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Navigation & chartwork

Why is AIS not a complete traffic picture?

Short answer

It depends on targets transmitting usable data and being received

AIS is reported data rather than physical detection of every object. It supplements systematic visual and radar observations. Revisit AIS Strengths and Limits.

Sources and scope

Reviewed by Richard Moore on . This answer is scoped to international collision-avoidance and small-craft radar practice; check the current chart, publication, local rules and official operational guidance before acting afloat.

Quick check

Why is AIS not a complete traffic picture?