How is the time determined for holdover with deicing fluid?

The time for holdover with deicing fluid is determined predominantly by the estimation of ice accumulation risk. This method involves assessing environmental factors that may contribute to the formation of ice, such as temperature, humidity, and ongoing precipitation.

When deicing fluid is applied to an aircraft, it provides a certain period during which the aircraft is protected from ice and snow accumulation. This protection time is known as the "holdover time." Estimating the risk of ice accumulation allows ground personnel to make informed decisions about whether the current deicing treatments provide adequate safeguarding for the duration of expected weather conditions before takeoff.

Other factors such as temperature and flight operations do play a role in overall procedures related to deicing, but they are not the primary determinants of holdover time. For instance, while temperature can influence the effectiveness of the deicing fluid, it is the comprehensive assessment of ice accumulation risk that directly dictates how long the aircraft remains safe from ice after treatment.