Error Sensitivity Analysis of the Integrated Noise Model
The Integrated Noise Model (INM) is an average value model used to predict aircraft noise levels in the vicinity of airports. The calculation is based on the equations developed by the Society of Automotive Engineers (SAE) in their aerospace information report AIR 1845.Input variables into INM consist of average values of the local atmospheric conditions (averaged over the period being modelled), while the aircraft's flight path and performance characteristics are approximated either using user-defined values or standard values contained in the INM database. The approximation, although necessary, will result in errors between the predicted noise level, and the actual single-event noise level on any given day.The noise calculation process relies on the use of a number of algorithms that approximate the effect of aircraft noise, and a database of Noise-Power-Distance (NPD) data.A method is developed for analysing and calculating the effect of errors in the inputs to each of the equations used within INM. A number of examples are considered covering a range of aircraft types over various flight conditions. The most influential variables are found to be aircraft weight, local pressure, and a number of aircraft flap and engine coefficients. The suitability of the approximative algorithms is not considered, however the effects of an error arising from them is.The main recommendation of this work is for the development of a computational method of analysing the effect of errors throughout the entire flight profile, perhaps as an addition to the INM.