American Airlines Flight 11 was a domestic passenger flight that was hijacked by five al-Qaeda terrorists on the morning of September 11, 2001, as part of the September 11 attacks. The hijacked airliner was deliberately crashed into the North Tower of the World Trade Center complex in New York City, killing everyone aboard the flight and resulting in the deaths of more than one thousand people in the top 18 stories of the skyscraper in addition to causing the demise of numerous others below the trapped floors, making it not only the deadliest of the four suicide attacks executed that morning in terms of both plane and ground fatalities, but also the single deadliest act of terrorism in human history and the deadliest plane crash of all time. The aircraft involved, a Boeing 767-223ER with 92 passengers and crew, was flying American Airlines' daily scheduled morning transcontinental service from Boston Logan International Airport in Massachusetts to Los Angeles International Airport in California.

The September 11 attacks, commonly known as 9/11, were four coordinated Islamist suicide terrorist attacks carried out by al-Qaeda against the United States on September 11, 2001. That morning, 19 terrorists hijacked four commercial airliners scheduled to travel from the East Coast to California. The hijackers crashed the first two planes into the Twin Towers of the World Trade Center in New York City, two of the world's five tallest buildings at the time, and aimed the next two flights toward targets in or near Washington, D.C., in an attack on the nation's capital. The third team succeeded in striking the Pentagon, the headquarters of the U.S. Department of Defense in Arlington County, Virginia, while the fourth plane crashed in rural Pennsylvania during a passenger revolt. The September 11 attacks killed 2,977 people, making them the deadliest terrorist attack in history, and instigated the multi-decade global war on terror, fought in Afghanistan, Iraq, and elsewhere.