Noise is created by aircraft approaching or taking off from airports and by taxiing aircraft and engine testing within the airport perimeter.

This results from air passing over the aircraft’s body (fuselage) and wings. This causes friction and turbulence, which make noise.

The amount of noise created varies according to the way the plane is flown, even for identical aircraft. Aircraft land with their flaps extended – this creates more friction (and produces more noise) than a plane with its flaps up.

The diagram above shows how airflow over a wing differs with the flaps up and down.

Engine noise is created by the sound of the moving parts of the engine and 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, although fan noise from the front of the engine can also be audible on the ground.