What is an alternate airport in IFR flight planning?

• A. An airport with the longest runway used for emergencies.
• B. An airport identified by ATC for vectoring in case of weather.
• C. The primary airport of a field with primary runway.
• D. An airport designated in IFR flight plan providing a suitable destination if landing at the intended airport becomes inadvisable.

Answer: (D)

An alternate airport is a designated backup destination in an IFR flight plan that provides a suitable place to land if landing at the intended airport becomes inadvisable. It’s chosen so you have a safe option in case weather, runway availability, or other conditions at the destination deteriorate. The alternate should have the necessary instrument approaches and be reachable with the planned fuel, and it’s typically within a reasonable distance.

This isn’t about the longest runway, a specific ATC vectoring point, or the primary airport of the field—the point is having a practical, instrument-landing-capable backup you can divert to if landing at the intended destination isn’t feasible.