This article discusses aircraft noise effect assessment with noise effect indexes, such as have recently been developed
for noise monitoring purposes at the airports of Zurich and Frankfurt. Aircraft noise indexes are noise
assessment instruments that express the overall effects of aircraft noise as a single figure which reflects the total
amount of people that are in some way affected by the noise of a particular airport. By accounting for the
most important effect measures (such as annoyance or awakening reactions) and by weighting these measures
according to the population density at each grid point within a defined geographic perimeter, noise effect indexes
provide residents and authorities with an integral picture of the total noise effect. The paper reviews basic features
of noise effect indexes and reports about the development and the current practical application of such indexes.
Moreover, it points to specific not yet fully resolved issues such as accounting for the diurnal variation of noise
effects, the definition of calculation perimeters, and the weighting of day and night effects including the question
of unification of different effect measures into one index.