FFI and FNI - two effect based aircraft noise indices at Frankfurt Airport

Within the planning process concerning the future expansion of Frankfurt Airport (construction of a new runway) in September 2007 the Regional Dialogue Forum Frankfurt Airport (RDF) proposed an Anti-Noise-Pact (ANP). ANP includes suggestions of upper limits and quantitative reduction goals for noise effects after the airport expansion and recommends the implementation of active noise control measures. Moreover, two regional aircraft noise indices for the description and control of the noise development in the vicinity of Frankfurt Airport are proposed. These are the 'Frankfurt Aircraft Noise Index' (FFI), and 'Frankfurt Night Index' (FNI). FFI is the primary index. Based on the 24 hours of the day, it describes the number of subjects highly annoyed by aircraft noise in areas within Ldn -contour 55 dB. FNI solely serves to assess nocturnal air traffic by displaying the number of awakenings additionally induced by aircraft noise emitted between 10pm and 6am, including regions where at least 0.5 additionally aircraft noise induced awakenings are expected. The proposed indices were subjected to a scientific evaluation by the authors of this contribution. In this contribution FFI and FNI and the involved requirements and objectives are described. It is concluded that effect based noise indices like FFI and FNI are in principle suitable to assess aircraft noise development around the airport as far as the underlying noise calculation method is able to reproduce the acoustical effects of changes in air traffic. However, several recommendations are given in order to improve the indices initially proposed by RDF.