When is a second alternate required?

• A. When conditions are marginal at the destination and alternate
• B. When destination is marginal only
• C. When alternate is marginal only
• D. Always required

Answer: (A)

In IFR flight planning, you consider alternates to ensure you have a viable landing option if the weather at the destination isn’t enough for a safe arrival. A second alternate becomes necessary only when both the destination and the first alternate are forecast to be marginal—that is, weather that is at or near the landing minimums for the published approaches.

So the correct situation is you file a second alternate when the forecast at the destination is marginal and the forecast at the first alternate is also marginal. If only one of them is marginal, a second alternate isn’t required. If both are reliably above minimums, you wouldn’t need a second alternate.