This Item provides a computerized method for estimating airframe noise in one-third octave bands over a frequency range set by the user. The OASPL is also computed. The polar and azimuthal angular ranges are specified by the user. Estimations are for free-field conditions in a still lossless atmosphere. The method is a semi-empirical one and requires knowledge of the geometric data of the aeroplane and of ambient atmospheric conditions for its input. Airframe elements considered are the wing@ the horizontal and vertical tailplanes@ slats and flaps@ and the undercarriage@ any combination of which may be used in the calculation of airframe noise. Computer programs@ known as ESDUpac A9023 and ESDUpac B9023@ are provided with this Item.