Noise and emissions
Whilst considering aircraft noise management strategies, it is also necessary to consider emissions of local air pollutants and carbon dioxide (CO2) from aircraft engines.
Most of the technological advances in aircraft design in the last 20 years have led to a reduction in both noise and CO2 emissions.
However, some have resulted in an increase in emissions of local air pollutants such as oxides of nitrogen (NOx). The challenge for the aviation industry is to address these three issues simultaneously.
Operational controls therefore need to be balanced. For example, the adoption of a reduced-thrust setting for an aircraft during take-off can reduce NOx emissions by up to 30% or more in some cases compared with a full thrust setting.
Many airlines already employ ‘reduced thrust’ as their standard operating procedure. From a noise perspective, this is beneficial in the immediate vicinity of the airport but there can be a small increase in the noise experienced farther away from the airport as the aircraft climbs at a shallower angle.
Heathrow has long been aware of the interdependencies and has undertaken a number of studies to help quantify the exact balance that needs to be struck for specific situations.
The level of scientific understanding of interdependencies is however incomplete, and Heathrow continues to promote further research through its support of research groups such as OMEGA and industry bodies like Sustainable Aviation.