Aircraft noise and aircraft noise protection

Air traffic noise is a constant subject of discussion in public debate, politics, and the media. In this article, you will learn how aircraft noise is generated and what noise protection measures are taken against it.

Increase in air traffic - challenge for the aviation industry

Air traffic has risen in recent years due to the steadily growing number of passengers for both business and leisure travel, as well as freight air traffic, new and changed flight routes, and the expansion and building of airports. With this, the burden on the affected residents also increases. These residents in particular must be protected, because not only are they getting continuously disrupted, but the burdensome noise level can also have consequences for their health. In order to avoid such negative effects, the aviation industry and politicians have the responsibility to protect the people concerned from aircraft noise pollution.

Emergence and measurement of aircraft noise

The noise perceived as particularly burdensome for humans is caused by, above all, the low-flying aircrafts, such as helicopters, small planes and military flight operations. This unpleasant noise, known as aircraft noise, is caused by engines and rotor blades, as well as by the wake turbulence created by the plane. The everyday workflow at the airport and the ground traffic on the runway are also causes of noise pollution. The aircraft noise is subject to considerable fluctuation both in terms of volume and duration, but a certain minimum load is always present.

In order to control the noise level and to meet the requirements of the air traffic law for airports, so-called noise monitoring stations are built in severely affected regions. Based on the data obtained, information on noise profiles and forecasts can be generated.

For the protection and relief of the people affected by the noise, it is necessary to constantly improve and extend active and passive noise protection measures.

Active noise control measures against aircraft noise

One way to protect the population from aircraft noise is active noise protection. That is, reducing the noise directly at the source.

These include the improvement of engine technology. Since the introduction of jet engines, the volume has already been reduced by 25 decibels. This corresponds to an 80% noise reduction. As a result, the more modern aircraft cause significantly less noise than the older aircraft. Even in future models, the arrangement of the engines is increasingly crystallised at the rear and above the fuselage, so that the noise radiates upwards rather than towards the ground.

Numerous research projects are being implemented and financially supported by the European Union with the aim of improving the noise situation. One example of this is the Clean Sky project. Here, among other things, aircraft manufacturers Airbus and Saab are developing a completely new, ten-meter long wing tip. Compared to conventional wing tips, the air resistance is to be significantly reduced, which in turn leads to a reduction in noise emissions. Another research project that is to lead to the development of low-noise technologies is called Single European Sky Air Traffic Management Research (SESAR). The main objective is to modernise and harmonise the European air traffic control systems, but also to contribute to the fact that in the future, take-offs and landings will be more frequently conducted with noise-reducing take-off and landing procedures.

A further measure involves the correct planning of the starting direction. The engine take-off causes a lot of noise in particular. It is precisely for this reason that these routes have to be planned with special care. The planning of the respective route takes place according to legal regulations and in consultation with the local flight commission. Different regulations are set for each runway. Achieving the lowest possible noise pollution for the respective population plays an important role. This can also lead to detours on the part of the airlines.

Even after landing, the plane still produces noise. For example, the cabin lighting or the air-conditioning system still requires electricity, which is produced by auxiliary engines. To counteract this, an increasing number of airports are trying to reduce this noise source by providing stationary power connections for parked airplanes or by using additional mobile electric vehicles to connect the machines to the ground power supply. Other causes of noise, many of which can be found on the airport grounds, include passenger buses, tankers and aircraft tractors. To reduce this, airports are increasingly moving to electric vehicles.

A further active noise protection measure to minimise noise is financial incentive. Each time the aircraft takes-off and lands, airlines must pay fees to the respective airports. These amounts vary according to the weight of the aircraft, the number of passengers and the time of day, and the individual noise output of the aircraft. With this measure, airports want to promote the use of quieter machines.

So-called noise emitters are another type of regulation for the active depletion of aircraft noise. For example, a concept was drafted at the Frankfurt airport, which contained a six-hour ban on take-offs and landings between 23:00 and 05:00. However, such restrictions on flight operation are to serve as a last resort measure to protect against aircraft noise. A consequence of these restrictions on the airline industry, the competitiveness of in this case German airports and airlines and the connection of Germany to the global economy would be severely impaired.

Aircraft engine is examined by engineers

In order to eliminate aircraft noise, aircraft and engine manufacturers work closely together © Airbus Press Centre

Passive soundproofing measures against aircraft noise

The investment in passive sound insulation mainly includes structural measures in residential buildings in order to keep the noise pollution as low as possible for the residents. Local residents may be reimbursed for expenses and costs for the necessary sound-proof windows and other protective measures.

Even the construction of special noise protection buildings directly on the airport grounds, for example, for engine testing, can reduce the noise on the ground.

The noise pollution caused by air traffic is increasing, particularly in the metropolitan areas, but the aviation industry and politicians are concerned with the reduction of aircraft noise. The results from today's research projects are also certainly going to be put into practice with time.

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