Holdover time begins at which moment?

• A. After the last deice/anti-ice fluid has dried
• B. When final application of the deice/anti-ice fluid commences
• C. At the moment the aircraft begins taxiing
• D. Upon reaching the gate

Answer: (B)

Holdover time is the protective window after de-icing/anti-icing fluid has been applied, during which the aircraft is expected to remain free from ice buildup under the current conditions. The clock starts at the moment the final application of the fluid begins, because that is when the protective film is being laid down and the conditions that determine how long protection will last come into effect. Starting the timer when the last application commences ensures you’re measuring the actual period during which the fluid can work as intended. It wouldn’t begin after the fluid has dried, when taxiing starts, or upon reaching the gate, since those moments don’t mark the start of the protective coating’s effectiveness.