To prevent these symptoms, it is recommended that an  ample supply of water be carried and used at frequent  intervals on any long flight, whether thirsty or not. The body  normally absorbs water at a rate of 1.2 to 1.5 quarts per hour.  Individuals should drink one quart per hour for severe heat  stress conditions or one pint per hour for moderate stress  conditions. If the aircraft has a canopy or roof window,  wearing light-colored, porous clothing and a hat will help  provide protection from the sun. Keeping the flight deck well  ventilated aids in dissipating excess heat.  the appropriate actions during routine occurrences, as well  as abnormal situations. The influence of alcohol drastically  reduces the chances of completing a flight without incident.  Even in small amounts, alcohol can impair judgment,  decrease sense of responsibility, affect coordination, constrict  visual field, diminish memory, reduce reasoning ability, and  lower attention span. As little as one ounce of alcohol can  decrease the speed and strength of muscular reflexes, lessen  the efficiency of eye movements while reading, and increase  the frequency at which errors are committed. Impairments  in vision and hearing can occur from consuming as little as  one drink.  Alcohol impairs the efficiency of the human body.  [Figure 17-8]  Studies have shown that consuming alcohol  is closely linked to performance deterioration. Pilots must  make hundreds of decisions, some of them time-critical,  during the course of a flight. The safe outcome of any flight  depends on the ability to make the correct decisions and take  The alcohol consumed in beer and mixed drinks is ethyl  alcohol, a central nervous system depressant. From a medical  point of view, it acts on the body much like a general  anesthetic. The “dose” is generally much lower and more  slowly consumed in the case of alcohol, but the basic effects  on the human body are similar. Alcohol is easily and quickly  absorbed by the digestive tract. The bloodstream absorbs  about 80 to 90 percent of the alcohol in a drink within 30  minutes when ingested on an empty stomach. The body  requires about 3 hours to rid itself of all the alcohol contained  in one mixed drink or one beer.  While experiencing a hangover, a pilot is still under the  influence of alcohol. Although a pilot may think he or she is  functioning normally, motor and mental response impairment  is still present. Considerable amounts of alcohol can remain  in the body for over 16 hours, so pilots should be cautious  about flying too soon after drinking.  Altitude multiplies the effects of alcohol on the brain. When  combined with altitude, the alcohol from two drinks may have  the same effect as three or four drinks. Alcohol interferes  with the brain’s ability to utilize oxygen, producing a form  of histotoxic hypoxia. The effects are rapid because alcohol  passes quickly into the bloodstream. In addition, the brain  is a highly vascular organ that is immediately sensitive to  changes in the blood’s composition. For a pilot, the lower  oxygen availability at altitude and the lower capability of  the brain to use the oxygen that is available can add up to a  deadly combination.  Intoxication is determined by the amount of alcohol in the  bloodstream. This is usually measured as a percentage by  weight in the blood. 14 CFR part 91 requires that blood  alcohol level be less than .04 percent and that 8 hours pass  between drinking alcohol and piloting an aircraft. A pilot with  a blood alcohol level of .04 percent or greater after 8 hours  cannot fly until the blood alcohol falls below that amount.  Even though blood alcohol may be well below .04 percent,  a pilot cannot fly sooner than 8 hours after drinking alcohol.  Alcohol  17-15  Figure 17-8.  Impairment scale with alcohol use.  Type Beverage  Typical Serving  Pure Alcohol  (oz)  Content (oz)  Table wine  Light beer  Aperitif liquor  Champagne  Vodka  Whiskey 4.0  12.0 1.5 4.0 1.0 1.25 .48  .38  .48  .50  0.01–0.05%  average individual appears normal  (10–50 mg)  0.03–0.12%*  mild euphoria, talkativeness, decreased  (30–120 mg)  inhibitions, decreased attention, impaired  judgment, increased reaction time  0.09–0.25%  emotional instability, loss of critical  (90–250 mg)  judgment, impairment of memory and  comprehension, decreased sensory  response, mild muscular incoordination  0.18–0.30%  confusion, dizziness, exaggerated  (180–300 mg)  emotions (anger, fear, grief), impaired  visual perception, decreased pain  sensation, impaired balance, staggering  gait, slurred speech, moderate muscular  incoordination  0.27–0.40%  apathy, impaired consciousness, stupor,  (270–400 mg)  significantly dGLYPH<df00>crGLYPH<df00>asGLYPH<df00>d rGLYPH<df00>sponsGLYPH<df00> to  stimulation, severe muscular  incoordination, inability to stand or walk,  vomiting, incontinence of urine and feces  0.35–0.50%  unconsciousness, depressed or  (350–500 mg)  abolishGLYPH<df00>d rGLYPH<df00>flGLYPH<df00>xGLYPH<df00>s, abnormal body  temperature, coma, possible death from  respiratory paralysis (450 mg or above)  * Legal limit for motor vehicle operation in most states is 0.08 or 0.10% (80–100 mg of alcohol per dL of blood). 