8 Other Factors 8.1 Altitude Illness You probably think of the bends as something that doesn't belong in an essay for pilots. It's something scuba divers have to worry about, not pilots. Well, there's a grain of truth in most misconceptions: if you're a diver, you are far more likely to get the bends if you fly soon after diving. As a rule of thumb, wait 24 hours before flying either as a passenger or pilot, after diving. If your dive has been deeper than 35 meters (120 ft), or if you will be above 8000 ft during flight, wait 48 hours. But you can get bent flying even if you're not a diver, if you go high enough, fast enough. There is a small but real risk of the bends any time you go above FL18, and a definite risk about FL25 (25,000 ft msl). It's not the altitude alone, but the rate of ascent that creates the risk. All the cases of the bends that I know of have been from ascents above 30,000 ft in strong wave conditions. Every glider pilot flying wave should consider "the bends" as a real risk when the wave is strong and deep. There are two useful steps you can take to reduce this risk. One is to take off from a mountain airport rather than a low-altitude field, to provide some preliminary decompression. Another is to make "decompression stops" in really good wave, to ensure there is time for nitrogen to escape from body tissues. I have not been able to find specific recommendations regarding safe rates of climb at altitude comparable to diving charts. (Sorry.) 8.2 Conditioning Maintaining some degree of cardiovascular conditioning through regular exercise is useful, not only in walking out for help after a landout, but also provides for a better response to stress in the cockpit. The deconditioned pilot reacts physically to stress with higher blood pressure, more rapid heart rate, and a greater degree of hyperventilation than the pilot who is conditioned. This is not an essay on conditioning, so I'll just suggest that you should at least take an hour-long walk thrice weekly. 8.3 Disease The effects of specific diseases, and of non-disease conditions such as intestinal gas, are sometimes very important to flying safety, but each of these would require an essay in itself. The important principle is that if you have any medical condition, you should educate yourself on its nature just as avidly as you educate yourself about the flight characteristics of your ship. By doing this you will be able to recognize signs of impending performance degradation or incapacitation and avoid risky flight. 8.4 Actinic damage Sunburn, corneal light injury, and the delayed effects of sun exposure are important to glider pilots. They affect comfort more than performance, so I will add material on these topics only if I get inspired, which I am not at the moment. Diffuse sunburn is characteristically associated with hypothermia during the 12 - 24 hours following exposure, due to the dilated blood vessels in sunburned skin radiating heat to one's surroundings. It is possible that exposure to intense light contributes to macular degeneration, but this is unproven.