Which statement about NSC is true?

• A. No clouds below 5,000 ft (or highest MSA) and no CB or TCU
• B. No clouds below 1,000 ft
• C. No significant weather present anywhere
• D. Visibility greater than 50 km

Answer: (A)

NSC means No Significant Cloud and it’s a shorthand used in aviation weather to flag that low-level clouds and convective hazards are not expected in the area. Specifically, it indicates there are no clouds down to about 5,000 ft above the surface (or above the highest published minimum safe altitude in the area) and no cumulonimbus or towering cumulus clouds. That’s why the statement that best matches NSC is: there are no clouds below 5,000 ft and no CB or TCU in the area.

Why the other options don’t fit: lowering the threshold to 1,000 ft isn’t how NSC is defined, so saying no clouds below 1,000 ft is incorrect. Claiming no significant weather anywhere is broader than NSC and not what this term specifies. And saying visibility exceeds 50 km isn’t what NSC communicates; NSC focuses on cloud presence, not direct visibility measurements.