JRC JMA-5912-6 Instruction Manual page 253

Relative Vector Mode
The relative vector does not represent the true motion of the target, but its relative relation with own ship.
This means that a target with its relative vector directed to own ship (passing through the CPA Limit ring) will
be a dangerous target. In the Relative Vector mode, it can be seen at a glance where the CPA Limit of the
dangerous target is.
CPA ring
Therefore, the True / Relative mode shall optionally be used for the purpose of observation: the True vector
mode for grasping the true aspect of a target, and the Relative vector mode for grasping a target's closest point
of approach (CPA).
[II] Vector Length (Vector Time)
The vector length of a target is proportional to its speed, and the vector time can be switched in a range of 1 to
60 minutes.
The diagram below illustrates a vector length of a target for 6 minutes, and the tip of the vector represents the
target's position expected to reach 6 minutes later.
Future predicted position
(6 min later in this example)
Refer to Section 5.1.7 Setting Vectors for how to change the vector time.
HL
HL
Current position
5-10
5.1 Preparation
The true vector is
not displayed
Relative vector
5