How noise is measured

Why and how is the noise around airports measured?

How we measure aircraft noise

It is important to know whether the noise levels are going up or down over time, and if so, by how much. In the UK, Government research into how communities respond to aircraft noise uses a particular measure known as “the equivalent continuous sound level” - or decibels “LAeq”. Following research, the Government announced that it accepted that the onset of statistically significant community annoyance is 54dB LAeq. 

Noise contours

The Government uses ‘noise contours’ to show areas affected by the air noise around airports. Similar to height contours on a map which show changes in ground levels over an area, the noise contours show areas where the noise level is above a certain LAeq value. The contours don’t show the noise that individual aircraft make, but rather the equivalent continuous sound level in decibels at a particular location due to aircraft noise.  

Every year the UK Civil Aviation Authority calculates the noise made between 07.00 and 23.00 over a 92 day period between June and September to provide LAeq daytime noise contours. Night noise contours are also calculated for the period between 23.00 and 07.00.  

Noise contours 2016

Below is the current daytime ‘noise contour map’ for the area around Gatwick. The contours are an irregular shape because aircraft need to take-off and land into wind. As the wind predominately comes from the west, the areas to the east of Gatwick tend to experience more arrivals noise, and the areas to the west more departures noise.

Day noise contours 2016

Daytime noise contours 2016

Night noise contours 2016

Night noise contours 2016

Noise contour report 

The noise exposure contours report (19MB) has been carried out on behalf of Gatwick Airport by the Environmental Research and Consultancy Department of the CAA. It provides LAeq day and night contours 2016 for the areas around the airport.*  


The report details average summer day and night LAeq noise exposure contours for 2016. It shows a small increase in both the size of the contour and the population within it, compared to 2015. However, there is a notable exception due to the positive impact of the adjustments made to the Airbus A319/320/321 aircraft which have resulted in a 1dB decrease in arrivals noise. 

Other facts to take into consideration are that the average number of aircraft movements over the 16 hour day period were up 4% compared to 2015 and the average movements over the 8 hour night period were also up 2%. 

Read the full Noise Exposure Contours for Gatwick Airport 2016 report
(Note: this is a very large file 19MB)

We produce a number of community reports for where our noise monitors are located. Read your local report here.

*Up until 2015, this work was carried out on behalf of the Department for Transport (DfT) but for this 2016 study, ERCD has been commissioned directly by Gatwick Airport. Noise contours for previous years were published by the DfT.