How do pilots interpret cloud cover percentage?

Pilots interpret cloud cover percentage using the octas system, which divides the sky into eight equal parts. Each octa represents one-eighth of the sky that is covered by clouds. This method allows for a standardized way of reporting and interpreting cloud coverage, providing clear and concise information on weather conditions during flight operations. For example, if a pilot observes that clouds cover four out of eight portions of the sky, it would be reported as four octas of cloud cover. This system aligns with international standards for reporting weather conditions, making it universally understood among pilots and meteorologists.

While other methods such as tenths or percentages may be intuitive, the use of octas is the prevalent practice in aviation to ensure consistency and clear communication about cloud cover, which is critical for flight planning and safety.