3.2.6 Analysis Regarding the Occurrence of the Accident
According to 2.1, 2.6.3, and 2.9, it is considered probable that the accident occurred as follows.
(1) While the Ship navigated on the Harima Nada Sea and proceeded toward the west entrance of
the Akashi Strait with the autopilot function, Officer A, who was on the sole look-out on the
bridge, began to feel drowsy when the Ship passed by the No. 1 Light Buoy in the Harima Nada
Traffic Route and navigated with the course set at approximately 068° toward the west
entrance of the Akashi Strait with a speed of approximately 15.5 kn using the autopilot
steering.
(2) Officer A began to feel drowsy and walked around in the bridge to relieve his drowsiness. Even
though he failed to relieve his drowsiness, he thought he would not fall asleep because he had
not slept during his watchkeeping duties in the past and he continued on the watchkeeping
duty by sitting on the Chair without his drowsiness relieved and without reporting to the
Master that he began to feel drowsy.
(3) As Officer A kept sitting on the Chair without his drowsiness relieved, he had fallen asleep
after the Ship passed by the No. 4 Light Buoy in the Harima Nada Traffic Route.
(4) Because Officer A had fallen asleep, the Ship navigated toward the Sea Wall and collided with
it.