FILE PHOTO: Doug Parker, chairman and chief executive officer of American Airlines Group Inc., Gary Kelly, chief executive officer of Southwest Airlines Co., Scott Kirby, president of United Airlines Holdings Inc., John Laughter, executive vice president and chief of operations at Delta Air Lines Inc., and Sara Nelson, international president of the Association of Flight Attendants-CWA, testify during a Senate Commerce, Science, and Transportation oversight hearing on Capitol Hill in Washington, D.C., U.S., December 15, 2021. Tom Brenner/Pool via REUTERS/File Photo