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Radar revision module 5 of 9

CPA

Radar Plotting and CPA

Relative motion, closest point of approach, target trails, and manual plotting discipline.

relative motionCPA

4 guided lessons · 8 practice questions · 8 flashcards

3 outcomes · self-guided revision
  • Explain relative motion, closest point of approach, target trails, and manual plotting discipline.
  • Apply relative motion to a realistic onboard situation.
  • Recall the core check: cPA is closest point of approach.

A self-guided revision companion that explains essential concepts, then helps you practise and test them. It supports—but does not replace—recognised instruction, practical training, assessment or certification. Access is a one-time payment, not a subscription.

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Lesson routeWhy Plotting Matters0/1 read

Lesson 1 of 1

Why Plotting Matters

Radar plotting turns a moving echo into a trend. It helps answer: Will the target pass clear? How close? When? Is my avoiding action working?

A single radar observation cannot prove CPA. Plotting needs repeated observations at known intervals, or a reliable tracking aid that you still monitor critically.

  • CPA is closest point of approach.
  • TCPA is time to closest point of approach.
  • Repeated observations reveal relative motion.
  • Plotting is only useful if the target is correctly tracked and own course/speed are known.
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