What must be true for an airport to be qualified as an alternate airport in case of an approved instrument approach?

To qualify as an alternate airport in the context of approved instrument approaches, specific weather criteria must be met to ensure that aircraft can safely land there if the primary airport is unapproachable.

In the case of a nonprecision approach, the minimum weather requirements stipulate that the forecast minimum ceiling must be at least 800 feet above ground level and visibility must be 2 statute miles (SM) or better. This standard is grounded in the need for sufficient visual references during the approach, critical for pilot safety and operational integrity.

These thresholds are set to ensure there is a reasonable assurance of adequate weather conditions at the alternate airport in case diversions are necessary. They are also aligned with regulatory requirements established by aviation authorities to promote safe flight operations under instrument flight rules (IFR).