# Modeling and Analysis of Noise Emission Using Data from Flight Simulators
## 2 Methods of Noise Modeling  
Methodology for noise pollution determination was based on existing models for real-world use. Aforementioned models are developed in accordance with recommendations published in ECAC.CEAC Doc 29 [34]. The created model is based on flight trajectory data acquired from X-Plane 11.55 that are used in conjunction with Noise--Power--Distancecharacteristics for type Boeing 737-800 that were accessed through the ANP (Aircraft Noise and Performance) Database, which is managed by Eurocontrol [35]. Analysis was performed for five factors that influence aircraft trajectory to a large degree, and thus, it is noise and pollutant emissions. The degree of this influence was assessed on the canvas of two departure procedures--NADP1 and NADP2. Due to the simplistic character of the carried out studies, the simulation scenarios were limited to the One Factor at a Time (OFAT) method, i.e., modifying only one factor during a single simulation while keeping the rest at their default setting. The red-colored cells correspond to the procedure NADP1, while blue-colored cells correspond to the procedure NADP2, as visible in the thrust reduction/acceleration column. This color scheme prevails through the entire paper to aid in differentiation between the two procedures. Although the modeling was based on the methodology presented in ECAC_CEAC Doc 29, it must have been simplified in certain areas, which were not objectives of the study. One of those simplifications was the negligence of modeling the effect of the aircraft's bank angle on noise propagation, as the established trajectories were a straight line extending on the runway track, i.e., no turns were made by the aircraft. Figure 2 presents only a broad overview of the steps in determining \(L_{Amax}\) and \(SEL\) parameters for a single noise event, and it shall not be treated as a technical guide of any sort due to its simplistic nature. All of the mathematical background regarding the modeling software created in MATLAB is provided in great detail as a part of the document [34]. It is not presented in this paper, as this paper would not provide any additional insight into the modeling process, which in itself is not vital to the proper understanding of the presented analysis. As depicted in Figure 2, the modeling process begins from carrying out simulations in a suitable Flight Simulator of choice. For the purposes of this paper, simulations were conducted in X-Plane 11.55 on a ZIBO Mod Boeing 737-800 fitted with CFM56-7B26 engines. The adequate data from the simulator concerning the aircraft's distance covered, altitude, True airspeed, thrust generated, and fuel burned are then imported into the modeling software and initially processed. The software chosen as a main computing environment for further modeling was MathWorks MATLAB R2022a. The take-off was performed using a standard method of engaging the auto-throttle with the TOGA pushbutton during take-off roll, which set the appropriate power setting programmed earlier in the virtual Flight Management Computer (FMC). The take-off was performed manually until 500 ft when the autopilot was engaged and followed the appropriate noise-abatement departure procedure (with thrust reduction altitude programmed in the FMC and acceleration altitude commanded manually by increasing the target speed bug on the Mode Control Panel (MCP)). Simultaneously with the process related to the flight trajectory, equally important NPD data from the ANP Database can be acquired. The database comprises a set of tabulated values of various noise metrics, such as \(L_{Amax}\) or \(SEL\). Each value corresponds to a specific value of thrust and distance from the observer. The data of the aircraft's thrust values and trajectory acquired from the flight simulator present a much broader spectrum of thrust values and distances than the NPD noise metrics in the database, so naturally, the noise data must be interpolated.