5.1 Mechanism of an Occurrence of Human Insufficient Behavior

　

 In the first step, a lot of the data concerning training utilizing ship-handling simulator was analyzed. All training using ship-handling simulator were carried out at the simulator center in Tokyo University of Mercantile Marine. The number of the data is 70 cases that are recorded by not only documents but also VTR. Moreover, all training scenarios were made based on the new met system for Captains and mates, and the contents of scenarios corresponding to congested area or restricted conditions are operated in not only basic training but also complex training such as BRM training. Table 3 shows representative 20 cases of them. In table 3, the events section indicates the contents caused by human insufficient behavior, and navigational environment at that time are indicated in the section of situation. Furthermore. DCPA and the kinds of vessels corresponding to abnormal closing caused by human insufficient behavior are also indicated in table 3. On the other hand, a quantity of the difference between attainable competency by mariner and required competency by navigational environment was shown as C-Q that was measured based on the concept of formula (3). And the second is used as the unit for dimension of those quantities. As the results of analysis, it was confirmed that human insufficient behavior occurred in the ratio of 55 to a 70 illustrations mentioned above. And it was also found that the condition, C < Q, was fulfilled on each situation. Consequently, it was clarified that human insufficient behavior occurred with high frequency under restricted conditions.

 In the second step, analysis of the mechanism concerning occurrences of human insufficient behavior was executed. Figure 4 show the representative 3 patterns of occurrences of human insufficient behavior, which are extracted from case analysis mentioned above. In figure 4, Q indicates a quantity of the task to be done according to navigational environment, and C indicates attainable competency by mariner. Usually, the conditions C > Q is fulfilled. Under occurrences of human insufficient behavior, however, the condition C < Q is fulfilled because attainable competency is gotten fewer due to superfluous time consumption toward previous task in abnormal situation (1). And abnormal situation (2) in figure 1 indicates other representative pattern of an occurrence of human insufficient behavior.

　

　

　

　

 In abnormal situation (2), it can be found that commencing time to accomplish the task to be done was delayed. Consequently, Q exceeds C" and human insufficient behavior occur. Furthermore, in abnormal situation (3), it can be found that there is no time to accomplish the final task because attainable competency toward previous task exceeds the line of limit. And it is possible to verify these abnormal cases caused by human insufficient behavior with the result of experiments or actual training records utilizing ship-handling simulator. Figure 5 indicates representative result of experiments for verification of proposal concept. The fairways shown in figure 5 indicate the Uraga Suido and Nakano-se traffic routes that are setting up in Tokyo Bay. These traffic routes were used for experimental scenario, and the condition, Q > C, was reproduced into the scenario. In the scenario, although final task was an altering course along the planned course on the fairways mentioned above, 3 kinds of tasks were given to subjects before executing of final task. Those 3 kinds of tasks are adjusting course under strong tideway, fixing own position by the date of GPS, and making a plan for maneuvering with consideration of the distance of new course. And subjects have to handle own ship on the next course, which is planned on the 3^rd task after accomplishment of 3 kinds of tasks mentioned above. On the other hand, required and attainable competency to accomplish each task can be estimated from figure 1 and figure 3 . And it could be calculated that attainable competency to accomplish all tasks on 3^rd grade navigation officer was 646 seconds. Then, for making the condition for an occurrence of human insufficient behavior, the initial position of this scenario was set up at the point of 600 seconds before typical altering point in this scenario. Consequently, the condition, Q > C, was fulfilled. And subjects for this experiment are a Captain who has the license for mariner master and a 3/0 who has the license for 2^nd grade navigation officer. As the result of experiments, it was confirmed that 3/O spent 659 seconds to accomplish 3 kinds of tasks before altering course, and overshooting caused by 3/O's insufficient behavior occurred. In figure 5, solid line indicates the trail of ship handling by Captain, and fine solid line indicates the trail of ship handling by 3/O. In this case, attainable time to alter course within a range designated was few seconds on 3/O. This case exactly corresponds to abnormal situation (1) in figure 4. And next illustrations indicate the abnormal situation (2) and (3). In abnormal situation (2), attainable competency toward Q, namely C", is gotten fewer due to delay of beginning time to execute former tasks. And abnormal situation (3) is the case in which there is no time to accomplish the final task due to excess of the time to accomplish previous or past task. These abnormal situations were confirmed from training records mentioned above. Figure 6 indicates the abnormal situation (2) and figure 7 indicates the abnormal situation (3).