Yes, you can use British Airways lounges while flying on American Airlines, provided you meet specific oneworld alliance criteria. In 2026, access is granted if you are flying in Business or First Class on an international flight, or if you hold oneworld Sapphire or Emerald status (equivalent to BA Silver or Gold). For example, a BA Silver member flying American Airlines in Economy from London to New York can access the BA Galleries Club lounge. However, if you are an American Airlines AAdvantage member flying on a purely domestic U.S. flight, you typically do not get lounge access unless you have high-tier status and are on a "premium" transcontinental route like JFK-LAX. Always present your digital boarding pass and physical/digital frequent flyer card at the lounge entrance to verify your eligibility under the latest alliance rules.