Definition
An anti-ice and deice system in which freezing-point depressant fluid (typically a glycol-based fluid) is pumped through small laser-drilled holes in panels along the leading edges of the wings, tail, and sometimes propeller and windshield. The fluid flows out across the surface, mixing with supercooled water droplets to lower their freezing point and prevent ice from forming, or breaking the bond of ice that has already begun to form so it sheds into the airstream.
Plain English
A system that pushes a special anti-ice fluid out through tiny holes along the front edges of the wings. The fluid coats the surface so ice cannot stick, and any ice already there loses its grip and blows away.
Context Anchor
Seen in discussions of aircraft anti-ice and deice systems, especially on airplanes approved for flight in icing conditions.
Derivation
Called 'weeping' because the fluid seeps out through the porous leading-edge panels much like tears weeping from an eye. The visual of liquid slowly oozing across a surface is exactly what gives the system its name.
Why Pilots Care
Ice on the wing disrupts smooth airflow and reduces lift, so the system helps maintain safe flight performance in icing conditions.
Analogy
Think of a damp sponge slowly releasing liquid across its surface. A weeping wing does something similar, but through engineered panels and with fluid made for ice protection.
Intuition Check
Do not read “weeping wing” as an accidental leak. Here, “weeping” means a controlled release of ice-protection fluid through the wing surface.
Example Sentence 1
Before entering the icing layer, the pilot activated the weeping wing system to coat the leading edges with anti-ice fluid.
Example Sentence 2
During the preflight inspection the pilot confirmed the weeping wing fluid reservoir was full and the pumps were operational.