Windshield Heat

Windshield heat is an electrical heating system built into the cockpit windshield that serves multiple critical functions: preventing ice and frost formation on the exterior surface, eliminating interior fogging and condensation, and maintaining the windshield at a temperature that keeps the glass or acrylic pliable enough to resist bird strikes.

Modern aircraft windshields are complex assemblies of multiple glass or acrylic plies with embedded heating elements (typically thin conductive film or wire grid). The heating system is thermostatically controlled to maintain optimal temperature — hot enough to prevent icing and maintain flexibility, but not so hot as to damage the windshield structure.

Windshield heat is typically activated before takeoff and remains on throughout the flight. Failure of a windshield heat system may be an MEL item (deferrable under certain conditions) or may require diversion, depending on the weather conditions and whether the remaining windshield panels have functioning heat.