TIMELINE: Remembering September 11, 2001 — 21 years later

Hijackers Mohamed Atta and Abdul Aziz al-Omari pass through security at Portland International Jetport in Maine at 5:45 a.m. Atta and al-Omari board a commuter flight to Boston Logan International Airport, where they connect to American Airlines Flight 11. Three other hijackers will join Atta and al-Omari aboard Flight 11.

Less than two hours later, the five terrorists who will hijack American Airlines Flight 77 are videotaped as they pass through Washington Dulles International Airport’s west checkpoint. Three of the hijackers, Nawaf al-Hazmi, Khalid al-Mihdhar, and Majed Moqed set off metal detectors, but no weapons are found. They proceed to the gate. The hijackers are carrying concealed knives on their persons or in their carry-on luggage.

Before 9/11, airports were not required to videotape security checkpoints. At that time, knives were allowed on planes if the blade was less than four inches in length.

September 11, 2001, is a primary election day in New York City. Primary elections are being held for mayor, public advocate, comptroller and other city offices.

American Airlines Flight 11 takes off from Boston. Eleven crew members, 76 passengers and five hijackers are on board. The aircraft is filled with 76,400 pounds of fuel for its transcontinental run to Los Angeles.

Al-Qaeda terrorists will hijack Flight 175 between 8:42 and 8:46 a.m. and reroute it toward Manhattan.

Flight attendant Betty Ann Ong alerts American Airlines ground personnel to a hijacking underway on Flight 11, reporting that the cockpit is unreachable. Using an inflight phone, Ong transmits detailed information about the hijacking on the call, which lasts about 25 minutes.

Shortly before Ong’s call, a hijacker, likely Satam al-Suqami, had stabbed the passenger seated directly in front of him in first class. Hijackers Mohamed Atta and Abdul Aziz al-Omari are seated in close proximity as well. The passenger, identified as Daniel M. Lewin by the flight crew, had served four years in the Israeli army. The Final Report of the National Commission on Terrorist Attacks Upon the United States speculates he may have tried to stop the hijackers. Lewin was likely the first person killed in the 9/11 attacks.

At 8:21 a.m., two minutes into Ong’s call, the hijackers turn off the plane’s transponder—a device that allows air traffic control to identify and monitor an airplane’s flight path. Meanwhile, American Airlines authorities relay details from Ong to their operations center in Texas. Five minutes later, Ong provides the hijackers’ seat numbers to American Airlines.

For a full transcript of Ong's call, click here.

In addition to Ong, the flight crew also included Madeline Amy Sweeney and Sara Elizabeth Low.

After several failed connections, at 8:32 a.m., flight attendant Madeline Amy Sweeney reports the hijacking of Flight 11 to a friend on the ground, a manager at Boston Logan International Airport. Over the course of approximately 12 minutes, Sweeney provides key information about the hijacking, including a description of the perpetrators.

American Airlines Flight 77, en route to Los Angeles, takes off from Washington Dulles International Airport. Six crew members, 53 passengers, and five hijackers are on board. The flight is loaded with 49,900 pounds of fuel. 

Aboard that flight was Dr. Bryan C. Jack, of Tyler. Dr. Jack served as the Director of the Programming and Fiscal Economics Division in the Office of Program Analysis and Evaluation (PA&E), in the Department of Defense. 

His responsibilities included the design and maintenance of the Future Years Defense Program and the development of the fiscal guidance by which the Secretary of Defense annually allocates funding to the military departments and defense agencies. Dr. Jack joined the Defense Department as an analyst in PA&E’s Strategic Forces Division in 1978. His career was marked by significant contributions to the analysis of U.S.-Soviet positions in the SALT II and START negotiations, to studies of force and program improvements for the NATO alliance, to cost analysis of strategic and other weapons systems, and to the operation and modernization of the department’s Planning, Programming, and Budgeting System. Dr. Jack was promoted to the Senior Executive Service in 1995. He was twice awarded the Defense Exceptional Service Medal, in 1998 and 2000.

Dr. Jack graduated from Tyler Legacy High School in 1970 as a National Merit Scholar and the male Presidential Scholar for the State of Texas. He graduated from the California Institute of Technology with honors in 1974 and studied in Japan as a Henry Luce Scholar in 1974-1975. Dr. Jack was a graduate student at CalTech and assistant to Albert Wohlstetter in 1975-1976, and received an M.B.A. from Leland Stanford University in 1978. He received his Doctorate in Economics from the University of Maryland in 1991. In 2000, he was appointed Adjunct Professor of Economics at The George Washington University.

Al-Qaeda terrorists will hijack Flight 77 shortly before 8:54 a.m. and reverse its route back toward Washington, D.C.

Attempting to communicate with passengers and crew inside Flight 11’s cabin, hijacker Mohamed Atta presses the wrong button, broadcasting instead to air traffic control and unwittingly alerting controllers to the attacks. Minutes later, Atta again makes an unintended transmission to ground control.

The transcript of the broadcast can be seen below:

8:24 a.m. ET: “We have some planes. Just stay quiet, and you’ll be okay. We are returning to the airport.”

Seconds later: “Nobody move. Everything will be okay. If you try to make any moves, you’ll endanger yourself and the airplane. Just stay quiet.”

8:34 a.m. ET: “Nobody move please. We are going back to the airport. Don't try to make any stupid moves.”

At least one of Atta’s transmissions is picked up by the pilot of Flight 175, Victor J. Saracini, who will inform the Federal Aviation Administration of what he has heard minutes before his own plane is hijacked.

Morning activities have commenced at the World Trade Center, a commercial building complex in lower Manhattan owned by the Port Authority of New York and New Jersey, an interstate agency. In addition to the signature Twin Towers (1 and 2 World Trade Center), the complex included a hotel (3 World Trade Center), four office buildings (4, 5, 6, and 7 World Trade Center), a shopping mall, restaurants, a public plaza, and a major transportation hub.

Around 8:30 a.m., roughly 80 people have gathered to attend the Risk Waters Group financial technology conference on the 106th floor of the North Tower. Seventy-two restaurant staff have arrived in advance of the morning’s breakfast service and conference preparation.

Other special events at the World Trade Center planned for September 11 include the annual National Association for Business Economics (NABE) conference, already underway in the Marriott hotel, an evening dance performance on the World Trade Center’s outdoor plaza, and a Peace Corps information session scheduled for 6 p.m. in 6 World Trade Center.

After hearing hijacker Mohamed Atta's transmission, Boston's air traffic control center alerts the U.S. Air Force's Northeast Air Defense Sector (NEADS), headquartered in Rome, New York. In response, NEADS mobilizes Air National Guard jets at Otis Air Force Base in Falmouth, Massachusetts, to identify and follow hijacked Flight 11.

Scheduled to leave Newark International Airport within minutes of the other hijacked flights, United Airlines Flight 93 takes off after a delay due to routine traffic. Seven crew members, 33 passengers, and four hijackers are on board the San Francisco–bound flight, which is filled with 48,700 pounds of fuel. 

Five hijackers crash American Airlines Flight 11 into floors 93 through 99 of 1 World Trade Center (North Tower). The 76 passengers and 11 crew members on board and hundreds inside the building are killed instantly. The crash severs all three emergency stairwells and traps hundreds of people above the 91st floor.

Dianne DeFontes, receptionist at law firm Drinker Biddle and Reath, recalls the impact of hijacked Flight 11 into the North Tower:

“When I got into my office, I took one last look out the window and then went to my desk. Then all of a sudden, this bang happened. The bang, and being thrown out of my chair, and having the door partially opened—it all happened at the same time. And not only that, but the conference room that was on my left—the ceiling fell down and hit the table and cracked the conference room table. So all this noise happened at once. I’m getting up, I started gathering my things. And then, while I’m getting my things together, the people from MetLife came across, and some of them had blackened faces. They said, ‘A plane hit the building. We watched it. We saw it hit the building, and our office exploded.’ I said, ‘Oh my God.’”

Constance Labetti, an Aon Corporation employee on the 99th floor of the South Tower, describes seeing Flight 11 heading toward the North Tower:

“So I stood up, and I just turned my body towards the window, and I could see the big airline coming straight towards us. It looked like it was coming towards us. Didn’t look like the plane was in any kind of duress. It was going straight towards what I thought was our building when, in actuality, Tower One was right in front of us. I just stood frozen. I didn’t move. I couldn’t move. I just stood at the window. I could see it coming closer and closer. I could see the AA on its tail. I could see the cockpit. I could see inside the cockpit, the tinted windows of the cockpit. That’s how close I was. I could see on the side some of the windows of the passengers were pulled down. And then it just bellowed into Tower One. And for a moment, just for that moment, I was almost [sighing] of relief, until I realized all those people that had just [been] killed in that tower.”

New York City emergency dispatchers send police, paramedics and firefighters to the North Tower.

Immediately after witnessing the crash from 14 blocks north of the World Trade Center, Battalion Chief Joseph Pfeifer directs New York City Fire Department (FDNY) dispatch to issue a second alarm. En route to the scene, he signals a third alarm, which calls for 23 engine and ladder companies, 12 chiefs, and 10 specialized units to respond to a plane crash at “Box 8087,” the FDNY’s shorthand reference for the World Trade Center. Vehicle drivers are instructed to park adjacent to the North Tower.

The Port Authority Police Department (PAPD), responsible for the safety and security of the World Trade Center in addition to regional bridges, tunnels, airports, and the Port of New York and New Jersey, mobilizes in response to the attack. Additional PAPD units from other posts dispatch to the World Trade Center to aid in evacuation and rescue.

WCBS Newsradio 880 producer Kelley Edwards and Jeff Caplan, a news anchor, describe the response to the emergency at the World Trade Center:

Kelley Edwards: "I’m just about fifteen blocks north of the World Trade Center right now on Seventh Avenue. Fire trucks are screaming down Seventh Avenue, trying to get to this fire. It looks like the fire is about ten blocks from the—excuse me, ten stories—from the top of the building. Flames are shooting out. Smoke is pouring out. This gash goes from one side of the building practically all the way to the other. You can see thick black smoke pouring out of the front of the building, the north side. I can also see it coming out of the west side, and it’s certainly cutting off the entire top of the building right now. It’s completely covered with smoke. You can barely see the top of the building. You can see flames shooting out of the east side of that gash. The gash seems to be getting bigger..."

For the full transcript from the broadcast, click here.

While visiting an elementary school in Sarasota, Florida, President George W. Bush is informed that "a small plane" has hit the North Tower. President Bush and his advisers assume the crash is a tragic accident.

“Your attention, please, ladies and gentlemen. Building Two is secure. There is no need to evacuate Building Two. If you are in the midst of evacuation, you may use the reentry doors and the elevators to return to your office. Repeat, Building Two is secure.” - Announcement made by a Port Authority fire safety employee, via the South Tower’s public address system, at approximately 8:55 a.m.

PAPD Sergeant  Al DeVona issues orders to commence the evacuation of both towers. One minute later, PAPD Captain Anthony Whitaker expands the order to include all civilians in the World Trade Center complex.

Earlier, at 8:52 a.m., a flight attendant, likely Robert John Fangman, had reached a United Airlines operator in San Francisco, California, and reported a hijacking underway. By 9 a.m., passengers Garnet Ace Bailey, Peter Burton Hanson and Brian David Sweeney have called family members.

Sweeney leaves a voicemail message for his wife, Julie, after his plane is hijacked:

Answering machine: "Message one."

Brian Sweeney: "Jules, this is Brian — listen, I’m on an airplane that’s been hijacked. If things don’t go well, and it’s not looking good, I just want you to know I absolutely love you, I want you to do good, go have good times, same to my parents and everybody, and I just totally love you, and I’ll see you when you get there. Bye, babe. I hope I call you."

"May I have your attention, please. Repeating this message, the situation occurred in Building One. If the conditions warrant on your floor, you may wish to start an orderly evacuation." - Announcement made by a Port Authority fire safety employee via the South Tower's public address system.

Five hijackers crash United Airlines Flight 175 into floors 77 through 85 of 2 World Trade Center (South Tower), killing the 51 passengers and nine crew members onboard the aircraft and an unknown number of people inside the building. The impact renders two of the three emergency stairwells impassable and severs a majority of the elevator cables in this area, trapping many above the impact zone and inside elevator cars.

Shortly after hijacked Flight 175 strikes the South Tower, some workers in the building jump or fall to their deaths, a phenomenon already witnessed after the attack on the North Tower. Estimates of the number of people who die as a result of falling from the Twin Towers range from 50 to more than 200.

In addition to requesting the shutdown of airspace over New York City, the New York City Police Department (NYPD) calls for a second Level 4 mobilization, bringing its total deployment to nearly 2,000 officers.

The New York City Fire Department (FDNY) issues a fifth alarm for the South Tower, deploying several hundred additional firefighters to the disaster. Additional companies and off-duty personnel from across the metropolitan area travel to the scene.

While visiting an elementary school in Sarasota, Florida, President George W. Bush learns from White House Chief of Staff Andrew Card that a second plane has crashed into the World Trade Center

Twenty-five minutes later, before leaving the school, President Bush delivers his first remarks on the attacks:

President Bush: "Ladies and gentlemen, this is a difficult moment for America.  I, unfortunately, will be going back to Washington after my remarks.  Secretary Rod Paige and the Lt. Governor will take the podium and discuss education.  I do want to thank the folks here at Booker Elementary School for their hospitality. Today we've had a national tragedy. Two airplanes have crashed into the World Trade Center in an apparent terrorist attack on our country. I have spoken to the Vice President, to the Governor of New York, to the Director of the FBI, and have ordered that the full resources of the federal government go to help the victims and their families, and to conduct a full-scale investigation to hunt down and to find those folks who committed this act. Terrorism against our nation will not stand. And now if you would join me in a moment of silence. May God bless the victims, their families, and America. Thank you very much."

President Bush and members of his staff depart Florida on Air Force One around 9:54 a.m. The plane leaves without a clear destination. President Bush prefers to return to Washington, D.C., but instead it is recommended he travel to Barksdale Air Force Base in Bossier City, Louisiana, as an appropriate and secure location for landing.

Mayor Rudolph (Rudy) Guiliani rushes to the NYPD command post near the World Trade Center.

Flight attendant Renée A. May calls her mother, Nancy May, and tells her that hijackers have seized control of the plane, forcing passengers and crew members to the rear. When they are disconnected, Nancy May calls American Airlines.

Minutes later, Flight 77 passenger Barbara K. Olson calls her husband, U.S. Solicitor General Theodore Olson, who is at his desk at the Department of Justice. She tells him hijackers have taken over the flight using knives and box cutters. Theodore Olson then alerts other federal officials.

A report by a U.S. Secret Service Agent of the possibility of additional hijacked planes prompts OEM to evacuate its headquarters at 7 World Trade Center.

U.S. Secret Service agents evacuate Vice President Dick Cheney to the Presidential Emergency Operations Center beneath the White House

Five hijackers crash American Airlines Flight 77 into the Pentagon. The 53 passengers, including Tyler native Dr. Bryan C. Jack, and six crew members on board perish. The crash and ensuing fire kill 125 military and civilian personnel on the ground.

The FAA orders all civilian planes in U.S. airspace to land and prohibits departures.

Evacuations begin at the White House and U.S. capitol, where the Congress is in session.

Throughout the morning, officials across the country are in the process of closing buildings, bridges and other public places.

Thirty-seven telephone calls are known to have been made from hijacked Flight 93, most placed from the rear of the plane. One of the last calls is made by passenger Edward P. Felt, who uses his cell phone to dial 9-1-1 after closing himself in a restroom to avoid detection. By 9:58 a.m., Flight 93 is flying so low that he succeeds in reaching an emergency operator in nearby Westmoreland County, Pennsylvania.

Alice Hoagland, mother of Flight 93 victim Mark Bingham, leaves a voicemail message for her son advising him to try to help overpower the hijackers:

“Mark, this is your mom. It’s 10:54 a.m. [actually 9:54 a.m.]. The news is that it’s been hijacked by terrorists. They are planning to probably use the plane as a target to hit some site on the ground, so if you possibly can, try to overpower these guys if you can. ’Cause they’ll probably use the plane as a target. So, I would say go ahead and do everything you can to overpower them ’cause they’re hell-bent. Try to call me back if you can. You know the number here. Okay, I love you, sweetie. Bye.”

After burning for 56 minutes, the South Tower collapses in 10 seconds. More than 800 civilians and first responders inside the building and in the surrounding area are killed as a result of the attack on the South Tower.

Continuity-of-government procedures, established to protect high-level government officials during national emergencies, are implemented for the first known time in American history.

Four hijackers crash Flight 93 in a field near the town of Shanksville in Somerset County, Pennsylvania, after passengers and crew storm the cockpit. The 33 passengers and seven crew members on board perish. The crash site is approximately 20 minutes’ flying time from Washington, D.C.

A damaged section of the Pentagon's west-facing outer ring collapses around this time.

The North Tower of the World Trade Center collapses after burning for 102 minutes. More than 1,600 people were killed as a result of the attack on the North Tower.

Near the World Trade Center when the South Tower collapses, Mayor Rudolph (Rudy) Giuliani and senior members of his administration find temporary shelter inside an office building close by. As the dust begins to settle, they walk north, intent on establishing a new base of operations for city government. Reporters catch up with the mayor, who urges the public at 11:02 a.m. to evacuate lower Manhattan. He will continue to address the public in briefings at temporary headquarters at the New York City Police Academy throughout the day.

“I would like to take this opportunity to tell everyone to remain calm and, to the extent that they can, evacuate lower Manhattan.” - New York City Mayor Rudolph Giuliani

The last flight still in the air above the continental United States lands. In two and a half hours, U.S. airspace has been cleared of an estimated 4,500 commercial and general aviation planes.

Plane passengers become stranded as flights are canceled. Others attempting to travel nationally by train, bus, or rental car find most options canceled or sold out within hours of the attacks.

Air Force One, carrying President George W. Bush and members of his staff, travels throughout the day in search of secure locations, landing at Barksdale Air Force Base in Louisiana around 11:45 a.m. and later landing at Offutt Air Force Base in Nebraska at 2:50 p.m. President Bush will return to the Washington, D.C., area that evening, landing at Andrews Air Force Base and taking a helicopter to the White House.

A lower section of the North Tower’s stairwell B survives the building’s collapse, protecting a group of 13 first responders and one civilian who had been attempting to evacuate down the stairs. Within hours of the tower’s collapse, the first responders emerge from the debris and direct rescuers to the civilian.

Within hours of the attacks, some rescue workers and journalists begin referring to the scene of mass destruction at the World Trade Center site as Ground Zero, a term typically used to describe devastation caused by an atomic bomb.

First responders, search and rescue teams, and volunteers continue to converge on Ground Zero throughout the day. Rescuers use special tools to peer into voids and search for remnants of stairwells and elevators that might shelter survivors. The last successful rescue will occur midday on September 12.

Rescuers free Port Authority employee Pasquale Buzzelli from the rubble of the North Tower. Buzzelli had been in the process of evacuating the North Tower when the building began to collapse from above. Situated somewhere between the 22nd and 13th floors, Buzzelli crouches into a fetal position and, hours later, wakes up on a slab in the building debris, 15 feet above the ground.

After burning for hours, 7 World Trade Center collapses. The 47-story tower had been evacuated earlier. There are no casualties.

“The search is under way for those who are behind these evil acts. I’ve directed the full resources of our intelligence and law enforcement communities to find those responsible and to bring them to justice. We will make no distinction between the terrorists who committed these acts and those who harbor them.” - U.S. President George W. Bush

Around this time, rescuers locate PAPD Officer William Jimeno and PAPD Sergeant John McLoughlin, injured but alive in the debris of the World Trade Center. They free Officer Jimeno after three hours of dangerous tunneling work. Sergeant McLoughlin’s rescue will take another eight hours.

NYPD Emergency Service Unit Detective Anthony Conti recalls search and rescue operations, including the rescue of PAPD Sergeant McLoughlin and PAPD Officer Jimeno, at Ground Zero on the evening of 9/11:

“The morning started great. I was actually having breakfast with a friend of mine—puts the TV on, and all this chaos is going on. And I turn around, and I say, ‘You’ve got to be kidding me.’ I called Operations, and I says, ‘I’m responding.’ So, we decided to take off, and we landed right in Battery Park City over there, and we actually wind up joining up with a search and rescue team on the ground there, off of West Street. Totally surreal. You could just feel the heat, just coming from the site..."

Workers will extricate the 18th survivor, Genelle Guzman, on the afternoon of September 12. She will be the last person rescued. Her savior, a dog, was profiled in the Animal Planet documentary, "Hero Dogs of 9/11."

President George W. Bush visited Ground Zero in New York City on September 14, 2001. Standing upon the debris of the World Trade Center, the president pledged that the voices calling for justice from across the country would be heard. As firefighter Bob Beckwith stood next to him listening, the President used this bullhorn to tell a group of first responders working in the debris, “I can hear you. The rest of the world hears you. And the people who knocked these buildings down will hear all of us soon.” 

Rescue workers cheered and chanted "USA! USA! USA!" in response to the President's words.

The bullhorn used by the President is one of many iconic artifacts found among the holdings at the George W. Bush Presidential Library and Museum on the campus of Southern Methodist University (SMU) in Dallas.

The James L. Zadroga 9/11 Health and Compensation Act, signed into law by President Barack Obama in early 2011, established the World Trade Center (WTC) Health Program. It ensures those exposed to the September 11, 2001, disaster continue to receive monitoring and treatment services for 9/11-related health problems through at least 2090. 

The WTC Health Program consists of a Responder Program (for rescue and recovery workers, including more than 15,000 New York City firefighters( and a Survivor Program (for those who lived, worked or went to school in lower Manhattan on 9/11). Services are also available for responders to the Pentagon and Shanksville, Pennsylvania, sites also attacked on 9/11. Eligible people can receive services, no matter where they now live in the U.S. 

In addition, the 9/11 Health and Compensation Act  reopened the September 11th Victim Compensation Fund. The fund allows those affected to file claims for economic losses due to physical harm or death caused by 9/11.

To all of those who serve or have served this country in the military or as first responders, we thank you. 

Let Sept. 11, 2001, continue to serve as a reminder to us that no matter how much evil there is in the world, there is still so much more good.

EDITOR'S NOTE: The 9/11 Memorial & Museum and the George W. Bush Presidential Library contributed to this report.