Which device provides signaling for both daytime and nighttime from a vessel?

Which device provides signaling for both daytime and nighttime from a vessel?

• A. Signal mirror
• B. Distress signal light
• C. MK-79 signal kit
• D. MK-124 day/night pyrotechnic device

Answer: (D)

Signals that work in both day and night use different cues for visibility: a daytime signal needs to stand out in bright sun, while a nighttime signal requires a bright, high-contrast flare. The MK-124 day/night pyrotechnic device is designed specifically for both conditions, providing a daytime signal and a nighttime signal from a single unit. Its designation itself indicates it’s meant for day and night use, making it the versatile choice for rescue visibility around the clock. Other options are best suited to a single condition: a signal mirror relies on sunlight during the day, a hand flare like the MK-79 is used at night, and a distress signal light is a battery-powered beacon rather than a dual-mode signaling device.

Signals that work in both day and night use different cues for visibility: a daytime signal needs to stand out in bright sun, while a nighttime signal requires a bright, high-contrast flare. The MK-124 day/night pyrotechnic device is designed specifically for both conditions, providing a daytime signal and a nighttime signal from a single unit. Its designation itself indicates it’s meant for day and night use, making it the versatile choice for rescue visibility around the clock. Other options are best suited to a single condition: a signal mirror relies on sunlight during the day, a hand flare like the MK-79 is used at night, and a distress signal light is a battery-powered beacon rather than a dual-mode signaling device.