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9/11: A Timeline of Terror

How 19 Al-Qaeda Terrorists Hijacked Four Planes and Attacked the U.S.

The September 11, 2001 terrorist attacks were the deadliest ever on U.S. soil, claiming the lives of 2,977 victims and triggering major U.S. policy changes and even war. Masterminded by al-Qaeda leader Osama bin Laden, they involved the hijacking of four planes, three of which were used as suicide attacks against major landmarks. The events of that day and the aftermath are forever seared into history.

The Road to 9/11

The story of 9/11 did not begin on the morning of September 11, 2001. The attacks were the culmination of a decade-long plot by al-Qaeda, an Islamist extremist network founded in 1988 by Osama bin Laden, a wealthy Saudi Arabian exile who had fought against the Soviet occupation of Afghanistan in the 1980s.

Fueled by a radical ideology that saw the U.S. as the root of all evil, bin Laden had declared a holy war against America, which he accused of exploiting the Muslim world. Al-Qaeda began a campaign of terrorism against U.S. targets, bombing American embassies in Kenya and Tanzania in 1998 and an American warship in Yemen in 2000. The CIA had tracked bin Laden since 1996 and had come close to assassinating him in 1998, but he continued to elude them.

After the embassy bombings, the FBI placed bin Laden on its Ten Most Wanted Fugitives list and began investigating al-Qaeda‘s presence in the U.S. In the summer of 2001, the CIA and FBI started to pick up an increasing amount of "chatter" indicating a major attack was in the works—but they lacked specific details on the timing, location, or method. A July 2001 FBI memo from its Phoenix field office warned that al-Qaeda operatives might be training at U.S. flight schools, while in August the CIA warned President Bush that bin Laden was "determined to strike in U.S."

The Hijackers

The 9/11 plot was set in motion in 1999 by Khalid Sheikh Mohammed, an al-Qaeda operative who had wire transferred money to one of the 1993 World Trade Center bombers. He proposed to bin Laden an elaborate plan to hijack 10 planes and crash nine of them into prominent U.S. buildings, with a tenth flying into Israel. Bin Laden scaled back the plan but provided four al-Qaeda operatives to help carry it out: Nawaf al-Hazmi, Khalid al-Mihdhar, Waleed al-Shehri and Satam al-Suqami.

Over the next two years, the "Hamburg cell" of radical Muslims that included Mohammed Atta, Marwan al-Shehhi, Ramzi Binalshibh and Ziad Jarrah became key players in the plot. All four had spent time in Afghanistan and pledged loyalty to bin Laden. In late 1999, Atta, al-Shehhi, and Jarrah enrolled in flight training in Florida, hoping to learn how to control large jet aircraft.

In all, 19 young men, most of them from Saudi Arabia, were selected by bin Laden and al-Qaeda to carry out the attacks. They were mostly educated, middle-class men in their 20s and 30s. Some had been radicalized through contacts with militant preachers or at training camps in Afghanistan and Pakistan. Others were university students in Germany who had embraced a virulent anti-Semitism and hatred of the U.S. The "muscle hijackers" were primarily Saudi men in their 20s who had been recruited through extremist mosques and were chosen for their strength, dedication, and discipline.

United Airlines Flight 175 crashes into the south tower of the World Trade Center

United Airlines Flight 175 crashes into the south tower of the World Trade Center complex in New York City during the September 11 attacks. (Source: Wikimedia Commons)

The Attacks Begin

American Airlines Flight 11

  • 7:59am: American Airlines Flight 11, a Boeing 767 with 92 people aboard, takes off from Boston‘s Logan Airport. It is scheduled to fly nonstop to Los Angeles.
  • 8:14am: The flight is hijacked when five al-Qaeda terrorists armed with box cutters storm the cockpit and kill the pilot and co-pilot. Egyptian-born hijacker Mohammed Atta takes the controls.
  • 8:24am: Flight 11 makes an unscheduled 100-degree turn and heads south towards New York City. Atta accidentally broadcasts a message meant for the passengers to air traffic control: "We have some planes. Just stay quiet and you‘ll be okay. We are returning to the airport."
  • 8:46am: Flying at about 465 mph, Flight 11 crashes into the north face of the North Tower of the World Trade Center, between floors 93 and 99. The plane enters the tower intact and severs all three emergency stairwells. People below the 92nd floor have little chance of escape. The crash instantly kills hundreds, including all 92 passengers and crew.

United Airlines Flight 175

  • 8:14am: United Airlines Flight 175, a Boeing 767 with 65 people aboard, departs from Boston also bound for Los Angeles.
  • 8:42am: Flight 175 veers wildly off its flight path, making a U-turn and heading toward New York City. Unlike Flight 11, its transponder signal is not turned off.
  • 8:47am: The FAA notifies NORAD about the suspected hijacking of Flight 175. Three F-15 fighter jets are scrambled from an Air National Guard base in Massachusetts, but they are not told why.
  • 9:03am: Flying at about 590 mph, Flight 175 crashes into the south face of the South Tower of the World Trade Center, between floors 77 and 85. Parts of the plane, including an engine, leave the building from its east and north sides. The crash kills all 65 passengers and crew.

The twin towers of the World Trade Center burn after being hit by planes

Smoke billows from the twin towers of the World Trade Center after they were hit by two hijacked airliners in a terrorist attack on September 11, 2001 in New York. (Source: Wikimedia Commons)

The Nation in Chaos

  • 9:30am: President Bush, speaking from a Florida elementary school, calls the crashes an "apparent terrorist attack on our country."
  • 9:40am: For the first time in history, the FAA grounds all flights nationwide. Hundreds of planes are forced to land at the nearest airport. All international flights headed for the U.S. are redirected to Canada.
  • 9:45am: In Washington, the White House and U.S. Capitol are evacuated amid fears that they could be additional targets. Government buildings across the country are also cleared.

American Airlines Flight 77

  • 8:20am: American Airlines Flight 77, a Boeing 757 with 64 people aboard, takes off from Washington Dulles for Los Angeles. Five hijackers are aboard.
  • 8:54am: The plane makes an unauthorized turn to the south and heads back toward Washington, D.C.
  • 9:37am: Hani Hanjour crashes the plane into the western side of the Pentagon. It is traveling about 530 mph and hits the first floor. The crash and resulting fire penetrate the three outer rings of the building. All 64 passengers are killed, as are 125 military and civilian personnel in the Pentagon.

United Airlines Flight 93

  • 8:42am: United Airlines Flight 93, a Boeing 757 with 44 people aboard, takes off from Newark International Airport bound for San Francisco. Four hijackers are aboard.
  • 9:28am: Hijacker pilot Ziad Jarrah mistakenly transmits a message to passengers to air traffic control: "Ladies and gentlemen, this is the captain. Please sit down, keep remaining seated. We have a bomb aboard."
  • 9:32am: A hijacker, likely Jarrah, announces in broken English: "This is the captain. I would like you all to remain seated. We have a bomb aboard, and we are going back to the airport, and we have our demands. So please remain quiet."
  • 9:35am: Passengers and crew begin making phone calls to family members and authorities to report the hijacking. They relay that the hijackers claim to have a bomb and that one passenger is dead and another is dying, likely the pilots based on the entry of the cockpit.
  • 9:57am: Passenger revolt begins. The cockpit voice recorder captures the sounds of a food cart crashing and passengers attempting to break through the door. One passenger can be heard shouting, "In the cockpit! If we don‘t, we‘ll die!"
  • 10:03am: Jarrah intentionally crashes the plane into a field near Shanksville, Pennsylvania, about 65 miles southeast of Pittsburgh, rather than cede control of the plane. The crash kills all 44 people aboard.

Debris from United Airlines Flight 93 in Shanksville, Pennsylvania

Debris from United Airlines Flight 93 smolders after the plane was crashed into a field in Shanksville, Pennsylvania during the 9/11 attacks. (Source: U.S. Government photo)

Collapse and Aftermath

  • 9:59am: After burning for 56 minutes, the South Tower of the World Trade Center begins to collapse. A massive cloud of dust and debris quickly fills lower Manhattan.
  • 10:28am: The North Tower of the World Trade Center collapses after burning for 102 minutes. More than 1,600 people are killed as the 110-story tower pancakes to the ground in just 12 seconds.
  • 5:20pm: 7 World Trade Center, a 47-story building heavily damaged by debris from the twin towers, collapses after burning for hours. It was the last building in the WTC complex to fall.
  • 8:30pm: President Bush addresses the nation from the White House. "Today, our fellow citizens, our way of life, our very freedom came under attack in a series of deliberate and deadly terrorist acts," he says. "Terrorist attacks can shake the foundations of our biggest buildings, but they cannot touch the foundation of America."

Aerial view of Ground Zero after the collapse of the World Trade Center towers

An aerial view of Ground Zero and the collapsed World Trade Center towers on September 17, 2001. (Source: U.S. Navy photo by Chief Photographer‘s Mate Eric J. Tilford)

In total, 2,977 people were killed in New York City, Washington, D.C., and Pennsylvania, along with the 19 terrorist hijackers aboard the four airplanes. At the World Trade Center, 2,753 died after the two planes slammed into the twin towers. That figure includes 343 firefighters and paramedics, 23 New York City police officers and 37 Port Authority police officers who were struggling to evacuate the buildings and save the office workers trapped on higher floors.

At the Pentagon, 189 people were killed, including 64 on American Airlines Flight 77 and 125 military and civilian personnel inside the building. Near Shanksville, 44 people died when United Airlines Flight 93 crashed into a field.

The September 11 attacks shook the nation to its core and prompted immediate changes to U.S. national security, foreign policy, and American life. On September 14, 2001, Congress passed the Authorization for Use of Military Force (AUMF), providing the President broad authority to fight a "war on terror." On October 7, 2001, the U.S. invaded Afghanistan to hunt down al-Qaeda and topple the Taliban regime that had provided it a safe haven. The following year, Congress created the Department of Homeland Security to coordinate domestic anti-terrorism efforts.

The attacks profoundly changed perceptions of Islam and Muslims in the U.S., fueling a spike in Islamophobia, hate crimes, and racial profiling of Arab and South Asian Americans. They also led to a curtailing of some civil liberties through the passage of the Patriot Act, which expanded government surveillance and law enforcement powers. And they sent the U.S. on a long and costly path of military intervention in the Middle East, including wars in Afghanistan and Iraq that would claim thousands more American lives.

In the two decades since that dark day, a number of 9/11 memorials, museums, and monuments have been built to honor the victims, including the National September 11 Memorial & Museum at the rebuilt World Trade Center site. Each year, communities across the nation hold remembrance services on September 11. A new tower, One World Trade Center, now rises above the Manhattan skyline, a symbolic 1,776 feet tall. And a whole generation has come of age learning about an event that reshaped the world into which they were born.

9/11 Memorial with One World Trade Center in background

The 9/11 Memorial honors the victims of the September 11, 2001 attacks with twin reflecting pools in the footprints of the fallen towers. The One World Trade Center rises in the background. (Source: Wikimedia Commons)

For all the progress that has been made, many questions about the 9/11 plot remain unanswered twenty years later, from the extent of Saudi government involvement to whether more could have been done to prevent it. Documents continue to emerge that shed new light on the attacks, even as some information is still being withheld or redacted. As recently as September 2021, President Biden ordered the Justice Department and other agencies to oversee a declassification review of investigation-related documents and release what they can over the next six months.

Perhaps the most fitting tribute to 9/11‘s legacy is a commitment to studying it from every angle—honoring those lost by piecing together the full historical record of that day, as a way to prevent future tragedies. Far more than a date on a calendar, September 11 was a hinge point in modern world history, the implications of which continue to reverberate and unfold, even two decades later.