Nominal Range is the distance a light can be seen based on what visibility condition?

• A. 20 nm visibility
• B. 10 nm visibility
• C. Meteorological visibility
• D. Geographic visibility

Answer: (B)

Nominal range is the distance a fixed light can be seen under a standard visibility condition. That standard is 10 nautical miles of meteorological visibility, which provides a uniform reference used for navigation aids. It’s different from geographic range, which is limited by the observer’s height and the Earth’s curvature, and from luminous range, which depends on the light’s intensity and atmospheric clarity but still uses the standard 10 NM baseline. So the distance defined for nominal range is 10 nautical miles of visibility.