^{Figure 1. Heathrow Airport, its noise contours and the community of Teddington (source: Strategic Noise Maps for Heathrow Airport 2016)}

London Heathrow Airport (LHR) serves more than 476,000 aircraft movements per year and carries approximately 78 million passengers. It is located 21 kilometres west of central London and employs over 76 thousand people – half of whom live in the surrounding five London Boroughs.

Noise regulations

Heathrow's strategy towards noise management has been a continuously evolving journey since the 1950s (see Figure 2 and 3). Today, noise is the primary constraint to Heathrow's development, notably obtaining permission to develop their third runway. In response, the airport has developed a lead-edge noise management team that can be considered at the forefront of international efforts to tackle noise, taking a pro-active stance by accepting that noise is an important issue for the local communities. By demonstrating a long history of noise management interventions, involvement in research programmes, and community engagement – for example, via Heathrow Community Noise Forum (HNCF) established in 2015.

^{Figure 2. Heathrow Airport's approach to noise management (source: Heathrow's Noise Action Plan)}

^{Figure 3. The evolving journey of Heathrow Airport's approach to noise (Source: Heathrow's "Our Approach to Noise")}

This case study describes the implementation of a steeper departure profile on the 'Detling' DET09 departure route, with the intention of understanding noise impact over the community at Teddington. This initiative was initially raised by community members and acted upon by the airport, therefore acting as a useful case study to understand the implementation of new operational procedures, and the role of community engagement.

Objective

To gather data regarding the noise environment in the Teddington Community, including noise and aircraft data, and to communicate this information to residents to explain local noise levels and aircraft operational data. It was also hoped that the data might identify operational changes that might allow the noise environment to be improved in residents' perception.

Approach

The airport took a pragmatic approach to these concerns, firstly, by listening to the community groups, and, secondly, by looking to validate their concerns through extensive testing and analysis of flight track data.

1. Multiple studies concluded that aircraft were outperforming the Instrument Flight Procedure (IFP) climb gradient (orange line in Figure 4). 99% of departing aircraft adhered to 4% climb requirement at 4000 ft. However, the analysis also showed that, at some point (between 1000 ft and 4000 ft), heavier departures (larger aircraft, namely A380s) were climbing at a shallower gradient, thus causing more noise to the communities below;
2. Other findings included an increase in A380 departures from Heathrow per day, meaning that community concerns were valid, but that these concerns were mostly in association with a limited number of heavy aircraft;
3. A discovery was made that daytime average aircraft noise levels had not changed substantially between 2011 and 2015, but that there was up to seven additional noise events per day, of which LA_MAX was greater than 65 dB. Also, there was a 1 dB increase in night-time noise, with no significant increase in the number of individual events;
4. Based on the analysis, a Teddington Community Noise Information Report was disseminated to concerned residents through consultation events. These events highlighted that residents believed a steeper departure gradient as implemented at other airports would help reduce noise problems. However, the face-to-face nature of the event enabled the airport to communicate that this gradient is based on a range of factors (i.e. runway length) and that the proposed gradient would be impossible to implement at Heathrow;
5. Although the steepest gradient was not feasible for the airport, the data did show that noise exposure on the ground could be reduced in the Teddington community by increasing the minimum departure gradient for aircraft following the Detling departure route from 4% to 5%. - demonstrating positive action to the local community, address the small number of non-compliant and underperforming heavy aircraft, but have relatively minimal impact to the majority of flights which were operating well in exceedance of both the 4% and 5% gradients (see Figure 4);
6. Testing took place regarding the new departure gradient to gather the knowledge on implications such as fuel burn, emissions, safety and changes to the distribution of noise due to an increased climb gradient. The latter is important as operational changes to a flight path mean that noise will shift elsewhere, potentially impacting other communities.

^{Figure 4. Illustration of the results of the analysis, showing how the vast majority of flights were well in exceedance of the 4% and 5% departure gradients (source: Teddington Community Noise Information Report)}

This study is a good example of open dialogues between communities and airports having the potential to lead to effective noise management interventions. In this case, a community concern was escalated to the airport management via existing communication channels. The airport responded by collecting data and disseminating this information clearly to residents. This data validated some of the community concerns and gave the airport data on which it could make operational changes that would improve the noise environment for those living in the Teddington community.  A range of novel communication methods was used to help describe the noise to community members, and consultation events with residents meant that misconceptions about aircraft capabilities could be corrected. After a one-year trial of increasing the departure gradient from 4% to 5% at 4000 ft, 14 out of 20 noise monitoring terminals showed a reduction in average maximum dB, although the benefits were mostly marginal. Other six noise monitoring terminals have shown an increase in average maximum dB, however, five of these terminals were located on the sidelines of aircraft noise exposure cones, in less populated areas. Whilst this case had a mostly marginal impact in terms of noise, and noise in the area continues to drive complaints, it nonetheless is a good example of an airport listening to its communities and responding to their concerns.