Airplane Cockpit Windscreens and Polarization
Most airplane cockpit windscreens are at least partially polarized from either built-in polarization or from windscreen heating elements.
When you look through a polarized windscreen the world looks normal.
But when you look at a polarized windscreen through polarized sunglasses you can get a rainbow effect, a marae pattern if you will, which makes it difficult to see through effectively, and it becomes a potential safety issue. Read more