The noise created by airplanes can be attributed to two factors. 1 Engine noise. 2. The reaction between air and the fuselage. For people who live close to an airport or live below a regular flight path, it is little comfort to know that airplanes are much quieter now than they were even 20 years ago. The other factor that offsets this apparent benefit is that there are now many more airplanes in our skies than ever before. While there have been advances in technology designed to reduce the noise levels from aircraft, for residents living close to airports, the problem of noise pollution continues.
The problem of aircraft noise has not been ignored by the aviation industry but understandably, they take a different view from those outside the industry. At least they do not deny that aircraft does create noise. For example, the official Heathrow Airport website includes pages on the subject of aircraft noise and provides this explanation on the causes:
“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.
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.”
It is refreshing to know that the BAA accept that noise pollution is a problem and that it continues to be an issue the industry are working on through improved technology. They also offer an interesting comment on why airplane noise can differ from person to person and often be affected even by weather conidtions. Their website goes on to say:
“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.
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.”
So it seems that the noise we hear when a plane passes overhead can be louder or softer depending on weather conditions and other factors that make what we hear different from one day to the next. One thing is for sure, the noise from airplanes will continue for the foreseeable future. The dream of noiseless passenger aircraft is a very long way off.