What temperature should de-icing fluid dispensed by a ground unit be?

De-icing fluid dispensed by a ground unit should be heated to achieve optimal effectiveness. Heated de-icing fluids have a higher viscosity, which allows them to spread more easily over the aircraft's surfaces and create a more effective barrier against ice and snow accumulation. This allows the fluid to work more efficiently by lowering the freezing point of the existing ice and preventing further accumulation.

Using heated fluid also helps in reducing the surface tension of the fluid, promoting better adhesion and coverage on the aircraft's surface. When de-icing fluids are applied at an appropriate temperature, they are more likely to provide a thorough melting action and ensure that any moisture that could form ice does not settle on the aircraft after the treatment. This is crucial for maintaining safety and performance during flight operations, as ice can significantly affect lift and control.

Other temperature choices, like cold or freezing, would not effectively manage ice and could lead to inadequate de-icing, thus not providing the necessary safety margin required for takeoff. Ambient temperature options, while potentially usable, may not provide the proactive measures needed to deal with severe icy conditions effectively.