When conducting operations in ground icing conditions, when are holdover timetables required?

Holdover timetables are vital for ensuring the safety of aircraft operations in ground icing conditions, as they provide guidelines on the effective duration of anti-icing and de-icing fluids. These timetables help determine how long a plane is protected after the application of these fluids, particularly in varying weather conditions.

The rationale for the answer focusing on Type IV anti-ice solutions specifically lies in the unique properties of these fluids. Type IV solutions are designed for longer-lasting protection against ice and snow accumulation compared to other types of de-icing fluids. Therefore, when they are employed, it becomes necessary to adhere to holdover timetables to ensure the correct and safe operational procedures are followed.

In contrast, even though holdover timetables are essential for maintaining safety, the other scenarios listed do not imply the same necessity. For example, using a different type of fluid may not have the same implications for holdover time, and conditions like light snowfall might not necessitate strict adherence to these timetables. Additionally, stating that holdover timetables are never required overlooks the critical role they play in maintaining safety during ground icing operations. Hence, focusing specifically on the use of Type IV anti-ice solution provides the best guideline for when holdover