Which device is primarily used for daylight signaling?

• A. Aldis lamps for daylight signaling.
• B. Morse code beacons for daylight signaling.
• C. Signal flags for daylight signaling.
• D. Radio telephone for daylight signaling.

Answer: (C)

Daylight signaling is all about something you can clearly see in bright light without needing power. Signal flags fit that need perfectly: their bright colors and standardized patterns are designed to be read at a distance during the day, so messages can be conveyed quickly by sight alone. Flags can be used from ships or shores, carried by hand, or displayed on a halyard, and they don’t rely on darkness or electrical devices.

Aldis lamps emit light for signaling, but such visual signals are best seen in low light or darkness; in bright daylight their flashes can be washed out. Morse code beacons and radio communications either rely on light in low visibility or on radio transmission, which isn’t a visual day signaling method. So the best choice for daylight signaling is signal flags.