While an industry veteran, AAL's new CEO, Robert Isom, appears to be committed to fixing a number of AAL's structural and endemic problems including those that have harmed its preference with coveted business passengers. JBLU grew rapidly during its first 15 years, in part because slot controls at NYC's largest airports limited competition and because legacy carriers had still not figured out how to compete effectively post 9/11. JBLU's margins began to erode in the late 2010s as Delta, JBLU's most direct competitor strengthened its operations at New York's LaGuardia and JFK airports where Delta (DAL) is the largest airline and also because Delta designated Boston as a hub due to growth at JetBlue's second largest operation.