In order to critically evaluate and comment on international regulation on aircraft noise exposure, the Dutch Rijksluchtvaartdienst (RLD) [Air traffic Service] requires insight into the future developments of air traffic. Influencing factors in relation to noise exposure are the size and the composition of the aircraft fleet. RAND Europe has been commissioned by the RLD and the Algemene Beleidsgroep Milieu en Ruimtelijke Ordening [General Policy Group on Environment and Spatial planning] to identify the composition of the European and American aircraft fleet in terms of the type of aircraft, sound-range and age of the fleet. Changes within the composition will be highlighted on the basis of analyses of the aircraft fleets of 1988, 1993 and 1998. Further a model will be developed to predict the composition of both the European and American aircraft fleet in 2008. Outcomes will inform current and future policy making in noise exposure.