What determines if an airport is qualified for alternate use regarding final approach NAVAIDs?

An airport qualifies for alternate use regarding final approach NAVAIDs when those NAVAIDs are unmonitored. This is crucial because unmonitored NAVAIDs typically indicate that they do not require continuous oversight, allowing pilots to rely on them for navigation during instrument approaches, especially when approaching an alternate airport. The use of unmonitored NAVAIDs signifies that while they are functional and can provide necessary guidance, their operational status and reliability are not constantly supervised.

In contrast, the monitoring of NAVAIDs involves regular checks and oversight, which can impact their use for alternate airport considerations. If a NAVAID is monitored, it indicates that any outages or malfunctions would be detected and addressed in real-time, which may not align with the requirements for alternate airport operations where pilots need assurance of NAVAID reliability without constant oversight.

Hence, when determining suitability for alternate use, the key factor is whether the NAVAIDs are unmonitored, as this plays a significant role in assessing the navigational reliability of the airport in question.