Air Departure Tax reduction in Scotland: noise impact assessment

2. Introduction

2.1. Background

2.1.1. The devolution of powers over Air Passenger Duty (APD) to the Scottish Parliament was recommended by the Smith Commission in November 2014. Following the passage of the Scotland Act 2016, the Scottish Parliament now has the power to legislate for Air Departure Tax, which will replace APD in Scotland. The Air Departure Tax (Scotland) Bill^[7] was introduced to the Scottish Parliament to provide for the replacement of UK APD with Air Departure Tax (ADT). The strategic objectives of the Bill were to:

• design and structure ADT in a way which boosts Scotland‘s air connectivity and economic competitiveness, encouraging the establishment of new routes which will enhance business connectivity and tourism; 
• create an environment which encourages airlines to base more aircraft in Scotland, which not only creates new routes but creates new jobs, including flight crew, cabin crew, engineering and ancillary support roles; and
• reduce the overall tax burden of ADT by 50% and to abolish the tax when resources allow.

2.1.2. The Scottish Parliament passed the Bill in June 2017 and the Air Departure Tax (Scotland) Act 2017^[8] has since been enacted. The Scottish Government is undertaking a range of assessments to develop an evidence base on the potential environmental impacts of an overall 50% reduction in ADT, which it will consider when determining rate amounts and bands to be included in the secondary legislation (Regulations) which will be created under the Act. 

2.1.3. This report describes the nature and significance of one such environmental impact, namely the potential changes in air traffic noise as a result of the reduction in the burden of air taxation. This assessment demonstrates that the Scottish Government is fully committed to quantifying the potential noise impacts of the proposed policy.

2.2. Environmental Noise Directive

2.2.1. In order to fulfil its obligations under the European Parliament and Council Directive for Assessment and Management of Environmental Noise 2002/49/EC (commonly referred to as the Environmental Noise Directive (END)), the Scottish Government published the Environmental Noise (Scotland) Regulations 2006. Under these Regulations, strategic noise maps must be produced for major roads, rail, airports and industry. 

2.2.2. The competent authorities (for airports, this is the airport operator^[9]) are then required to establish Noise Action Plans (NAPs) based on the mapping results. NAPs are intended to provide a framework to manage environmental noise and its effects. They also aim to protect quiet areas in agglomerations (large urban areas) where the noise quality is good^[10].

2.2.3. Under Round 1 of the END (submitted to the European Commission in 2007), noise maps were produced for the following airports: Aberdeen, Edinburgh, Glasgow and Prestwick. Aberdeen, Edinburgh and Glasgow airports each produced a NAP. Under Round 2 of the END (2012), Prestwick was omitted, and Dundee was introduced. Edinburgh and Glasgow airports both published NAPs in 2014^[11,12] Aberdeen International Airport published in 2013^[13]. Each of these documents contained the 2011 L_den^[14] and 2011 L_Aeq,16h noise contours for the airport. The Scottish Government published a NAP for Dundee Airport in 2014^[15]. Further noise mapping and NAPs were produced in 2018 by Aberdeen International, Edinburgh and Glasgow airports as required by END Round 3 (2017). 

2.2.4. The need for major airports to provide NAPs highlights the ongoing commitment to protect communities from being impacted by adverse levels of noise. Any change in infrastructure or policy that is likely to result in changes in airport operations may further impact on these communities and, if significant changes are proposed, may result in noise impacts on previously unaffected communities. As the proposed reduction in ADT has the potential to result in a significant increase in activity in and around airports, it was considered that there should be an understanding of the potential noise impacts that may arise. This understanding of potential noise impacts will inform decisions on whether, when and at what pace to proceed with a reduction in ADT.  

Sources of Noise

2.2.5. The proposed reduction in ADT has the potential to increase the number of sources of noise. The introduction of, or changes to, these noise sources may result in short and/or long-term impacts on sensitive receptors^[16] . The significance of these impacts will depend on the absolute level of noise and change in noise level, the sensitivity of the receptor and the effectiveness of any mitigation measures that are implemented.

2.2.6. The noise sources that have been included in this study are directly related to aircraft take-off and landing. These have the biggest potential to result in noise impacts due to the number of people living near flight paths that may be affected. Noise sources that may change but have been excluded from the assessment are as follows:

• Aircraft taxiing and engine testing – Depending on the proximity of taxi-routes and engine test areas to sensitive receptors, noise from aircraft taxiing and ground running may be audible at sensitive receptors. However, in general, noise from these activities tends to be confined within the boundaries of the aerodrome. Additionally, the land surrounding aerodromes tends to be used for non-noise sensitive uses. Consequently, it is considered that any intensification of these activities as a result of a reduction in ADT is unlikely to result in overall noise impacts.
• Airport vehicular traffic – increases in passengers may result in increases in airport vehicular traffic. As this traffic is confined to within the aerodrome boundaries, potential increases in noise are unlikely to breakout and impact on sensitive receptors. Consequently, impacts from airport vehicular traffic have been excluded.
• Road and rail traffic to and from the airports – it is considered that, although there is likely to be increases in road and rail traffic to accommodate increases in passengers, these increases are likely to occur on transport routes that currently experience a high volume of movements, and hence percentage changes in traffic volumes, and corresponding changes in noise, would be small. However, any increases in operating hours (e.g. to accommodate delivery of supplies to service an increase in passenger numbers) could potentially have an impact on night-time traffic noise. It is unknown at this stage of the assessment if changes in infrastructure and operations would be required to accommodate additional passengers. Consequently, impacts due to road and rail traffic have been excluded.
• As with road and rail infrastructure, it is unknown at this stage of the assessment if airports will require additional infrastructure to cope with potential increases in passengers. Consequently, potential impacts from construction noise due to new airport infrastructure have been excluded.

2.3. Aims and Objectives

2.3.1. The primary aim of this research is to assess the potential impact on noise levels at Scottish airports of the Scottish Government’s plans to reduce the overall burden of ADT by 50%. The specific objectives were to:

a) Establish the current situation with regard to the production of noise maps within the NAPs at Scotland’s airports and specifically Aberdeen (ABZ), Glasgow (GLA), Prestwick (PIK), Edinburgh (EDI), and Inverness (INV) airports.

b) Assess the extent to which the current outputs (or soon to be outputs) under the END noise mapping exercise will be sufficient in terms of content and coverage to stand as a baseline against which to measure the impact of the expected reduction in ADT.

c) Develop additional (appropriate) baseline noise maps where it is considered that the existing or proposed noise maps for Scottish airports are insufficient, incomplete in their coverage or are unlikely to be available to fit in with the research timings of this project. 

d) Develop appropriate noise impact assessments for each affected airport based on scenarios to be provided by Scottish Government and, where necessary, take account of exogenous changes such as housing growth in the vicinity of the affected airports.

e) Produce a national aggregate impact assessment relative to baseline of the noise impact resulting from the plans to reduce the overall burden of ADT by 50%. 

f) Produce an accompanying narrative setting out the approach, the key uncertainties and the sensitivity of the results to the development of Scottish airports in terms of passenger numbers, air traffic movements and extent of the operational day, considering the potential impact from a change in the number of night time movements.

2.4. Report structure

2.4.1. The remainder of this report is structured as follows:

• Section 3 sets out the approach to the impact assessment.
• Section 4 sets out the noise impact prediction methodology, which details the noise modelling methodology, the methodology for determining baseline and future ATMs and the methodology for identifying receptors within noise contour predictions.
• Section 5 presents the results of modelling and examines the potential impacts resulting from changes in noise levels.
• Section 6 concludes with a summary of the main findings.

2.4.2. This is primarily a technical report, though we have sought to present it in as accessible form as possible allowing for the subject matter. If readers wish to focus on the tax reduction impacts, then Sections 5 and 6 are the most relevant. As Sections 3 and 4 (along with Annex A) are more technical in nature and deal with the noise methodology itself, they may be of less interest to those interested in the tax reduction impacts. However, we feel it is important to lay out in detail the methodology underpinning the conclusions of the tax reduction impacts. Those who wish to learn about the methodology, and therefore fully understand the impact of tax reductions on airport noise levels, should also read Sections 3 and 4. 

2.4.3. The detailed methodology for noise mapping is provided in Appendix A.