It is illegal to fly a plane while drunk.

28-1465
Aircraft; operation while under influence of liquor or drug; prohibited.

It shall be unlawful for any person to operate or be in the actual physical control of any aircraft while under the influence of alcoholic liquor or of any drug or when that person has five-hundredths of one percent or more by weight of alcohol in his or her body fluid as shown by chemical analysis of his or her blood or breath.