open to debate as to whether we would have reached 4.3% by 2015 if the target had been less ambitious,” Jopson told GreenAir. “It’s taken us a huge amount of effort just to get to where we are and has involved over 200 changes to UK airspace.


“At the same time as we are working to keep UK airspace safe – our primary role – we also need to create the extra capacity to cope with increased traffic demand, and in a responsible manner that reduces fuel burn and emissions. We remain committed to our 2020 target, it’s just we will need to work even harder to reach it.”


Many of the improvements in the early stages of the programme were small efficiency gains and “tweaks”, related Jopson. “What we need now is to deliver big changes and airspace modernisation,” he said.


In addition to the self-imposed carbon reduction target, NATS’ environmental performance is also measured under an initiative called 3Di that it developed in conjunction with the UK Civil Aviation Authority (CAA) and introduced in 2012. The three-dimensional inefficiency (3Di) methodology measures NATS contribution to shrinking ATM-related CO2 emissions and financially penalises or rewards performance. The lower the 3Di score, the better the performance.


Handling around 2.3 million flights during the year, NATS average score in 2015 was 30.1, just behind the target of 29.7 but within the service performance range – called the ‘dead band’ – set by the regulator, whereby NATS is neither penalised nor rewarded. However, this compares with an average score of 29.8 the previous year and, looking ahead, a tightening of the target score to 29.3 in 2016. The dead band is also progressively narrowing each year out to 2020.


“Set in the context of growing traffic, the target is getting tougher and if we can’t make changes then we will go into penalties,” noted Jopson.


NATS is addressing the challenge on two fronts. Firstly, it is engaging with its operational communities located around the UK and making extensive use of its Flight Optimisation System (FLOSYS), a tool that equips controllers to analyse the environmental efficiency of flights in near real-time. It takes radar data that is updated every three minutes and combines it with the 3Di metric to produce a graphical representation of every flight in UK airspace that can better identify operational improvements to help airlines reduce fuel burn and emissions on an aircraft-by-aircraft basis.


Although this has provided a better understanding of where the inefficient hot spots are in the network, Jopson said structural changes are also required to the airspace system. The first phase of an airspace change over the south-east of England started in February this year, which includes a point merge arrival system for London City airport that keeps arrivals over the sea instead of over land, new departure routes for London City to enable aircraft to climb to higher altitudes more quickly and changes to allow daytime traffic departing Stansted to climb higher more quickly.


“Additionally, some of the solutions to our congested airspace actually lie outside our boundaries,” said Jopson. “For example, when an aircraft is approaching our airspace and there is a system delay, we can request a neighbouring ANSP to contact the aircraft and ask it to slow down and so delay it entering a holding pattern.”


This arrivals management collaboration with ANSPs in France, Ireland and the Netherlands – called XMAN (Cross Border Arrival Management) – has streamlined the flow of aircraft into Heathrow. What started as a trial has now entered permanent operational service and Jopson reported NATS is looking to expand the procedure to other airports. “The benefits are quite significant,” he said.


XMAN has cut by up to a minute the time spent holding, so saving fuel and CO2 emissions as well as reducing noise for affected communities, says the Responsible Business report. It is intended to be deployed at 24 airports across Europe by 2024 under the Single European Sky initiative.


Another initiative expected to provide substantial fuel and emissions savings in the future will see NATS’s Prestwick control centre providing free-route airspace above 25,500 feet in 2017, with Swanwick control centre implementing it above 33,500 feet in 2021. The Borealis Alliance will create a single area of high altitude airspace covering nine northern European countries that will enable users to plan and take the most cost-effective, fuel-efficient and timely routes across the entire Borealis airspace rather than following pre-defined routes. NATS is in the process of introducing free-route into areas of Scottish airspace before extending it more widely cross the UK.


There will also be huge benefits to be realised from improvements to North Atlantic airspace, said Jopson, where NATS has been able to safely reduce aircraft separation and allow aircraft to reach their optimum cruise level more quickly.



Balancing CO2 and noise concerns


Balancing CO2 emission reductions with community noise concerns is a major challenge for the ANSP, particularly as the skies above the UK are some of the busiest in the world. Modernising congested airspace to make it more efficient is critical but change is generally viewed with suspicion by the public, says NATS’ Head of Corporate Affairs, Jane Johnston, in the report.


“Some recent trials of new aircraft procedures have affected communities in ways we simply didn’t expect,” she writes. “Complaints have increased and many new local noise action groups are now working to stop any change at all. While change could actually address many of the worst problems, we have a big job to persuade people of that.”


New technology has enabled more precise flight paths for aircraft arriving at airports through performance-based navigation (PBN), but can bring both environmental benefits and problems, as a recent trial around Heathrow demonstrated.


“The issue with PBN is that it is very accurate and unlike traditional navigation where there are route variations, in this case routes are very concentrated and provide a different problem for communities,” said Jopson. The Heathrow trial involved tightly controlled alternating PBN routes that provided affected communities with respite at certain times of the day – a world first, believes Jopson.


“We didn’t know if this was feasible, which is why we trialled it,” he said. “But we did get some negative reaction and we have learned that we need to work much more closely with communities when we design airspace and routes. It’s a two-way process in which we need to recognise better the community viewpoint, and communities in turn need to understand what is possible with this new technology.”


Jopson is sure PBN can provide significant fuel burn and emission reductions as well as beneficial noise outcomes and points to its recent successful implementation at Stansted and Luton where NATS worked with the airports to design routes around communities to avoid noise impacts.


PBN has been mandated across Europe by the early part of the next decade, he reported, and will be rolled out globally through ICAO. “That’s why we are taking a proactive stance now to understand best how to deploy it,” he said. “Some countries have already gone ahead with it but in some instances law suits have resulted.”


A tried and tested procedure to reduce emissions and noise is through continuous descent operations (CDOs), involving arriving aircraft employing a smooth continuous descent instead of a series of steps. NATS has been working with 15 UK airports and 22 airlines to make this practice more widespread.


In 2015 it recorded 781,899 CDO flights, an additional 31,639 on the previous year and representing a CDO rate of 77% of all flights. However, in 2014 the increase in the number of CDO flights was higher at 36,682 and the percentage of flights carrying out CDOs has remained static since 2013, although the rate is as high as 85% in the London area.


As NATS continuously monitors CDOs, it is able to supply all UK airports and airlines with performance data but Jopson admits it has been tough to drive change. In conjunction with UK industry group Sustainable Aviation, NATS has been educating airlines on the environmental, social and health benefits CDOs can bring, even if the procedure means extra effort from pilots and air traffic controllers.



Industry sustainability


Jopson is the current Chair of Sustainable Aviation, which has over 40 UK members and signatories covering airlines, airports, air navigation services and aerospace manufacturers, with a number of working groups overseen by Programme Director, Dr Andy Jefferson. It also has an independent advisory board of external sustainability experts representing academia, NGOs, trade unions, government and the CAA to challenge and track the work programme. According to Jopson, the national initiative, which aims to make the industry “cleaner, quieter, smarter”, is unique in the aviation world, although interest had been shown from elsewhere in setting up something similar.


Having passed its tenth anniversary late last year, Sustainable Aviation releases regular reports that measure and track the progress of the industry against its goals. It also produces technical papers that provide guidance and voluntary codes of practice for industry on issues such as cabin waste recycling and reducing the environmental impacts of ground operations and arriving and departing aircraft.


Jopson is particularly pleased with what he describes as the “robust, evidence-based” roadmaps Sustainable Aviation has published to support how the UK aviation industry can grow sustainably, which have so far covered CO2, noise and sustainable fuels. The CO2 roadmap, released in 2012, had become an influential report that had been well-received by government and regulators, he said. It is currently being updated to reflect the latest traffic forecasts and recent future technology scenarios, and is due for publication later in the year.


“Noise is also of course a big issue for the industry so we will also look at updating our noise roadmap next year with more information, for example, on how the aircraft fleet is changing and operational procedures we are implementing,” he reported. “Local air quality has become another important issue and we are developing an initial position paper that we expect to have ready by this autumn.”


As well as helping those within the aviation industry advance their day-to-day sustainability practices, the strength of Sustainable Aviation, said Jopson, was in presenting a united cross-industry position to regulators, government and also the travelling public.


“My fundamental premise is that despite being a competitive and complex industry, we are stronger when we collaborate, and we can deliver more together than independently.”





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