here is a paragraph that may help give you some help: some argue that the negative financial effects experienced by the airline industry following the 9/11 attacks only hastened an industry reorganization that would have come sooner or later. Many airlines, including US Airways, which filed for bankruptcy after the attacks, had long-standing financial issues prior to these events. Other airlines had over-stretched during better financial positions in the 1990s, negotiating plump contracts with unions and purchasing new planes. The downward dive in passenger demand after 9/11 forced airlines to tighten their belts, re-negotiating contracts and grounding planes. Increased competition from efficient low-cost airlines could have also had this effect over a longer timeline.