摘要: The relative effectiveness of three changes in aircraft operating procedures and/or aircraft hardware in reducing noise exposure around three major airports (O'Hare International Airport, Chicago, John F. Kennedy Airport, New York... 展开 The relative effectiveness of three changes in aircraft operating procedures and/or aircraft hardware in reducing noise exposure around three major airports (O'Hare International Airport, Chicago, John F. Kennedy Airport, New York, and Los Angeles International Airport) were rated by determining the relative change in land areas falling within Noise Exposure Forecast (NEF) 30 and 40 contours. For projected 1975 operations, sets of NEF contours were calculated for changes which included: power cutbacks after takeoff and two segment approaches for all aircraft, and retrofit of current four-engine turbofan aircraft with either acoustically - lined nacelles or with a 'quiet' engine under development by NASA. (Author) 收起