Navigation General · Radar Plotting & CPA
Which action, if taken by own ship, would NOT directly change the CPA of an approaching target as seen on a true-motion radar display?
- AAltering course 30° to starboard
- BReducing speed by 4 knots
- CIncreasing radar gain to maximum✓ Correct
- DAltering course 30° to port
Explanation
Increasing radar gain is a display adjustment and has no effect on the actual closest point of approach between the two vessels. Only physical changes to own ship's course or speed (or the target's maneuvers) alter the CPA. Maximum gain may saturate the display with noise but does not change the vessels' trajectories.
Authority: Radar Navigation Manual (Pub. 1310), Ch. 4
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