Why am I hearing aircraft noise?
If you are hearing aircraft noise then it will mean you live or work near Edinburgh Airport or directly under a flight path. This will mean you'll potentially hear aircraft approaching, landing and taking off.
How and why is airport noise measured?
Aircraft noise is measured for many reasons. It is important to know whether the noise levels are going up or down over time, and if so, by how much. We have three off-airport noise monitors to assist us in measuring aircraft noise.
Under UK legislation the most common method for measuring noise at airports is the Equivalent Continuous Sound Level, dB LAeq which predicts average noise levels for the busiest 16 hours of the day, between 0700 -2300 from mid-June to mid-September. In line with UK Government policy, this metric is used in the production of airport masterplans.
What's the average noise level near you?
The UK Government advises that communities are significantly affected by aircraft noise above 57dB LAeq. This is used as the starting point in airport and aircraft noise policies. The contours are presented from 57 to 72 dB LAeq in steps of 3 dB. When assessing loudness a change of 3 dB is the minimum perceptible under normal conditions. To show where the different average noise levels are around the airport, the Government has developed maps showing 'noise contours'. Below is a link to the 'noise contour map' for the area around Edinburgh. The map shows the contours for 2011, combining noise for all flights, regardless of the wind direction and therefore of the direction the aircraft were flying. The contours are an irregular shape because you get more noise at the ends of the runway (where aircraft take off and land) than at the sides.
The link below to the Scottish Government Noise Mapping website which provides the contour mapping on which our draft NAP 2018-2023 will be based. https://noise.environment.gov.scot/
How many people are affected?
In the last 20 years the Edinburgh Airport 57dB noise contour has shrunk to an area of 13km2. This is because aircraft are quieter than they used to be. Based on the 2011 Census data there are around 3,300 people within this contour.
Taking off and the importance of wind direction
Another basic aspect of aviation safety is that aircraft need to land and take off into the wind. They can take off in the same direction as the wind, but this is only allowed if the wind speed is up to 5 knots, which is little more than a breeze.
Around 70% of the time the wind at Edinburgh comes from the west. So aircraft tend to take-off over Newbridge most of the time. On the occasion that flights do take-off to the east, towards Cramond, the Government has set a take-off flight path known as Standard Instrument Departure (SID).
There are three SID's used when aircraft are flying to the west and two when they are flying to the east. The first part of a SID is known as a Noise Preferential Route (NPR) and these are 3km wide and are designed to make sure aircraft avoid flying over areas where lots of people live until they reach 3,000ft. At 3,000ft ATC can direct the aircraft off the flight path towards its destination.
The split in take-off direction is almost completely dependent on the wind direction and speed, and so varies from year to year and month to month. In fact, the length of time that the runway operates in one direction can vary from a few hours to a few months: it all depends on the weather.
If you live under one of these take-off flight paths, then you will probably hear some noise when that particular flight path is being used. If you live beyond the flight path then you might sometimes hear noise when the aircraft leaves the flight path to head towards its destination.
If you live alongside (but outside) a flight path, you might hear noise if an aircraft flies outside the flight path. This can happen if ATC tells a pilot to leave a flight path for an operational reason (such as to avoid bad weather). We take 'track keeping' (staying on the flight path) very seriously and aircraft only deviate from the flight path in exceptional circumstances.
Edinburgh's predominant wind direction
Living or working under the approach path
While there are defined flight paths for take-offs, there are none for landings until aircraft are established on the Instrument Landing Systems (ILS), also known as the final approach. On final approach, the aircraft has to line up with the runway from several miles away.
When an aircraft arrives in the local airspace ATC directs each aircraft on an individual course onto the final approach and brings it into land. This is very different to take-off, where aircraft can climb steeply and quickly and turn while it climbs. There is more operational flexibility at take-off than there is in landing.
Many people are not bothered by aircraft noise during the day when ambient noise levels are higher, but they can be affected at night.
There are no restrictions on night flying at Edinburgh Airport. Night time is regarded as the period between 23:00 and 06:00. Generally, there are no passenger services flying at this time, with night flights tending to be mail and cargo operators - such as DHL, TNT and Royal Mail.
Whilst most people will be affected by aircraft noise during the landing and take-off cycle we are also working with airlines to address aircraft noise on the ground.
So what are we doing to reduce ground noise?
Examples of steps we are taking include restricting the duration and location of engine testing, encouraging airlines to taxi with one engine. We're also working with ATC to cut down the amount of time that aircraft wait to take off, or are taxiing, so that the engines aren't running for so long.