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21 Accidents/Incidents by Type 180 160 140 120 # of Events 100 80 60 40 20 0 LDOR LDUS TOOR Accidents 121 48 55 Incidents 153 45 37 Type of Event Figure 8. Distribution of events by type. A summary of anomalies by category for takeoff overrun rubber). For contaminated runways, ice was the most pre- events is presented in Figure 13. For most of the events there dominant contaminant in the accidents and incidents evalu- were anomalies in the takeoff procedures. When there were ated. Three additional factors with high incidence for landing anomalies related to weather conditions there were signifi- overruns are long touchdown, high speed during the ap- cantly more events in the accident category than incidents. proach, and the presence of rain. The same conclusion is generally true for human errors, while According to the numbers presented in Figure 15 for system faults are mostly related to incidents. LDUS, the most frequent anomaly was low visibility, followed Anomalies reported or identified were included within each by rain, particularly for the accidents. Gusting conditions had of these categories, as shown in Figure 14 for LDOR events. high incidence for these accidents. As expected, approaches Only the anomalies having more than 10 percent incidence are below the glide path are an important anomaly for this type reported here, but a comprehensive list of anomalies is avail- of event. Visual illusion was a significant factor only for land- able in the accident/incident database. ing undershoots. The highest incidence anomalies for landing overrun are The presence of rain, gusting, crosswind, and low ceiling contaminated and wet runways. Sometimes these anomalies conditions were most predominant for these accidents when occur in combination (e.g., a wet runway contaminated with compared to incidents. Figure 16 depicts the most frequent anomalies for TOOR Events by Type events. As expected, rejecting the takeoff operation at high speeds led to the majority of accidents and incidents. The sec- TOOR ond most important anomaly was incorrect planning, such 20% as: aircraft overweight, short takeoff distance available, and incorrect load distribution in the aircraft. Basically, the fac- tors are equally frequent for accidents and incidents, except for the presence of rain, gusting, and crosswind conditions. These were more important for accidents when compared to incidents. A summary of the most frequent anomalies for all events by accident type is shown in Table 5. The "X" represents the LDOR anomaly was present in more than 10 percent of the cases for LDUS 60% the specific event type: LDOR, LDUS, or TOOR. 20% Unreported Events When using U.S. accidents and incidents as a sample, the number of reported incidents (53 percent) is close to the Figure 9. Distribution by type of event. number of accidents (47 percent), when it was expected to see