What are the minimum weather requirements for an alternate airport with two usable precision approaches?

For an alternate airport that has two usable precision approaches, the minimum weather requirements are specifically outlined in aviation regulations. In this case, the correct answer is 400-1, which means that to use an airport as an alternate, you need an expected ceiling of at least 400 feet above ground level and visibility of at least 1 mile.

This standard is established to ensure that pilots have adequate conditions to approach and land at the alternate airport if needed. The rationale behind the 400-1 requirement is based on the availability of precision approaches, which are designed to provide a more accurate and stable approach path compared to non-precision methods. Such precision approaches significantly enhance safety in challenging weather conditions, thus justifying the lower minimums.

In contrast, the other options present higher minimums that are generally applicable in cases of lesser precision or non-precision approaches. Hence, while they may ensure safer operations under different circumstances, they do not apply when two precision approaches are available at the alternate airport. Understanding this distinction is crucial for planning alternate airports properly within the context of Canadian aviation regulations.