DIN 45684-1 describes a method for the calculation of sound exposure in the vicinity of airfields, which can be used for most aircraft types. The method is based on a classification of aircraft into aircraft groups. Tabular data of acoustic parameters and flight performance of the aircraft groups is made available in this standard for the calculation of exposure. This standard contains the parameters of sound emissions of ultra-light aircraft, power gliders, propeller aircraft and jet aircraft with a maximum take-off mass of up to 20 000 kg, as well as helicopters with a maximum take-off mass of up to 10 000 kg. The purpose of this standard is to calculate the sound exposure in the vicinity of existing or planned airfields and to supply the basis for later assessment. For this purpose, the calculation method described in this standard provides acoustic parameters for an arbitrary site in the vicinity of an airfield as a result. In practice aircraft noise protection calculation methods have proved necessary, especially for sound exposure forecasts. Such methods shall be able to model the sound propagation over larger distances taking into account meteorological influences. They are particularly necessary for urban land-use planning, airport planning, specification of noise mitigation measures, noise control. The update of DIN 45684-1 has become necessary as the AzB (German Instructions on the Calculation of Noise Protection Areas) have been revised. Significant modifications include the use of the sound power level as a parameter as well as in the conditions for the sub-segment method and the raster image. DIN 45684-2 (currently under revision) describes a measurement method for emissions for the determination of acoustic parameters on the basis of the calculation method in accordance with DIN 45684-1. The committee responsible for this standard is NA 001-01-02-01 UA "Fluggeräusche" ("Aircraft noise") at DIN.