Mohammed Atta flies Colgan Air (Portland International Jetport, Portland, Maine to Logan International Airport, Boston, Massachusetts), along with Abdulaziz al-Omari.

Atta calls another hijacker to confirm the attacks are on while sitting at Logan International Airport.

American Airlines Flight 11 takes off from Logan International Airport bound for Los Angeles, California. The flight gets away late.

The last radio communication is made from Flight 11. A recording of what is believed to be Atta's voice says, "Nobody move. Everything will be Ok. If you try to make any moves, you'll endanger yourself and the airplane. Just stay quiet." The flight path begins to stray away from the one scheduled and begins to move southward.

United Airlines Flight 175, another fully-fueled plane, carrying 56 passengers and nine crew members, departs from Boston's Logan Airport, also bound for Los Angeles.

The FAA's Boston Center flight controllers decide that Flight 11 has probably been hijacked. American Airlines Flight 77, with 58 passengers and six crew members, departs from Washington's Dulles International Airport for L.A.

Flight 11's transponder signal is turned off but the plane remains on radar screens.

Boston Center control notifies Northeast American Defense Sector (NEADS), the northeast sector of NORAD, of the hijacking of Flight 11. The controller requests military help to intercept the aircraft.

United Airlines Flight 93, takes off with 37 passengers and seven crew members from Newark International Airport, bound for San Francisco International Airport, following a 40 minute delay due to congested runways. Its flight path initially takes it close to the World Trade Center before moving westward.

The FAA's New York Center requests information about Flight 11 over the radio. Flight 175 responds, "Ah, we heard a suspicious transmission on our departure out of Boston, ah, with someone, ah it sounded like someone keyed the mikes and said, ah, everyone stay in your seats." New York Center acknowledges and says it will pass the information on.

Two F-15 fighter jets are scrambled from Otis Air Force Base in Massachusetts, intended to intercept Flight 11. Because Flight 11's transponder is off, Air Force pilots do not know which direction to travel to meet the plane.

Flight 11 crashes at roughly 490 mph into the north side of the north tower of the World Trade Center. It hits between floors 94 and 98. The aircraft enters the tower mostly intact. It plows to the building's core, severing all three gypsum-encased stairwells dragging combustibles with it.

At least 100 people, primarily in the north tower, trapped by fire and smoke, jump to their deaths.

The first news and radio organizations report on an explosion at the World Trade Center.

The F-15's at Otis Air Force Base are airborne. Still lacking an intercept vector for Flight 11, they are not aware the flight has already crashed. The fighter jets are sent to military controlled airspace off Long Island and ordered to remain in a holding pattern.

Announcements are made by officials in the still undamaged south tower of the World Trade Center that the building is 'secure', and that people may return to their offices, over the building wide public address system.

Flight 175 crashes at about 590 mph into the south side of the south tower, making impact between floors 78 and 84. By this time, several media organizations are covering the first plane crash; millions see the impact live. Parts of the plane leave the building at its east and north sides, falling to the ground six blocks away.

President Bush enters a classroom of Emma E. Booker Elementary School in Sarasota, Florida, as part of a scheduled visit to promote education. The President is aware that an aircraft has struck one of the World Trade Center towers. He and the staff with him assume it is a small general aviation aircraft. He elects to continue his schedule.

The FAA bans takeoffs of all flights bound to or through the New York Center airspace from airports in that Center as well as three adjacent Centers -- Boston, Cleveland, and Washington. This is referred to as a First Tier groundstop and covers the Northeast quadrant from North Carolina north and as far west as eastern Michigan.

After brief introductions, President Bush is about to begin reading with the students when Chief of Staff Andrew Card interrupts to inform him, "A second plane hit the other tower, and America is under attack."

The FAA bans all takeoffs nationwide for flights going to or through New York Center airspace.

The F-15 fighter jets from Otis Air Force base leave military air space near Long Island, bound for Manhattan.

President Bush leaves the classroom he has been since 9:03, and is whisked to another, comandeered by the Secret Service. It contains a telephone, television showing the news coverage, and several senior staff members. The President accumulates information and prepares brief remarks.

The Otis Air Force base F-15's establish an air patrol over Manhattan.

The FAA bans takeoffs of all civilian aircraft regardless of destination -- a national groundstop. It is the first such grounding in American history. All military bases in the United States are ordered to increase its threat conditions to Delta status.

Hijackers storm the cockpit on Flight 93 and take over the flight. The entry of the hijackers is overheard by flight controllers in Cleveland.

President Bush makes his first public statements about the attacks in front of an audience of 200 teachers and students at the elementary school. He states that he will be going back to Washington, that "we've had a national tragedy", and leads in a moment of silence. After the speech, he leaves the school for Sarasota-Bradenton International Airport to board Air Force One.

Flight 93 reverses direction and starts flying eastward.

Flight 77 crashes into the western side of the Pentagon and starts a violent fire. The section of the Pentagon hit consists mainly of renovated unoccupied offices. All 64 persons onboard are killed, as are 125 Pentagon personnel.

United States airspace is shut down. No civilian aircraft are allowed to take off, and all aircraft are ordered to land at the nearest airport as soon as practical. All international flights headed for the United States are diverted to Canada. The FAA announces that all civilian flights are suspended until at least noon on September 12th. The groundings last until September 14th.

The White House and Capitol are evacuated and closed.

President Bush leaves Sarasota, Florida on Air Force One. The plane reaches cruising altitude and circles for approximately 40 minutes while the destination of the plane is discussed.

The south tower of the World Trade Center collapses, 55 minutes 51 seconds after the impact of Flight 175. Its destruction is viewed and heard by a vast television and radio audience. As the roar of the collapse goes silent, tremendous gray-white clouds of pulverized concrete and gypsum rush through the streets.

United Airlines Flight 93 is crashed by its hijackers southeast of Pittsburgh in Somerset County, Pennsylvania. Reports indicate that passengers had learned about the World Trade Center and Pentagon crashes on cell phones and at least three were planning on resisting the hijackers. This was confirmed by a flight recorder.

Part of the Pentagon collapses.

The north tower of the World Trade Center collapses from the top down, as if being peeled apart. Probably due to the destruction of the gypsum-encased stairwells on the impact floors, no one above the impact zone in the north tower survives. The Marriott Hotel, located at the base of the two towers, is also destroyed.

Air Force One, carrying the President, turns for Barksdale Air Force Base in Shreveport, Louisiana.

Another hijacked jumbo jet is claimed to be headed for Washington, D.C. F-15s are scrambled and patrol the airspace above Washington, D.C. while other fighter jets sweep the airspace above New York City. They have orders, first issued by Vice President Cheney and later confirmed by President Bush, to shoot down any potentially dangerous planes that do not comply with orders given to them via radio.

New York mayor Rudy Giuliani orders an evacuation of lower Manhattan.

Five stories of part of the Pentagon collapse due to the fire.

American Airlines confirms the loss of its two aircraft.

United Airlines confirms the loss of Flight 93 and states that it is "deeply concerned" about Flight 175.

United Airlines confirms the loss of its two aircraft.

President Bush arrives at Barksdale Air Force Base in Shreveport, Louisiana. The President makes a brief and informal initial statement to the effect that terrorism on U.S. soil will not be tolerated, said that "freedom itself was attacked this morning by a faceless coward and freedom will be defended." He also said that the "United States will hunt down and punish those responsible for these cowardly acts."

Los Angeles International Airport (LAX), the intended destination of Flights 11, 77 and 175, is shut down.