US Airways filed for bankruptcy twice, first in August 2002, then in September 2004. The airline had a history of financial difficulty, aggravated further by the Sept. 11th terrorist attacks.
Delta Airlines, the nation's third largest airline, went bankrupt in 2005 when the airline was unable to sustain the spike in fuel prices that came in the wake of Hurricane Katrina, and was overtaken by competing low-fare carriers. Eventually Delta exited bankruptcy in April 2007.
Northwest Airline, announced they were filing for bankruptcy for the same reasons in 2005, but emerged from bankruptcy in May 2007.
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