For those unfamiliar with the US commercial aviation industry, Atlanta-based Delta Air Lines is one of the largest and most important carriers in the United States. The airline operates a legacy business model, meaning that it primarily caters to passengers traveling for business between cities across the United States and the world, and efficiently connects them through its major hubs. The airline has a total of nine different operational hubs, with the largest of these being Atlanta Hartsfield-Jackson International Airport (ATL).