De-icing fluid application & timing
Before any fluid:
- De-icing and anti-icing fluid never used unless aircraft manufacturer approves it (TC AIM AIR 2.12.2).
- PIC must ensure crew members and passengers are informed of decision to de-ice or anti-ice before it happens, CAR 602.11(7).
- De-ice shortly before takeoff (TP 10643).
Heat and fluid (TC AIM AIR 2.12.2 unless noted):
- Raise skin temperature (refuel with warm fuel, use heated FPD fluid, or both): helps stop ice or frost forming before takeoff.
- Heated fluid's thermal energy plus high-pressure spray: speeds de-icing considerably.
- Higher glycol concentration: some protection against refreezing, little against fresh accumulation. Winter wash water can leave its own ice coating if careless (TP 1102).
- Apply evenly, adequate thickness per manufacturer's recommendation, especially on leading edge of wing and horizontal stabilizer.
Two-step procedure (TP 10643):
| Step | Fluid |
|---|---|
| 1. Deice | Hot water, or hot FPD/water mix |
| 2. Anti-ice (over the deiced surface) | Type II, III, or IV |
- Anti-ice within about 3 minutes of heated de-ice: wing can refreeze before anti-ice film forms (TP 10643 caution).
- One-step method (heated FPD only, no second fluid): thin residual film, very limited anti-icing protection.
Never apply SAE Type II, III, or IV directly to (TP 10643, p.44):
- Cockpit windows
- Nose of fuselage
- Pitot heads
- Static ports
- Angle-of-attack sensors
- Air inlets, intakes
- Engines
- Control surface cavities
- Lower side of radome
Sensor orifices and probes (static ports, pitot tubes, air intakes, temperature sensors): caution with any fluid. Direct spray can damage equipment or leave residue giving faulty readings (TP 10643, para 38).
Trap: stopping after heated de-ice; anti-ice must follow within about 3 minutes.
References
- TP 10643 (When in Doubt... Small and Large Aircraft)
- TC AIM AIR 2.12.2
- TP 1102 (Flight Training Manual)
- CAR 602.11(7)