What disqualifies an alternate during flight operations?

An alternate airport must meet specific operational requirements to be considered valid during flight operations. One critical aspect is the type of navigational aid (NAVAID) availability at the alternate airport.

The correct answer highlights a condition where all compatible approaches to the alternate airport rely on unmonitored NAVAIDs. If this is the case, it disqualifies the airport from being a suitable alternate because unmonitored NAVAIDs can lack the reliability and assurance needed for safe navigation during inclement weather or low visibility conditions. Monitored NAVAIDs provide enhanced safety through continuous monitoring, making it easier for pilots to trust the navigation information they receive.

In contrast, the other options may not directly relate to the disqualification assessment concerning NAVAIDs. For instance, referencing the availability of weather reporting or the runway length at the alternate airport does not inherently affect the fundamental navigational safety criterion tied to monitored versus unmonitored NAVAIDs. This highlights the importance of understanding the operational standards required for an alternate airport's approval during flight planning.