A transparent, solid-state, electrochromic device is described. It demonstrates deep switching in the near infrared and visible spectral regions and good room temperature cycling stability. The response appears reasonably uniform over a 14 cm x 28 cm area, which gives hope for achieving large parts for cockpit and cabin windows. The reversible darkening of the transparency, controlled by an applied voltage or current, has potential application in aircraft to reduce glare and solar heat load to pilots and passengers. The active material in the device is a thin tungsten oxide film which is incorporated into a complex, multilayered structure, essentially that of a transparent battery. The performance of the window is discussed in terms of its configuration, its similarities with commercial batteries and issues critical to aircraft.