Harmonisation of noise limit schemes for European airports contribute to smooth functioning of the internal market. In this study for the European Commissions, DG TREN, different degrees of harmonisation are presented. The key question that has been answered is primarily in what way could noise limits be defined. The report presents a framework for distinguishing different types of noise limiting schemes. It also proposes a combined scheme with limits which could partly be locally and partly be internationally set. For more information please contact Huib van Essen.