Under what condition do you need a takeoff alternate?

The requirement for a takeoff alternate is specifically related to situations where the weather conditions at the departure airport are below the minimums specified for landing. This is crucial for safety because if a pilot takes off and then is unable to return to the departure airport due to deteriorating weather conditions, they must have an alternate airport designated where landing can be safely performed. In such cases, the takeoff alternate serves as a backup option to ensure that the flight can still land safely if necessary.

On the other hand, having perfect weather conditions does not necessitate a takeoff alternate, as there would be no concern about not being able to return to the launch point. Similarly, altitude limitations like being above flight level 200 (FL200) do not directly correlate with the need for a takeoff alternate; rather, it's about safe landing options in adverse weather conditions. Lastly, operating over water does not inherently require a takeoff alternate either unless the same weather conditions apply. Thus, the key condition here is the need for safety and preparedness when weather is below landing minimums.