The cloud criterion is reached when the cloud base is below which threshold?

• A. When broken (BKN) or overcast (OVC) below aerodrome's highest alternate minimum cloud base or 1500 ft, whichever is greater
• B. Cloud base above 2000 ft
• C. Cloud base between 3000 and 4000 ft
• D. Cloud base at 1000 ft or higher

Answer: (A)

In IFR planning for alternates, the weather standard includes a cloud base criterion. You compare the aerodrome’s highest alternate minimum cloud base with 1500 ft, and take the higher of the two as the threshold. If the actual cloud base (when the sky is broken or overcast) drops below that threshold, the cloud criterion isn’t met for using that aerodrome as an alternate. This rule ensures you have enough ceiling to execute the approach and possible missed approach safely, especially when visibility is limited. Therefore, the relevant threshold is the greater of the aerodrome’s highest alternate minimum cloud base or 1500 ft. The other numeric options don’t reflect this combined rule.