De icing fluid is only effective for a set period of time > Holdover Time (HOT) is the length of time an aircraft can wait after being treated prior to takeoff

De icing fluid is only effective for a set period of time > Holdover Time (HOT) is the length of time an aircraft can wait after being treated prior to takeoff. Holdover time is influenced by the fluid dilution, ambient temperature, wind, precipitation, humidity, aircraft skin material, aircraft skin temperature, and other factors. If the Holdover Time is exceeded the aircraft must be re-treated before takeoff.