The September 11 attacks involved passenger airplanes.
American Airlines , Inc. ( AA ) , commonly referred to as American , is a major American airline headquartered in Fort Worth , Texas . American Airlines Flight 11 was a domestic passenger flight that was hijacked by five al-Qaeda members on September 11 , 2001 , as part of the September 11 attacks . American Airlines Flight 77 was a scheduled American Airlines domestic transcontinental passenger flight from Washington Dulles International Airport in Dulles , Virginia , to Los Angeles International Airport in Los Angeles , California . September 11 attacks . Four passenger airliners operated by two major U.S. passenger air carriers ( United Airlines and American Airlines ) -- all of which departed from airports in the northeastern United States bound for California -- were hijacked by 19 al-Qaeda terrorists . A third plane , American Airlines Flight 77 , was crashed into the Pentagon ( the headquarters of the United States Department of Defense ) in Arlington County , Virginia , leading to a partial collapse of the building 's western side .