Managing environmental impacts around airports

There are two main European regulatory measures for managing the impact of aircraft noise around airports. The first is the Environmental Noise Directive [1] that promotes effective monitoring and management of noise impacts alongside national and local initiatives. The other is the Balanced Approach Regulation [2] [3] that establishes airport noise management elements, including rules and procedures on the introduction of noise-related operating restrictions ( Figure 6.1. ).

EASA performs two specific roles in support of the above regulatory measures. The first is to verify and publish aircraft noise and performance data, which is used in models to calculate airport noise contours and assess the surrounding noise impact. This dataset ensures that airport noise modelling in Europe is robust and harmonised. The second role is to collect noise certificate documentation from aircraft with a maximum take-off mass greater than 34,000 kg, or 19 passenger seats or more, operating at European airports. To fulfil these roles, the Agency has launched the Aircraft Noise and Performance (ANP) database and the Environmental Portal [4] through which appropriate stakeholders can submit and share information.

In line with the Environmental Noise Directive, aircraft noise management at airports involves monitoring and assessing the situation, and then defining a baseline, future objectives and an associated noise action plan. The Balanced Approach plays a key role in this action plan and consists of the following core elements:

1. Reduction of noise at source involving research programmes aiming at reducing aircraft noise through technology and design.
2. Land-use planning and management policies to avoid incompatible developments such as residential buildings in noise-sensitive areas.
3. Noise abatement operational procedures [5]  to enable the reduction or redistribution of noise around the airport and make full use of modern aircraft and air navigation capabilities.
4. Operating restrictions on aircraft that limit access to or reduce the operational capacity of an airport, for instance noise quotas or flight restrictions.

Greater emphasis may be placed on certain elements of the Balanced Approach compared to others, depending on the airport noise abatement objectives and the cost of mitigation measures [6] [7] . Whilst recognising that operational restrictions should be used only after consideration of all other elements of the Balanced Approach, 79% of European airports recently surveyed by Airport Council International Europe (ACI-E) indicated that they employ various measures (e.g. restrictions on noisier aircraft, night flight restrictions, runway restrictions, noise budgets and movement caps). The scope of operating restrictions varies on an airport-by-airport basis and the aircraft noise certification basis. Unlike for aircraft compliant with Chapter 3 of ICAO Annex 16 Volume I, restrictions of Chapter 4 and 14 aircraft should be of a partial nature and not totally prohibit access of these aircraft to the airport concerned.

A recent study for the European Commission on the application of the Balanced Approach Regulation concluded that some Member States have the same competent authority for this Regulation and the Environmental Noise Directive, whereas others have different authorities. While the Regulation is considered to have clear and accountable processes to engage and consult stakeholders, the study noted that it would be beneficial to clarify objectives and procedures by means of best practice guidance to follow when selecting and implementing noise reduction measures.

The consultation and collaboration of stakeholders (e.g. airports, airlines, air navigation service providers, local authorities, local communities) is critical in order to identify optimum solutions to mitigate environmental impacts around airports while taking into account potential system constraints. The EUROCONTROL ‘Collaborative Environmental Management’ (CEM) specification was initially developed in 2014 to facilitate these discussions and can be adapted to suit local needs.

The CEM specification [8]  was updated in 2021 in order to meet the growing sustainability challenges that the aviation sector is facing. This update included:

• enabling the implementation of the new measures that may be initiated in response to the EU Green Deal (e.g. use of SAF and inclusion of SAF providers);
• strengthening the local community engagement and the collaboration with local authorities (e.g. through support from the Airport Regions Council);
• references to new legislation and voluntary industry schemes (e.g. Airport Carbon Accreditation);
• reflecting the growing importance of new markets (e.g. Drones, Urban Air Mobility); and
• case studies featuring best practices in stakeholder engagement and noise abatement from operational initiatives.

The CEM specification has been endorsed by ACI-E as an industry recommended practice, and greater coordination with the Airports Regions Council is foreseen to reinforce the exchange of environmental technical information and extend the cooperation on good practices.

Building on CEM, the SESAR Total Airport Management project is working on bringing collaboration in airport management to the next level by developing active real-time airport environmental performance management tools that incorporate key parameters into the Airport Operations Plan (AOP), which integrates with the Network Manager. Performance dashboards combine fuel burn / CO₂ emission metrics with air quality and noise indicators to enable trade-off assessments. They will be able to support, for example, runway configuration management, optimisation of gate or taxi route allocation, arrival/departure route allocation and conformance to agreed noise and air quality levels at specific monitoring stations [9] [10] .

Conventional navigation places limitations on a more efficient use of the airspace and can result in an unnecessary environmental impact. The use of Performance Based Navigation (PBN) enables an optimum aircraft flight path trajectory to mitigate environmental impacts, particularly in the vicinity of airports, without having to overfly ground-based navigation aids. This means that PBN routes and procedures can be placed:

• to avoid noise-sensitive areas around an airport. The concentration of flight paths, and thus aircraft noise, can be a benefit if these flights avoid densely populated residential areas [11] . Alternating flight paths through an area may also be possible to provide predictable respite for affected communities;
• to enhance vertical profiles (e.g. Continuous Descent Operations and Continuous Climb Operations) in terminal airspace, whereby more efficient vertical profiles can be flown, resulting in lower emissions and noise [12] ; and
• to enable shorter routes between origin and destination airports to reduce overall fuel burn.

Regulation (EU) 2018/1048 [13]  requires the gradual implementation of PBN routes and approach procedures by 6 June 2030 to replace existing conventional navigation procedures in the Single European Sky. Two interim deadlines of December 2020 and January 2024 have also been set to prioritise the publication of new PBN routes and approach procedures [14] . The Regulation 2018/1048 also requires coordination with all affected stakeholders and the approval of transition plans to detail what will be implemented and by when. In order to avoid potential negative impacts during the airspace redesign, it is important to follow a CEM approach as the scope of the environmental benefits will be dependent on the local airport circumstances. With the data available in mid 2022, PBN implementation is, in most cases, subject to a significant delay.

In 2019, a partial assessment of environmental benefits from PBN was performed by the SESAR Deployment Manager covering certain operational initiatives at 18 airports. These PBN operations noted a reduction in the “Arrival Sequencing and Metering Area (ASMA)” time, which measures the delay in the arrival flow of air traffic, thereby enabling significant savings in time, fuel and CO₂ emissions (2.6 million tonnes between 2014- 2030). This CO₂ saving is significant and represents about 20% of the total expected CO₂ savings from future SESAR operational initiatives out to 2030.

SESAR has defined and validated a concept for the use of a Second (alternative) Runway Aiming Point (SRAP) on approach in place of the runway threshold [15] . Aircraft are cleared to land using this second aiming point depending on their wake turbulence category and their need for more or less runway length, thereby enabling the inbound aircraft to reduce noise footprint and possibly reduce runway occupancy time and/or taxi-in time depending on the local airport layout. In addition, SESAR has developed the Increased Glide Slope (IGS) concept, which facilitates a steeper 4.5 degree approach (instead of the usual 3 degree) to the airport runway threshold that helps to reduce noise ( Figure 6.2. ).

These innovative procedures can be combined to further increase benefits and are already in the pre- industrialisation stage. Following extensive simulations, the SESAR large scale demonstration DREAMS conducted a live trial campaign in 2021 and 2022 in Germany, Italy and the Netherlands [16] .