JRC JMA-7710-6 Instruction Manual page 36

1.6
Basic Concept of Collision Avoidance ····················································
Collision avoidance has two aspects: prediction and avoidance of collision. The prediction of
collision is to predict that plural ships come across at a point, and the avoidance is to maneuver
ships so as not to come across at the same point with other ships.
In actual practice of maneuvering ships, however, a closed area should be considered instead of a
single point. This concept is the CPA (Closest Point of Approach). To predict a collision, it is
also necessary to take into account the times that ships take to reach the CPA, and these times are
called the TCPA (Time to CPA), which is used to judge dangers of collision. Fig. 1.9 shows the
chart called "Collision Triangle."
Fig. 1.9 Collision Triangle
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