Related Clues:

• Worrisome letters to send
• It may go up in smoke
• Flashed message
• Help line?
• 'SOS!'
• Brand invented by an aluminum pot salesman
• Mariner's ''Mayday!''
• Emergency letters
• Titanic's call
• Scary signal
• Plea from the sea
• Castaway's call
• "--- yer old man!"
• Stranded traveler's signal, perhaps
• Seaman's "Help!"