Rum Runners (flexible, plastic flasks designed to be "hidden" in luggage) are technically allowed on a plane, but you must follow strict TSA and FAA liquid regulations in 2026. If you are taking them in a carry-on bag, each flask must be 3.4 oz (100ml) or less and fit within your single quart-sized clear plastic bag. In checked luggage, you can carry larger quantities of alcohol, but there is a major legal catch: FAA regulations strictly prohibit travelers from consuming their own alcohol on board an aircraft unless it is served by a flight attendant. If you are caught using a Rum Runner to spike your drink mid-flight, you can face civil penalties up to $40,000 and possible criminal charges for interfering with crew members. While people use Rum Runners primarily to "smuggle" alcohol onto cruise ships (where they are often confiscated at the gangway), using them on a flight is a high-risk gamble. For 2026 travelers, the best use for a Rum Runner is to carry a favorite spirit to your final destination to enjoy after the flight, rather than attempting to use it during your journey.