How does Type IV anti-icing fluid differ from Type I fluid?

Type IV anti-icing fluid is designed to be thicker than Type I fluid, which allows it to adhere to aircraft surfaces more effectively. This characteristic contributes to a longer protection period against the accumulation of ice and snow on the aircraft. The increased viscosity of Type IV fluid helps provide a more durable anti-icing barrier, allowing it to remain effective for a longer duration, even in conditions where ice formation is likely.

In contrast, Type I fluid is thinner and is primarily used for de-icing, which means it works to remove existing ice or snow but provides shorter protection afterward. Thus, while Type I is effective in immediate de-icing situations, Type IV is specifically formulated to give longer-term protection against ice formation, making it suitable for use in varying weather conditions where longer hold times are necessary.