DALLAS — The president and No. 2 executive at American Airlines has left the company and taken the same job with rival United Airlines.

United Continental Holdings Inc. said Monday that Scott Kirby has been named president and will oversee operations, sales and other duties.

Kirby, 49, was often seen as a likely successor to American Airlines Group Inc. CEO Doug Parker. Instead, he will add airline-industry expertise to United’s management.

Chicago-based United is led by Oscar Munoz, a longtime railroad executive who became CEO less than a year ago and missed several months after a heart attack and transplant.

In a statement, Munoz said Kirby “is a proven leader, whose deep airline experience and expertise will further accelerate our efforts to build the best airline in the industry.” Munoz said Kirby’s hiring culminated the building of his senior leadership team, which included this month’s hiring of a new chief financial officer and chief commercial officer.

Investors have been pushing Munoz to speed up improvement to the airline’s operations and financial performance. Earlier this year, two activist shareholders threatened a proxy battle if Munoz did not surround himself with more people experienced in the airline industry.

Kirby’s departure from American breaks up what was an unusually long-tenured management team for the airline business. Kirby worked for Parker at America West Airlines and US Airways, where he rose to president in 2006. Both men took the same jobs at American after engineering the December 2013 merger with US Airways.

American said Kirby’s departure came after discussions about CEO succession and “career expectations” of its executives. Lead outside director John Cahill said the company was looking forward Parker’s leadership “for many years to come.”

Kirby will get a termination package valued at $13.2 million in cash and stock, according to an American Airlines regulatory filing.

Kirby’s replacement at American will be another member of that team, Robert Isom, 52, the airline’s chief operating officer.

Isom joined US Airways in 2007 and was credited with reducing that airline’s flight delays. When US Airways management took control of post-merger American, he kept the chief operating officer’s job at the combined carrier, which is based in Fort Worth, Texas.