Frost, snow, and ice on your aircraft are hazardous to takeoff and safe flight. So hazardous, in fact, that the Federal Air Regulations prohibit takeoff when any frozen precipitate is evident on the lifting surfaces, control surfaces, or propeller(s) of your aircraft.

These frozen precipitates can change your airfoils' shape, inhibiting smooth airflow over your wing, tail, and propeller surfaces. They can adversely affect your aircraft's performance and flight characteristics, resulting in decreased thrust and lift, increased drag and stall speed, altered stall characteristics and handling qualities, unanticipated trim changes, and unpredictable stability and control problems. And it doesn't take much; frozen accumulations the thickness and surface roughness of medium-to-course sandpaper on the leading edge and upper surfaces of your airfoil can reduce wing lift by as much as 30%, and can increase drag by 40%!

Further, the degradation of aircraft performance and flight characteristics due to frost, snow or ice formations is very unpredictable, can occur suddenly, and is highly dependent upon the design of each individual aircraft. As such, all frozen contaminants must be removed from critical areas of the aircraft prior to departure. These include airfoil leading edges, upper & lower wing and tail surfaces, all control surfaces, propellers, windshields, fuel tank/cap vents, stall warning devices, antennas, landing gear, and exposed instrumentation devices (pitot-static probes, static ports)

Remember, the Pilot-in-Command holds the ultimate responsibility to remove all frozen contaminants from critical aircraft surfaces and components, to conduct visual and tactile inspection the aircraft after deicing procedures and prior to takeoff, and to ensure that the aircraft is safe for departure....

Deicing of small aircraft can be accomplished by placing the aircraft in a warm hanger until dry, by covering the critical areas of the aircraft (wing covers, etc), by mechanical means (brooms, scrapers, etc), by direct infrared heating, and by approved deicing fluids...The method used to deice small aircraft is largely dependent upon the facilities available and individual preference. Warm hangers and wing covers are effective, but may not be available; mechanical removal of frozen precipitates is difficult, time consuming, and potentially damaging to your aircraft. In many instances, FAA-approved SAE Type I deicing fluids may be the most effective alternative.

Caution: Do not use unapproved deicing fluids. They may not be compatible with aircraft materials and may have characteristics that impair aircraft performance & flight characteristics or cause control surface instabilities. The use of automotive antifreeze is not approved by the FAA.

The proper use of hot deicing fluids can effectively remove frost, snow and ice from your aircraft prior to takeoff. FAA-approved SAE Type I deicing fluids are suitable for all fixed wing, metal aircraft. They’re formulated specifically for deicing aircraft on the ground. Note, however, that they provide no protection against icing in flight.

These deicing fluids are principally freezing point depressant (FPD) liquids. Sprayed hot on the aircraft’s surfaces, they help (1) melt the frozen precipitates by direct thermal action, and (2) lower the freeze point of the frozen precipitates below the ambient air temperature, allowing it to liquefy and melt off. Depending upon the type and density of the frozen precipitate, repeated applications of the deicing fluid may be required, until the fluid penetrates to the aircraft surface, and all frozen precipitates have melted. Heating the deicing fluid (to a maximum of 160°F) is highly recommended to accelerate the melting process and to decrease the amount of deicing fluid used.

When the deicing fluid has penetrated to the aircraft’s surfaces and all the frozen precipitate has melted, the residual (diluted) liquid film could potentially refreeze, due to a number of causes.  To prevent this refreezing, a buffer of at least 18°F (10°C) between the freeze point of the deicing fluid and the ambient air temperature is required. Ice-Offä 'Formula I' has a minimum freeze point of -30°F (-34°C); do not use ‘Formula I’ below -12° F (-24°C). Some specially formulated SAE Type I deicing fluids (including Ice-Offä 'Formula I-Plus') are designed for lower temperature application, and can be used to around -26°F (-32°C). Consult your specific product data sheet.

SAE Type I deicing fluids are not "anti-icing" fluids. However, properly applied, they will help prevent the re-formation or accumulation of frost, snow or ice in the presence of continued precipitation or frost-forming conditions for a limited time. This "Holdover Time" begins with the commencement of the final application of deicing fluid, and expires when the deicing fluid loses its effectiveness.

The  "Holdover Table" for SAE Type I deicing fluid is presented in these web pages as a guideline for use in departure planning, and should be used in conjunction with your pre-takeoff check procedures. It presents an estimated range of time that the applied deicing fluid can be expected to be remain effective against continuing frost or frozen precipitation, dependent principally upon the outside air temperature and type of precipitate. Note however that these times are variable with weather conditions, and that high rates of precipitation, high atmospheric moisture content, high wind velocity, and jet blast can reduce the estimated time of effectiveness.