The DLR-project FluiD-21 is concerned with the development of the aircraft noise around the airports in Germany from the year 2000 to the middle of the 21st century. Until the middle of the 21st century the air traffic will increase, the almost old noisy aircraft will be replaced by new quieter ones. Furthermore, the society will be stressed by higher environmental awareness and psychological factors. Technical measures to reduce aircraft noise might compensate a part of the increasing noise sensitivity of the population. For the target investigations of FLUID-21, the noise of aircraft with ultrahigh bypass turbo engines must be known well, because these types will be the dominated ones in the future. The first of these aircraft are in use now and their noise values are measured. Therefore, the effects of comprehensive adoption of these aircraft types can now be calculated sufficiently. Political goals (for example the ACARE FlightPath 2050 Goals) can be verified. As the case may be recommendations will be given. In cooperation with other institutes of the DLR, the focus of the Department of Aviation Economics is on providing aircraft movement forecasts, a model of the aircraft fleet development, and an assessment of regulatory measures to influence aircraft noise.