All About Aircraft De/Anti-Icing Fluid Types
Aircraft deicing and anti-icing fluids are the core component of most aircraft de/anti-icing operations (although mechanical methods such as brushing can be used too). There are various types of fluid with differing technical properties: some are more suitable for removing frozen ice contamination from aircraft, whilst others prevent it from reoccurring.
Read on to find out about the different types of aircraft de/anti-icing fluids; about the testing and regulatory environment surrounding them, and the services Miles Aviation Consulting Ltd and our team of de/anti-icing and ground operations specialists can provide you.
The basics of aircraft de/anti-icing
Aircraft de-icing is the process of removing frozen contaminant i.e. ice, snow, frost or slush from the surfaces of an aircraft, notably the wings, tail, horizontal stabiliser and fuselage. Failure to remove frozen contaminant prior to flight creates a safety risk which, if ignored, could result in fatal consequences.
On a “clean” wing, airflow flows freely over the smooth surface and produces lift. A “contaminated” wing interrupts airflow and reduces and inhibits the ability to produce lift. Frost or ice with a thickness of just 3 to 5 mm can reduce lift by 30%.
In most cases, contamination is removed prior to flight through the application of De and Anti-Icing fluids. De-Icing fluid is normally applied heated, designed to melt the ice and ‘cleans’ the aircraft. This is normally followed by an application of Anti-Icing fluid, which is a thickened fluid, adhering to the aircraft surfaces, protecting them from re-freezing.
What are the different types of de/anti-icing fluid?
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 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 for prevention purposes.
TYPES II, III & IV
These are non-Newtonian (meaning its viscosity can alter) viscous fluids used for anti-icing purposes. They have a longer 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 for those aircraft which 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.
Required for use in winter aircraft operations, de/anti-icing fluids have a freeze point as low as, or below, -37 degrees Celsius. Deicing fluid is most effective when applied hot, whereas anti-icing fluids are more effective when applied cold. Types II and IV are the most commonly used types in the industry.
Fluid testing and industry standards relating to de/anti-icing fluid
These fluids must be tested regularly, both at delivery, as well as whilst in-service, for their viscosity, refractive index (concentration), pH levels, and for any visible contamination. Deicing and anti-icing processes play vital roles in the safety of any aircraft, therefore checks and measures must be in place. Fluids falling below manufacturer limits may not perform as expected; HOT must be correctly calculated.
This is a highly controlled part of the industry with strict training requirements and industry standards for de/anti-icing procedures, as well as fluids, set out by SAE International. Industry standards for the manufacturing of de/anti-icing fluids are determined by SAE International in documents AMS1424/1428.
Aircraft de/anti-icing: A highly controlled part of the industry with high safety importance
You can read more about aircraft de/anti-icing processes, what’s involved, and why they are so important, in our blog ‘What is Aircraft Deicing?’ by clicking here. Fundamentally, using de/anti-icing fluids to remove frozen contamination from aircraft is vital to ensure safe aircraft operations even throughout the harshest of cold weather conditions and operating environments. Significant testing, training, and industry best-practices ensure this happens effectively.
Would you like more information about aircraft de/anti-icing, and the services we at Miles Aviation Consulting can provide?
We are specialists in de/anti-icing, ground operations and ground handling - and can provide your organisation with high-quality training courses, documentation and ground operations manuals, audit services, and consulting/project support. If you have a bespoke requirement and think we can help, don’t hesitate to get in touch with our team.
Did you know…
We provide high quality training courses in de/anti-icing processes, including management training, instructor training, and front-line operator training. See our course pages below to find out more about our specialist de/anti-icing training offering:
