Evaluation and prediction of airport noise in Japan

In 1973, Japan adopted WECPNLJ which is defined as a modified index of ICAO WECPNL, as an index of aircraft noise evaluation, and enacted“Environmental Quality Standard for Aircraft Noise.”So the Government has made all countermeasures to alleviate the aircraft noise impact around the airport.As a result, the noise exposure situation has been greatly improved for these twenty-five years.To evaluate noise exposure, an aircraft noise prediction model(JCAB Model)was developed by Civil Aviation Bureau of the Ministry of Transport of Japan(JCAB).The procedure for aircraft noise prediction has not been changed basically, but JCAB has been trying to improve the accuracy of noise prediction.First, this paper briefly reviews the Standard and a noise evaluation index WECPNLJ in the Standard.Then, it describes the basic idea of an airport-noise prediction model JCAB Model, which has been developed by JCAB, together with some recent result of examination about the accuracy of noise prediction.Finally, it refers to the relationship between WECPNLJ and Lden.