When does holdover time begin?

Holdover time refers to the duration during which anti-icing fluids remain effective on an aircraft after application, protecting it from the accumulation of ice or snow. This time is critical to ensure that the aircraft is safe for takeoff, particularly in winter weather conditions.

Holdover time begins when the final de-icing or anti-icing application commences. This is because the effectiveness of the anti-icing fluid is determined by the specific conditions and the time elapsed since it was applied. Starting holdover time at this point allows crews to accurately monitor the duration of effectiveness and manage the aircraft's readiness for departure.

Understanding that holdover time is linked to the application of anti-icing procedures is essential for maintaining safety and ensuring that the aircraft does not become ice-laden before takeoff. Other options indicate different stages in the pre-flight timeline, but they do not specifically relate to the critical timing of anti-icing fluid application, which is why they do not adequately define when holdover time begins.