During 1956, six airlines — the Big Four, National, and Northwest — signed an agreement limiting the number of alcoholic drinks, other than beer and wine, to two 1.6-ounce drinks per passenger. The agreement applies only in the continental United States. A bill prohibiting the serving of alcoholic drinks on domestic flights was passed as a safety measure by the House of Representatives. It was not passed by the Senate, although it was supported by pilots and stewardesses.
Air Passenger Transportation (Limitation of Alcoholic Drinks) using Air Transportation in 1956 as reference