Aeromedical Factors

• Select approach and departure routes that avoid AAAA highways and residential areas where illumination MMMMIIII EEEE can impair night vision. DDDD YYYY CCCC RRRR UUUU OOOO GGGG LLLL Self-Imposed Stress GGGG SSSS HHHH YYYY PPPP N f P th l i i i a l g g o t h h t c t s t , a a c n f n a l i c n d g a h m c u t o s a n e c n t a y s r n e o s l l e f b - t l e f h im - i m s im p t o o y p r s p e o e e s d f e o a d s f t t i s r g s e t t r u s r e i e s s n o s s g s r o s r b . a s y n S c d o k a m n n s o t l e r i w m e o s i f i n s t f t g n h u i e t l g h s h t e e h t a f f v a a n i c c s t t i d o o o a n r r y s s . PPPOOOOOO EEEE RRL XXXX CC HHHH C PPP OO AA HH O AA H UU NN YY UU N Y SS SS DD S SS D II TT I II TT I CCC TTT IIIIOO II AA OO I A OOO LL NN L NN NNN CCCC NNNN OOOO DDDD UUUU EE TT EE TT FF RR FF RR IIII IIII CCCC TTTT II II II II EE OO EE OO NNNN NNNN CCCC AAAA YY LL YY LL are listed in the following paragraphs. [Figure 17-20] CCCC AAAA BBBB AAAALLLLCCCCOOOOHHHHOOOOLLLL OOOO TTTT Drugs Drugs can seriously degrade visual acuity during the day and especially at night. Pilots who become ill should consult an Figure 17-20. Self-imposed stress. aviation medical examiner (AME) or flight surgeon as to which drugs are appropriate to take while flying. affects peripheral vision and dark adaptation. The results are the same as those for hypoxia caused by high altitude. Exhaustion Smoking 3 cigarettes in rapid succession or 20 to 30 cigarettes within a 24-hour period may saturate from 8 to 10 percent Pilots who become fatigued during a night flight will not be of the capacity of hemoglobin. Smokers lose 20 percent of mentally alert and will respond more slowly to situations their night vision capability at sea level, which is equal to a requiring immediate action. Exhausted pilots tend to physiological altitude of 5,000 feet. concentrate on one aspect of a situation without considering the total requirement. Their performance may become a Hypoglycemia and Nutritional Deficiency safety hazard depending on the degree of fatigue and instead of using proper scanning techniques may get fixated on the Missing or postponing meals can cause low blood sugar, instruments or stare off rather than multitask. which impairs night flight performance. Low blood sugar levels may result in stomach contractions, distraction, Poor Physical Conditioning breakdown in habit pattern, and a shortened attention span. Likewise, an insufficient consumption of vitamin A may To overcome poor physical conditioning, pilots should also impair night vision. Foods high in vitamin A include participate in regular exercise programs. People who are eggs, butter, cheese, liver, apricots, peaches, carrots, squash, physically fit become less fatigued during flight and have spinach, peas, and most types of greens. High quantities of better night scanning efficiency. However, too much exercise vitamin A do not increase night vision but a lack of vitamin in a given day may leave crew members too fatigued for A certainly impairs it. night flying. Distance Estimation and Depth Perception Alcohol Knowledge of the mechanisms and cues affecting distance Alcohol is a sedative and its use impairs both coordination estimation and depth perception assist pilots in judging and judgment. As a result, pilots who are impaired by alcohol distances at night. These cues may be monocular or binocular. fail to apply the proper techniques of night vision. They are The monocular cues that aid in distance estimation and depth likely to stare at objects and to neglect scanning techniques. perception include motion parallax, geometric perspective, The amount of alcohol consumed determines the degree to retinal image size, and aerial perspective. which night vision is affected. The effects of alcohol are long lasting and the residual effects of alcohol can also impair Motion Parallax visual scanning efficiency. Motion parallax refers to the apparent motion of stationary Tobacco objects as viewed by an observer moving across the landscape. When the pilot or crewmember looks outside the Of all the self-imposed stressors, cigarette smoking most aircraft perpendicular to the direction of travel, near objects decreases visual sensitivity at night. Smoking significantly appear to move backward, past, or opposite the path of increases the amount of carbon monoxide carried by the motion; far objects seem to move in the direction of motion hemoglobin in red blood cells. This reduces the blood’s or remain fixed. The rate of apparent movement depends on capacity to combine with oxygen, so less oxygen is carried the distance the observer is from the object. in the blood. Hypoxia caused by carbon monoxide poisoning 17-25