Travel United Airlines CEO Oscar Munoz to step down in May, will be replaced by president Scott Kirby December 5, 2019 Dawn Gilbertson, USA TODAY Comments Off on United Airlines CEO Oscar Munoz to step down in May, will be replaced by president Scott Kirby Oscar Munoz joined United Airlines in 2015 and suffered a heart attack shortly after. Scott Kirby joined United in 2016 from rival American.