Navigation General · Radar Principles
Radar shadow occurs when:
- ARain clutter masks targets beyond a precipitation cell
- BA large target or land mass blocks the radar beam, creating an undetectable zone behind it✓ Correct
- CThe antenna tilt angle is set too high, causing the beam to overshoot surface targets
- DSea clutter returns obscure a vessel close aboard
Explanation
Radar shadow (also called radar shadow zone) is the area hidden behind an obstruction — such as a headland, large ship, or island — where the radar beam cannot penetrate. Targets in this shadow are invisible on the display. Understanding shadow sectors is critical to safe watchkeeping because a vessel may be undetected even though the radar is operating normally.
Authority: Radar Navigation Manual (Pub. 1310), Ch. 3
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