9/11: How the devastation unfolded 20 years ago

10 September 2021, 18:08

On September 11 2001, four commercial flights flying from the north eastern US to California were hijacked mid-flight.

The nineteen hijackers, spread across the four flights, were with terrorist group al Qaida.

Their goal was to crash the four flights into prominent US buildings, damaging or destroying them and causing mass casualties.

9/11 terror attacks: 20 years on

Three buildings were destroyed and one badly damaged. The exact death toll is not known, but the official count was 2,996.

Here’s how the devastation unfolded on that day 20 years ago.

Tuesday September 11, 5:45am

The first of the hijackers begin their passage through airport security. Back in 2001, security was very different to the way it is now. Blades shorter than four inches were allowed on flights, and there was no need to remove your shoes for checks. Some of the hijackers did set off the metal detectors, but they were allowed through.

7:49am

American Airlines Flight 11 takes off from Boston, destined for Los Angeles. It will be the first plane to be hijacked. On board are 11 crew members, 76 passengers and five hijackers.

Less than half an hour later United Airlines Flight 175 takes off, also flying from Boston to Los Angeles. It will become the second flight to be hijacked. There are nine crew members, 51 passengers and another five hijackers on board.

8:19am

Betty Ann Ong, a flight attendant on Flight 11, contacts American Airlines ground personnel and says she thinks the plane is being hijacked. She says one of the hijackers stabbed a passenger and the cockpit is "unreachable".

The passenger, Daniel M. Lewin, was reportedly stabbed because he tried to stop the terrorists. He was likely the first person to be killed in the 9/11 attacks.

Ms Ong’s call lasts around 25 minutes. Two minutes in, hijackers turn off the plane’s transponder, meaning air traffic control can no longer monitor Flight 11’s route.

8:20am

American Airlines Flight 77, the third flight that will be hijacked, takes off from Washington to Los Angeles. There are six crew members, 53 passengers and five hijackers on board.

8:24am

One of the hijackers on Flight 11, Mohamed Atta, accidentally presses the wrong button and sends out some transmissions. One of them is picked up by the pilot of Flight 175 – the second flight – who is unaware that he too has hijackers on board his plane.

8:30am

Morning activities begin at the World Trade Center (WTC). There are a number of events, including a financial technology conference on the 106th floor, with 80 attendees and 72 restaurant staff.

8:37am

Boston air traffic control alerts the military after hearing the hijacker’s accidental transmissions from Flight 11. Jets are mobilised to follow the hijacked aircraft.

8:42am

United Airlines Flight 93 takes off with seven crew members, 33 passengers and four hijackers on board. The plane was scheduled within minutes of the other three, but it was delayed due to routine traffic.

At this point all four aircraft are in the air, but only one is known to have been hijacked.

8:46am

Flight 11 crashes into the North Tower.

It hits floors 93-99. All passengers and crew on board are killed, as well as hundreds inside the building. All three emergency stairwells are destroyed, leaving hundreds trapped above floor 91. Shortly afterwards people begin falling from the building.

Emergency services are dispatched and instructed to park directly next to the tower.

8:50am

President George W. Bush, on a visit to a school in Florida, is alerted. At this point he and his advisers assume the crash is an accident.

8:52am

Robert John Fangman, a flight attendant, contacts a United Airlines operator and reports that the second flight, Flight 175, has been hijacked.

8:55am

The South Tower is declared "secure" by a Port Authority fire safety employee. People are told there is no need to evacuate, and those who were already leaving are told to return.

However, just four minutes later the evacuation of both towers is ordered, and one minute later, the entire WTC complex.

9:00am

By now, several passengers on board Flight 175 have phoned family members. The evacuation order for the South Tower has not yet been broadcast.

9:02am

The evacuation order for the South Tower is broadcast. People are told to "start an orderly evacuation" - but just one minute later, Flight 175 crashes into the South Tower.

The plane hits floors 77-85. All 51 passengers and nine crew members are killed, plus an unknown number inside the building. Two of three emergency stairwells are destroyed and most lift cables are severed, trapping people at the top floors.

As with the North Tower, people begin falling or jumping. The number of people thought to have died this way varies from 50 to more than 200.

The emergency response escalates and the airspace over New York City is closed.

9:05am

President Bush is informed of the second crash. At this point he and his advisers realise the crashes are not accidents.

9:12am

Renée A. May, a flight attendant, calls her mother and tells her that Flight 77, the third flight, has been hijacked. She then calls American Airlines, and minutes later another passenger, Barbara K. Olsen, calls her husband, US Solicitor General Theodore Olson at the Department of Justice. He alerts other officials.

9:28am

Flight 93, the fourth flight, is highjacked. Flight controllers on the ground overhear hijackers taking control of the cockpit.

9:30am

The Mayor’s Office of Emergency Management evacuates its headquarters at 7 WTC - a 47-storey building next to the Twin Towers - after more hijacked planes are warned of.

9:37am

Flight 77 crashes into the Pentagon, the base for the US military. All 52 passengers and six crew are killed, as well as 125 military and civil personnel on the ground. Just over half an hour later part of the outer ring of the building collapses.

9:42am

The Federal Aviation Authority orders all flights in US airspace to land, and all departures are prohibited. However there are around 4,500 planes in the air above the US and it will be another two and a half hours before the last one is grounded.

Minutes later the White House and Capitol are evacuated.

9:58am

One of the last calls is made from Flight 93, the fourth and final hijacked flight. A total of 37 known calls were made from this plane, but one of the last was a 911 call from Edward P. Felt. At that point the plane was flying so low that he managed to reach an emergency operator.

9:59am

The South Tower of the WTC collapses in just 10 seconds, after being on fire for 56 minutes. More than 800 people are killed in and around the building, including civilians and emergency responders.

10:07am

Flight 93 crashes into a field in Pennsylvania, approximately 20 minutes flying time from Washington D.C, after passengers and crew stormed the cockpit.

All 33 passengers and seven crew are killed. It is thought the intended target for Flight 93 was either the White House or the Capitol.

10:28am

The North Tower collapses after burning for 102 minutes. Around 1,500 people are killed.

For the ensuing hours, a massive rescue operation was launched to comb through the debris of the collapsed buildings. Fourteen survivors – 13 responders and one civilian – were found in an intact part of a stairwell in the debris of the North Tower. Later, a Port Authority employee is found alive on a slab of debris 15 feet above the ground.

None of the survivors were from above the impact zone.

5:20pm

7 WTC collapses. It had already been evacuated so there were no further casualties.

Wednesday September 12, midday

The 18th, and last, survivor is found in the rubble of the South Tower.

The 9/11 attacks remain the deadliest terrorist attack in history.

In the 20 years since, a number of memorials have been built to remember those who died and commemorate the heroic actions of passengers and crew on Flight 93.