Ice, snow, and frost on your aircraft can prevent a safe takeoff, and are hazardous to safe flight. In fact, the FARs prohibit takeoff when frozen contaminates are evident on the wings, propellers or control surfaces of your aircraft. These frozen precipitates can change your airfoils' shape and inhibit smooth airflow over your wing, tail, and prop 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. Further, the degradation of aircraft performance and flight characteristics due to ice, snow or frost formations is very unpredictable, can occur suddenly, and is highly dependent upon the design of each individual aircraft.

'Anti-icing' fluids are to be used on contaminate-free aircraft (after deicing operations or when the aircraft has been hangered), and provide protection against continuing ice, snow and frost accumulations while taxing for takeoff. These fluids represent a significant improvement in 'anti-icing' protection and provide increased "holdover time" vs. the Type I fluids.

'Anti-icing' fluids, like deicing fluids, are sprayed directly onto the aircraft's critical components -- especially the upper wing and horizontal stabilizer surfaces. However, anti-icing fluids are typically applied undiluted and cold, and once applied, are much more viscous than the Type I deicing fluids. As such, they tend to cling to the aircraft surfaces rather than running off, and may be applied to a much thicker layer. Since a greater amount of fluid remains on the aircraft's surfaces (vs. the Type I fluids), they "absorb" and "melt" continuing frozen precipitation, helping prevent their further accumulation -- subject to a number of factors such as the skin temperature of the aircraft, type and rate of precipitation, outside air temperature, atmospheric moisture constant, and wind velocity. Caution though – these fluids must be removed before actual takeoff, specifically by the 'shearing effect' of wind velocity on the takeoff roll. As such, they are applicable only to fixed wing aircraft with a rotation speed of 85 knots or more.

The airframe manufacturers often provide specific anti-icing (and deicing) recommendations. Follow those, as well as any of specified by the FAA for your particular aircraft or operation. Consult SAE-ARP 4737 guidelines & FSAT 0205 (www.faa.gov/avr/afs/fsat/fsat0205.doc) for additional data.

Since the anti-icing fluids can only be applied to contaminate-free aircraft surfaces, ground deicing might be required prior to the application of anti-icing fluids. The proper use of Ice-Offä 'Formula I' or ‘Formula I-Plus’ SAE Type I deicing fluids, as approved by the FAA and various aircraft manufacturers, can be effective in removing ice, snow and frost from all fixed wing, metal aircraft. These fluids are formulated specifically for the ground deicing of aircraft, are sprayed directly onto the aircraft to help melt frozen precipitates, and should be applied hot (160° F maximum) to accelerate the melting process. Refer to the directions included with Ice-Offä deicing fluids for further information.

Ice-Offä Brand 'Formula IV' is an FAA-approved, SAE Type IV 'anti-icing' fluid (under the ‘KilFrost ABC-S’ formulation – Table 4C in FAA FSAT 0205 for Part 135 operators). It conforms to the requirements of SAE-AMS 1428 and ISO 11078. For the best anti-icing capabilities, it should be applied undiluted and cold, at ambient air temperatures down to -18°F / -28°C, on uncontaminated critical aircraft surfaces. Do not apply 'Formula IV' over existing accumulations of ice, frost, or snow; deice the aircraft first with hot SAE Type I deicing fluid and then apply 'Formula IV'. Also, note that like all ground deicing and anti-icing fluids, 'Formula IV' provides no protection against icing in flight.

The  "Holdover Table" for 'Formula IV' SAE Type IV anti-icing fluid presented in these web pages is 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 fluid can be expected to be effective, 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.

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 and anti-icing procedures and prior to takeoff, and to ensure that the aircraft is safe for departure.

MM Caution: The responsibility for the application of the data presented remains w/ the user. A close visual and tactile inspection after deicing and immediately prior to takeoff is essential to assure that the aircraft is free of frost, ice or snow accumulations.