Introduction to Glider Flying > Introduction to Glider Flying > Medical Factors Associated with Glider Flying > Alcohol

Everyone knows that alcohol impairs the effi-ciency of the human mechanism. Studies have positively proven that drinking and performance deterioration are closely linked. Pilots must make hundreds of decisions, some of them time-criti-cal, during the course of a flight. The safe out-come of any flight depends on your ability to make the correct decisions and take the appropri-ate actions during routine occurrences, as well as abnormal situations. The influence of alcohol drastically reduces the chances of completing your flight without incident. Even in small amounts, alcohol can impair your judgement, decrease your sense of responsibility, affect your coordination, constrict your visual field, diminish your memory, reduce your reasoning power, and lower your attention span. As little as one ounce of alcohol can decrease the speed and strength of your muscular reflexes, lessen the efficiency of your eye movements while reading, and increase the frequency at which you commit errors. Impairments in vision and hearing occur at alco-hol blood levels as low as .01 percent.

The alcohol consumed in beer and mixed drinks is simply ethyl alcohol, a central nervous system depressant. From a medical point of view, it acts on

Figure 1-14. Scuba divers must not fly for specific time periods following dives to avoid the bends.

your body much like a general anesthetic. The “dose” is generally much lower and more slowly con-sumed in the case of alcohol, but the basic effects on the system are similar. Alcohol is easily and quickly absorbed by the digestive tract. The blood-stream absorbs about 80 to 90 percent of the alco-hol in a drink within 30 minutes on an empty stomach. The body requires about three hours to rid itself of all the alcohol contained in one mixed drink or one beer.

When you have a hangover, you are still under the influence of alcohol. Although you may think that you are functioning normally, the impairment of motor and mental responses still remains. Considerable amounts of alcohol can remain in the body for over 16 hours, so you should be cautious about flying too soon after drinking.The effect of alcohol is greatly multiplied when a person is exposed to altitude. Two drinks on the ground are equivalent to three or four at altitude. The reason for this is that, chemically, alcohol interferes with the brain’s ability to utilize oxygen. The effects are rapid because alcohol passes so quickly into the bloodstream. In addition, the brain is a highly vascular organ that is immediately sen-sitive to changes in the blood’s composition. For a pilot, the lower oxygen availability at altitude, along with the lower capability of the brain to use what oxygen is there, adds up to a deadly combination.

Intoxication is determined by the amount of alco-hol in the bloodstream. This is usually measured as a percentage by weight in the blood. 14 CFR part 91 requires that your blood alcohol level be less than .04 percent and that eight hours pass between drinking alcohol and piloting an aircraft. If you have a blood alcohol level of .04 percent or greater after eight hours, you cannot fly until your blood alcohol falls below that amount. Even though your blood alcohol may be well below .04 percent, you cannot fly sooner than eight hours after drinking alcohol. Although the regulations arequite specific, it is a good idea to be more conser-vative than the regulations.