The use of the airport noise contour has become popular in airports around the globe. What is an airport noise contour, and how does it work? The one that is in use in London is a good example of what an airport noise contour should and can do for a community or communities, as is the case here. Noise levels are monitored and kept track of in order to place them into categories. Ground noise as well as noise from above is tracked in the same way. Both aircraft departures and arrivals are closely monitored, as these seem to be the occasions when the most noise pollution occurs. When the data for a set length of time has been collected and analyzed, the various airlines that fly into London are asked to use certain types of operating procedures that do not make as much noise. Procedures are put into place for the suspension of both noise from the air and noise from the ground. Incentives are given to those who comply with the procedures, while penalties are assessed to those who do not.