After two decades of attempts to improve the performance of Europe’s fragmented air traffic network through better airspace integration, the EU’s legislative bodies have reached a provisional agreement that could finally lead to the substantial carbon emission savings, by as much as 10%, offered by the reform. First launched by the European Commission in 1999, the Single European Sky initiative has faced procrastination and delay, not least by a number of EU member states seeking to maintain their national interest, particularly over air navigation charges. Under the agreed reform, the aim is to increase Europe’s constrained capacity, lower navigation costs and increase the adaptability of the airspace system, while also reducing aviation’s climate impact. The agreement has been welcomed by air navigation service providers but representatives of Europe’s airline industry fear the reform will not go far enough.

“I am delighted with this result, concluded under our presidency, which will enable major progress to be made in reducing CO2 emissions from the aviation sector, and will also give member states more tools to limit the nuisance generated by aeronautical activity,” commented Belgium’s mobility minister, Georges Gilkinet, in a Council statement. “Although much remains to be done to help the sector achieve carbon neutrality, and we will continue to work towards this, the efforts made by all parties to bring this new legal framework for Europe’s skies to a successful conclusion are to be applauded.”

The text agreed by the Council, representing EU member states, and the European Parliament provides for binding targets and incentives to make flights more efficient and climate friendly, with an independent and permanent advisory Performance Review Board (PRB), set up under the regulatory EU Aviation Safety Agency (EASA) and funded by the EU, to help the Commission and states take decisions on the implementation of these plans. The Commission will adopt EU performance targets on airspace capacity, cost efficiency and climate and environmental factors for air navigation services, with performance reviewed at least every three years.

The Commission will also be required to conduct a cost-benefit study to help define how charges levied on airspace users – airlines or private aircraft operators – for the provision of air navigation services could encourage them to use the most fuel-efficient routing available and/or clean propulsion technologies. Mandatory modulation of en route charges will be introduced to encourage users to support improvements in environmental and climate performance.

The deal also provides the potential for more competition in the air navigation services market. It also requires member states to designate a national supervisory authority (NSA) to assess compliance of air navigation service providers (ANSPs) with economic requirements, such as financial sustainability and organisational structure, in cooperation with the national competent authority in charge of ANSP certification. The NSAs and the Commission are together to assess the performance of air navigation services “in accordance with the subsidiarity and proportionality principles”.

Following the introduction of the Single European Sky (SES) initiative in 1999, two legislative packages were adopted: SES I in 2004 and SES II in 2009. The Commission presented a revision in 2013, the SES 2+ package, which was adopted by the Parliament in a first-reading position in 2014, but the Council could not agree a complete position and an upgrade was subsequently proposed by the Commission in 2020.

The new provisional agreement is now subject to approval by member state representatives through the Council, the European Parliament’s transport committee and the full Parliament before the draft legislative acts are formally adopted by the co-legislators.

“The deal signifies a shift towards efficiency and sustainability in air traffic management. The current nationalistic airspace architecture hampers progress, leading to longer flights, increased emissions and unnecessary costs,” said Marian-Jean Marinescu, the Parliament’s lead rapporteur on the SES file, in a statement. “It’s high time to finally prioritise efficiency over nationalism, to pave the way for safer, more cost-effective and environmentally-friendly air travel in Europe.”

The agreement has been welcomed by CANSO, the trade body for ANSPs, which said it hoped the legislation would help the EU achieve its “seamless skies” ambition.

“We note that SES 2 will introduce mandatory modulation of en route charges to encourage airspace users to follow fuel-efficient routings, subject to a cost-benefit analysis,” said CANSO. “We call for this to encompass the principle of revenue neutrality for ANSPs, so that they receive the same fees for the provision of their services. It will be important for ANSPs to be able to balance offering environmental routings with the provision of capacity to airspace users.”

Added CANSO Director Europe Affairs Tanja Grobotek: “We look forward to receiving and analysing the final text. CANSO stands ready to provide support to the EU institutions when they draw up the implementing legislation to ensure there is a common interpretation, legal certainty and efficient implementation.”

However, Ourania Georgoutsakou, Managing Director of Airlines for Europe (A4E), expressed doubts over the package. “We are currently digesting the final agreement. We have been consistent in calling for a SES that delivers for airlines, passengers and the planet. On first look, it seems this agreement is still some way off this,” she said. “This will not be the end of A4E’s efforts to achieve a seamless, digital and a truly Single European Sky that will reduce delays, improve efficiency and reduce carbon emissions.”

A4E has concerns over the scope and independence of the PRB, with states potentially having the opportunity to influence the body and reduce the chance of actual improvements. It questions whether the PRB and/or NSAs will have enforcement powers and whether states can determine and also deviate from targets as they wish.

The European Regions Airline Association (ERA) described the provisional agreement as disappointing and a missed opportunity. “Based on ERA’s initial assessment, and subject to a detailed and thorough review, it is understood that this agreement does not go far enough to address the needs of Europe’s regional airlines, the needs that ERA has consistently advocated for since the Commission published to recast proposal in 2020,” it said.

Added ERA Director General Montserrat Barriga: “At first glance, several concessions appear to have been made that unfortunately reduces the likelihood of the substantial improvements that we have pushed for in terms of airspace capacity, operational efficiency and sustainability. It’s clear that further efforts will be required to address today’s aviation challenges effectively.”

Eurocontrol’s latest flight trends forecast shows the number of flights in the 44-state ECAC region is likely to reach 10.6 million in 2024, a growth of 4.9% compared to 2023 and accounting for 96% of 2019 levels. It expects this trend to continue, with an increase to 10.9 million (99%) in 2025, and further to 11.2 million (101%) by 2026. Beyond 2025, and subject to political and economic uncertainties, flight growth is expected to average 2.0% per year, rising to over 12 million flights in 2030.

Photo: The Bremen air traffic control centre (© DFS Deutsche Flugsicherung GmbH) 

As part of the climate neutral by 2050 binding target of the European Green Deal, the EU has set an interim goal of cutting emissions by at least 55% by 2030, based on 1990 levels, and is working on a set of proposals under the ‘Fit for 55’ package to revise and update EU legislation, and put in place new initiatives to ensure EU polices are line with the climate goals. The package has important implications for aviation, and pan-European air navigation organisation Eurocontrol has released an assessment of what it means in practical terms and the extra costs of decarbonisation measures to meet the 2030 target. In a ‘Think Paper’, its analysis shows a 55% reduction is achievable, even under a strong recovery in traffic, but is heavily reliant on market-based measures, mainly via the EU Emissions Trading System (EU ETS), which it forecasts will make an 83% contribution to the net reduction. Eurocontrol estimates that a combination of additional emissions trading costs, taxes on kerosene and extra costs from a sustainable aviation fuel mandate will result in additional cumulative costs to the aviation industry of €62 billion ($65bn) over the period 2022-2030, although positive measures could reduce this extra cost by €33 billion ($35bn).

The estimates are based on three traffic scenarios – high, base and low – that were published in the recent Eurocontrol Aviation Outlook 2050. The organisation contends the high scenario, with the most traffic, is counterintuitively the most efficient to reach net zero emissions by 2050 at lower cost. Under its high scenario, SAF becomes available (at an economically attractive price), allowing blending of SAF at percentages higher than regulatory requirements. If the high scenario occurs, the kerosene taxation paid by the industry therefore is likely to be greatly reduced, argues the paper. The extra costs for increasing the share of SAF are estimated by Eurocontrol to be relatively low compared to EU ETS and kerosene taxation costs.

The revision of the Energy Tax Directive would implement the new energy taxation principle that ramps up taxes on kerosene for intra-European flights over a 10-year transition period from the beginning of 2024, while applying a zero-minimum rate to SAF. A proposed revision by the Commissions to the EU ETS directive would see the current level of free allowances to aircraft operators cut by 25% annually starting in 2024 and phased out completely by 2027. Eurocontrol’s high scenario is expected to be less impacted by the reduction than its base and low scenarios.

Assessing the potential cumulative costs to the airline industry over the 2022-2030 period of the additional European decarbonisation policy action, Eurocontrol breaks them down as follows:

• €29 billion in extra costs on a kerosene tax applied to intra-EEA flights;
• €23 billion in extra costs from the emissions trading systems in the EU, Switzerland and the UK; and
• €10 billion in extra fuel blend costs applied in all ECAC states based on 5% SAF / 95% kerosene mix.

In 2030 alone, the extra cost to the industry is estimated at €14 billion. However, a positive impact of measures such as the implementation of the Single European Sky, other operational improvements and accelerated fleet renewal could, says the paper, drastically reduce the extra cost by €33 billion over the period to 2030, lowering the cumulative cost to industry to €29 billion.

As well as recommending airlines to accelerate the pace of fleet renewal by 3-7 years, the paper calls for accelerated development of CO2-efficient and disruptive technologies while improving current fleet technology, which could be enabled at EU or pan-European level.

However, it adds, SAF usage is the most important industry-driven decarbonisation measure and Eurocontrol sees the ReFuelEU Aviation initiative as essential in enabling a swift ramp up of production and usage. As well as a legally-binding mandate, voluntary arrangements and financial incentives should be encouraged for higher SAF uptake, it suggests. Additionally, there should be a push for a larger share of e-kerosene to stimulate higher investment in green hydrogen production facilities as well as facilitation of access to feedstocks and renewable energy.

Support will also be required in motivating public and private investors to fund sustainable solutions for the aviation sector through, for example, green funds, grants and state-backed loans that can be enabled by the EU Taxonomy, adds the paper.

“There is a pressing need to swiftly ramp up SAF production and usage to enable SAF to compete with conventional kerosene,” said Eamonn Brennan, Eurocontrol’s Director General. “If the sector returns to profitability, our high traffic scenario will drive increased revenues that will play a fundamental role in accelerating investment in new technology and thus driving the sustainability transformation. We need to accelerate aviation decarbonisation by prioritising actions, fostering the transition by inter alia offering financial support and encouraging alliances and balancing taxation with the need for aviation to recover.”

Meanwhile, a coalition of European aviation associations and SAF suppliers have called for a new supporting mechanism under the EU ETS whereby aircraft operators would still be granted allowances commensurate to the overall CO2 reduced by the uplifting of SAF, with a higher multiplier applied to synthetic fuels.

“Such a mechanism would not compromise the main objective to strengthen the ETS,” they said in a letter to the Commission. “The mechanism would further incentivise the deployment of sustainable renewable fuels and synthetic fuels, and would be key to bridging today’s price gap with conventional jet fuel. It would provide an additional incentive for airlines to decarbonise with the use of SAF, including above the mandated minimum blend. The mechanism would treat all operators equally and help level the playing field in global competition.”

Ahead of the G7 Summit this week, Heathrow Airport has become the first major UK airport to incorporate sustainable aviation fuel (SAF) into its main fuel supply system by taking delivery of a batch of HEFA-blended fuel produced by Neste and supplied by Vitol Aviation. The amount supplied is only equivalent to powering between five and 10 short-haul flights but the airport said it aimed to serve as proof of concept to enable much greater use of SAF in the future. Heathrow is calling on the UK government to set escalating mandates requiring a minimum of 10% SAF use by airlines by 2030, increasing to at least 50% by 2050. It notes that 58% of Heathrow airlines by air traffic movements have already committed to 10% SAF usage by 2030. Eurocontrol estimates that during pre-pandemic 2019, just 39 of 1,657 European airports accounted for 80% of conventional fuel used by departing aircraft and suggests it would be more efficient to concentrate SAF supply on these 39 airports.

Commenting on Heathrow’s first incorporation of SAF into its operation, Chief Executive John Holland-Kaye said: “As we get ready to welcome the G7, we can demonstrate how this technology can significantly cut carbon from aviation, whilst protecting its benefits. The UK government now has an opportunity to create a new British growth industry by backing SAF production and also be leaders in the race to a net zero 2050.”

The Neste MY SAF supplied to Heathrow was produced from sustainable waste and raw materials such as used cooking oil and animal and fish fat waste, with a claimed lifecycle GHG emissions reduction of up to 80% compared to fossil jet fuel.

“We are pleased that Vitol are enabling Neste MY SAF to be used at Heathrow, one of the leading global hub airports,” said Jonathan Wood, Neste VP Europe for Renewable Aviation. “We are also proud to play a role in lower-emission travel to the G7 conference, where sustainability will be one of the key topics.”

Added Vitol Aviation’s Leticia Hachuel: “We are delighted to be the first to deliver SAF to Heathrow. Whilst this is a proof of concept, the need to realise lower-emission options for flying is critical and we are looking at how we can use our expertise to offer more sustainable options.”

The airport, which has set an objective to become one of the most sustainable airports in the world, said SAF was the key tool in the decarbonisation of aviation and with the UK hosting COP26 in Glasgow later this year, it was time for government, investors and industry to collaborate in scaling up the use of SAF to ensure real momentum this decade.

“Now is the time for less talk and more action, and government ministers should set an escalating mandate to blend SAF into fuel and stable incentives over five to 10 years to foster investment in production,” said Holland-Kaye.

A briefing by Eurocontrol says at only 0.05% of total jet fuel consumption pre-Covid, the use of SAF remains very low in Europe but if a 10% target by 2030 could be achieved, CO2 emissions from EU departing flights could be reduced by 8%. Besides the need to stimulate SAF uptake, it points out another crucial issue is the logistics of getting fuel to airports. Before the Heathrow announcement, only seven of the 39 major EU airports – Frankfurt, Paris CDG, Amsterdam, Helsinki, Stockholm-Arlanda, Hamburg and Munich – have started to supply SAF, finds Eurocontrol. Providing a 12.5% SAF blend to these 39 airports would achieve the same 8% reduction in CO2 emissions from flights departing the EU, it argues.

However, with SAF currently more than twice as expensive as fossil jet fuel, the use of 12.5% SAF in the mix would lead to a corresponding increase in fuel costs for airlines and tempting some to increase their use of economic tankering to avoid paying the SAF premium. Tankering has the effect of increasing the weight of the aircraft because of the extra fuel uplifted, and therefore CO2 emissions. Eurocontrol also suggests the increase in SAF costs would also reduce the competitiveness of airlines operating from the EU and it may therefore require re-balancing policy measures.

Photo: Heathrow Airport

The aviation sector’s efforts to mitigate anthropogenic climate change have predominantly focused on CO2 emissions. However, the non-CO2 effects created by aircraft flying at cruise altitude have been found to be larger than the impact from CO2 alone, and estimated at two thirds of the net radiative forcing from aviation, but this has been largely unaddressed by the airline industry and policymakers. This is mainly due to uncertainties over the scientific understanding through a lack of reliable data and how best to overcome the effects through aircraft operations, as well the inability to agree on what policy measures should be introduced to deal with the issue. Susan van Dyk reports on a recent conference hosted by the Royal Aeronautical Society’s Greener by Design Specialist Group, in collaboration with German aviation research organisation DLR, which presented the latest scientific studies on non-CO2 impacts and potential strategies and policies for mitigation.

Non-CO2 climate effects come from NOx emissions, soot from fuel combustion, water vapour and formation of persistent contrails (contrail cirrus) which contribute to increased cloudiness. Unlike CO2 impacts, non-CO2 effects depend on the location and time of emissions and this plays a role in selecting suitable mitigation steps. The climate impact of aviation from non-CO2 effects can be mitigated through various measures, including new engine technologies to reduce emissions, use of sustainable aviation fuel and air traffic management (ATM) strategies.

Contrail cirrus formation has the largest positive net (warming) effective radiative forcing (ERF) effect, followed by CO2 and NOx emissions. Contrail cirrus alone contributes >50% of the net ERF impact and is therefore an important target for mitigation of non-CO2 effects. Contrails are formed by aircraft through condensation of the water vapour from fuel combustion. While most contrails disappear relatively quickly, persistent contrails form cirrus clouds under certain temperature and humidity conditions. The cirrus clouds have some cooling effect by reflecting the sunlight, but also has a warming effect by trapping heat radiating from the earth’s surface.

Mitigation through flight diversion aims at avoidance of ice supersaturated regions (ISSR) where contrail cirrus formation has the greatest impact. The net warming effect of contrail cirrus is also greatest between 3pm until 6am and flight diversion is focused on this time period. Contrail avoidance through diversion of flights and ATM measures could represent a fast way (hours or days) to reduce the impact of aviation on the earth radiation budget.

Flight diversion and contrail avoidance is the current focus of live trials in the Maastricht Upper Area Control (MUAC). Dr Rudiger Ehrmanntraut, Senior Project Manager at Eurocontrol, explained that vertical diversion, 2000 ft above the ISSR or 2000 ft below the ISSR during the time period of 4pm to 6am, is the main approach during this project to avoid persistent contrail formation. A crucial prerequisite, he said, is the accurate prediction of ISSRs and potential areas of persistent contrail formation using meteorological data.

Dr Marc Stettler from Imperial College London has been carrying out research on the extent of flight diversion that will be required. His work has demonstrated that only 2.2% of flights account for 80% of the total net energy forcing due to contrails. Therefore, total fleet diversion is not necessary to achieve a significant impact, he argued. By diversion of 1.7% of flights, contrail radiative forcing can be reduced by 59%. If flight diversion is used simultaneously with cleaner engines, the contrail radiative forcing can be reduced by 92% (which amounts to 57% of the total radiative forcing).

However, flight diversion increases fuel consumption and CO2 emissions. Professor Ian Poll from Cranfield University quantified this fuel penalty for avoiding ISSRs and concluded the overall extra fuel burn was insignificant. If an aircraft is diverted 2000 ft above the ISSR, there is a 1.5% increase in fuel, and 1.4% when diverted 2000 ft below. However, this fuel penalty is only for the duration of the diversion, not the whole flight. A reduction in altitude results in a reduction in NOx emissions as an added benefit.

A significant contributor to formation of persistent contrails is the creation of soot as a result of fuel combustion. Studies at DLR by Professor Christiane Voigt’s research group show that 80% of soot particles form ice particles, which leads to persistent contrails. Lower soot formation will impact contrails and contrail cirrus formation and reduce some of the climate impacts of non-CO2 emissions. Reduction of soot particles causes a non-linear decrease in radiative forcing and it has been demonstrated that a 50-70% reduction in ice particles leads to 20-40% reduction in contrail radiative forcing. According to Voigt’s research, the main cause of soot formation is the aromatics in jet fuel, so reducing soot emissions can be achieved by decreasing the aromatic content. She said an effective way of reducing the aromatic content is through the use of sustainable aviation fuel (SAF). Currently available SAF, based on hydrotreatment of fats, oils and greases (called HEFA), is almost entirely composed of paraffins and cycloparaffins with virtually zero aromatics.

ASTM jet fuel specifications require aromatics at a minimum of 8.5% by volume and a maximum of 25%. A minimum aromatic content is considered essential to maintain seal integrity in the engine and aircraft and prevent seals from leaking. Current certification under ASTM D7566 only permits a 50% blend of HEFA with conventional fossil jet fuel and the blend must contain at least 8.5% aromatic content by volume. An earlier study, published in Nature in 2017, was carried out with a 50% blend of HEFA and demonstrated a reduction in the particle number and mass emissions immediately behind the aircraft by 50-70%. It concluded the effect was mainly due to reduced aromatics content and reduced soot particle formation.

Recent research as part of the ECLIF3/ND-MAX campaign, a collaboration between DLR and NASA, has also confirmed a strong reduction in soot emission indices by using low aromatic fuels. According to Voigt, her research has shown naphthalenes are more efficient soot precursors compared to monocyclic aromatics and decreased naphthalene content decreased the soot formation. She emphasised that stronger reductions in aromatics in jet fuels are needed to reduce persistent contrails and this will require changes in certification standards to permit fuel with lower than 8.5% aromatics. In addition, certification should also permit the use of 100% alternative jet fuels rather than the current maximum of 50%.

Rolls-Royce and Airbus recently announced what they say is the world’s first in-flight emissions study using 100% sustainable aviation fuel (see article). The ongoing Emission and Climate Impact of Alternative Fuels (ECLIF) project studies the impact of 100% SAF on aircraft emissions and performance. Paul Madden, Energy Emissions Expert from Rolls-Royce, told the conference there had been no operability issues or seal leakage problems as a result of using 100% SAF in the aero engine manufacturer’s engines, although he conceded this may not be the case in older engines.

Madden also explained some of the modified engine operations that Rolls-Royce is implementing, such as the lean burn engine, which can improve NOx emissions and soot formation. NOx emissions are not reduced through the use of SAF, and cleaner burning engines will be the main approach for mitigation.

Stephen Arrowsmith, Chief Expert on Environmental Protection at the European Aviation Safety Agency (EASA), highlighted the potential policy measures that could be implemented to address non-CO2 impacts as published in a recent EASA report (see article). The EU Emissions Trading System (EU ETS) currently only addresses CO2 emissions through policy.

The report divided policy options into three categories: financial/market-related, fuel and ATM. Financial measures suggested include a monetary charge levied on aircraft NOx emissions on one side and/or the inclusion of such emissions under the EU ETS on the other. Potential fuel-related measures could encompass the reduction of aromatics within fuel – leading to cleaner fuel burn and reduced nvPM emissions – and the mandatory use SAF. Both measures would target soot emissions and associated formation of contrail cirrus clouds.

Proposed measures in the ATM category are avoidance of ice-supersaturated areas and a climate charge. Flight diversions to avoid ice supersaturated areas would reduce the formation of contrail-cirrus clouds, while a climate charge would address all non-CO2 effects (NOx, water vapour, soot, sulphates, contrails). Several research issues would have to be addressed before these measures could be implemented, said Arrowsmith. Fuel-related measures could potentially be implemented in the short term (2-5 years), while other measures will likely take longer to implement (5-8 years) due to outstanding research questions, he believes.

The conference succeeded in highlighting the important, but somewhat overlooked, climate impact of non-CO2 effects from aviation. It demonstrated this impact can be significantly mitigated through modified air traffic management and use of sustainable aviation fuels with low aromatic content.

Photo: NASA’s ‘airborne laboratory’ flies close behind the DLR A320 Advanced Technology Research Aircraft (ATRA), flying through the Airbus’ exhaust plume. On board, scientists measure the composition of the exhaust stream and analyse the effects of biofuels like HEFA on the formation of soot particles and ice crystals (credit: DLR/NASA/Friz)

About the author

Susan van Dyk

A Research Associate at the University of British Columbia in Canada, Susan is a scientist and independent researcher specialising in biofuels and renewable energy, with a particular focus on sustainable aviation fuels. She has published numerous peer-reviewed papers and been the author of multiple reports on drop-in biofuels and SAF. She has worked on a number of Canadian biojet initiatives. Susan can be contacted through her website https://www.svdconsulting.ca/

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The European aviation sustainability Destination 2050 initiative identifies a route to achieving net zero CO2 emissions by 2050 through a combination of four key measures. These comprise: Improving aircraft and engine technologies, which could achieve emission reductions of 37%; using sustainable aviation fuels (SAFs), estimated to achieve emission reductions of 34%; implementing economic measures, contributing 8%; and improving air traffic management and aircraft operations, expected to achieve emission reductions of 6%. Air traffic management (ATM) uniquely provides an opportunity to deliver fast, measurable gains to help to meet interim targets in the next 15 years, writes Jenny Beechener. Measures already underway as part of the European Commission Single European Sky (SES) initiative – recently updated in September 2020 to take into account the objectives of the Commission’s Green Deal – have actually accelerated during the recent period of low traffic.

European air navigation service providers (ANSPs) have implemented more than three quarters of initial Free Route Airspace (FRA) – mandated by the end of 2022 under EC SES Implementing Regulation (EU) No 116/2021. While traffic flows must still be segregated for safety reasons, the FRA environment allows airspace users to plan more efficient flight paths between defined entry and exit points thanks to a reduction in intermediate waypoints. Eurocontrol estimates once free route airspace is fully implemented Europe-wide, potential savings could reach 3,000 tonnes fuel/day and 10,000 fewer CO2 tonnes/day.

Taking advantage of quiet skies, ANSPs managing the European core area introduced FRA in the region’s busiest airspace to enable airspace users to file optimised flight-plans and route profiles. Airspace users gained access to FRA on many night networks in addition to FRA around the clock in upper airspace controlled by Maastricht (since December 2019) and Karlsruhe (since February 2021) control centres, with major centres in both France and Switzerland preparing to implement similar procedures from the end of 2021.

The traffic downturn and increased availability of air traffic controller expertise during the pandemic enabled implementation of further airspace management projects aimed at building better foundations for sustainable operations going forward. ANSPs operating within Functional Airspace Block Europe Central (FABEC) airspace, an area handling more than 55% of European flights, removed over 500 flight level caps and air traffic flow and capacity management measures in the first six months. These measures are used to manage traffic during periods of high demand.

In addition, airspace users saved on advice of FABEC air traffic controllers 68 million track miles during the actual flight compared with filed airline flight plans, reducing carbon dioxide emissions by 1.4 million tonnes. By the end of 2020, horizontal flight efficiency in FABEC airspace reached 97.06%, exceeding SES performance targets and close to the optimum possible.

The challenge is to maintain the shorter flight-plannable route options as traffic returns, prompting several new initiatives involving neighbouring ANSPs. Among early measures, ANSPs in Switzerland and Germany shortened routes over the Alps by 15 nautical miles in June 2020, saving flight time and reducing fuel consumption. Flights destined for northern Italy now follow a more direct route across central and southern Germany, and similar changes are being considered for flights from north east Europe destined for airports in Spain and North Africa. The two ANSPs also introduced permanent procedures that enables airspace users to remain at fuel-efficient cruising heights for longer and to reach higher altitudes earlier across the international boundary. Flight arrivals cross the border 2,000-4,000 ft higher than previously and Frankfurt departures entering Swiss airspace are no longer held at FL320 but can enter at any altitude, generating an average saving of 32kg of fuel or 100kg of carbon dioxide per flight.

Graph showing the vertical profiles of daily Frankfurt departures to the south via Zurich ACC before (in red) and after (in green) the introduction of new cross-border procedures between Germany and Switzerland, saving 100kg of CO2 per flight.

New sector boundaries are being introduced as part of the Cooperative Optimisation of Boundaries, Routes and Airspace (COBRA) project. COBRA aims to reduce complexity and provide more efficient traffic management by replacing coordination between multiple sectors with bilateral handovers and the provision of new route options. For example, shorter routes along the Karlsruhe – Maastricht boundary simplify connections between adjacent approach centres and improve vertical profiles for several arrivals and departures to and from hub airports in the core area of Europe. The procedures are supported by validation simulations, controller training and new concept of operations with implementation expected in 2022. Maastricht Upper Area Control Centre (MUAC) is also engaged in a sectorisation review to identify improvements to flight planning which aims to deliver further network improvements in 2021/22.

Since March 2021, MUAC airspace sector organisation is better suited to the European concept of free route airspace and ready to support higher traffic levels as soon as commercial schedules resume. Benefits include a reduction in flight planning restrictions and the creation of several shorter flight-plannable route options. Simulations predict that on the basis of pre-pandemic traffic, the change will bring a weekly CO2 saving potential of 6,700 kg and offer flight-plannable gains of 280 nautical miles.

While these measures aim to save flight miles and reduce carbon emissions, other greenhouse gas emissions such as NOx and particulate matter provide the focus for separate ATM research. Preliminary findings show about half the climate impact of aviation originates from non-carbon dioxide effects of kerosene use, including the soot particles emitted from aircraft that lead to formation of contrails. The SESAR Exploratory Research project FlyATM4E is investigating the impact that weather situations and aircraft trajectories have on the formation of contrails and their persistence. The research partners aim to develop a concept to identify climate-optimised aircraft trajectories to enable an eco-efficient reduction in aviation’s climate impact, taking into account the balance between contrail avoidance and additional fuel burn.

In a practical application, MUAC is examining how relatively minor operational measures such as small flight level changes, for example diverting aircraft 2000 ft up or down from their normal flight path, can reduce persistent contrail formation and contrail cirrus. The trial includes creating a contrail prevention system; implementing operational procedures for contrail prevention; and the validation of the methodology with satellite image analysis by the project partner DLR.

Engaging with airspace users and ensuring network constraints are kept to a minimum are key steps in ensuring airlines take advantage of more efficient flight trajectories, enhance fuel efficiency and lower emissions. However, to be successful these measures depend upon more than just ANSP activities. Pan-European agency Eurocontrol published an assessment of benefits arising from operational ATM improvements examining fuel burn from take-off to landing across the whole ATM network in December 2020. The report concludes that reducing air transport emissions by up to 10% requires different tools, policy measures and the full collaboration of all the various involved aviation stakeholders. It emphasises the need for collaboration in the roles and responsibilities of each operational stakeholder, from ANSPs to airlines, including airports and the Network Manager, through mechanisms such as collaborative decision-making (A-CDM).

Photo: Eurocontrol Maastricht Upper Area Control Centre

About the author

Jenny Beechener

Jenny is a freelance airspace management writer covering manned and unmanned air traffic sectors. Previous roles include Editor of Jane’s Airport Review, Editor of Jane’s Air Traffic Control and Managing Editor of Air Traffic Management. She can be contacted at jennifer.beechener@btinternet.com.

According to data compiled by Europe’s air navigation agency Eurocontrol, the exceptional decline in 2020 air traffic due to the Covid pandemic travel restrictions led to an overall fall in CO2 emissions from flights across Europe of 56.9% last year compared to 2019. Using the global standard of assigning CO2 emissions to the country of departure, the decline was a similar 54.5%. The data shows a considerable variation between countries in their CO2 reductions, which was driven by differences in the local fleet (lighter or heavier, younger or older aircraft), flight distances (short or long haul), mix of market segments (cargo, scheduled and business aviation) and by the extent of Covid restrictions on flights. For example, departing flights from Belgium were down by around half in 2020 but CO2 emissions were only reduced by 30%. In a new set of traffic scenarios for the period up to June 2021, Eurocontrol expects air traffic to be around 64% down in January 2021 compared to January 2019 and says the situation is quickly deteriorating as many countries across Europe are imposing stricter travel controls in response to the latest waves of Covid and risks associated with new variants.

Europe’s major aviation countries experienced declines in CO2 emissions from departing flights around the European average: France -55%, Germany -53% and the United Kingdom -60%. Tourism-reliant countries recorded steeper declines, for example Greece -64%, Italy -65% and Spain -64%. The reduction in emissions from flights from the Netherlands was just 41%.

A major reason for the decline in emissions of just 30% from Belgian flights was due to the high proportion of cargo flights, which increased from 11% to 25% in 2020 compared to 2019, reported a Eurocontrol ‘data snapshot’. Cargo flights use larger aircraft and fly further than the Belgian average, it said, and therefore generate above-average CO2 emissions. A second reason was that due to short-haul cancellations, the average scheduled flight was much longer than in 2019, so emitted more CO2.

Brussels Airport said its cargo operations had experienced greater demand than ever in 2020, experiencing a 2.2% year-on-year increase in cargo volumes. The strongest growth was in the full-freighter segment, which was up 43% on 2019, and express services saw a year-on-year increase of 18%. This year, the number of vaccine shipments from Brussels Airport is already rising.

“The year 2020 truly was a very unusual and difficult year for the aviation industry. Fortunately, our cargo department has been in great demand throughout the crisis, particularly for the transport of pharmaceuticals and perishables, and for e-commerce,” said the airport’s Chief Executive, Arnaud Feist. “The major role Brussels Airport played since the end of November in the transport of Covid-19 vaccines will undoubtedly continue throughout 2021.”

However, airlines are having to dramatically reduce their capacity with the stricter travel restrictions now being applied across Europe, said Eurocontrol.

“It is clear that the months of February and March will be exceptionally low across the network, except for cargo, some business traffic and skeleton schedule services,” predicted Eamonn Brennan, Director General of Eurocontrol. “Even April is expected to perform very poorly, with only a limited pick-up for the Easter period. Flights in Europe will probably only be around 25-30% of normal. It is a complete disaster for European aviation – an industry that’s already on its knees.”

At a global level, new forecasts from airports association ACI World indicate a slow, uneven and uncertain recovery in 2021. By the end of 2020, the global airport industry had experienced a reduction of more than 6 billion passengers, representing a decline of 64.2% on the previous year, according to ACI’s latest Covid-19 impact analysis. Its World Airport Traffic Forecasts report shows that over the next five years, passenger traffic worldwide is expected to grow at an annualised rate of +2.4%. While markets with significant domestic traffic are not expected to recover to pre-Covid levels before 2023, markets with a significant share of international traffic will recover much more slowly, expects ACI.

The report shows the Asia-Pacific and Latin America-Caribbean regions are predicted to experience the fastest growth, achieving five-year growth rates of +3.5% and +3.1%, respectively. Africa, Europe, the Middle East and North America will see a more modest expansion, with growth ranging from +1.2% to +1.9%, it says.

China is expected to become the largest passenger market in 2031, surpassing the US, and is projected to continue to dominate passenger rankings in 2040 with just over 3.6 billion passengers, an 18.3% share of the global passenger traffic market. The US and India follow, with 2.9 and 1.3 billion passengers, respectively. Together, the three countries will handle almost 40% of global passenger traffic.  

Photo: Vaccines being loaded at Brussels Airport