As others said, on a US based carrier, the drinking age is 21, no matter from where the flight originates.
People Also Ask
Can You Drink Your Own Alcohol On a Plane? The short answer is a resounding “no.” U.S. Federal Aviation Administration (FAA) regulations state that drinking your own alcohol on a commercial flight is prohibited, and those who don't comply could face upwards of $40,000 in fines.
Under current FAA regulations, passengers aren't allowed to drink alcohol while flying unless it's served by a flight attendant. Your flight attendant also isn't allowed to serve you if you're intoxicated.
Does Delta ask for ID for alcohol? No need for ID - the airline already knows your age as a part of the APIS data. For at least some airlines, whether a passenger is over 21 or not IS shown on the manifest.
While that may seem like an easy option drinking on a plane has many negative side effects. And drinking on a plane not only affects you during the flight but possibly for days after as well. The next time you have to fly, avoid the booze. You will be more alert and readier to take care of business when you get there.
Alcohol or liquor is permitted if it's in your checked baggage or purchased after the security checkpoint for your carry-on, as long as it meets carry-on guidelines and the following: Alcohol content may not exceed 140 proof. Up to 5 liters of alcohol per person between 48 and 140 proof is permitted.
Whether you check in on delta.com, the Fly Delta app or in-person at the airport, you'll be expected to present government-issued photo identification along with your boarding pass.