FAA “Bottle To Throttle” Rule: A Danger Window Every Pilot Should Know

FAA “Bottle To Throttle” Rule: A Danger Window Every Pilot Should Know

Jackson Barnett
Jackson Barnett

Principal Attorney

What’s the FAA’s “Bottle To Throttle” rule? It’s the number of hours before a flight that a pilot must stop drinking alcohol. And it’s a rule that many pilots have heard of, but wish they knew the specifics before they were pulled from the cockpit just prior to departure.

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%. Some airlines, such as United Airlines, have an even stricter Bottle To Throttle window in which the pilot must abstain from alcohol for 12 hours before a flight.

How Are Pilots Tested For Alcohol Before Flying?

While some FAA guidelines may state that you should not fly while under the influence of alcohol, the reality is that not every pilot exhibits good judgment the way they should.

Fortunately, Department of Transportation / FAA 14 CFR Part 121 clarifies this point further to state that any person who performs a safety-sensitive function for a regulated employer is subject to testing.

This testing can include:

  • Random tests
  • Reasonable suspicion tests
  • Return to duty tests
  • Follow-up tests
  • Post-accident tests

Employees Subject to Random Alcohol Testing

From the FAA’s Memorandum on Alcohol Testing:

“Alcohol testing is performed using an evidential breath-testing device approved by the National Highway Traffic Safety Administration and listed on its Conforming Products List of Evidential Breath Measurement Devices. A DOT contract breath alcohol technician will conduct alcohol testing. There are two tests administered to determine a prohibited alcohol concentration. The screening test is conducted first. If the screening test is above the allowed limit, a confirmation test isconducted after 15 minutes from the screening test. The results of the confirmation test determine the action to be taken.”

Can A Pilot Be Removed From A Flight If Their Blood Alcohol Level Is Lower Than 0.04%?

Yes. Should your blood alcohol concentration be between .02% – .039% on an alcohol test, you could still be very well removed from a flight.

“As little as one ounce of liquor, one bottle of beer or four ounces of wine can impair flying skills, with the alcohol consumed in these drinks being detectable in the breath and blood for at least 3 hours.”

– FAA, “Fitness for Flight”

The “Real” Waiting Period After Bottle To Throttle

If you’ve had anything to drink, the body doesn’t always cooperate on the exact timetable as an FAA rule stating when it’s acceptable to fly. There is the hangover effect to consider.

In other words, 8 hours bottle to throttle doesn’t necessarily mean that it’s a good idea for a pilot to enter the cockpit. In fact, the longer you err on the side of caution, the better. Some pilots have a much broader window in which they will not use alcohol within 24 hours of flying.

The FAA states, “Even after the body completely destroys a moderate amount of alcohol, a pilot can still be severely impaired for many hours by a hangover.” 

No amount of black coffee, cold showers or breathing 100% oxygen will remove the alcohol in your body any faster. So, if you have to wait longer to fly based on what your body is telling you, don’t ignore it. Flying with a hangover can be as deadly as flying after drinking within the last 8 hours.  

Are You Really Ready To Fly?
A Formula For Calculating The Answer

The Bottle To Throttle guideline of 8 hours may sound reasonable on paper, but a pilot could still feel intoxicated, even after the 8-hour window has expired.

Pure alcohol leaves the body at an average rate of about 0.015g / 100mL per hour. Put another way, for men, this is the rate of about one standard drink per hour.

We often think that the size of individual influences our concentration of alcohol, but that’s only partially true. The hourly rate of elimination of alcohol is actually the same in every person. Size has no bearing on that. Gender, illness and medication can cause the BAC to increase more quickly and fall more slowly. Eating food actually slows the body’s absorption rate of alcohol, peaking appx 30 minutes to 4 hours after consumption. (see reference)

Estimate your BAC – Know your Limits

For example, let’s say that a male pilot who weighs 150 lbs. has consumed 4 craft beers with an ABV of 5.8% over 4 hours. The airman’s BAC is around 0.088%.

He then waits 4 hours after his last drink until he thinks he is ready to fly.

4 hours without another drink SOUNDS good.
But is he really ready to fly? Let’s calculate it.

Here’s how that breaks down in a formula you can use to approximate your Blood Alcohol Content (BAC) level:

 (elimination rate x number of hours since last drink)

(estimated BAC) – (elimination rate x hours since last drink)

(0.088) – (.015 x 4 hours = .12) = 0.028 BAC

(0.088) – (.015 x 5 hours = .12) = 0.013 BAC

(0.088) – (.015 x 6 hours = .12) = 0.002 BAC

The airman may think he’s in the clear after 6 hours. But remember, illness, gender, food, and medications can all play a factor. Is risking your career for a few hours of drinking worth the cost?

Use This Formula In The
Bottle To Throttle Danger Window

Just as you can use this tool to calculate your own BAC, the FAA and HIMS AMEs use this formula to calculate (backward) your estimated BAC at the time of consumption. The real danger here is not what your BAC is at the time you’re testing, but how high your BAC was when you were drinking. This is a leading indicator of substance abuse and dependence and almost a guarantee that the airman will be subject to the HIMS protocols.

Surprised? Don’t be. Plug this formula into the window of time you or a fellow pilot have had since your last drink. It’ll reveal a telling piece of data that just may save your life and many others at the same time.


Bottle To Throttle Fallout:

Legal and Medical Consequences of Failing An Alcohol Test

An airman who fails a random alcohol test will likely face a Loss of job -or- Employer HIMS program and Legal Action by the FAA.

Legal actions include:

  • Letter of Investigation
  • Notice of Proposed Certificate Action
  • Emergency Order of Suspension
  • Emergency Order of Revocation

At Barnett Law Offices, we have years of experience working with pilots trying to operate an aircraft who have failed a random drug or alcohol test.

Working with Barnett Law Offices to guide you through the process as your advocate will make your process much less turbulent.

As you navigate the complexity of a failed alcohol test, our aviation attorneys at Barnett Law Offices can work with you through the entire process and put you in the best possible position for recertification and help you with the legal actions the FAA will likely take on your certificates.

To take the next step and schedule a confidential consultation with an aviation attorney from our firm, call Barnett Law Offices at (800) 578-5512.