There are approximately 100,000 licensed airline pilots in the United States. Of these, over 83 percent are male.
FAA regulations state that pilots may never have a BAC or blood alcohol concentration of more than .04 percent when reporting for duty or at any time while on duty. FAA regulations also require that airline pilots not consume any alcoholic beverages within 8 hours of a scheduled flight.
Some airlines have more stringent requirements and require no alcohol within 12 hours of flying. They may also require alcohol testing to determine if you’re fit to fly.
However, under certain circumstances, the FAA 8-hour limit rule, even if strictly observed, can still result in alcohol concentration levels exceeding .04 percent when the airline pilot reports for duty.
Effects and Influence of Alcoholic Beverages
Alcohol is a drug, a toxin to the body and brain. In most pilots, it causes a slowed reaction time and impaired judgment, memory, motor skills, and reasoning.
This is evident in the phenomenon of “lost weekends” and blackouts experienced by heavy drinkers. This is due to alcohol’s effects on the brain’s memory centers.
An intoxicated pilot is a danger not only to themselves but also to the crew, passengers, other planes traveling the flight lanes, and everyone on the ground.
Commercial pilots are required by FAA regulations to self-report any DUI conviction within 60 days of such occurrence. An airline pilot must also inform the AME of any DUI convictions during their next medical examination.
Federal Aviation Administration Rules for Alcohol Consumption
FAA regulations forbid alcohol intake within 8 hours of flying. Many pilots and crew members refer to this rule as “from bottle to throttle.”
However, this rule doesn’t necessarily mean a pilot or crew member will be below the .04 percent BAC limit by the time they report for duty.
Unless commercial pilots abstain from alcoholic beverages before a flight, a BAC well exceeding the .04 percent limit is possible while not technically violating the FAA alcohol 8-hour rule.
The FAA alcohol rule states that a pilot and any crew member may not consume alcohol within 8 hours of flying and may never have a BAC exceeding .04 percent when reporting for duty and while operating a plane. It places no limitations on alcohol consumption other than that.
However, alcoholic beverages consumed before a flight complying with the FAA rule can still result in a BAC level too high for duty. This is why United and Delta’s alcohol policy includes a 12-hour limit on alcoholic beverage consumption before flying instead of an 8-hour one.
These extra four hours allow the body to metabolize alcohol to the point of being below the .04 percent BAC limit as long as the pilot stops drinking 12 hours before their scheduled flying time. If there is reasonable suspicion that a pilot or crew member is under the influence of alcohol, they may be required to undergo alcohol testing.
The BAC Arithmetic for Airline Pilots
Here is how a pilot following the 8-hour rule for alcohol before a scheduled flight can still have a BAC exceeding .04 percent by flying time:
The body can only metabolize alcoholic beverages at a certain rate, about 0.015mg per hour. This works out to roughly one drink per hour if one drink is defined as one shot of distilled liquor, 5 ounces of wine, or 12 ounces of beer.
However, body weight and gender are also key factors. Women typically have a much higher body fat composition and fat-to-water ratio than men.
This higher ratio typically means that a woman absorbs alcohol faster than a man. Men also tend to have more of the liver enzyme DHA or dehydrogenase responsible for breaking pure alcohol down.
Here is the formula for the BAC to drop to a certain level:
Body weight times number of drinks/elimination rate times number of hours since the last alcoholic beverage was consumed.
Examples of this follow below.
Let’s say our hypothetical pilot, off duty and not due to report to fly until 8 AM the next day, has a few drinks. They are not doing anything wrong because it’s before 8 PM the day before.
We will use 155 pounds for the pilot’s weight for demonstration purposes. Alcoholic beverages enter the system and influence it quickly, so shortly after a person has one standard drink, their BAC will rise to .03 percent. This is already most of the allowed limit, but there is also 12 hours until their flight.
This is not a problem. Their BAC will be zero before operating an aircraft as long as no further alcoholic beverage is consumed.
However, let’s say this hypothetical pilot continues to drink and has six drinks within a few hours that same evening. This still isn’t illegal or against FAA rules because the individual stops all alcohol consumption just before midnight per FAA rules.
Using the formula for alcohol elimination from the body, we can see that this pilot’s BAC would still be above .04 percent at flight time:
(0.03 X 6) – (0.015 X 8) = 0.06%
This is for a 155-pound person.
A 200-pound person would have a BAC of 0.02 percent after one standard drink. That calculation would go like this:
(0.02 X 6) – (0.015 X 8) = 0
The larger individual would have a zero BAC by the time of duty as long as no more than six drinks were consumed, and the pilot stopped all alcohol consumption 8 hours before flight time.
However, if the 200-pound individual had another two drinks for a total of eight during this same time period, they would have a BAC of .04 percent when reporting for duty, which violates the FAA regulations against operating an aircraft with a BAC of .04 percent or higher.
Variations in BAC can occur not only from body weight and gender but ancestry.
As a group, Asians tend to have a relative genetic deficiency of DHA. So, pilots of both sexes of Asian descent may be at a particular risk of still having a BAC higher than the FAA allows from prior alcohol consumption, even though they didn’t violate the FAA’s “bottle to throttle” rule.
When an extra four hours for a total of 12 hours of prohibited alcohol consumption is figured in, all of our hypothetical weight pilots would have a BAC of less than .04 percent by their 8 AM flight, provided they followed the rule and had their last drink at or before 12 hours before flight time.
This is why it makes sense for airlines to require abstinence from alcohol for 12 hours before operating an aircraft rather than 8 hours. If you or a crew member are asked to undergo alcohol testing and have a high BAC level, you may be escorted away by law enforcement or local authorities.
The Addicted Pilot
Consuming alcohol in secret is harder compared to other drugs because of its pungent, characteristic odor and the fact that an inebriated person’s behavior is obvious. However, some pilots may drink excessively while off duty, leading to a covert alcohol abuse problem.
Drug addictions and alcohol problems will eventually compromise the pilot’s ability to safely fly an aircraft in one way or another because alcohol abuse is a progressive disease.
People who abuse drugs and other substances become adept at hiding their alcohol problems and rarely admit it or seek help unless compelled to do so after blood alcohol tests.
It is not known exactly how many American pilots may be in this stage of the addiction process, but pilots at United and Delta caught reporting for duty while drunk prove that the number isn’t zero.
In 2018, the FAA issued about 1,200 medical certificate clearances to airline pilots recovering from substance abuse, primarily alcohol.
The Takeaway
Each airline has strict rules about pilot and crew behavior before and during flights. This includes drinking outside of the FAA or airline guidelines and taking medication that may compromise the safety of passengers and other crew members.
This applies to prescribed drugs, too.
Intoxicated pilots under the influence would likely be prevented from operating the aircraft by fellow crew members who are obligated by law and company policy to protect the safety of passengers and the airline from liability.
Airlines have procedures in place to identify pilots with possible substance abuse problems. Help is available for these individuals, especially if they admit their problem and ask for assistance before problems due to their impairment occur.
Airlines conduct random employee urine testing with and without cause to help protect passengers, other crew members, and everyone sharing the same skies.