Human factors is a combination of aviation medicine, psychology, engineering and ergonomics. It encompasses all of these factors trying to understand the man/machine interface in the aircraft. It has its roots in aviation accident investigations resolving these where no clear technical cause could be found when aircraft became more and more reliable over the years.
An airplane should be preflighted and determined fit to fly, but what about the pilot? When using alcohol or drugs the pilot must evaluate if the substances have any influence on the ability to fly safely.
Having a bit of knowledge about the effects of alcohol, drugs or medication on the human body does not create a physician out of you but you will have a greater understanding and how to avoid the side effects when the flight is due.
Any nervous system depressant could be fatal when flying as a pilot. We all should be very aware that this is a combination that is bound to cause accidents, it does that in normal road traffic and aviation is no different in this regard.
This substance gets into the brain very easily, mainly because alcohol is fat-soluble and the brain consists a great deal of it. It can be detected even after 14 hours of consuming a normal standard drink (which contains about 10 - 15 mg of alcohol).
The effects of alcohol on a human ability to make decisions, good judgments and balance are well known. And these effects have proven disastrous in daily road traffic and aviation. Every year, people die because someone thought that one more drink was not a problem.
Obviously, as with driving: alcohol and flying do not go together.
Rule makers have decided that at least 10 hours (some say even 12, and this varies per country) should pass after the last drink and starting to fly. Needless to say that if the person is flat out drunk, he or she will not be able to fly safely 10 hours later. Wait at least 24 hours before even thinking of getting back into the cockpit.
There is no place in aviation for the alcoholic pilot. It is as simple as that. If the pilot is diagnosed as such the pilot may not fly again until it is clear that drinking will never be a problem again, but how can you be sure? Counseling may be huge part of the process of recovery from any drinking problem.
Mood and mind influencing drugs as LSD, speed, marijuana, cocaine, heroine or others have radical effects on the brain possibly damaging it. Its use is therefore prohibited for pilots. No exception there, really, if you are on these drugs: stay away from the cockpit a.s.a.p!
The drugs mentioned above can not be classified as safe. However, mild drugs as pain killers, paracetamol or aspirin can be used as long as there is no side effect for the pilot. Nasal sprays (hay fever allergy) can be used safely as these normally do not enter the blood stream. Take care though with antihistamines which are used orally, these are known to have sleepiness as a side effect.
Some types of sleeping pills can be used by pilots, these are usually the short acting variant and should have little side effects. They are mainly used by pilots crossing multiple time zones. Do consult an AME if you think you might need them.
Drugs not suitable for pilots are stimuli for the nervous system as anti-depressants, anti-anxiety (Valium) and or strong pain killers.
Antibiotics are used to fight a bacterial infections in the body. These could have side effects possibly worse than the illness itself, consult an aviation medical examiner (AME) before taking any of these drugs. Which is also advisable to do if you think you have a condition that would need drugs to counter it. It is far better to be safe than sorry.
ALWAYS read the information folder that is supplied with these medications, if there is any mention of not operating heavy machinery then do not fly when you need and use these drugs, simple as that.
While not directly related to any danger in aviation, smoking can cause problems later on in life by increasing the chance on a possible life threatening disease. Lung cancer, asthma, strokes or heart problems are all related to smoking in one way or another.
Not smoking contributes to a healthy and longer life.
Regular exercising has proven to increase your health and stamina. Daily walking of at least 30 minutes, using the stairs, weekly running (meaning not training for a marathon) and bicycling will keep you healthy and in good shape as well!
There is a short mnemonic for the pilot to use to assess if they or their passengers are fit to fly: The I'm safe checklist. Read that page as it contains valuable information for aviatiors.