Specifically, the Federal Aviation Administration rulebook states that a pilot may not use alcohol within 8 hours of a flight and cannot have a blood alcohol content above 0.04%.

Under the standard FAA (Federal Aviation Administration) regulations, a pilot must wait a minimum of 8 hours from their last drink before they are allowed to perform any flight duties; this is famously known as the "bottle to throttle" rule. However, in 2026, most major commercial airlines enforce a much stricter 12-hour or even 24-hour abstinence policy. Furthermore, a pilot is strictly prohibited from flying if they have a Blood Alcohol Concentration (BAC) of 0.04% or higher, which is half the legal limit for driving in many U.S. states. It is also illegal to fly while experiencing the effects of a hangover, as the lingering dehydration and cognitive fog can impair judgment and reaction times just as much as active intoxication. In countries like India, the DGCA has a "zero-tolerance" policy where any detectable level of alcohol leads to immediate license suspension. These rules are strictly enforced through random "breathalyzer" tests at the gate to ensure the absolute safety of the millions of passengers flying every day.