Why must a small craft remain in the risk picture when its echo fades in rough water?
Short answer
Aspect and set-up can weaken a real return; collision risk remains
Echo strength is conditional. A fading return does not remove the physical contact: track it with repeated, independent evidence. Revisit Echo Strength, Aspect, and Reflectors.
Quick check
Why must a small craft remain in the risk picture when its echo fades in rough water?