What is the minimum visibility requirement at an alternate airport?

The minimum visibility requirement at an alternate airport is established to ensure that pilots have adequate conditions for landing, should they need to divert to that airport. According to aviation regulations, the appropriate criterion for visibility is defined as 1 statute mile (SM) above the lowest compatible minimum for the instrument approach procedure that will be used for landing.

This requirement is in place to provide a safety margin; by specifying visibility that is above the minimum, it allows for variations in weather and provides pilots with a buffer to make safe decisions regarding their approach and landing. Such standards are crucial for maintaining safety during flight operations, especially when the intended airport is not accessible due to poor weather conditions.

The other options outline different visibility figures that may not align with the established regulations for alternate airports. Maintaining a requirement of 1 SM above the lowest compatible visibility minimum ensures that pilots have a reliable guideline for making safe alternate landing choices.