Overview
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Replace with overview of wing anti-ice, engine anti-ice, probe heat, window heat, and rain protection.
The 747-400 ice protection uses engine bleed air for wing leading-edge (slats) anti-ice and engine cowl anti-ice. Probes (pitot, static, AOA, TAT) and windows are electrically heated. Rain protection on windshields uses windshield wipers and rain repellent fluid system (where installed).
Components
| Wing Anti-Ice | Bleed air to leading-edge slats (sections 1–14) |
| Engine Anti-Ice | Bleed air to engine cowl (4 engines independent) |
| Probe Heat | Pitot (4), Static (multiple), AOA (3), TAT (2) — auto when eng running |
| Window Heat | L1/R1 (forward), L2/R2 (side), L3/R3 (aft) — anti-ice + anti-fog |
| Windshield Wipers | L + R, multiple speeds |
| Rain Repellent | Fluid system (varies by tail) |
Operation
- Engine anti-ice: ON when icing conditions exist with TAT ≤ 10 °C and visible moisture
- Wing anti-ice: ON in icing conditions; OFF for takeoff in many SOPs (verify)
- Probe/window heat: Automatic when applicable
Limits
- Wing anti-ice not certified for icing on the ground (use Type I/II/IV fluids)
Notes / Personal
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User notes.