Related Clues:

• "Send help!"
• Distress letters
• Certain smoke signal
• Plea at sea
• Rescue request
• Foundering call
• 'May-day!'
• Distressing letters
• Coast Guard concern
• It may be tapped out
• Titanic message
• Letters of distress
• Cry for help
• Morse mayday
• Message in a bottle, maybe