Alcohol

The effects of alcohol on pilot performance. 

Alcohol is a central nervous system depressant.

Alcohol is very fat soluble and the brain contains a large amount of fat so alcohol gets into the brain very readily and has subtle and sometimes profound effects, particularly on decision making, judgment and balance.

These effects have, been shown to be disastrous in the flying environment, especially in an emergency situation.

Furthermore, even when there is no more alcohol in the blood, there may still be effects of alcohol in the brain for considerably longer.