What does the term 'Mayday' indicate?

The term 'Mayday' is an internationally recognized distress signal used in maritime communication. It indicates an urgent and life-threatening situation where a vessel or its crew are in grave and imminent danger and immediate assistance is required. The use of 'Mayday' is governed by the International Radiotelephony Spelling Alphabet, and its repetition three times ('Mayday, Mayday, Mayday') signals to all nearby vessels that a serious emergency exists, prompting them to take immediate action to assist.

In contrast, the other options do not convey the same urgent and critical context. A request for routine maintenance does not imply any immediate danger, and neither does a request for additional crew or a weather advisory, which are more routine operational communications rather than distress signals. Understanding the significance of 'Mayday' is crucial for ensuring a timely and appropriate response in emergency situations.