If you only have AIS, how should you verify the status of another vessel?

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Multiple Choice

If you only have AIS, how should you verify the status of another vessel?

The important idea is to verify another vessel’s status by combining AIS information with what you can actually observe and by evaluating the collision risk using Closest Point of Approach. AIS gives you identity, position, course, and speed, but it can be stale, incomplete, or unreliable in some situations. Seeing the vessel visually confirms its presence and movement and helps check for any discrepancies in the AIS data. Using CPA (and TCPA) lets you translate relative motion into a clear assessment of collision risk: if the predicted closest point is within your safety thresholds, you know you need to take action, such as changing course or speed. This approach is more robust than relying on AIS alone or on a single method of communication. Relying only on radar data won’t confirm the vessel’s identity or status, and assuming AIS accuracy without verification can be risky. While VHF calls can help confirm who you’re dealing with, you may not always have reliable or timely VHF contact, so cross-checking with visual observations and risk assessment from CPA provides a more dependable verification method.

The important idea is to verify another vessel’s status by combining AIS information with what you can actually observe and by evaluating the collision risk using Closest Point of Approach. AIS gives you identity, position, course, and speed, but it can be stale, incomplete, or unreliable in some situations. Seeing the vessel visually confirms its presence and movement and helps check for any discrepancies in the AIS data. Using CPA (and TCPA) lets you translate relative motion into a clear assessment of collision risk: if the predicted closest point is within your safety thresholds, you know you need to take action, such as changing course or speed. This approach is more robust than relying on AIS alone or on a single method of communication.

Relying only on radar data won’t confirm the vessel’s identity or status, and assuming AIS accuracy without verification can be risky. While VHF calls can help confirm who you’re dealing with, you may not always have reliable or timely VHF contact, so cross-checking with visual observations and risk assessment from CPA provides a more dependable verification method.

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