Noise around the airport

Why and how is the noise around airports measured?
The noise from planes is measured for many reasons. It’s important to know whether the noise levels are going up over time, and if so, by how much.

In Britain, the Government (i.e. The Department for Transport) measures the noise from aircraft every year and produces annual ‘noise contours’. These are calculated by averaging out the noise levels during the day (a 16-hour day) during the summer period. The amount of noise is given in decibels (dB).

This averaging-out means that the day’s high and low levels of noise are levelled out to give a single figure. The Government calls this averaged decibel measurement ‘LAeq’, and this is the most common international measure of aircraft noise. As a measurement, it means ‘equivalent continuous noise level’.

There are other units of measurement that can be used, and you can read about these and other technical noise information in BAA’s Issue Brief on noise, which can be found on this website www.baa.com/publications.

For more information about Government noise contours. please visit www.dft.gov.uk and www.caa.co.uk on behalf of the Government.

Noise limits
Noise contours are used to measure overall contours however the individual noise level made by every departing planes is also measured as these planes have to meet noise limits, set by the Government, which vary depending on the time of day or night. The limits are:

94 decibels (Maximum level) during the day. (7am – 11pm)
89 decibels (Maximum level) in the ‘shoulder period’ (6am -7am and 11pm to 11.30pm)
87 decibels (Maximum level) at night (11.30pm to 6am)

There are a number of noise monitors at specific locations around the Airport which permanently monitor departing planes to ensure the limits are met. If the limits are broken BAA fines the airlines involved and the money raised is used for projects in the local community. Planes that break the noise limits on departure are fined £500 if they are up to 3 decibels over the limit and £1,000 above that.

What’s the average noise level near you?
In the UK, the Government says that people start being significantly annoyed by aircraft noise at 57 decibels, averaged over 16 hours (57dB LAeq). They use this as the starting point in policies on noise from planes around airports.

To show where the different average noise levels are around the airport, the Government has developed maps with ‘noise contours’.

Below is the ‘noise contour map’ for the area around Heathrow. The maps work like a normal contour map that you would use for walking, or in geography.

 Click here to view an example.

The contours are an irregular shape because you get more noise at the ends of the runways (where planes take off and land) than at the sides.

This shows the contours for the averaged-out 57 decibels (57dB LAeq) for 2003, combining noise for all flights, regardless of the wind direction and therefore of the direction the planes were flying.

How many people are affected
In the last 20 years at Heathrow, the number of people who live within the 57 decibel contour has fallen a great deal, because planes are quieter now.

In 1980, there were 944,000 people living in the 57 decibel noise contour around Heathrow.

By 2003, this had fallen to just 264,000 people. This is even though there was a rapid growth in air travel at the same time, from around 273,000 flights a year in 1980 to 460,000 flights in 2003.