Stewart, Air Europa’s country director UK and Ireland, takes over from Bob Schumacher of United Airlines, who has held the role since 2013.
Daniel Bainbridge, regional manager UK and Europe at Malaysia Airlines, has been appointed deputy chair.
Bar, the Board of Airline Representatives, represents 71 scheduled carriers in the UK in their engagement with government departments, regulators and airport operators.
Stewart said: “Having been involved on the board of Bar UK for a number of years it is a great honour to be taking on the role of chair at such a crucial time for our sector and I look forward to working with our CEO, Dale Keller and the board, as we look to shape the future of our industry and strengthen the importance of Bar UK to its membership.
“The airline community are hugely grateful to Bob Schumacher for his nine years of leadership and dedication as chair and I am delighted that he has agreed to continue on the board, as his wealth of experience will be invaluable moving forward.”