Air Departure Tax reduction in Scotland: noise impact assessment

6. Summary Of Main Findings

6.1.1. 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 a) to f) can be found in Section 2.3. The following section provides a summary of main findings for each objective.

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. 

6.1.2. Taking a), b) and c) together, this study contains analysis of NAPs and END noise mapping for each of five Scottish airports. At the time of undertaking this study, Round 3 of END mapping was not publicly available and there was subsequent uncertainty over Round 3 noise modelling methodologies. Consequently, it was determined that it would be appropriate to undertake a noise modelling exercise that included the current baseline scenario (based on underlying air traffic growth to 2022) in addition to future scenarios involving different patterns of air traffic determined by potential reductions in ADT for four Scottish airports. The maps are outlined in Figure C.1 to C.10 of Appendix C.

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.

6.1.3. Analysis of 2016 ATM data were undertaken for each of the four airports – Aberdeen, Edinburgh, Glasgow and Prestwick. The results of this analysis were extrapolated using future passenger forecasts to provide representative ATM data for a future baseline scenario and six future ADT reduction scenarios. These passenger forecasts were made available from a related study from Peter Brett Associates (see 4.4.1 above) which calculated the net economic impacts of each of the scenarios. Noise modelling of each scenario was undertaken and the anticipated change in the population that would become exposed to aircraft noise under each scenario was identified. The key results of predicted changes in noise levels are presented in Chapter 5.

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%. 

6.1.4. A sum of the total change in affected population for all airports and the results of the sister study (the economic impact assessment of ADT reductions) from which the noise results are generated, are summarised in Table 16 below but are presented in full in Table 15 of Chapter 5.  

Table 16: Summary of Noise Assessment and Economic Impact Assessment

6.1.5. The main conclusion is that Scenario 1c (100% cut in Band A and Zero Pass Through, shaded dark grey) is the scenario that generates the greatest economic benefit (£721 million) to Scotland but also generates the largest increase in population affected by aircraft noise both during the day (10,902 people) and at night (11,875 people). This conclusion was expected given that a scenario involving Zero Pass Through is logically one which involves the greatest supply-side response from airlines which in turn would generate greater aircraft noise. Conversely, Scenario 2a (100% cut in Band B and Full Pass Through, shaded light grey) is the scenario that generates the least (in fact, negative) economic benefit (-£453 million) to Scotland but also generates the lowest increase in population affected by aircraft noise both during the day (1,274 people) and at night (1,577 people).

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.

6.1.6. The results of this assessment can be seen as an indication of the potential impacts at each airport that may result due to changes in ADT. The noise modelling methodology applied in this assessment was adopted for the purposes of maintaining consistency with the economic assessment of reductions in ADT (as mentioned in 1.1.2 and 6.1.3). Due to the potential different approaches in noise modelling methodology, the results of this assessment should not be directly compared with information contained in individual airport Noise Management Plans which were compiled for purposes other than potential changes in ADT.

6.1.7. It should be noted that the noise assessment does not consider potential changes in the character of the aircraft fleet leaving from and arriving at Scotland’s airports. With the introduction of ICAO Chapter 14 (standards of aircraft) in 2017, there is a current trend in the industry to upgrade aircraft types with new, quieter aircraft. The rate at which new aircraft will be introduced into service at each airport is dependent on the respective airline operators. Consequently, due to the uncertainty regarding future fleets, this assessment has not considered the potential introduction of new aircraft variants. As such, increases in affected properties as a result of changes in ADT may potentially be smaller than shown in the results presented in this report, though it is not possible to describe the (unknown) extent of the over-estimation for the precise reason outlined above.