During instrument flight training, the pilot must have his/her view through the aircraft windscreen restricted to simulate low-visibility conditions while permitting the pilot to view the instrument panel. In one current method, a hood is draped across the aircraft windscreen, or a face mask or blackened glasses are worn by the pilot. All such current methods create potentially hazardous disorientation and an unnatural environment for the trainee. In particular, the face mask and blackened glasses restrict the pilot’s peripheral vision, and require uncomfortable and unnatural head positions in order to see the entire instrument panel.
Researchers at NASA’s Langley Research Center have developed and tested special glasses to be worn by a pilot during instrument flight training. Using novel sensors to determine head position, the glasses restrict the view out of the aircraft windscreen, but allow the pilot to clearly see the entire instrument panel, providing a much more realistic low-visibility instrument flying experience.
The technology combines electro-actively controlled liquid crystal lenses with a means for determining the pilot’s head position. When the pilot’s head is positioned to look outside the front or side windscreens, the lenses restrict light transmission. When the pilot’s head is lowered to view the instrument panel or other cockpit displays, the lenses allow light transmission so that the view of the instruments is unimpeded. Light transmission through the lenses can be selectively controlled by the system, ranging from 0.1% to 10%. The lenses are mounted in conventional eyeglass frames.
The frames include a detection system to determine the position and orientation of the pilot’s head. Circuits within the frames activate the lenses to restrict light transmission when the pilot’s head is oriented to look out the windscreen. A PC, linked to the aircraft flight computer or altimeter is also in the control loop and turns off the system to allow unimpeded visibility when the aircraft is below 200 feet, or for other specified conditions. This system can be easily modified to fit over prescription eyeglasses or sunglasses.
This technology can be used in pilot glasses for instrument flight training and simulation of reduced visibility conditions, military goggles to protect aircrews from lasers or bright detonations, gaming and virtual reality goggles to restrict or allow selective vision based on a user’s line of sight, and transition lenses for eyewear that darken when looking toward the Sun.