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 2017

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 2017

Night noise contours 2017

Noise contour report 

The noise exposure contours report 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 2017 for the areas around the airport.


The report details average summer day and night LAeq noise exposure contours for 2017. It shows that – thanks to an initiative to modify the A320 family of aircraft so they make less noise - Gatwick’s noise footprint shrank by 3% in 2017 - compared to 2016, despite aircraft movements increasing by 1%. Find out more information about our noise footprint.

Read the full Noise Exposure Contours for Gatwick Airport 2017 report. (Note: this is a large file 17MB)

Historic reports

Since 2015, all noise contour reports have been commissioned by Gatwick Airport Limited.You can read the 2016 report, as well as historic reports produced by the DfT.