What is the requirement for holding at an alternate airport in terms of duration?

The requirement for holding at an alternate airport is indeed a minimum of 30 minutes. This duration is significant because it allows pilots to manage unforeseen circumstances such as weather changes, fuel considerations, or logistical delays that could affect the safety of the approach and landing at the primary airport.

When planning a flight, especially in conditions where alternate airports are required (such as with limited visibility at the destination), the regulation ensures that pilots have enough time to safely navigate to their alternate, assess the situation, and make informed decisions. The 30-minute criterion embodies the need for safety and preparedness in flight operations, serving as a buffer to accommodate any potential complications during final approach to the alternate airport.

Shorter durations may not provide enough time to handle such unforeseen issues effectively, while longer ones would be excess and could result in unnecessary fuel consumption and time lost. Hence, the 30-minute requirement represents a balanced approach to ensuring safety in aviation operations.