American Airlines operates one of the largest Airbus A321neo fleets in the world, using the narrowbody aircraft to serve a variety of domestic and international routes. However, not every A321neo in its fleet is quite the same. Among its aircraft are 10 examples inherited from Alaska Airlines, which originally acquired them following its takeover of Virgin America. Although these aircraft offer similar capabilities to American’s other A321neos, their original design has created an unusual fleet-management challenge.