Noise from aircraft mostly impacts those who live around airports.
The industry has been working to reduce noise for decades. On average, aircraft are already 50% quieter today than they were ten years ago, and 75% quieter than the first generation of jet aircraft. It is estimated that the noise footprint of each new generation of aircraft is at least 15% lower than that of the aircraft it replaces.
In 2013, the International Civil Aviation Organization (ICAO), the United Nations’ intergovernmental body on aviation, introduced the fourth new noise certification standard in its history, Chapter 14. The requirement is that new aircraft types are least seven decibels (summed over the three assessment points) quieter than those built to the previous Chapter 4 standard. The purpose of these aircraft noise standards is to ensure that the best noise technology continues to be used on future aircraft types.
The certification was one in a series of measures to reduce jet engine noise. In fact, ICAO estimates that between 1998 and 2004, the number of people exposed to aircraft noise around the world was reduced by 35%.
ICAO advocates a balanced approach to noise reduction. This combines noise reduction at source; land-use planning and management; operational procedures; and flight restrictions. The aim is to maximise the environmental benefit at lowest cost.
From looking at such factors as the proportion of air travelling through the engines, the size of the fan blades in the engine, the position of the engine on the aircraft body and even the size and number of flaps that help control the wing shape, research and development on noise has been extensive. The latest large aircraft, the Boeing 787 and Airbus A380 have noise ‘footprints’ that are remarkably small. The new Bombardier CSeries aircraft will make use of new Pratt & Whitney technology, ‘geared’ turbofan engines, which further cut noise and emissions.
The industry is working hard to make aircraft a further 50% quieter by 2020. There is a powerful incentive to continue tackling this issue, as concerns over noise pollution can – and do – affect the viability and acceptability of airport expansion plans.
Air traffic management
Controlling where the planes fly when departing and approaching airports has an important impact on noise exposure. The placement and use of runways is fundamental and preferred runway use can, for example, try to maximise night time approach and departure tracks over a sea or lake where the noise impact is minimal.
Air traffic management can be used to map out flight tracks that avoid the most highly populated areas. Recent developments in required navigation performance mean that aircraft can now follow designated tracks very precisely. This can avoid random track spreading and the resulting ‘spaghetti’ radar flight track maps, but track concentration can mean that a smaller number of residents are subjected to a higher number of flyovers. Air traffic management and airspace design needs to be undertaken with careful consultation of community groups. Issues such as the relative benefits of track concentration versus track dispersion need to be carefully considered.
Airlines and pilots with input from the air navigation service providers and airport operators can develop and implement noise abatement procedures such as reduced thrust take-off, displaced landing thresholds, continuous descent operations.
In parallel with aircraft noise minimisation through technology and air traffic management, land-use planning is a crucial process for minimising the number of people exposed to high levels of aircraft noise. Airports need to work with local authorities to put in place zoning rules in areas impacted by high levels of aircraft noise. Effective land-use planning can discourage or prevent inappropriate new residential, health or educational developments, and encourage light industry or storage areas not sensitive to aircraft noise. In some areas, sound insulation and ventilation can be required for new or existing dwelling to at least improve the indoor noise levels.
In most jurisdictions, however, airport operators have no authority or control of land-use planning off the airport site and can only seek and encourage local government to protect airports from the encroachment of residential and other noise sensitive land use. In these areas, the industry encourages governments to take a long-term proactive planning approach to using land around airport facilities to ensure that now and in the future, there will be no development that could be impacted by aircraft noise.
However, in tackling some environmental issues, compromises need to be made. For example, the aviation industry and governments must make a choice between shortening routes to reduce the amount of fuel used and maintaining noise abatement procedures – sometimes the shortest route into an airport can take flights over communities. This is a delicate balancing act.