# Impacts of Flight Operations on the Risk of Runway Excursions
## 4 Operational Analysis of Crucial Stages
### Holistic Analysis  
During the holistic analysis, we focused primarily on the variations in the control column, pitch angle, angle of attack, and inertial vertical speed of the aircraft. The control column is the main device that controls the aircraft to perform flare and ground operations. Pitch angle is employed to analyze the aircraft's attitude, and through controlling the pitch angle, one can adjust both the aircraft's angle of attack and the elevator's deflection, thereby modifying the lift and drag forces and maintaining control during landing. The analysis of inertial vertical speed and vertical acceleration provides valuable insights into the aircraft's vertical performance and efficiency. The analysis of vertical acceleration is closely associated with flight loads and passenger comfort. Based on Figure 2, Style 1 operation exhibits high velocity and significant inertial vertical speed, yet results in a short ground distance and an average touchdown duration of 9.74 s. This indicates that the pilot, in order to achieve a relatively short ground contact, maintains a substantial pitch angle post-flare, with the maximum pitch angle occurring when the deceleration board is engaged. Analysis of the angle of attack at various points reveals that Style 1 consistently sustains a heightened angle post-flare, whereby increasing the angle of attack at the critical angle yields a greater lift coefficient. This serves to expedite the reduction in inertial vertical speed, resulting in effective vertical speed control. Although the vertical acceleration during landing is generally large, appropriate management of touchdown load is achieved despite a relatively high ground speed during the landing process. Therefore, Style 1 can be characterized as an aggressive deceleration type. Style 2 operations are relatively conservative, characterized by an extended touchdown duration averaging 11.03 s. A significant pitch angle is maintained at the runway threshold and during the flare, while the angle of attack remains relatively modest throughout, possibly to mitigate the risk of hard landings. However, this approach may result in insufficient reduction in inertial vertical speed. Additionally, the average speed during \begin{table}
\begin{tabular}{c c c c c} \hline  & **Monitoring Indicators** & **Averages** & **Standard Deviations** & **Standard Errors** \\ \hline \multirow{2}{*}{Style 3} & Groundspeed & 129.78 kt & 8.22 & 0.57 \\  & Airspeed & 128.45 kt & 6.80 & 0.47 \\ \hline \end{tabular}
\end{table} 
Table 6: _Cont._  
Figure 2: Comparison of aircraft attitude and control. reverse thrust initiation is minimal, at 129.65 knots. Consequently, Style 2 can be classified as a conservative landing type. Style 3 represents a wind-affected type of landing. With a touchdown duration of 10.49 s, the landing process is notably influenced by wind speed, resulting in significant roll angles and extensive control wheel input. In light of the above, Style 1 can be considered a relatively radical operational approach. It clearly possesses advantages in mitigating the risk of runway excursion, as such maneuvers effectively reduce the touchdown distance. On the other hand, Style 3, characterized by larger control inputs and higher rates of heading change, increases the risk of runway excursion. The clustering center of this style exhibits the highest risk of runway excursion. Lastly, Style 2 is associated with a prolonged touchdown phase, inadequate descent rate control, and, consequently, an increased risk of runway excursion. Upon analysis of the vertical acceleration, as depicted in Figure 3, it is evident that the average touchdown acceleration for Style 1 stands at 1.193 g. However, the maximum acceleration during the landing process reaches 1.336 g. Moreover, 28 flights within Style 1 experienced a maximum acceleration upon landing exceeding 1.5 g, with the highest recorded at 1.76 g, indicating a risk of excessive landing accelerations.