Causes of aircraft noise

What causes aircraft noise?
If we’re talking basic physics, the noise from a plane is caused by two things: by air going over its fuselage and wings (or ‘airframe’) and by the engines.

Airframe noise occurs when air passes over the plane’s body (the fuselage) and its wings. This causes friction and turbulence, which make a noise. Even gliders make a noise when in flight – and they have no engines at all.

The amount of noise this creates can vary – according to the way the plane is flown – even for identical aircraft. Planes land with their flaps down, this creates more friction (and produces more noise) than a plane with its flaps up (see diagram above).

Engine noise is created by the sound from the moving parts of the engine, just like in a car, but also by the sound of the air being expelled at high speed once it has passed through the engine. Most of the engine noise
comes from the exhaust or jet behind the engine as it mixes with the air around it.

Modern noise levels
Believe it or not, planes today are much quieter than they were 40, 30 or even 20 years ago. And these will be replaced by even quieter aircraft in the future.

But, of course, even though each individual aircraft is quieter, there are more planes flying now than there were then. This means that the average level of noise is lower than before, but you hear individual planes more often. This makes it even more important that we keep on working to get the noise levels down. On this website we tell you what improvements have been – and are being made – to aircraft design to reduce noise
even more.

Perceptions of noise
Different people hear and react to noise differently at different times and in different places and circumstances. What really annoys one person might not bother another.

This means that people’s attitudes to noise are a very important factor. Attitudes and reactions are just as important as the reading on a noise meter, but they are less well understood than the technical science of sound-generation and measurement.

This isn’t just about one person’s awareness and sensitivity compared to another’s. For the same person, noise can also seem different depending on the level of background noise (such as cars, lorries or the sounds of everyday life).

The same noise might sound different because of the weather and what the person is doing at the time. For example, wind can blow sound waves away, humidity can make the noise sound different – rain can even make a difference. You might even notice plane noise differently because you’ve just read this information.

This is why the same plane, flying in the same direction, at the same height, over the same place, at the same time of day, can sound very different to someone from one day to another.

Please remember that if you hear a plane, it doesn’t mean that it is doing anything that it shouldn’t. If you are concerned, or want to know more, you are always welcome to contact the airport’s Operations Communications Team who can answer your questions. Their contact details can be found on this website.

Why am I hearing aircraft noise?
If you are hearing aircraft noise, it will be for one or more of these reasons:

1. You live or work very close to the airport, and hear planes landing, taking off, and moving around on the ground.
2. You live or work under a flight path and hear planes taking off.
3. You live or work under the approach path and hear planes coming in to land. 
4. You live or work under an aircraft ‘stack’ and hear planes in the stack.
5. You live or work between a stack and an airport and hear planes as they approach the airport.