Combining with US Airways would strengthen American along the East Coast and slightly expand its international routes, but airline mergers are notoriously difficult.
US Airways is still dealing with two largely separate workforces nearly seven years after it was formed by a combination with America West. It has taken United longer than expected to combine workforces and reservations systems with Continental. AMR has an unhappy history with mergers; acquisitions of Reno Air and TWA created more problems than prosperity.
Size matters in the airline industry. Business travelers in particular are attracted to airlines that fly more often and to more of the places that they want to go.
American was the world's biggest airline by passenger traffic as recently as 2008. But Delta Air Lines Inc. leap-frogged it by buying Northwest Airlines, and United became No. 1 in 2010 when it combined with Continental to form United Continental Holdings Inc.
AMR and US Airways had combined revenue of $37.03 billion in 2011, just behind United's $37.11 billion and ahead of Delta's $35.12 billion.
Airlines are often ranked by traffic measured in miles flown by paying passengers. By that standard, AMR and US Airways together slightly surpassed United, 207.71 billion miles to 207.53 billion, while Delta had 192.77 billion, according to each company's 2011 results filed with the Securities and Exchange Commission.
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