FILE - In this Wednesday, Feb. 23, 2011 file photo, a plane flies overhead as a United Airlines 747-400 sits parked in the foreground at San Francisco International Airport in San

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FILE - In this Wednesday, Feb. 23, 2011 file photo, a plane flies overhead as a United Airlines 747-400 sits parked in the foreground at San Francisco International Airport in San Francisco. The merger of American and US Airways means there have now been four megamergers in five years for the airline industry, during which the title of No. 1 airline changed three times. Consolidation has given the industry pricing power and helped usher in a period of stability and, for the most part, profitability. (AP Photo/Eric Risberg, File) less