The Federal Aviation Administration (FAA) requires that airline pilots have a blood alcohol concentration (BAC) of .04% or less when flying. This is lower than the legal BAC limit for other drivers, which is .08%.
There are several reasons why the FAA has a lower BAC limit for pilots. First, alcohol impairs judgment and reaction time. Second, it increases the chance of errors and accidents. Third, it dehydrates the body, which can lead to fatigue.
Pilots who violate the FAA's BAC limit may be subject to civil penalties, including a fine of up to $1,250 and suspension of their pilot's license. They may also face criminal charges, including imprisonment for up to one year.