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Optical Radiation Transmittance of Aircraft Windscreens and Pilot Vision
Three windscreens were from large commercial jets (MD 88, Airbus A320, and Boeing 727/737); two from commercial, propeller-driven passenger planes (Fokker 27 and the ATR 42); one from a small private jet (Raytheon Aircraft Corporation Hawker Horizon); and two from small general aviation (GA), single-engine, propeller-driven planes (Beech Bonanza and Cessna 182). The two GA aircraft windscreens were plastic (polycarbonate); the others were multilayer (laminated) composite glass.
RESULTS: UV transmittance for both glass and plastic windscreens was less than 1% for UV-B (280-320 nm) radiation. In the UV-A portion (320-380 nm) of the spectrum, transmittance differences increased from 0.41% to 53.5%, with plastic attenuating more UV radiation than glass. For visible light, average transmittance from 400-600 nm (violet to orange) was similar (82.8% ± 4.6%) for both windscreen materials, while from 625 to 775 nm (orange to red), the difference in average transmittance increased from 9.1% to 40.0%, respectively, with plastic transmitting longer wavelengths more efficiently.
CONCLUSIONS: Both types of windscreens blocked most of the more harmful UV-B radiation; however, glass laminate windscreens allowed higher levels of potentially damaging UV-A radiation to be transmitted than did plastic. Professional pilots who routinely fly at higher altitude for longer periods of time than private pilots should take special precautions to protect their eyes from UV exposure.