Can technology deliver acceptable levels of aircraft noise?

Meeting community expectations on aircraft noise has always presented a challenge to aircraft and engine manufacturers and to those involved in airport planning and air traffic management. It has been a critical issue for communities living close to airports since the introduction of turbojet and turbofan powered aircraft in civil aviation in the late 1960s and early 1970s. The technical progress which has been made during this period in reducing aircraft noise at source and mitigating its effects by noise reduction technologies is not widely understood or appreciated by the community. These remarkable achievements will be reviewed here, and an assessment presented of current progress towards meeting ambitious new environmental targets for aircraft entering service between now and 2050. While much has been achieved, opportunities still exist to exploit further significant reductions in noise both for current aircraft layouts but also in the longer term for future aircraft and engines which may differ significantly from current configurations. The main sources of aircraft noise will be reviewed and areas identified in which the greatest noise reductions have been achieved. Areas will also be highlighted where future gains are likely. Much of the discussion will revolve around measures of the noise of a single aircraft at takeoff or approach. This forms the basis for noise certification metrics and the focus of industry efforts to reduce aircraft noise. This is only a part of the complex jigsaw of issues however which define the aircraft noise problem. These include the public’s perception of what actually constitutes a noise nuisance and also critically the rate at which an expanding commercial fleet transitions to newer quieter aircraft.