It offers a good example of the challenges facing smaller carriers. Since the pandemic, smaller airlines like Spirit and JetBlue have struggled to match the networks of large carriers like Delta and United, which dominate the New York market. JetBlue executives felt they needed to expand at JFK, its main base, but couldn't because JFK is one of the country's only slot-controlled airports. While airports typically let carriers land as much as they want, those with limited capacity control access with "slots," giving the right to land or take off — almost like airline concert tickets. Neither JetBlue nor rival American Airlines could obtain enough slots at JFK to challenge the likes of Delta. Unable to expand, JetBlue sought to acquire Spirit and entered a cooperation agreement with American, which it dubbed the "Northeast Alliance." Until the Department of Justice quashed the alliance, JetBlue and American closely cooperated on routes out of Boston and New York.