Throughout the history of pressurized aircraft, the accumulation of fog on cockpit windows has presented a challenge to the flight of aviators. Given that windshield or side window fog can obstruct clear flight path visibility, the real-time detection of environmental humidity conditions conducive to windshield and/or side window fog is an important cockpit input needed to ensure normal flight operations, especially during the flight phases of approach and landing.
In the aerospace industry certification regulations mandate that any aircraft window heat system must provide anti-fog capability to ensure the at least a portion of the interior surfaces of the cockpit windshield and side windows remain clear of fog to the extent that both pilots have clear visibility of a typical flight path. In order to achieve this directive, any anti-fog system that is installed must be capable of maintaining a window clear of fog at any cockpit ambient dew point temperature.
Historically, the majority of aircraft have not had an automatic real-time window fog detection/prediction system installed, but rather depended on the physical identification of windshield or side window fog by the flight crew and subsequent manual activation of fog protection systems. Alternatively, some aircraft have been equipped with electric or pneumatic anti-fog systems to prevent the formation of fog on windshield surfaces from ever occurring in the course of a given flight. But these anti-fog systems are typically operated for the entire flight and therefore impose excessive energy and fuel burn requirements since the systems are often operating when fog accumulation conditions are not present.
Therefore, it may be desirable to have a system and method that takes into account at least some of the issues discussed above, as well as possibly other issues.