Recent work related to the aircraft noise problem has presented the opportunity to obtain a great deal of measured data of the landing noise produced by present day jet aircraft. The quantity of the measured data allows a statistical evaluation of the results. This paper presents the results of noise-level measurements made underneath the landing flight path at Los Angeles International Airport. The study study included measurements of noise spectra produced by 142 four-engine turbofan and 100 three-engine turbofan aircraft. Statistical analysis based on the measured data shows that the noise levels produced at a given ground station beneath the landing path are not part of a parent distribution that is Gaussian. The analysis also shows that the variation in noise levels is not correlated with aircraft altitude variations; i.e., the noisiest aircraft are not necessarily the lowest in altitude. The conclusion is reached that noise levels on the ground are greatly dependent on aircraft engine power setting during final approach to landing.