No other effect of air transport operations is felt as directly and individually as aircraft noise. Aircraft landing or take-off at airports generate high levels of noise that occur as quickly as they fade. The number of people affected by aircraft noise is determined by the number of aircraft movements, by the types of aircraft used, and by the population patterns around the airport.

Containing noise generated by aircraft operations whilst meeting increased demand is a major challenge for industry whether  it's airports, airlines or aircraft and engine manufacturers. The three methods currently available to do so are:

• land use planning: control of land use near airports is vital if the noise reductions already achieved are not to be offset by people moving closer to airports. Future improvements will depend to a great extent on keeping populations a certain distance away from airports and maintaining a quiet buffer zone which is kept free of residential, or other noise-sensitive development.
• noise reduction at source: the air transport industry has achieved major reductions in the noise made by typical commercial jet aircraft. Aircraft entering today's fleets are 20dB quieter than comparable aircraft 40 years ago.
• use of noise abatement operating measures: the use of preferential runways and routes and noise abatement procedures for take-off, approach and landing, help attenuate the impact of noise at and around airports. The success of these measures, however, depends on the physical layout of the airport and its surrounding.

Regulation of aircraft noise

Noise levels from commercial aircraft have traditionally been regulated through International Civil Aviation Organization (ICAO) noise certification standards.  These standards have gradually been tightened since 1971. Since 1 January 2006, a new, more stringent standard (Chapter 4) has come into effect, requiring new aircraft designs to be 10 decibels quieter, on a cumulative basis, than the previous Chapter 3 standard.

As a result of improvements in technology, there has been a significant reduction in total noise exposure around airports as fleets gradually incorporate quieter aircraft. 

• The "noise footprint" of a modern jet aircraft is less than 15% of that of the aircraft it replaces.
• The world fleet has more than tripled in size over the last 25 years, but the average fleet age has remained constant at around 11 years. 

Although noise from individual aircraft has steadily decreased, the level of noise disturbance at an airport is also determined by the frequency of aircraft movements and the proximity and density of communities to an airport's arrival and departure routes.

Despite the continuous improvements and research efforts, disturbance by aircraft noise continues to be perceived as the single most important environmental issue around airports, particularly in high income countries. Aircraft noise during night hours is increasingly linked to health effects including sleep loss and/or disturbed sleep.

This has resulted in noise-related capacity constraints at many of the world's major airports.  Some airports have reached their noise capacity limits prior to having made full use of their infrastructure, while others have failed to obtain planning approval for further development - simply because of the noise implications from resulting traffic growth. 

Balanced approach

To ensure that noise management at airports develops in a balanced and coordinated way, the International Civil Aviation Organization (ICAO) Assembly - which took place in autumn 2001 - adopted a complete international framework for a balanced approach to aircraft noise management, to be applied on an airport by airport basis. This instrument aims to ensure that airports and airlines can "strike a balance" between stricter environmental measures and the need to meet the current and future demand for air transport.

The "Balanced approach" combines four main elements:

• noise reduction at source;
• operating restrictions of aircraft which marginally comply with Chapter 3;
• land use management and planning; and
• noise abatement procedures.