US Patent 7348896 Aircraft security method

A security method obscures the visibility through an aircraft's windshield upon determining the existence of a potential security problem, such as a terrorist attempting to take unauthorized control of the aircraft. The windshield can be obscured by various means such as actuating a liquid crystal system of a chromogenic glass pane; automatically drawing a shade or curtain in front of, behind, or within the windshield; and applying to or within a windshield an opaque or translucent fluid. Although an obscured windshield would likely impede the terrorist, it would not create a problem for a skilled pilot that is more familiar with the aircraft and its instruments. Determining whether a potential security problem exists can be accomplished in various ways such as scanning ID cards; reading passwords; communicating with the flight crew; actuating emergency buttons aboard the aircraft; and comparing cell phone numbers, voice imprints, or facial images to a database.