Flying and Health — Page 108, Lesson 164

I want to walk you through the section on alcohol and its effects on flying. This is a critical topic because alcohol is one of the most common and dangerous substances a pilot can encounter, and the regulations around it are strict for good reason. Let's start with the basics. Alcohol, specifically ethyl alcohol or ethanol, is not digested in the human body like food. Instead, it is absorbed directly from the stomach and intestines into the bloodstream. About 20% is absorbed from the stomach, and the remaining 80% comes from the intestines. Once it's in the blood, it is carried to every part of the body. The liver is the organ responsible for eliminating alcohol. It does this by chemically changing the alcohol into water and carbon dioxide. Drunkenness occurs when a person drinks alcohol faster than the liver can dispose of it. In other words, if the rate of intake exceeds the rate of elimination, the blood alcohol level rises, and intoxication sets in. Now, let's talk about the rate at which the body breaks down alcohol. The body eliminates alcohol at a rate of approximately one unit per hour. However, there are many individual differences, so this is a rough average. To give you a practical idea, one unit is roughly equivalent to half a pint of beer, an imperial glass of wine, or a tot of spirits. For a more precise measurement, alcohol is removed from the blood at a rate of approximately 15 milligrams per 100 millilitres per hour. Let me put that into context. If someone consumes 1½ pints of beer or three whiskies, that will result in a blood alcohol level of about 45 to 50 milligrams per 100 millilitres. At the elimination rate of 15 milligrams per 100 millilitres per hour, it can take up to 4 hours for the blood level to return to normal. That's four hours just to get back to zero, and that's assuming no additional alcohol is consumed. The absorption rate into the blood is not constant; it varies depending on several factors. These include the type of drink—alcohol with fizzy mixes is absorbed much quicker than straight alcohol. Body weight is another factor, and in fact, it is the most important one. The amount of food in the digestive tract also matters, as does individual metabolic differences. So a heavier person with a full stomach who drinks straight spirits will absorb alcohol more slowly than a lighter person drinking fizzy cocktails on an empty stomach. Here's a crucial point that goes against popular belief: you cannot speed up the rate at which alcohol is eliminated from the body. Things like drinking black coffee, taking steam baths, or getting fresh air will not change the rate of oxidation—that's the chemical process by which the liver breaks down alcohol. Even sleeping off the effects will actually cause the rate of oxidation to be prolonged, because body functions and metabolic rates are slowed during sleep. Eating while drinking will only slow the rate at which alcohol is absorbed into the blood, not the total amount absorbed. It in no way affects the rate at which oxidation occurs. So the liver works at its own pace, and nothing you do will hurry it along. Once alcohol is in the bloodstream, it acts as a central nervous system depressant. Some critical areas of the brain are especially vulnerable, particularly the inhibition centre. Even small amounts of alcohol can produce a range of effects that are directly dangerous for flying. Let me list them for you: - Impaired judgement. - Impaired ability to reason. - Degraded muscular coordination. - Lack of inhibition and self-control, resulting in increased recklessness. - Degraded vision. - Balance and sensory illusions. - Disrupted sleep patterns—alcohol degrades REM sleep and causes early waking. - Heightened susceptibility to hypoxia, which is the lack of sufficient oxygen. - Physical damage to the liver, heart, brain, and blood cells with repeated use. - Disrupted short and long-term memory. - Slowed reaction times. - And a particularly insidious effect: a false perception that performance has improved. This means a pilot may feel they are flying better when they are actually impaired. These effects are worsened at high altitude, where oxygen is less. So the combination of alcohol and altitude is especially dangerous. Finally, I want to cover the levels of consumption that can cause permanent damage to the body. For men, any consumption above five units daily or 21 units per week is considered harmful. For women, the threshold is lower: three units daily. These are not limits for safe flying—they are limits for avoiding permanent physical damage. For flying, the rules are far stricter, and you should have zero alcohol in your system before any flight. That covers the key points on alcohol from this section.