Instead , some airlines have debanked their hubs , introducing a " rolling hub " in which flight arrivals and departures are spread throughout the day . This phenomenon is also known as " depeaking " . While costs may decrease , connection times are longer at a rolling hub . American Airlines was the first to depeak its hubs , trying to improve profitability following the September 11 attacks . It rebanked its hubs in 2015 , however , feeling the gain in connecting passengers would outweigh the rise in costs
September 11 attacks
September 11 attacks
Airline hub