What is meant by the term "holdover time" in aviation?

Holdover time in aviation refers specifically to the estimated duration that deicing fluid remains effective in preventing ice accumulation on an aircraft's surfaces. This concept is crucial for aircraft operations in winter weather conditions, where ice and snow can pose significant safety hazards. When an aircraft is deiced, the application of deicing fluid provides a protective layer that enhances the aircraft's ability to maintain optimal performance during takeoff and flight.

Understanding holdover time is vital for ground crew and flight operations, as it helps determine how long the aircraft can remain stationary after deicing before takeoff must occur. If an aircraft exceeds its holdover time without taking off, new deicing measures might be needed to ensure safety and performance. Holdover times vary based on a range of factors, including the type of deicing fluid used, ambient temperature, and weather conditions, which directly impact the effectiveness of the fluid in preventing ice formation.