# Modeling and Analysis of Noise Emission Using Data from Flight Simulators
## 3 Comparative Analysis
### Baseline Scenario Comparison  
Presented in Table 1, the first and seventh scenario are referred to as \"baseline scenarios\" for procedures NADP1 (red-colored) and NADP2 (blue-colored), respectively. They correspond to an aircraft taking off at a maximum take-off weight, in a standard flap configuration, and in standard ISA conditions (i.e., 15 \({}^{\circ}\)C temperature and 1013.25 hPa sea level pressure) using a maximum take-off thrust of 26,000 pounds of force. Both procedures assume 1500 feet above aerodrome elevation as a thrust reduction height but differ in the acceleration altitude, which is 3000 feet for NADP1 and 1500 feet for NADP2.  
Figure 4 presents the profile view of aforementioned baseline scenarios alongside two differential noise maps that were created through the subtraction of \(L_{Amax}\) and \(SEL\) noise levels of both scenarios for each observer: \(L_{Amax}^{NADP2}-L_{Amax}^{NADP1}\) and \(SEL_{2}-SEL_{1}\). The subtraction order implies the following interpretation of colors on the noise maps:  
* Warmer colors (shifted towards red)--the red trajectory (NADP1) is quieter from the perspective of this particular observer;
* Cooler colors (shifted towards blue)--the blue trajectory (NADP2) is quieter from the perspective of this particular observer.  
The noise maps present the difference based on a sixteen-point scale between values of \([-2\;\mathrm{dB},\;2\;\mathrm{dB}]\) so that every color change corresponds to the change of 0.25 dB between the two scenarios.  
It is evident that for the majority of the observers, i.e., in the most areas, there is little to no difference in noise between the two procedures. The most pronounced effect is observed between 6 and 12 km from the start of roll. Along this segment, the NADP1 presents the most visible advantage directly underneath the aircraft's trajectory, which is most apparent on the \(L_{Amax}^{NADP2}-L_{Amax}^{NADP1}\) noise map (the middle one).  
However, due to excess lateral attenuation of the trajectory at a lower altitude, i.e., the blue one (of NADP2), the observers alongside the same segment (between 6 and 12 km), which are laterally displaced from the trajectory, experience lower noise levels from the NADP2 trajectory. The ECAC.CEAC Doc 29, Vol. 2 provides more insight into the lateral attenuation theory, which this model accounts for, despite there being an increasing number of articles criticizing present methods of modeling this effect [37].  
After the \"crossover point\", at which the trajectories of both scenarios cross in the vertical plane, the blue NADP2 trajectory offers a minimal advantage over the red NADP1 trajectory, although the difference is less than 1 dB.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline ID. & **Take-Off Mass [kg]** & **Take-Off Thrust** & **Outside Air** & **Take-Off Flap** & **Thrust Reduction/Acceleration** \\  & & [lbf] & **Temperature** [\({}^{\circ}\)C] & **Configuration** & **[ft AAL]** \\ \hline
1. & 79,000 & 26,000 & 15 & F5 & 1500/3000 \\
2. & 65,000 & 26,000 & 15 & F5 & 1500/3000 \\
3. & 79,000 & 26,000 & 32 & F5 & 1500/3000 \\
4. & 79,000 & 26,000 & 15