The September 11 attacks of 2001 were a unique act of terrorism, constituting a media event on a scale not seen since the advent of civilian global satellite links. Instant worldwide reaction and debate were made possible by round-the-clock television news organizations and by the Internet. As a result, most of the events were known by a large portion of the world's population as they occurred.

The attacks themselves lasted less than two hours; the first hijacking commenced at approximately 8:14 am, and the final hijacked plane crashed at 10:03 am. All times given are in Eastern Daylight Time, (UTC−04:00).

Major events of 9/11/2001

7:59 a.m.: American Airlines Flight 11, a Boeing 767 with registration number N334AA, carrying 76 passengers (excluding the hijackers) and 11 crew members, departs 14 minutes late from Logan International Airport in Boston, bound for Los Angeles International Airport. Five hijackers are on board. Hijacker and ringleader Mohamed Atta would pilot the plane into the North Tower of the World Trade Center.

8:14: United Airlines Flight 175, a Boeing 767, with registration number N612UA carrying 56 passengers (excluding the hijackers) and 9 crew members, departs 14 minutes late from Logan International Airport in Boston, bound for Los Angeles International Airport. Five hijackers are on board. Lead hijacker-pilot Marwan al-Shehhi would pilot the plane into the South Tower of the World Trade Center.

8:14: Flight 11 is hijacked over Central Massachusetts, turning first northwest, then south heading straight to New York.

8:20: American Airlines Flight 77, a Boeing 757 with registration number N644AA with 58 passengers (excluding the hijackers) and 6 crew members, departs 10 minutes late from Washington Dulles International Airport, for Los Angeles International Airport. Five hijackers are on board. Lead hijacker-pilot Hani Hanjour would pilot the plane into the West side of the Pentagon.

8:42–8:46 (approx.): Flight 175 is hijacked above northwest New Jersey, about northwest of New York City, continuing southwest briefly before turning back to the northeast. At this time estimate, Flight 11 is about to descend over New York and is just minutes away from crashing.

8:42: United Airlines Flight 93, a Boeing 757 with registration number N591UA with 37 passengers (excluding the hijackers) and 7 crew members, departs 42 minutes late from Newark International Airport (later Newark Liberty International Airport), bound for San Francisco International Airport. Four hijackers are on board. The lead hijacker-pilot is Ziad Jarrah. At this time, Flight 175 is being hijacked and Flight 11 is about to descend to New York and is 4 minutes away from crashing.

8:46:40: Flight 11 crashes into the north face of the North Tower (1 WTC) of the World Trade Center, between floors 93 and 99. All passengers aboard are instantly killed along with an unknown number inside the building. The aircraft enters the tower on impact.September 11 Attack Timeline , 9/11 Memorial and Museum. Retrieved July 31, 2021.

8:51–8:54 (approx.): Flight 77 is hijacked above southern Ohio, turning to the southeast. The transponder is turned off by hijacker-pilot Hani Hanjour.

9:03:11: Flight 175 crashes into the south face of the South Tower (2 WTC) of the World Trade Center, between floors 77 and 85. All passengers and crew are killed together with an unknown number inside the building. Parts of the plane, including the starboard engine, leave the building from its east and north sides, falling to the ground six blocks away.

9:28: Flight 93 is hijacked above northern Ohio, turning to the southeast.

9:37:46: Flight 77 crashes into the western side of the Pentagon. All 58 passengers and crew were killed aboard the aircraft, as well as an additional 125 (including emergency workers) on the ground. The crash starts a violent fire.

9:45: United States airspace is shut down by the Federal Aviation Administration; all operating aircraft are ordered to land at the nearest airport, and international flights are not permitted into the airspace.

9:57: The passengers aboard Flight 93 begin a revolt, planned by Todd Beamer, Mark Bingham, Tom Burnett, Jeremy Glick, and others, moving against the hijackers in an attempt to take back the plane.

9:58:59: The South Tower of the World Trade Center collapses, 56 minutes after the impact of Flight 175. Impact speed of the plane is considered one of the likely factors of the shorter amount of time between impact and collapse than that of the North Tower.

10:03:11: Flight 93 is crashed by its hijackers as a result of fighting in the cockpit southeast of Pittsburgh in Somerset County, Pennsylvania. Later reports indicate that passengers had learned about the World Trade Center and Pentagon crashes and were resisting the hijackers. The 9/11 Commission believed that Flight 93's target was either the United States Capitol building or the White House in Washington, D.C. but Khalid Sheikh Mohammed claims that the United States Capitol was the main target.

10:15: All five stories of the Pentagon on the west side, where American 77 crashed, collapse due to the fire started by the crash.

10:28:25: The North Tower of the World Trade Center collapses 1 hour and 42 minutes after the impact of Flight 11. The Marriott Hotel, located at the base of the two towers, is also destroyed.

5:20:33 p.m.: The 47 story 7 World Trade Center collapses after debris from the collapse of WTC 1 hitting it earlier in the day cause fires that eventually weaken the core columns.

Detailed timeline of events

5:00 a.m. 5:01: Ziad Jarrah in Newark calls Marwan al-Shehhi in Boston; this call was most likely to confirm the hijackers were ready to carry out the attack.

5:33: Mohamed Atta and Abdulaziz al-Omari check out of their room at a Comfort Inn in South Portland, Maine, and leave the hotel to drive Atta's rental car to nearby Portland International Jetport.

5:40: Atta and al-Omari arrive at Portland International Jetport.

5:43: Atta and al-Omari check in at the US Airways counter at Portland International Jetport, receiving their boarding passes for US Airways Express Flight 5930, operated by Colgan Air to Boston Logan International Airport in Massachusetts. Atta asks for their boarding passes for their connecting flight, American Airlines Flight 11 from Boston to Los Angeles International Airport, as well. Ticket agent Mike Tuohey informs Atta that the pair will need to check in again upon arrival in Boston to receive their second boarding passes. Tuohey would later recall that Atta appeared angry when told of this, leading him to briefly worry that the pair could be terrorists before they moved on.

5:45: Atta and al-Omari pass through security at Portland International Jetport, consisting of a walk-through metal detector and an X-ray screener for bags. Atta is randomly selected by the Computer-Assisted Passenger Prescreening System (CAPPS), requiring his checked bags to undergo extra screening for explosives, but does not receive any additional scrutiny himself.

6:00 a.m. 6:00: Colgan Air Flight 5930 departs from Portland with Atta and al-Omari on board.

6:00: Polls open for primaries for the New York City mayoral elections, as well as other local offices.

6:15: Hamza al-Ghamdi and Ahmed al-Ghamdi arrive at Boston Logan International Airport by taxi, having stayed the night at a Days Inn in Brighton, Massachusetts."Flights Hijacked on September 11, 2001", United States of America v. Zacarias Moussaoui, March 31, 2006, pages 73-111.

6:20: The al-Ghamdi brothers check in at the United Airlines ticket counter for United Airlines Flight 175. Ahmed al-Ghamdi checks in two bags. Both men are confused by the standard security questions they were asked, but they received their boarding passes without incident.

6:22: Nawaf al-Hazmi and several men who have not been conclusively identified check out of the Residence Inn by Marriott in Herndon, Virginia.

6:31: President George W. Bush goes for an early-morning jog around the (now demolished) Colony Beach and Tennis Resort in Longboat Key, Florida, where he and his staff had spent the night.

6:31: Ahmed al-Ghamdi's two checked bags are loaded onto Flight 175.

6:45: Colgan Air Flight 5930 arrives at Logan International Airport, and Atta and al-Omari deplane. Separately, Satam al-Suqami, Waleed al-Shehri, and Wail al-Shehri arrive at Logan in their own rental car at the same time.

6:45: Al-Shehhi arrives at Logan International Airport and checks in for Flight 175. He checks in one bag.

6:48: Jarrah checks out of the Days Inn in Newark, New Jersey.

6:51: Al-Shehhi's checked bag is loaded onto Flight 175.

6:52: Al-Shehhi calls Atta's cell phone from a payphone in Logan's Terminal C to confirm that the plans for the attacks are set.

6:53: Fayez Banihammad and Mohand al-Shehri arrive at Logan International Airport and check in for Flight 175. Banihammad checks in two bags.

6:57: Banihammad's two checked bags are loaded onto Flight 175.

7:00 a.m. 7:03–7:39: Jarrah and his hijacking team arrive at Newark International Airport (now Newark Liberty International Airport) and check in for United Airlines Flight 93.

7:15 (approx.): Khalid al-Mihdhar and Majed Moqed arrive at Washington Dulles International Airport and check-in for American Airlines Flight 77.

7:18: Al-Mihdhar and Moqed arrive at the security checkpoint at Washington Dulles International Airport. Both set off alarms and are consequently given a more thorough search.

7:23–7:28: Al-Shehhi and his hijacking team board Flight 175.

7:29 (approx.): Nawaf al-Hazmi and Salem al-Hazmi arrive at Washington Dulles International Airport and check-in for Flight 77.

7:31–7:40 (approx.): Atta and his hijacking team board Flight 11.

7:35: Hani Hanjour arrives at the security checkpoint at Washington Dulles International Airport. He passes through the checkpoint without suspicion or setting off any alarms.

7:36: The al-Hazmi brothers arrive at the security checkpoint at Washington Dulles International Airport. Salem does not set off any alarms. Nawaf does and is given a more thorough search. Security camera footage shows that Nawaf has an unidentified item in his back pocket.

7:39–7:48: Jarrah and his hijacking team board Flight 93.

7:46: Flight 11 is pushed back from Gate B32 at Logan International Airport.

7:50–7:55 (approx): Hanjour and his four fellow hijackers board Flight 77.

7:58: Flight 175 is pushed back from Gate C19 at Logan International Airport.

7:59: Flight 11, a Boeing 767 carrying 81 passengers and 11 crew members, departs 14 minutes late from Logan International Airport in Boston. Its destination is Los Angeles International Airport (LAX) in Los Angeles, California.

8:00 a.m.

8:00: Flight 93 is pushed back from Gate A17 at Newark International Airport.

8:03: President Bush has his daily intelligence briefing. The material is routine, mostly concerning the Al-Aqsa Intifada and other Israeli-Palestinian issues. He calls Condoleezza Rice about one item, but there is no mention in the report of Osama bin Laden or al-Qaeda, nor are there any final warnings about the terrorist plot now actively in motion. The briefing lasts about twenty minutes, after which he says goodbye to the resort staff and departs in his motorcade. As the President's scheduled event is considered a garden variety trip to promote his education agenda, accompanied by low-level aides and reporters, Chief of Staff Andrew Card remarks to him "It should be an easy day."

8:05: Delta Air Lines Flight 1989 departs Boston for Los Angeles.

8:09: Flight 77 is pushed back from Gate D26 at Dulles International Airport.