Outside Air Temperature (OAT) One-Step Procedure Deicing/Anti-icing Two-Step Procedure
First Step : Deicing Second Step Anti-icing1
-3.C (27.F) and above 50/50 Heated2 Type II/III/IV Heated water of a heated mix of Type I, II, III or IV with water 50/50 Type II/III/IV
-14.C (7.F) and above 75/25 Heated2 Type II/III/IV Heated suitable mix of Type I, Type II/III/IV and water with FB not more than 3.C (5.F) above actual OAT 75/25 Type II/III/IV
-25.C (-13.F) and above 100/0 Heated2 Type II/III/IV Heated suitable mix of Type I, Type II/III/IV and water with FP not more than 3.C (5.F) above actual OAT 100/0 Type II/III/IV
Below -25.C (-13.F) Type II/III/IV fluid may be used below -25.C (-13.F) provided that the freezing point of the fluid is at least 7.C (13.F) below OAT and that aerodynamic acceptance criteria are met. Consider the use of Type I when Type II/III/IV fluid cannot be used (see Table 6).
1 To be applied before first step fluid freezes, typically within 3 minutes. 2 Clean aircraft may be anti-iced with unheated fluid.
NOTES
.
For heated fluids, a fluid temperature not less than 60.C (140.F) at the nozzle is desirable.
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Upper temperature limit shall not exceed fluid and aircraft manufacturers’ recommendations.
CAUTIONS
.
Wing skin temperatures may differ and in some cases may be lower than outside air temperatures; a stronger mix (more glycol) may be needed under these conditions.
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Whenever frost or ice occurs on the lower surface of the wing in the area of the fuel tank, indicating a cold soaked wing, the 50/50 dilutions of Type II,III or IV should not be used for the anti-icing step because fluid freezing may occur.
.
An sufficient amount of anti-icing fluid may cause a substantial loss of holdover time. This is particularly true when using a Type I fluid mixture for the first step in a two step procedure
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