ACROSS the United States on the morning of 11 September 2001, to be known forever after as 9/11, thousands of planes took off between 7.59 and 8.42am.

Four of those flights, bound for the West Coast, were hijacked: American Airlines Flight 11 from Boston to Los Angeles, United Airlines Flight 175, also going from Boston to Los Angeles, American Airlines Flight 77 from Washington DC to Los Angeles, and United Airlines Flight 93 from Newark to San Francisco.

The hijackers had no guns or bombs, but they had knives, a kind the world would soon come to know as box cutters, and mace.

The airport security system flagged that some of the hijackers were suspicious and that their checked bags should be held until it was confirmed the passengers had boarded the plane.

But in the end these malevolent passengers and their luggage all got through airport security, just as they had got through the intelligence and surveillance apparatus of the FBI and the CIA in the months and years leading up to this moment.

American Airlines Flight 11, a Boeing 767, took off from Logan International Airport in Boston at 7.59am. It was what pilots call ‘a clear-and-a-million day’, a gorgeous autumn day offering unlimited visibility.

On board were the five hijackers as well as nine flight attendants, two pilots and seventy-nine passengers.

These were real people with meetings to get to, lunches to have and families and friends to love, but skyscrapers and jet planes, saturation coverage and the war on terror subsume the individual humans inside.

They blur the magnitude of the loss of these strangers to us. But perhaps to the people who loved them, they intensify it.

One of those on board was Betty Ong. She was a flight attendant on Flight 11, working that day in coach class. We know what happened on that doomed flight because of her reports and those of another flight attendant, Amy Sweeney.

Betty called the American Airlines reservations office in North Carolina, in contravention of her training, which said that all communications must come from the cockpit only.

But the pilots in the cockpit were not answering and she, and the passengers she was responsible for, were in the midst of the worst thing that could happen, worse than she could have imagined.

“I don’t know, I think we’re getting hijacked,” she says to the airline staff on the ground. Betty Ong was on the phone for twenty-three minutes.

There’s a recording of her making this call, and the age we’re in means that you don’t have to travel to the US and seek permission to sit in a special booth to listen to it. I listened to her voice on my computer via the Washington Post website, sitting in my own house.

Betty had done her job for more than a decade, and it shows; her voice is calm as she conveys information about a stabbing and explains they are unable to reach the cockpit.

Over and over she recites that she’s number three on the flight and that number one, the pilot, has been stabbed.

The line is bad and she has to repeat who she is, answer that she’s sitting in the jump seat, no, she’s not a passenger, she’s a senior attendant, that it’s Flight 11, not 12, that they’re going to Los Angeles, that mace has been sprayed and they can’t breathe, that attendants have been stabbed.

Listening to her relay these basic facts is excruciating. It would be anyway, but we know what’s going to happen next.

First Officer Thomas McGuinness, 42, a former navy pilot, would have been number two on the flight, after Captain John Ogonowski.

I mention the copilot because we have the same name, a meaningless coincidence but who knows, maybe our ancestors were from the same part of Northern Ireland.

Thomas McGuinness had a wife called Cheryl, who shared his deep Christian faith; after that day she would write a book about grief, her husband and Jesus.

Thomas McGuinness’s Portsmouth, New Hampshire neighbour told USA Today that Tom was a “faith-based man”.

Cheryl and Tom had two teenagers, one of whom went on to become a pilot himself. First Officer McGuinness must have seen Mohamed Atta and the other hijackers, the terrorists, who got into the cockpit. Maybe he was stabbed like the flight attendants and at least one of the passengers, or maced, or God knows.

Atta was the only one of the five death-obsessed jihadists on board who could fly a plane. He crashed it, the only jet he had ever flown, into the North Tower of the World Trade Center at 8.46am.

“The plane struck the tower” is not a phrase you want anyone learning English to have to know, to say, to think. Subject, verb, object. But it happened that day. Twice. The Twin Towers of the World Trade Center each had 110 floors.

American Airlines Flight 11 flew into the North Tower (1 WTC) between the 93rd and 99th floors at 495 miles per hour.

Loaded with 9000 gallons of jet fuel, it was transformed into a weapon. A fireball exploded and burst down elevator shafts onto the 77th and 22nd floors, right down to the lobby and basement levels, where you could smell fuel.

The extraordinarily riveting 9/11 Commission Report from which these facts come, improbably a best-selling government document, produced by a committee and short-listed for literary prizes, says that the building’s three stairwells were impassable from the 92nd floor up. Hundreds of people died on impact. Hundreds more were trapped.

There is footage of this, the first plane crashing into the North Tower, but most of the world tuned in when it was already on fire. We could not have imagined that there would be another plane.

United Airlines Flight 175 was that other plane. It took off from Boston fifteen minutes after the American Airlines flight. It had seven flight attendants, two pilots and fifty-six passengers, including a family, Charles Falkenberg and Leslie Whittington and their two young daughters.

They were on their way to Canberra, where Leslie, an economist, was to be a visiting professor at the Australian National University.

The plane hit the South Tower (2 WTC) at 9.03am. In that moment eyewitnesses on the ground, those in nearby buildings or billions, like me, watching on television, knew this was no accident.

Numb with disbelief, incredulous, all of us who saw that second plane knew that it was on a terrible mission. All of a sudden it seemed anything could happen. What next?

By now the whole world was watching on TV. I was on the phone to Adam in Manila. “Are you watching this?” I asked. “Are you watching this?” he answered. “Turn on the television, now” was what people said to each other. Watch this. Easier to issue that instruction than to explain images that were unfathomable. Our eyes couldn’t believe what we were seeing. But we knew we were watching history.

The hijackers had been heard to say “we have some planes”. Nobody knew how many. Nothing like this had ever happened in the United States.

No US commercial airliner had been hijacked since 1986, when four men tried to take control of a Pan Am plane before it left the ground in Karachi, Pakistan.

Within the hour we would know there were two more planes. All except one of the four murderous pilots turned off their transponders so the airlines, air traffic controllers and security forces had no primary radar contact and communications were lost, except for random transmissions they picked up because the impostor pilots didn’t know how to operate the on-board PA systems.

The third plane, American Airlines Flight 77, would crash at full throttle into the Pentagon at 9.38am. The years that have passed between that happening and me typing this sentence make it no less shocking.

The Pentagon! The heart of American military might, the pivot from which a global superpower, an empire, exerts its force.

We might have assumed only a mighty national military force would attack the capital, Washington DC. The Cold War was over — who might that attacker have been?

Strategy may be about executing the unexpected and, on the other hand, expecting it yourself, but who could have anticipated this kind of surprise attack: a commercial airliner being used as a weapon, with six crew and fifty-eight passengers aboard, aimed at the Pentagon?

The Pentagon is a modern fortress, structured in five rings. This plane penetrated four of them. There’s no footage of it happening, and it’s probably correct to say that the Pentagon is the element of the 9/11 attacks most often forgotten.

So let’s not forget that everyone on board, and 125 of the 20,000 military and civilian staff who worked within the Pentagon were killed. Many survivors suffered horrific burns. Most of those who died were civilians.

The fourth plane, United Airlines Flight 93, crashed into a field in Shanksville, Pennsylvania, after its passengers realised they too were players in a diabolical plan.

There were forty of them on board, fewer on that flight than usual, a simple coincidence. Unlike the other flights this one had four rather than five hijackers — the intended fifth had been refused entry to the US in August by a suspicious immigration officer in Orlando, Florida.

The flight from Newark was running twenty-five minutes late. Rather than storming the cockpit from first class, where they were seated, within half an hour of take-off as the other hijackers did that day, the hijackers waited forty-six minutes.

Alarmed passengers and crew began contacting family, friends and colleagues on the ground. The hijackers didn’t stop these calls, which meant that those on board got the vital information that two other aircraft had crashed into the World Trade Center.

From the air they kept the phone lines open so people on the ground could hear what was happening. Defiant, the passengers voted to fight back against the hijackers.

In the face of near-certain death, imagine having the wherewithal to organise a vote, let alone one where your choice is to go passively, to make peace with the world and die telling someone on the end of the line that you love them, or engage in violent assault yourself, fighting, charging, battering with whatever you can.

Huddled at the back of the plane the passengers voted in favour of counter-attack. Desperate, their weapons were forks, fire extinguishers, trolleys, boiling water. “Let’s roll,” one of them cried.

Their heroism and sacrifice, in the midst of chaos and panic, stopped that plane from being flown into the Capitol or the White House in Washington DC.

This was an edited extract from The Year Everything Changed by Phillipa McGuinness. (Vintage, $34.99).