On Sept. 11, 2001, at 7:58 a.m. EDT, United Airlines Flight 175 departed from Boston headed for Los Angeles.
At 7:59 a.m., American Airlines Flight 11 departed from Boston headed to Los Angeles.
At 8:10 a.m., American Airlines Flight 77 departed from Dulles International Airport near Washington, D.C. headed for Los Angeles.
At 8:19 a.m., a flight attendant on Flight 11 made the first report of trouble in the skies that day, calling the airline’s North Carolina office to report an emergency. Soon after, air traffic controllers declared the flight to be hijacked.
At 8:24 a.m., a hijacker on Flight 11 inadvertently broadcasted a message intended only for the plane's passengers. It was heard by the pilot of Flight 175, who reported it to air traffic control, not knowing his plane would soon be hijacked, too. "We have some planes. Just stay quiet, and you will be OK," terrorist Mohammed Atta had said.
At 8:42 a.m., United Airlines Flight 93 departed from Newark, New Jersey, headed to San Francisco.
At 8:46 a.m., Flight 11 crashed into the North Tower of the World Trade Center.
At 8:50 a.m. then-President George W. Bush was at an elementary school preparing to read to students. His staff informed him that a plane had hit one of the World Trade Center towers. At the time, they believed it to be an accident.
At 8:52 a.m., a flight attendant on Flight 175 called American Airline’s office and reported the plane had been hijacked. Both pilots were dead, another flight attendant was injured and the hijackers were flying the plane.
At 8:56 a.m., American Airlines lost contact with Flight 77, becoming the second plane confirmed to be in trouble that morning.
At 9:02 a.m., an evacuation order was broadcast inside the South Tower of the World Trade Center.
At 9:03 a.m., Flight 175 crashed into the South Tower of the World Trade Center.
At 9:05 a.m., Bush sat in front of a group of students reading to them. Chief of Staff Andrew Card calmly walked to him, bent over and whispered, "A second plane hit the second tower. America is under attack."
At 9:28 a.m., air traffic control in Cleveland received a transmission from one of the pilots of Flight 93: “Mayday.”
At 9:34 a.m., air traffic control at Ronald Reagan Washington National Airport notified the Secret Service that an unknown aircraft was headed toward the White House. The plane would soon turn toward the Pentagon.
At 9:37 a.m., Flight 77 crashed into the Pentagon.
At 9:58 a.m., the South Tower collapsed, taking only 10 seconds to do so.
At 9:58 a.m., a customer service supervisor was talking to passenger Todd Beamer, who had used an air phone to try to call his wife. The supervisor said Beamer reported that hijackers had killed one passenger and taken over the cockpit. His last words heard on the phone were, “Are you ready? OK. Let’s roll.”
At 10:02 a.m., Flight 93 crashed into a field in Shanksville, Pennsylvania.
At 10:28 a.m., the North Tower collapsed.
Nearly 3,000 people were killed that day. In the following days, weeks and months, Americans were largely united behind the well-known, often stated but far too infrequently followed ideal that “there is more that unites us than divides us.”
Twenty years later, we are not living that ideal, America seemingly more divided than ever. Let us never forget how our world changed in those two hours and 29 minutes, and how in some of our darkest moments we became a beacon of unity and of American exceptionalism.