What needs to be checked to ensure a legal alternate?

To determine the legality of an alternate airport for a flight, it is essential to check the weather conditions at that alternate airport. The visibility and cloud cover must meet specific criteria established by regulations, which state the minimum weather requirements for an airport to be designated as an alternate. If the weather is below these minimums, the alternate cannot be considered legal, as it may not be viable for landing if the main destination experiences adverse conditions.

This emphasis on weather ensures that pilots have viable options in case of an unforeseen situation upon arrival, promoting safety during the flight. Other factors, such as flight plans, air traffic control clearances, and aircraft weight, are important for overall flight operations but do not specifically determine whether an alternate airport is legally acceptable.