Variability in Aircraft Flyover Noise Measurements

Abstract

The increasing interest in aircraft flyover noise measurements and in noise monitoring around airports has raised questions as to the variability in in aircraft flyover noise measurements. This paper reviews the results of repeated aircraft noise measurements for two major classes of observations: Repeated measurements of a single aircraft flown by a skilled flight test crew, made over short time periods under controlled conditions (measurements typical of those required for FAA noise certification tests); and repeated noise measurements extended over periods of one to 30 days at civil airports during routine operating conditions, where there is no special control of operations or detailed information as to exact aircraft configurations. As might be expected, the variability in the later class of observations is inherently greater than in measurements under carefully controlled conditions. Results are reported for several different noise measures, including the effective perceived noise level, the single event level, and the maximum A-level. Comparisons are made between two methods of averaging noise level data, arithmetic and energy averaging, since both methods are of interest depending on the study application.