When is a takeoff alternate required?

A takeoff alternate is required when the weather conditions at the departure airport are below the authorized landing minimums for the approach procedure being used. This ensures that if a return to the departure airport is necessary shortly after takeoff, the aircraft can safely land at the takeoff alternate, which must have weather conditions that meet the required minima. In this context, the requirement for a takeoff alternate serves to enhance safety, providing an additional landing option that guarantees compliance with regulatory weather standards.

The other scenarios, such as destination weather being below minimums or inadequate fuel, do not specifically trigger the requirement for a takeoff alternate. Although these situations are critical considerations for flight planning and safety, they address different regulatory guidelines. Similarly, the availability of alternates is important, but it does not directly relate to the specific condition of departure weather being inadequate for a safe takeoff.