On September 11, 2001, terrorists hijacked four passenger flights in the United States. This overview follows the 9/11 Commission, National Institute of Standards and Technology (NIST), and 9/11 Memorial sources linked below. Times in the source timeline use U.S. Eastern Time.
Four flights and the day’s attacks
American Airlines Flight 11 and United Airlines Flight 175 struck the World Trade Center towers in New York. American Airlines Flight 77 struck the Pentagon. United Airlines Flight 93 crashed near Shanksville, Pennsylvania, after passengers and crew resisted the hijackers. The 9/11 Memorial records 2,977 people killed in the attacks, excluding the hijackers.
Why the World Trade Center towers collapsed
NIST concluded that aircraft impacts damaged structural elements and dislodged fireproofing; subsequent fires weakened affected structures and contributed to collapse initiation. NIST did not conclude that the steel melted. WTC 7 was not hit by an aircraft: debris from the collapse of WTC 1 damaged it and started fires, and prolonged fires led to structural failure.
Investigations and later measures
The 9/11 Commission documented intelligence and coordination failures before the attacks. The USA PATRIOT Act became law on October 26, 2001; the Aviation and Transportation Security Act established the Transportation Security Administration. Later surveillance authorities, including FISA Section 702, have their own statutory histories and should not be conflated with the immediate 2001 response.
Frequently asked questions
When did 9/11 happen? September 11, 2001.
How many planes were hijacked? Four passenger aircraft.
Were the Twin Towers brought down because their steel melted? NIST’s explanation concerns impact damage, fireproofing loss, and weakening from fires; it did not conclude that the structural steel melted.
Was WTC 7 hit by a plane? No. NIST says debris and fires were involved in its collapse.
This historical summary relies on the primary sources listed below and does not endorse unsupported conspiracy claims.
Video and references
- 9/11 Memorial timeline and casualty information
- 9/11 Commission Report
- 9/11 Commission Report
- 9/11 Commission Report
- 9/11 Commission Report
- NIST World Trade Center investigation
- NIST World Trade Center investigation
- U.S. Department of Justice source
- Aviation and Transportation Security Act
- Intelligence.gov: FISA Section 702
- Reference: www.nsa.gov
- Original video on YouTube
- Browse the source YouTube channel
- Browse a playlist from the source channel
- Browse a playlist from the source channel