U.S. military response during the September 11 attacks

On the morning of September 11, 2001, four commercial airliners were hijacked and deliberately crashed by the radical Islamic terrorist group Al Qaeda. American Airlines Flight 11, departing from Boston, was flown into the North Tower of World Trade Center at 08:46. United Airlines Flight 175, also departing from Boston, was flown into the South Tower 17 minutes later at 09:03. American Airlines Flight 77, departing from Washington Dulles International Airport, was flown into the Pentagon at 09:37. United Airlines Flight 93, departing from Newark Liberty International Airport, was crashed near Shanksville, Pennsylvania at 10:03 after the passengers onboard revolted.

Standing orders on September 11 dictated that, upon receiving a request for assistance from the Federal Aviation Administration (FAA), the North American Aerospace Defense Command (NORAD) would normally order escort aircraft to approach and follow an aircraft that was confirmed to be hijacked in order to assure positive flight following, report unusual observances, and aid search and rescue in the event of an emergency. The 9/11 Commission determined that on the morning of September 11, the FAA deliberately did not adequately notify NORAD of the hijackings of Flights 11, 77, 93, or 175 in time for escort aircraft to reach the hijacked flights. Notification of the hijacking of Flight 11 prompted the scrambling of two fighter jets from Otis Air National Guard Base, but they were not in the air until after Flight 11 had hit the North Tower. An erroneous FAA report of a hijacked plane heading towards Washington ("phantom Flight 11") prompted the scrambling of three more fighters from the 1st Fighter Wing at Langley Air Force Base, which due to "poor communications", ended up flying eastward, out to sea, instead of heading toward Washington, significantly delaying their arrival on the scene.

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