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What is the most accurate description of TYPE 1 and TYPE 2 ICING fluids?
  • A
    TYPE 1 fluid is a de-icing fluid that removes icing contaminants efficiently, although it only offers protection against contamination for a limited period. TYPE 2 fluid is an anti-ice fluid that gives protection against contamination for a longer time than the TYPE 1 deicing fluid.
  • B
    TYPE 1 fluid is an anti-ice fluid that gives lasting protection against contamination. TYPE 2 fluid is a combination of de-icing/anti-icing fluid.
  • C
    TYPE 1 and TYPE 2 fluids always apply for helicopter de-icing/anti-icing operations.
  • D
    TYPE 1 fluid is an anti-ice fluid that gives protection against contamination for a longer time than the TYPE 2 deicing fluid. TYPE 2 fluid is a de-icing fluid that removes icing contaminants efficiently, although it only offers protection against contamination for a limited period.

Refer to figure.
There are four main types of deicing and anti-icing fluid: Type I through to Type IV. They each have different viscosities and properties, which make them best suited for different circumstances or for aircraft with different operating capabilities. They are also typically, dyed in different colours to allow for differentiation.

  • TYPE I

This is a Newtonian fluid (meaning its viscosity remains constant) and is generally used only for aircraft deicing to remove initial contamination from aircraft surfaces. It is not effective as an anti-icing fluid as it has a negligible holdover time (HOT), meaning frozen contaminants start to re-form too quickly after treatment, thus making it operationally unviable

  • TYPES II, III & IV

These are non-Newtonian (meaning its viscosity can alter) viscous fluids used for anti-icing purposes. They have a longer holdover time (HOT), making them viable for ice prevention and anti-icing needs. These types differ mostly based on the operational capabilities of the aircraft they are being applied to - Type II, for example, is suited to aircraft with rotation speeds exceeding 100 knots, and Type III is for those aircraft that rotate below this speed. Type IV has similar aircraft capability to Type II; however, it is differentiated by its longer HOT - making it more suitable for busier aerodromes or those with limited remote de/anti-icing facilities.

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