# Classification and Causes Identification of Chinese Civil Aviation Incident Reports
## 4 Cause Extraction
### Causes Description  
There are always several causes behind every unique event. In the example in Figure 1, the distraction of the pilots, lack of cross-checking, interfering movements, complex weather (thunderstorms), and poor communication between the pilots and traffic controllers were the causes to be identified. These causes are not independent but are interrelated logically and temporally. The HFACS model [33] was adopted to categorize causes structurally. In this study, we categorize causes into four categories: Equipment, Environment, Human, and Organization. Before identification, reports were labelled manually according to the content.  
In implementing the labelling, we performed a content analysis on the 1775 reports of the dataset in Section 3. As shown in Table 7, 25 causes were listed, along with their coding scheme and occurrences. In detail, equipment causes are mechanical and electrical faults that occur during the flight or design phase. Environmental factors are elements that are beyond human control, such as the external environment and unexpected situations. Human attributes are unsafe actions of humans consisting of decisions, skill-based or perceptual errors, violations of pilots, inadequate supervision by traffic control, and incorrect  
\begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline  & **DP** & **EB** & **GOM** & **EI** & **CS** & **TS** & **MB** & **LP** & **CI** & **BS** & **Other** \\ \hline DP & 36 & 1 & 2 & 0 & 0 & 0 & 1 & 3 & 0 & 0 & 0 \\ EB & 0 & 24 & 1 & 1 & 0 & 0 & 2 & 0 & 0 & 0 & 1 \\ GOM & 2 & 1 & 30 & 0 & 3 & 0 & 3 & 1 & 0 & 1 & 0 \\ EI & 1 & 0 & 1 & 15 & 0 & 0 & 0 & 0 & 0 & 0 & 0 \\ CS & 0 & 0 & 1 & 0 & 4 & 0 & 0 & 0 & 0 & 0 & 0 \\ TS & 0 & 0 & 0 & 0 & 0 & 4 & 0 & 0 & 0 & 0 & 0 \\ MB & 0 & 0 & 0 & 3 & 0 & 0 & 48 & 1 & 0 & 0 & 0 \\ LP & 4 & 1 & 1 & 1 & 0 & 0 & 0 & 27 & 0 & 0 & 0 \\ CI & 1 & 0 & 0 & 0 & 0 & 0 & 0 & 4 & 0 & 0 \\ BS & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 123 & 0 \\ Other & 0 & 0 & 1 & 0 & 0 & 0 & 0 & 0 & 0 & 1 \\ \hline \hline \end{tabular}
\end{table}
Table 6: Confusion matrix of classification for the test dataset.  
\begin{table}
\begin{tabular}{l c c c} \hline \hline  & **Precision** & **Recall** & **F1-Score** & **Support** \\ \hline Bird strike & 0.99 & 1.00 & 0.99 & 123 \\ Deviation from procedure & 0.82 & 0.84 & 0.83 & 43 \\ Mechanical breakdown & 0.89 & 0.92 & 0.91 & 52 \\ Ground operation and maintenance & 0.81 & 0.73 & 0.77 & 41 \\ Landing problems & 0.84 & 0.79 & 0.82 & 34 \\ Engine breakdown & 0.89 & 0.83 & 0.86 & 29 \\ Environmental incident & 0.75 & 0.88 & 0.81 & 17 \\ Cabin safety & 0.57 & 0.80 & 0.67 & 5 \\ Communication interruption & 1.00 & 0.80 & 0.89 & 5 \\ Tail strike & 1.00 & 1.00 & 1.00 & 4 \\ Other & 0.50 & 0.50 & 0.50 & 2 \\ \hline Weighted value & & 0.85 & 0.86 & 0.85 & 355 \\ \hline \hline \end{tabular}
\end{table}
Table 5: Final classification results.  
actions of the ground crew. Organization causes influences flights at the management level, including shortcomings in standards, supervision, or pilot training. The role of a cause may vary across incidents. For example, in the case of bird strike, engine failure, and landing problem events, engine failure is a precursor, a consequence, and both a precursor and a consequence.