For a CPA Alarm to sound, which condition must be met?

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Multiple Choice

For a CPA Alarm to sound, which condition must be met?

CPA alarms are built on predicting where and when two vessels will be at their closest point of approach. To warn you effectively, the system uses two thresholds: how close the vessels would get (the range at CPA) and how soon that closest point would occur (the time to CPA). The alarm sounds only when both conditions indicate a real risk: the predicted CPA distance is within the minimum safe range and the time to reach that CPA is within the alert window. If only the distance is small but the CPA would occur far in the future, there’s time to maneuver and the alert isn’t as urgent. If only the time to CPA is short but the CPA distance is still safely large, there isn’t an immediate danger. Requiring both criteria helps avoid nuisance alarms and ensures you’re warned when a genuine collision risk exists.

CPA alarms are built on predicting where and when two vessels will be at their closest point of approach. To warn you effectively, the system uses two thresholds: how close the vessels would get (the range at CPA) and how soon that closest point would occur (the time to CPA). The alarm sounds only when both conditions indicate a real risk: the predicted CPA distance is within the minimum safe range and the time to reach that CPA is within the alert window. If only the distance is small but the CPA would occur far in the future, there’s time to maneuver and the alert isn’t as urgent. If only the time to CPA is short but the CPA distance is still safely large, there isn’t an immediate danger. Requiring both criteria helps avoid nuisance alarms and ensures you’re warned when a genuine collision risk exists.

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