When should a vessel raise a distress signal?

A vessel should raise a distress signal when it is in danger and requires immediate assistance. This is the fundamental purpose of a distress signal, which is designed to alert other vessels and rescue services that the situation is critical and that help is needed as soon as possible. Whether due to navigation hazards, mechanical failure, adverse weather conditions, or other emergencies, the primary goal of signaling distress is to ensure the safety of everyone on board and to facilitate a timely rescue.

The other options do not accurately reflect the circumstances under which a distress signal should be raised. Scheduled safety drills are essential for training purposes but do not constitute a real emergency that necessitates a distress signal. Similarly, entering a busy harbor may present challenges, but it does not imply the immediate need for assistance. Lastly, while a crew member falling overboard is serious, the appropriate response would depend on the situation's specifics. If the incident poses an immediate danger to the vessel or crew, a distress signal may be warranted, but it is not universally applicable to all cases of a person overboard.