While ground troops have taken enthusiastically to night vision goggles (NVGs), pilots are not nearly as happy with there "see in the dark" gadgets. The reasons are simple, if pilots make one mistake while flying at night, they are dead. On the ground, bumping into a tree at night or misjudging the distance when you leap across a stream in the dark are painful to the infantryman, not fatal. Helicopter pilots have been the heaviest users of night vision goggles. The latest versions weigh about 12 ounces, and this reduces earlier complaints about the weight (over a pound) when the goggles were worn for several hours of night flying. But there are still problems with night vision goggles and weather conditions. High humidity or heavy cloud cover make the goggles less reliable. While flying low this can be very dangerous, causing pilots to fly too close to the ground or not be able to see obstacles like power lines and buildings. In the late 1990s, the U.S. Air Force developed special software that would analyze the weather reports and warn pilots if their NVGs were going to be compromised by bad weather.
But even under the best of conditions, there are other problems with NVGs. Resolution and visual acuity, depth perception, and field of view are reduced from normal levels (without NVGs and in daylight). NVGs provide a dangerous illusion of what the wearer is actually seeing. The field of view (40 degrees) was only about a quarter of what a pilot sees when not using the NVGs. Moreover, there is the hassle of looking away from the NVG eyepieces to check cockpit instruments. While the first pilot NVGs available in the 1980s had all these problems, they did allow a determined pilot to fly at night. In 1989, the third generation NVGs showed up, providing sharper images and less eye strain. This was followed by in the early 1990s by even better and easier to use models. But the major shortcoming remained training. NVGs cannot easily be used in simulators, so most of the training has to be done in the actual aircraft. This is expensive, and dangerous. The higher accident rate for pilots using NVGs demonstrates this. While a pilot with NVGs can see for several kilometers (depending on how much moonlight and starlight is available), the vision is not the same as seeing the same terrain in daylight. One proposed solution is to put small infrared cameras on the pilots helmet and display the images on the pilots wrap around goggles. This could be possible in the next few years. But for the moment, pilots carry on with their $12,000 NVGs.
